Rare-earth ion-doped garnets with excellent luminescent properties show great potential for temperature sensing,displays,and nondestructive detection.However,their limited luminescent modes and low photoluminescence q...Rare-earth ion-doped garnets with excellent luminescent properties show great potential for temperature sensing,displays,and nondestructive detection.However,their limited luminescent modes and low photoluminescence quantum yields(PLQY)restrict further applications.In this study,we synthesized Al^(3+),Er^(3+)-co-doped Gd_(3)Ga_(5)O_(12) garnets with multimode luminescence via a high-temperature solid-state method.Notably,the preferential substitution of Al^(3+)ion at octahedral-coordinated GaI sites significantly enhanced the charge density and electron transition probability,achieving a PLQY enhancement of the downshifting luminescence from 35.1%to 68.5%.Al^(3+)ion also influences electron relaxation during up-conversion luminescence,resulting in a color shift from red to yellow to green.Additionally,Al^(3+)incorporation increased the photoelectric conversion efficiency of light-emitting diodes from 2.9%to 6.3%and improved temperature sensing sensitivity from 2.7%to 5.1%K⁻1.This work provides new insights into the photophysical mechanisms and underscores the key role of Al^(3+)ion in optimizing the optical properties of garnet-based materials.展开更多
A novel series of Ce^3＋-doped Yb3 Al（5-x）GaxO（12）（x = 0, 1,2, 3,4, 5） powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The...A novel series of Ce^3＋-doped Yb3 Al（5-x）GaxO（12）（x = 0, 1,2, 3,4, 5） powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al^3＋ sites with Ga^3＋ in 0.5 at%Ce：Yb3 Al（5-x）GaxO（12）（x = 0,1, 2, 3, 4, 5） garnets were discussed. With the increase of Ga^3＋ ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb^3＋ ＋ Ce^3＋→ Yb^2＋ ＋ Ce^4＋ electron transfer reaction.展开更多
A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates th...A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates the formation of single cubic phase. Vibrating sample magnetometry (VSM) and a superconducting quantum-interference device (SQUID) were used to measure the magnetic properties, especially the magnetization and thermo-magnetic behavior. The magnetization curves exhibit the typical characteristics of ferrimagnetic materials at both 4.2 K and at room temperature. The samples have a low coercivities (between 20 and 40 Oe) and saturation magnetizations as high as 36 emu/g at 4.2 K. The saturation magnetization decreases with V and Ca contents, reaching about 8 emu/g at 4.2 K (x = 1). For all samples, the saturation magnetization decreases with increasing temperature, whereas the Curie temperature increases for small values of x, from 557 K for x = 0 to a maximum of 590 K for x = 0.2. For larger values of x, it decreases and reaches 525 K for x = 1.0. The basic experimental trends reflect the occupancy of the tetrahedral 24d sites by vanadium in combination with the predominant intersublattice exchange constant Jad, although the nonzero magnetization at x = 1.0 indicates that about 10% of the substituted V atoms goes onto the octahedral 16a sites.展开更多
Crustal anatexis in continental subduction zones has great bearing on chemical differentiation of the continental crust at convergent plate boundaries.This was experimentally investigated for ultrahigh-pressure(UHP)me...Crustal anatexis in continental subduction zones has great bearing on chemical differentiation of the continental crust at convergent plate boundaries.This was experimentally investigated for ultrahigh-pressure(UHP)metafelsic rocks at 0.5-3.0 GPa and 650-900℃.The results show that partial melting begins at about 750℃ when pressure drops from 3.0 to 2.0 GPa,corresponding to decompressional exhumation of the deeply subducted continental crust.As the pressure further decreases to 1.0 GPa,the partial melting degree reaches the maximum of~25%at 900℃.Partial melts produced in these experiments are rich in silica and alkali,and poor in iron,manganese and magnesium.As the degree of partial melting increases,the composition of partial melts gradually converges toward homogeneous one.In the absence of free water,the partial melting of metafelsic rocks were triggered by the breakdown of hydrous minerals.At low temperatures of~750℃at 1.0-2.0 GPa,phengite dehydration melting occurs at first,giving rise to small amounts of felsic melts and peritectic K-feldspar.As the temperature rises up to 850-900℃,biotite begins to break down and gives rise to large amounts of felsic melts and peritectic minerals such as garnet,K-feldspar and orthopyroxene.It is noted that peritectic garnet is much different from anatectic garnet crystallized from anatectic melts and metamorphic garnet formed through metamorphic dehydration reaction under subsolidus conditions.The peritectic garnet is characterized not only by anhedral shapes with many multiphase crystal inclusions but also by compositions poor in spessartine and grossular but rich in almandine and pyrope.On the other hand,the anatectic garnets are characterized not only by euhedral shapes with few inclusions but also by compositions rich in grossular and spessartine but poor in almandine and pyrope.These observations provide experimental constraints on the origin of garnets in UHP metamorphic rocks,which have great bearing on understanding of anatectic metamorphism in collisional orogens.展开更多
In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclu...In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observa-tions and studies confirmed that these lamellae are phlogopite. They are colourless and acicularin section, generally 0.5-5μm in width and 10-100μm in length. Nevertheless, fine lamellae,0.05-0.1μm wide and 1-2μm long, are also well developed. Along [111] of the garnet, three setsof phlogopite lamellae show oriented arrangement approximately at angles of 60°-70°, indi-cating that these lamellae might be the product of exsolution from garnet as a result ofpressure-release when eclogite ascended from the relatively deep level to the relatively shallowlevel of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found ingarnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been re-ported that the identified exsolution minerals include pyroxene and rutile. This is the first timethat phlogopite exsolution lamillae were found in eclogite inclusions in the world.展开更多
Garnet is an important rock forming mineral of high pressure and ultrahigh pressure metamorphic rocks. Its popular isomorphism complicates its chemical composition and crystal structure. The selected area electron ...Garnet is an important rock forming mineral of high pressure and ultrahigh pressure metamorphic rocks. Its popular isomorphism complicates its chemical composition and crystal structure. The selected area electron diffraction (SAED) and the high resolution electron microscopy (HREM) are used in this work to study the microstructures and ultrastructures of garnets in the jadeite quartzite from Dabie Mountains, China. The microstructures of the garnet occur mainly as free dislocations, dislocation walls, stacking faults, dislocation networks and sub grain boundaries. The dislocation density is ρ=n ×10 8/cm 2 ( n =1.7—7.5) and the deformation mechanism is the dislocation glide and dynamic recovery. The superstructures of the garnet crystal revealed by HREM occur mainly as dislocations, faults, domain structures and lattice deformations, indicating the strong stress during the formation of the jadeite quartzite.展开更多
Rare earth iron garnets R3Fe5-xMnxO12（R=Pr, Nd, Sm, Eu） were prepared through mild hydrothermal me- thod. The initial alkalinity of solutions was thought to play an important role in governing the content of Mn. The...Rare earth iron garnets R3Fe5-xMnxO12（R=Pr, Nd, Sm, Eu） were prepared through mild hydrothermal me- thod. The initial alkalinity of solutions was thought to play an important role in governing the content of Mn. The effect of substitution Fe^3＋ ions by Mn^3＋ ions on magnetic properties was investigated. The saturation magnetizations of Mn-doped samples are larger than that of corresponding parent compounds due to the moment of Mn^3＋ ion being smaller than that of Fe^3＋. It is clearly shown that incorporation of Mn^3＋ gives rise to significant variations in the Curie temperature. With increasing of Mn content x, Curie temperatures reduced sharply for the garnets, which could be explained by the exchange interaction between a-d Fe^3＋ being reduced in these compounds.展开更多
Spectra of absorption, luminescence, magnetic circular dichroism （MCD）, and magnetic circular polarization of lumines- cence （MCPL） in Gd3Ga5O12：Eu3＋ and Eu3Ga3O12 garnets were studied within the visible spectra...Spectra of absorption, luminescence, magnetic circular dichroism （MCD）, and magnetic circular polarization of lumines- cence （MCPL） in Gd3Ga5O12：Eu3＋ and Eu3Ga3O12 garnets were studied within the visible spectral range at 300 K. Analysis of the spectral and temperature dependences of the magnetooptical and optical spectra made it possible to identify the magneto-dipole （MD） and electro-dipole （ED） 4f→4f transitions occurring between Stark sublevels of the 7FJ （J=1, 2） and 5D0 multiplets in Eua＋-containing garnet structures. Quantum mechanical ＂mixing＂ had significant influence on quasi-degenerate states of the non-Kramers rare-earth Eu3＋ ion for Eu3GasOl2 in MCD due to forbidden MD transition 7F1→SD0 and for GdaGasOiE：EU3＋ in MCPL due to MD 4f→4f transition 5Do→7F1 and forced ED-transition 5Do→7F2. A parameterized Hamiltonian defined to operate within the entire 4f（6） ground electronic configuration of Eu3＋ ion was used to model the experimental Stark levels, including their irreducible rep- resentations and wavefunctions. The crystal-field parameters were determined through a Monte-Carlo method in which nine in- dependent crystal-field parameters, Bkq, were given random starting values and optimized using standard least-squares fitting between calculated and experimental levels. The final fitting standard deviation between 57 calculated-to-experimental levels was 0.73 meV.展开更多
The rare earth iron garnets R3Fe5O12（R=Sm, Eu） were synthesized under mild hydrothermal conditions, and their crystal growth was found to be sensitive to alkalinity, reaction temperature and time. The as-prepared sa...The rare earth iron garnets R3Fe5O12（R=Sm, Eu） were synthesized under mild hydrothermal conditions, and their crystal growth was found to be sensitive to alkalinity, reaction temperature and time. The as-prepared samples were characterized by powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, infrared spectra（IR） and Raman spectrum. The M vs. H loops and magnetic parameters have been traced with a vibrating sample magnetometer（VSM） and superconducting quantum interference devices（SQUIDs） magnetometer. We proposed the formation mechanisms and formulated a reasonable explanation for their growth habits. Different morphologic characteristics were observed by changing alkalinity in the reaction systems. The magnetic studies gave saturation magnetization（Ms） and Curie temperature（TC）. The magnetic behaviors of Sm3Fe5O12 and Eu3Fe5O12 in mild hydrothermal systems are comparable with those in high temperature solid state reactions.展开更多
Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs(Foliation Intersection Axis)formed normal to tectonic shortening directions.Thanks...Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs(Foliation Intersection Axis)formed normal to tectonic shortening directions.Thanks to technological advances in X-ray computed micro-tomography(XCMT),FIAs can now be readily determined in relatively large samples in contrast to previous methods that require the preparation of a set of radial vertical and horizontal thin sections of samples.XCMT scanning not only alleviates tedious thin section based procedures but also illuminates the complete internal architecture of a rock sample allowing three-dimensional(3D)quantitative shape analysis of an individual porphyroblast as well as precise measurement of FIAs.We applied the technique to a sample from the Hunza Valley in the Karakoram metamorphic complex(KMC),NW Himalayas,containing numerous garnet porphyroblasts with spiral-shaped inclusion trails.The XCMT imaging reveals an E-W trending FIA within the sample,which is consistent with orthogonal N-S collision of the India-Kohistan Island Arc with Asia.Garnet long axes(X_(GT))have variable plunges that define a broad sub-vertical maximum and a small sub-horizontal maximum.The X_(GT) principle maxima lie at N-090 and N-120.Smaller maxima lie at N-020 and N-340.Geometric relationships between X_(GT) axes and FIA orientation in the sample suggest that porphyroblast shapes are controlled by the geometry of the lens-shaped microlithons in which they tend to nucleate and grow.The orientation of inclusion trails and matrix foliations in the sample are correlated with three discrete tectono-metamorphic events that respectively produced andalusite,sillimanite and kyanite in the KMC.Late staurolite growth in the sample reveals how the rocks extruded to the surface via a significant role of roll-on tectonics,which can be correlated with the Central Himalayas.展开更多
The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies f...The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies from chartreuse to dark yellow brown and to russet.The brown garnet(Grt1)is related to pyrrhotite and chalcopyrite,and the green garnet(Grt2)is associated with lead–zinc mineralization.LA-ICP-MS is the induced coupled plasma mass spectrometry.This paper has used this technique to investigate Grt1 and Grt2.Grt1 develops core–rim textures with strong oscillation zone occurring in rim,whereas Grt2lacks core–rim textures and featured by oscillation zone.LA–ICP–MS analysis shows that garnets of Mengya’a are rich in CaO(29.90–37.52%)and FeO(21.17–33.35%),but low in Al_(2)O_(3)(0.05–4.85%).The calculated end members belong to grandite(grossular–andradite)garnets andradite.The negative Al(IV)versus Fe^(3+),positive Al(IV)versus total Al stoichiometric number,the positive Al(IV)versus Fe^(3+),and the negative Al(IV)versus total REE,all indicate that the substitution of REEs in garnets is controlled by YAG.All Garnets are depleted in large lithophile elements(e.g.,Rb=0.00–4.01 ppm,Sr=0.03–8.56 ppm).The total REE in Grt1 core is high(ΣREE=233–625 ppm),with HREE enriched pattern(LREE/HREE=0.33–1.69)and weak negative Eu anomalies(δEu=0.21–0.47).In contrast,the total REEs in the Grt1 rim and Grt2 are low(ΣREE=12.4–354 ppm;ΣREE=21.0–65.3 ppm),with LREE enriched pattern(LREE/HREE=0.54–34.4;LREE/HREE=11.4–682)and positive Eu anomalies(δEu=0.35–27.2;δEu=1.02–30.7).After data compilation of garnet chemicals,we found that the early fluid responsible for the core of Grt1 was a relatively closed and chloride-depleted fluid system.It was close-to-neutral,with a low water–rock ratio.The core of garnet was formed by fluid diffusion in metasomatic processes.The fluid was changed into a relatively open system with reduced,chloride-rich,and weakacid fluid.It was fluid infiltration and metasomatism that resulted in the formation of Grt1 rim and Grt2.展开更多
Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when prob...Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when probing by laser beam various sites of separate magnetic domains of the film. Registered in our experiments the nonlinear and linear components of EMO effect does not remain to constants at optical scanning of various points of the magnetic domain. I.e. the local EMOE picture from the separate sites of the domain must be more informative than an averaged one in the multidomain case.展开更多
Subduction zones are important for oxygen cycling between deep and surficial Earth reservoirs.Highly oxidizing materials from Earth’s surface may be transported to the mantle along with the subducting slabs and alter...Subduction zones are important for oxygen cycling between deep and surficial Earth reservoirs.Highly oxidizing materials from Earth’s surface may be transported to the mantle along with the subducting slabs and alter the redox states of the mantle wedge and the 410–660 km transition zone.The circulation of oxygen or oxidizing fluids in subduction zones and how subducted materials influence the deep mantle are poorly constrained.Here we report growth of Fe-Mn garnet from highly oxidized pelagic ferromanganese chert within a high-pressure metamorphic complex in the Qilian Orogen,North West(NW)China.Two types of ferric-iron-rich garnets were identified.Type I is spessartine garnet that has clear compositional zonation of Al2O3-FeOt-MnO oscillatory growth.The Fe^(3+)/∑Fe ratio in the core is as high as 1.0,but decreases to 0.1 in the outer rim,along with an increase of Fe2+content and a significant decrease in Mn content.Type II is andradite-calderite garnet that contains extremely high Fe^(3+).Our results have two implications:(1)continuous reduction of Mn^(4+)(to Mn^(2+))and Fe^(3+)(to Fe2+)from the ferromanganese chert as garnet growth must be accompanied by releasing large quantity of oxygen or highly oxidized fluids during prograde high-pressure metamorphism in subduction zones,and(2)Fe^(3+)-rich garnets together with hematite in the subducting slab can remain stable over a large pressure range,and provide an alternative interpretation for the high content of Fe^(3+)in the deep mantle.Our results are significant for understanding the oxygen recycling in oceanic cold subduction zones,and the initiation of the Great Oxygen Event(GOE)as well.展开更多
The compositions of Jurassic detrital garnets in Hefei Basin are complicated. Contents of the end member are from zero to 43% for pyrope, from less than 1% to 50% for grossular, from 2% to 92% for almandine, and from ...The compositions of Jurassic detrital garnets in Hefei Basin are complicated. Contents of the end member are from zero to 43% for pyrope, from less than 1% to 50% for grossular, from 2% to 92% for almandine, and from zero to 88% for spessartine. Part of relatively pyrope-rich detrital garnets might be originated from high pressure-ultrahigh pressure metamorphic rocks. Contents of spessartine in garnets from the present metamorphic rocks of the Dabie Mountains, including the greenschists of Foziling Group, are lower than 30%. Therefore, they would not be the source of the spessartine-rich detrital garnets in the Jurassic sedimentary rocks of the Hefei Basin. Chemical compositions of the Jurassic detrital garnets in the Hefei Basin have some characteristics in the distribution with strata, which can be applied to study of the sedimentary filling sequence and stratigraphic correlation.展开更多
A few texturally-zoned garnets were found in a polymict peridotite (JJG1414) from the Cretaceous kimberlite, Kimberley South Africa. The systematic analyses of electron and ion microprobe as well as laser fluorination...A few texturally-zoned garnets were found in a polymict peridotite (JJG1414) from the Cretaceous kimberlite, Kimberley South Africa. The systematic analyses of electron and ion microprobe as well as laser fluorination technique reveal the existencal of marked elemental and oxygen isotopic zonation in these gamed. corresponding to the textural zonation. The rims are normally enriched in Ca, Ti, Cr, LREE. Sr, Nb, and depleted in Mg, Al and 18O. It is demonstrated that these gamats were infiltrated by melts/fiuids, probably representing the disequilibrated products of fluid-asssted mantle deformation.展开更多
Palaeozoic kimberlites from Mengyin, Shandong and Fuxian, Liaoning, eastern China, contain plenty of mantle xenoliths (peridotites, eclogites) and megacrystic minerals. In-situ electron and ion microprobe analyses on ...Palaeozoic kimberlites from Mengyin, Shandong and Fuxian, Liaoning, eastern China, contain plenty of mantle xenoliths (peridotites, eclogites) and megacrystic minerals. In-situ electron and ion microprobe analyses on garnets from these xenoliths and megacrysts as well as relevant theoretical modeling reveal that these garnets were more or less affected by kimberlitic silicate melts prior to the encapsulation, in which eclogitic garnet from Fuxian, Liaoning Province, was little affected by mantle metasomatism, representing the primitive depleted mantle composition. In contrast, garnet from Mengyin, Shandong Province, and all megacrystic garnets were completely modified by metasomatic melts/fluids and reached perfectly chemical equilibrium, thus reflecting the characteristics of the enriched mantle. It is inferred that old lithospheric mantle beneath the North China craton was fairly strongly modified by metasomatism before Palaeozoic kimberlite emplacement.展开更多
Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes,but very few studies have been ...Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes,but very few studies have been performed for Fe-Mn interdiffusion.In this study,Fe-Mn interdiffusion rates in natural single crystals of Mn-bearing garnet with 750 ppm H2O are determined at 6 GPa and 1273-1573 K in a Kawai-type multi-anvil apparatus.Diffusion profiles were acquired by electron microprobe and fitted using Boltzmann-Matano equation.The experimental results show that the Fe-Mn interdiffusion coefficient(DFe-Mn)slightly decreases with increasing XFe.The experimentally determined DFe-Mn in Mn-bearing garnet can be fitted by the Arrhenius equation:DFe-Mn(m2/s)=D0XFenexp(-E*/RT),where E*=(1-XFe)E*Mn+XFeE*Fe,D0=8.06-6.04+9.87×10-9 m2/s,E*Mn=248±27 KJ/mol,E*Fe=226±59 KJ/mol,n=-1.36±0.51.The comparing the present results with previous experimental data suggest that water can greatly enhance the DFe-Mn in garnet.Our results indicate that the time required for homogenization of the compositional zoning of a garnet is much shorter than previously thought.展开更多
To develop efficient luminescence and optical thermometry materials for color display and non-contact temperature measurement,novel RE^(3+)(RE=Eu,Sm)doped self-activated Na_(2)LuMg_(2)V_(3)O_(12)phosphors were prepare...To develop efficient luminescence and optical thermometry materials for color display and non-contact temperature measurement,novel RE^(3+)(RE=Eu,Sm)doped self-activated Na_(2)LuMg_(2)V_(3)O_(12)phosphors were prepared by a typical solid-state reaction method.Their crystal structure,morphology,multi-color luminescence and temperature sensing properties were elaborately investigated.Under UV light excitation,an intense and broad green-yellow emission band from VO_(4)^(3-)group is observed in the Na_(2)LuMg_(2)V_(3)O_(12)matrix,indicating its potential application in solid state lighting.After the incorpo ration of Eu^(3+)and Sm^(3+)ions,efficient energy transfer(ET)from VO_(4)^(3-)group to Eu^(3+)/Sm^(3+)ions occurs and the emission color of the samples can be readily tuned among different color ranges.Besides,based on the change of luminescence intensity and lifetimes of VO_(4)^(3-)group in Na_(2)LuMg_(2)V_(3)O_(12):Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):Sm^(3+),the ET efficiency was analyzed and the mechanism is illustrated.Finally,large discrepancy between the thermal stability of VO_(4)^(3-)group and Eu^(3+)/Sm^(3+)ions is observed in the temperature-dependent emission spectra of Na_(2)LuMg_(2)V_(3)O_(12):Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):Sm^(3+).By taking advantage of the luminescence intensity ratio(LIR)between VO_(4)^(3-)group and Eu^(3+)/Sm^(3+)ions in Na_(2)LuMg_(2)V_(3)O_(12):0.01Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):0.07Sm^(3+),two new types of optical thermometry mediums were designed and their basic temperature sensing parameters were calculated.展开更多
Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for decipherin...Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.展开更多
The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the inter...The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the interlayer coupling and switching mechanisms in YIG/Py(permalloy)heterostructures based on gadolinium gallium garnet(GGG)and SiO_(2)substrates.We observe antiferromagnetic interlayer coupling between Py and YIG on SiO_(2)substrates,whereas ferromagnetic interlayer coupling is observed on GGG substrates.Using polarized neutron reflectometry with depth-and elementresolved measurements,we obtain an in-depth understanding of the magnetic interactions between the YIG and Py layers.We demonstrate that polycrystalline YIG gives rise to antiferromagnetic interlayer coupling.This work provides valuable insights into designing and controlling magnetic coupling in hybrid structures for spintronic applications.展开更多
基金supported by the Guangxi Natural Science Foundation(Grant No.2025GXNSFDA069038)The Guangxi Science and Technology Plan Project(Grant No.AA23073018)+1 种基金the National Natural Science Foundation of China(Grant Nos.22175043 and 52162021)the Open Foundation of State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures(Grant No.MMCS2023OF05).
文摘Rare-earth ion-doped garnets with excellent luminescent properties show great potential for temperature sensing,displays,and nondestructive detection.However,their limited luminescent modes and low photoluminescence quantum yields(PLQY)restrict further applications.In this study,we synthesized Al^(3+),Er^(3+)-co-doped Gd_(3)Ga_(5)O_(12) garnets with multimode luminescence via a high-temperature solid-state method.Notably,the preferential substitution of Al^(3+)ion at octahedral-coordinated GaI sites significantly enhanced the charge density and electron transition probability,achieving a PLQY enhancement of the downshifting luminescence from 35.1%to 68.5%.Al^(3+)ion also influences electron relaxation during up-conversion luminescence,resulting in a color shift from red to yellow to green.Additionally,Al^(3+)incorporation increased the photoelectric conversion efficiency of light-emitting diodes from 2.9%to 6.3%and improved temperature sensing sensitivity from 2.7%to 5.1%K⁻1.This work provides new insights into the photophysical mechanisms and underscores the key role of Al^(3+)ion in optimizing the optical properties of garnet-based materials.
基金Project supported by National Natural Science Foundation of China(11475242,51272263)K.C.Wong Magna Fund in Ningbo University
文摘A novel series of Ce^3＋-doped Yb3 Al（5-x）GaxO（12）（x = 0, 1,2, 3,4, 5） powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al^3＋ sites with Ga^3＋ in 0.5 at%Ce：Yb3 Al（5-x）GaxO（12）（x = 0,1, 2, 3, 4, 5） garnets were discussed. With the increase of Ga^3＋ ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb^3＋ ＋ Ce^3＋→ Yb^2＋ ＋ Ce^4＋ electron transfer reaction.
文摘A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates the formation of single cubic phase. Vibrating sample magnetometry (VSM) and a superconducting quantum-interference device (SQUID) were used to measure the magnetic properties, especially the magnetization and thermo-magnetic behavior. The magnetization curves exhibit the typical characteristics of ferrimagnetic materials at both 4.2 K and at room temperature. The samples have a low coercivities (between 20 and 40 Oe) and saturation magnetizations as high as 36 emu/g at 4.2 K. The saturation magnetization decreases with V and Ca contents, reaching about 8 emu/g at 4.2 K (x = 1). For all samples, the saturation magnetization decreases with increasing temperature, whereas the Curie temperature increases for small values of x, from 557 K for x = 0 to a maximum of 590 K for x = 0.2. For larger values of x, it decreases and reaches 525 K for x = 1.0. The basic experimental trends reflect the occupancy of the tetrahedral 24d sites by vanadium in combination with the predominant intersublattice exchange constant Jad, although the nonzero magnetization at x = 1.0 indicates that about 10% of the substituted V atoms goes onto the octahedral 16a sites.
基金supported by the National Natural Science Foundation of China (Nos.41822201 and 41772048)the BType Strategic Priority Program of the Chinese Academy of Sciences (No.XDB41000000)the Fundamental Research Funds for the Central Universities of China
文摘Crustal anatexis in continental subduction zones has great bearing on chemical differentiation of the continental crust at convergent plate boundaries.This was experimentally investigated for ultrahigh-pressure(UHP)metafelsic rocks at 0.5-3.0 GPa and 650-900℃.The results show that partial melting begins at about 750℃ when pressure drops from 3.0 to 2.0 GPa,corresponding to decompressional exhumation of the deeply subducted continental crust.As the pressure further decreases to 1.0 GPa,the partial melting degree reaches the maximum of~25%at 900℃.Partial melts produced in these experiments are rich in silica and alkali,and poor in iron,manganese and magnesium.As the degree of partial melting increases,the composition of partial melts gradually converges toward homogeneous one.In the absence of free water,the partial melting of metafelsic rocks were triggered by the breakdown of hydrous minerals.At low temperatures of~750℃at 1.0-2.0 GPa,phengite dehydration melting occurs at first,giving rise to small amounts of felsic melts and peritectic K-feldspar.As the temperature rises up to 850-900℃,biotite begins to break down and gives rise to large amounts of felsic melts and peritectic minerals such as garnet,K-feldspar and orthopyroxene.It is noted that peritectic garnet is much different from anatectic garnet crystallized from anatectic melts and metamorphic garnet formed through metamorphic dehydration reaction under subsolidus conditions.The peritectic garnet is characterized not only by anhedral shapes with many multiphase crystal inclusions but also by compositions poor in spessartine and grossular but rich in almandine and pyrope.On the other hand,the anatectic garnets are characterized not only by euhedral shapes with few inclusions but also by compositions rich in grossular and spessartine but poor in almandine and pyrope.These observations provide experimental constraints on the origin of garnets in UHP metamorphic rocks,which have great bearing on understanding of anatectic metamorphism in collisional orogens.
文摘In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observa-tions and studies confirmed that these lamellae are phlogopite. They are colourless and acicularin section, generally 0.5-5μm in width and 10-100μm in length. Nevertheless, fine lamellae,0.05-0.1μm wide and 1-2μm long, are also well developed. Along [111] of the garnet, three setsof phlogopite lamellae show oriented arrangement approximately at angles of 60°-70°, indi-cating that these lamellae might be the product of exsolution from garnet as a result ofpressure-release when eclogite ascended from the relatively deep level to the relatively shallowlevel of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found ingarnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been re-ported that the identified exsolution minerals include pyroxene and rutile. This is the first timethat phlogopite exsolution lamillae were found in eclogite inclusions in the world.
基金This paperis supported by the National Natural Science Foundation of China( No.49872 0 69)
文摘Garnet is an important rock forming mineral of high pressure and ultrahigh pressure metamorphic rocks. Its popular isomorphism complicates its chemical composition and crystal structure. The selected area electron diffraction (SAED) and the high resolution electron microscopy (HREM) are used in this work to study the microstructures and ultrastructures of garnets in the jadeite quartzite from Dabie Mountains, China. The microstructures of the garnet occur mainly as free dislocations, dislocation walls, stacking faults, dislocation networks and sub grain boundaries. The dislocation density is ρ=n ×10 8/cm 2 ( n =1.7—7.5) and the deformation mechanism is the dislocation glide and dynamic recovery. The superstructures of the garnet crystal revealed by HREM occur mainly as dislocations, faults, domain structures and lattice deformations, indicating the strong stress during the formation of the jadeite quartzite.
基金Supported by the National Natural Science Foundation of China(Nos.90922034,20771042)
文摘Rare earth iron garnets R3Fe5-xMnxO12（R=Pr, Nd, Sm, Eu） were prepared through mild hydrothermal me- thod. The initial alkalinity of solutions was thought to play an important role in governing the content of Mn. The effect of substitution Fe^3＋ ions by Mn^3＋ ions on magnetic properties was investigated. The saturation magnetizations of Mn-doped samples are larger than that of corresponding parent compounds due to the moment of Mn^3＋ ion being smaller than that of Fe^3＋. It is clearly shown that incorporation of Mn^3＋ gives rise to significant variations in the Curie temperature. With increasing of Mn content x, Curie temperatures reduced sharply for the garnets, which could be explained by the exchange interaction between a-d Fe^3＋ being reduced in these compounds.
基金Project supported by National Natural Science Foundation of China(11205116)International Cooperation Program of the Ministry of Science and Technology of China(2011DFR50580)
文摘Spectra of absorption, luminescence, magnetic circular dichroism （MCD）, and magnetic circular polarization of lumines- cence （MCPL） in Gd3Ga5O12：Eu3＋ and Eu3Ga3O12 garnets were studied within the visible spectral range at 300 K. Analysis of the spectral and temperature dependences of the magnetooptical and optical spectra made it possible to identify the magneto-dipole （MD） and electro-dipole （ED） 4f→4f transitions occurring between Stark sublevels of the 7FJ （J=1, 2） and 5D0 multiplets in Eua＋-containing garnet structures. Quantum mechanical ＂mixing＂ had significant influence on quasi-degenerate states of the non-Kramers rare-earth Eu3＋ ion for Eu3GasOl2 in MCD due to forbidden MD transition 7F1→SD0 and for GdaGasOiE：EU3＋ in MCPL due to MD 4f→4f transition 5Do→7F1 and forced ED-transition 5Do→7F2. A parameterized Hamiltonian defined to operate within the entire 4f（6） ground electronic configuration of Eu3＋ ion was used to model the experimental Stark levels, including their irreducible rep- resentations and wavefunctions. The crystal-field parameters were determined through a Monte-Carlo method in which nine in- dependent crystal-field parameters, Bkq, were given random starting values and optimized using standard least-squares fitting between calculated and experimental levels. The final fitting standard deviation between 57 calculated-to-experimental levels was 0.73 meV.
基金Supported by the National Natural Science Foundation of China(Nos.90922034, 20771042)
文摘The rare earth iron garnets R3Fe5O12（R=Sm, Eu） were synthesized under mild hydrothermal conditions, and their crystal growth was found to be sensitive to alkalinity, reaction temperature and time. The as-prepared samples were characterized by powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, infrared spectra（IR） and Raman spectrum. The M vs. H loops and magnetic parameters have been traced with a vibrating sample magnetometer（VSM） and superconducting quantum interference devices（SQUIDs） magnetometer. We proposed the formation mechanisms and formulated a reasonable explanation for their growth habits. Different morphologic characteristics were observed by changing alkalinity in the reaction systems. The magnetic studies gave saturation magnetization（Ms） and Curie temperature（TC）. The magnetic behaviors of Sm3Fe5O12 and Eu3Fe5O12 in mild hydrothermal systems are comparable with those in high temperature solid state reactions.
文摘Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs(Foliation Intersection Axis)formed normal to tectonic shortening directions.Thanks to technological advances in X-ray computed micro-tomography(XCMT),FIAs can now be readily determined in relatively large samples in contrast to previous methods that require the preparation of a set of radial vertical and horizontal thin sections of samples.XCMT scanning not only alleviates tedious thin section based procedures but also illuminates the complete internal architecture of a rock sample allowing three-dimensional(3D)quantitative shape analysis of an individual porphyroblast as well as precise measurement of FIAs.We applied the technique to a sample from the Hunza Valley in the Karakoram metamorphic complex(KMC),NW Himalayas,containing numerous garnet porphyroblasts with spiral-shaped inclusion trails.The XCMT imaging reveals an E-W trending FIA within the sample,which is consistent with orthogonal N-S collision of the India-Kohistan Island Arc with Asia.Garnet long axes(X_(GT))have variable plunges that define a broad sub-vertical maximum and a small sub-horizontal maximum.The X_(GT) principle maxima lie at N-090 and N-120.Smaller maxima lie at N-020 and N-340.Geometric relationships between X_(GT) axes and FIA orientation in the sample suggest that porphyroblast shapes are controlled by the geometry of the lens-shaped microlithons in which they tend to nucleate and grow.The orientation of inclusion trails and matrix foliations in the sample are correlated with three discrete tectono-metamorphic events that respectively produced andalusite,sillimanite and kyanite in the KMC.Late staurolite growth in the sample reveals how the rocks extruded to the surface via a significant role of roll-on tectonics,which can be correlated with the Central Himalayas.
基金funded by the Surface Project of National Natural Science Foundation of China(41372093)。
文摘The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies from chartreuse to dark yellow brown and to russet.The brown garnet(Grt1)is related to pyrrhotite and chalcopyrite,and the green garnet(Grt2)is associated with lead–zinc mineralization.LA-ICP-MS is the induced coupled plasma mass spectrometry.This paper has used this technique to investigate Grt1 and Grt2.Grt1 develops core–rim textures with strong oscillation zone occurring in rim,whereas Grt2lacks core–rim textures and featured by oscillation zone.LA–ICP–MS analysis shows that garnets of Mengya’a are rich in CaO(29.90–37.52%)and FeO(21.17–33.35%),but low in Al_(2)O_(3)(0.05–4.85%).The calculated end members belong to grandite(grossular–andradite)garnets andradite.The negative Al(IV)versus Fe^(3+),positive Al(IV)versus total Al stoichiometric number,the positive Al(IV)versus Fe^(3+),and the negative Al(IV)versus total REE,all indicate that the substitution of REEs in garnets is controlled by YAG.All Garnets are depleted in large lithophile elements(e.g.,Rb=0.00–4.01 ppm,Sr=0.03–8.56 ppm).The total REE in Grt1 core is high(ΣREE=233–625 ppm),with HREE enriched pattern(LREE/HREE=0.33–1.69)and weak negative Eu anomalies(δEu=0.21–0.47).In contrast,the total REEs in the Grt1 rim and Grt2 are low(ΣREE=12.4–354 ppm;ΣREE=21.0–65.3 ppm),with LREE enriched pattern(LREE/HREE=0.54–34.4;LREE/HREE=11.4–682)and positive Eu anomalies(δEu=0.35–27.2;δEu=1.02–30.7).After data compilation of garnet chemicals,we found that the early fluid responsible for the core of Grt1 was a relatively closed and chloride-depleted fluid system.It was close-to-neutral,with a low water–rock ratio.The core of garnet was formed by fluid diffusion in metasomatic processes.The fluid was changed into a relatively open system with reduced,chloride-rich,and weakacid fluid.It was fluid infiltration and metasomatism that resulted in the formation of Grt1 rim and Grt2.
文摘Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when probing by laser beam various sites of separate magnetic domains of the film. Registered in our experiments the nonlinear and linear components of EMO effect does not remain to constants at optical scanning of various points of the magnetic domain. I.e. the local EMOE picture from the separate sites of the domain must be more informative than an averaged one in the multidomain case.
基金supported by the National Key Research and Development Program of China(2023YFF0803803)the National Natural Science Foundation of China(91955202).
文摘Subduction zones are important for oxygen cycling between deep and surficial Earth reservoirs.Highly oxidizing materials from Earth’s surface may be transported to the mantle along with the subducting slabs and alter the redox states of the mantle wedge and the 410–660 km transition zone.The circulation of oxygen or oxidizing fluids in subduction zones and how subducted materials influence the deep mantle are poorly constrained.Here we report growth of Fe-Mn garnet from highly oxidized pelagic ferromanganese chert within a high-pressure metamorphic complex in the Qilian Orogen,North West(NW)China.Two types of ferric-iron-rich garnets were identified.Type I is spessartine garnet that has clear compositional zonation of Al2O3-FeOt-MnO oscillatory growth.The Fe^(3+)/∑Fe ratio in the core is as high as 1.0,but decreases to 0.1 in the outer rim,along with an increase of Fe2+content and a significant decrease in Mn content.Type II is andradite-calderite garnet that contains extremely high Fe^(3+).Our results have two implications:(1)continuous reduction of Mn^(4+)(to Mn^(2+))and Fe^(3+)(to Fe2+)from the ferromanganese chert as garnet growth must be accompanied by releasing large quantity of oxygen or highly oxidized fluids during prograde high-pressure metamorphism in subduction zones,and(2)Fe^(3+)-rich garnets together with hematite in the subducting slab can remain stable over a large pressure range,and provide an alternative interpretation for the high content of Fe^(3+)in the deep mantle.Our results are significant for understanding the oxygen recycling in oceanic cold subduction zones,and the initiation of the Great Oxygen Event(GOE)as well.
文摘The compositions of Jurassic detrital garnets in Hefei Basin are complicated. Contents of the end member are from zero to 43% for pyrope, from less than 1% to 50% for grossular, from 2% to 92% for almandine, and from zero to 88% for spessartine. Part of relatively pyrope-rich detrital garnets might be originated from high pressure-ultrahigh pressure metamorphic rocks. Contents of spessartine in garnets from the present metamorphic rocks of the Dabie Mountains, including the greenschists of Foziling Group, are lower than 30%. Therefore, they would not be the source of the spessartine-rich detrital garnets in the Jurassic sedimentary rocks of the Hefei Basin. Chemical compositions of the Jurassic detrital garnets in the Hefei Basin have some characteristics in the distribution with strata, which can be applied to study of the sedimentary filling sequence and stratigraphic correlation.
文摘A few texturally-zoned garnets were found in a polymict peridotite (JJG1414) from the Cretaceous kimberlite, Kimberley South Africa. The systematic analyses of electron and ion microprobe as well as laser fluorination technique reveal the existencal of marked elemental and oxygen isotopic zonation in these gamed. corresponding to the textural zonation. The rims are normally enriched in Ca, Ti, Cr, LREE. Sr, Nb, and depleted in Mg, Al and 18O. It is demonstrated that these gamats were infiltrated by melts/fiuids, probably representing the disequilibrated products of fluid-asssted mantle deformation.
文摘Palaeozoic kimberlites from Mengyin, Shandong and Fuxian, Liaoning, eastern China, contain plenty of mantle xenoliths (peridotites, eclogites) and megacrystic minerals. In-situ electron and ion microprobe analyses on garnets from these xenoliths and megacrysts as well as relevant theoretical modeling reveal that these garnets were more or less affected by kimberlitic silicate melts prior to the encapsulation, in which eclogitic garnet from Fuxian, Liaoning Province, was little affected by mantle metasomatism, representing the primitive depleted mantle composition. In contrast, garnet from Mengyin, Shandong Province, and all megacrystic garnets were completely modified by metasomatic melts/fluids and reached perfectly chemical equilibrium, thus reflecting the characteristics of the enriched mantle. It is inferred that old lithospheric mantle beneath the North China craton was fairly strongly modified by metasomatism before Palaeozoic kimberlite emplacement.
基金supported by the National Natural Science Foundation of China (41973056,41773056)Key Research Program of Frontier Sciences of CAS (ZDBS-LY-DQC015)to B.Zhang+1 种基金the Fundamental Research Funds for the Central Universities (K20210168)Data presented as part of this study are available from Zenodo (https://doi.org/10.5281/zenodo.7080353).
文摘Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes,but very few studies have been performed for Fe-Mn interdiffusion.In this study,Fe-Mn interdiffusion rates in natural single crystals of Mn-bearing garnet with 750 ppm H2O are determined at 6 GPa and 1273-1573 K in a Kawai-type multi-anvil apparatus.Diffusion profiles were acquired by electron microprobe and fitted using Boltzmann-Matano equation.The experimental results show that the Fe-Mn interdiffusion coefficient(DFe-Mn)slightly decreases with increasing XFe.The experimentally determined DFe-Mn in Mn-bearing garnet can be fitted by the Arrhenius equation:DFe-Mn(m2/s)=D0XFenexp(-E*/RT),where E*=(1-XFe)E*Mn+XFeE*Fe,D0=8.06-6.04+9.87×10-9 m2/s,E*Mn=248±27 KJ/mol,E*Fe=226±59 KJ/mol,n=-1.36±0.51.The comparing the present results with previous experimental data suggest that water can greatly enhance the DFe-Mn in garnet.Our results indicate that the time required for homogenization of the compositional zoning of a garnet is much shorter than previously thought.
基金Project supported by Natural Science Foundation of Shandong Province(ZR2020KF017,ZR2020QE053,ZR2023QB261)the Natural Science Foundation of Anhui Province(2108085MB53)。
文摘To develop efficient luminescence and optical thermometry materials for color display and non-contact temperature measurement,novel RE^(3+)(RE=Eu,Sm)doped self-activated Na_(2)LuMg_(2)V_(3)O_(12)phosphors were prepared by a typical solid-state reaction method.Their crystal structure,morphology,multi-color luminescence and temperature sensing properties were elaborately investigated.Under UV light excitation,an intense and broad green-yellow emission band from VO_(4)^(3-)group is observed in the Na_(2)LuMg_(2)V_(3)O_(12)matrix,indicating its potential application in solid state lighting.After the incorpo ration of Eu^(3+)and Sm^(3+)ions,efficient energy transfer(ET)from VO_(4)^(3-)group to Eu^(3+)/Sm^(3+)ions occurs and the emission color of the samples can be readily tuned among different color ranges.Besides,based on the change of luminescence intensity and lifetimes of VO_(4)^(3-)group in Na_(2)LuMg_(2)V_(3)O_(12):Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):Sm^(3+),the ET efficiency was analyzed and the mechanism is illustrated.Finally,large discrepancy between the thermal stability of VO_(4)^(3-)group and Eu^(3+)/Sm^(3+)ions is observed in the temperature-dependent emission spectra of Na_(2)LuMg_(2)V_(3)O_(12):Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):Sm^(3+).By taking advantage of the luminescence intensity ratio(LIR)between VO_(4)^(3-)group and Eu^(3+)/Sm^(3+)ions in Na_(2)LuMg_(2)V_(3)O_(12):0.01Eu^(3+)and Na_(2)LuMg_(2)V_(3)O_(12):0.07Sm^(3+),two new types of optical thermometry mediums were designed and their basic temperature sensing parameters were calculated.
基金financially supported by the National Natural Science Foundation of China(No.41930215)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)。
文摘Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.
基金supported by the National Key Basic Research Program of China(Grant Nos.2021YFA1400300 and 2023YFA1610400)the National Natural Science Foundation of China(Grant Nos.12204268,52371169,52130103,and U22A20263)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023B1515120015)the Open Research Fund of Songshan Lake Materials Laboratory(Grant No.2022SLABFN13)。
文摘The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the interlayer coupling and switching mechanisms in YIG/Py(permalloy)heterostructures based on gadolinium gallium garnet(GGG)and SiO_(2)substrates.We observe antiferromagnetic interlayer coupling between Py and YIG on SiO_(2)substrates,whereas ferromagnetic interlayer coupling is observed on GGG substrates.Using polarized neutron reflectometry with depth-and elementresolved measurements,we obtain an in-depth understanding of the magnetic interactions between the YIG and Py layers.We demonstrate that polycrystalline YIG gives rise to antiferromagnetic interlayer coupling.This work provides valuable insights into designing and controlling magnetic coupling in hybrid structures for spintronic applications.
