The thermophysical properties of expanded liquid mercury have been investigated along the liquid-vapor coexistence curve by using Monte Carlo and Molecular Dynamic simulations. For the purpose, an empirical state depe...The thermophysical properties of expanded liquid mercury have been investigated along the liquid-vapor coexistence curve by using Monte Carlo and Molecular Dynamic simulations. For the purpose, an empirical state dependent interatomic potential for the region of dense metallic liquid is used, while the state dependence is not necessary near the cliffcal point. In order to test the validity of this potential, we determine the surface layering and the sound velocity, two properties very sensitive to the choice of the potential. Our results are in quite good agreement with other theoretical results and to the experimental data available in the literature.展开更多
Non-equilibrium phases formed in melt-quenched CuIn（SexTe1-x）2 system, where x = 0.1, 0.2, 0.4, 0.5, 0.6, 0.8 and 0.9, have been studied using Rietveld refinement of the crystal structure and Raman spectroscopy. Res...Non-equilibrium phases formed in melt-quenched CuIn（SexTe1-x）2 system, where x = 0.1, 0.2, 0.4, 0.5, 0.6, 0.8 and 0.9, have been studied using Rietveld refinement of the crystal structure and Raman spectroscopy. Results of structure refinement have showed that all the samples, except the CuIn（Se0.1Te0.9）2, are heterogeneous. All the observed non-equilibrium phases are quaternary system and are found to have chalcopyrite structure （I42d）, in accordance with the CuInTe2-CuInSe2 phase diagram. The lattice constants deduced from the refinement have showed linear variation with Se content. A detailed analysis of the characteristic Al modes present in the Raman spectrum of individual sample has corroborated the results obtained from the structure analysis. The position of Al mode of individual phase is found to vary linearly with Se content, which suggests that CuIn（SexTe1-x）2 system exhibits single-mode behaviour.展开更多
The transport properties of gluon in color space in a system of coexistence of both hadronic and QGP phases are investigated from the quantum transport equation of gluon.
The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theore...The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.展开更多
Solid solutions of Na_(0.5) Bi_(0.5) TiO_(3)(NBT)and BiNi_(0.5) Ti_(0.5) O_(3)(BNiT)were prepared by a solid-state reaction route,and their electrical properties investigated by a combination of impedance spectroscopy...Solid solutions of Na_(0.5) Bi_(0.5) TiO_(3)(NBT)and BiNi_(0.5) Ti_(0.5) O_(3)(BNiT)were prepared by a solid-state reaction route,and their electrical properties investigated by a combination of impedance spectroscopy and electromotive force measurements to explore the possibility of developing mixed ionic-electronic conductors based on NBT.Phase analysis showed that BNiT has a large solid solution limit in NBT(60 mol%based on X-ray diffraction),and the room temperature crystal structure changes from rhombohedral to pseudo-cubic with increasing BNiT content.Neutron diffraction revealed the coexistence of rhombohedral and tetragonal phases when the BNiT content≥40 mol%.Electrically,incorporation of BNiT induces p-type electronic conduction into NBT by hopping of holes between Ni^(2+)(Ni_(Ni)^(x))and Ni^(3+)(Ni·Ni),and therefore changes the electrical conduction mechanism systematically from predominant oxide-ion conduction to mixed ionic-electronic conduction and then to predominant p-type electronic conduction.The total conductivity of the solid solutions showed a“V-shape”variation with increasing BNiT content.Possible mechanisms for the phase evolution and the conductivity-composition relationships are discussed.Achieving high levels of ionic and electronic conductivity simultaneously in NBT by introducing elements with variable oxidation states remains challenging due to the competition between an enhanced electronic component and a suppressed ionic component.Low levels of BNiT incorporation are,however,beneficial to reducing the dielectric loss of NBT for dielectric applications.展开更多
In the framework of nonperturbative quantum field theory, the critical phenomena of one-dimensionalextended Hubbard model (EHM) at half-filling are discussed from weak to intermediate interactions. After the EHMbeing ...In the framework of nonperturbative quantum field theory, the critical phenomena of one-dimensionalextended Hubbard model (EHM) at half-filling are discussed from weak to intermediate interactions. After the EHMbeing mapped into two decoupled sine-Gordon models, the ground state phase diagram of the system is derived in anexplicit way. It is confirmed that the coexisting phases appear in different interaction regimes which cannot be foundby conventional theoretical methods. The diagram shows that there are seven different phase regions in the groundstate, which seems not to be the same as previous discussions, especially the boundary between the phase separationand condensed phase regions. The phase transition properties of the model between various phase regions are studied indetail.展开更多
The temperature dependence of the magnetic properties was systemically studied by dc/ac magnetization and specific heat measurement for heavy rare earth HoCrO3 chromites.The results revealed the existence of complex p...The temperature dependence of the magnetic properties was systemically studied by dc/ac magnetization and specific heat measurement for heavy rare earth HoCrO3 chromites.The results revealed the existence of complex phase coexistence and competitive magnetic behavior in HoCrO3 chromites.It was found that,in the region of higher temperature above 141.0 K,HoCrO3 behaved as a typical Curie-Weiss paramagnetic（PM）.And in the region of low temperature,a novel magnetization behavior was observed with negative magnetization（diamagnetism-like） characteristics under an external field of 100 Oe and M-T curves exhibited two symmetrical branches for field cooling（FC） and zero field cooling（ZFC） modes.This behavior indicated the coexistence of canted antiferromagnetic（CAFM） and weak ferromagnetic（FM） phase.These also exhibited the existence of competition mechanism below characteristic temperature TN1=141.0 K and the magnetic order of Ho ion below 7.5 K.The current complex magnetization might be attributed to the interaction between paramagnetic Ho3＋ moments and canted Cr3＋ moments.展开更多
Replacement of samarium(Sm) with abundant yttrium(Y) can help solve the potential shortage of Sm in the preparation of promising Sm2 Fe17 Nx magnets.In this article,phase composition,microstructure and magnetic proper...Replacement of samarium(Sm) with abundant yttrium(Y) can help solve the potential shortage of Sm in the preparation of promising Sm2 Fe17 Nx magnets.In this article,phase composition,microstructure and magnetic properties of(Sm1-yYy)2 Fe17Nx(y=0,0.2,0.4,0.6,0.8,1.0) were investigated.Maximum energy product(BH)max is improved when less than 40 at% Y is doped in(Sm1-yYy)2 Fe17Nx powder.In particular,when 20 at% Y replaces Sm,(BH)max of(Sm1-yYy)2 Fe17Nx powder increases by 15.1% from 131.7 to151.6 kJ/m3.The effect of annealing temperature on the structural properties of high Y doping(Sm0.6Y0.4)2 Fe17 and the magnetic properties of the corresponding nitrides were subsequently investigated.In the RE2 Fe17 phase grain combination process,the interlaced structure of the rhombohedral Th2 Zn17-type structural phase and the hexagonal Th2 Ni17-type structural phase is formed.Due to shortrange exchange coupling,the nitride with the highest content of two interlaced RE2 Fe17 phases has the highest magnetic properties:Br=1.23 T,HcJ=443.9 kA/m and(BH)max=197.6 kJ/m3.展开更多
We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-base...We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-based atomic force microscope in ambient conditions, and the stacking particles form Au nanoparticle-aggregated nanowire while the nozzle retracts from the surface. Their mechanical properties with relatively low elastic modulus are in situ investigated by using the same apparatus.展开更多
An analysis of heterophase states was carried out for ferro-active solid solutions of the system(1-x-y)NaNbO_(3)-x KNbO_(3)-y CdNb_(2)O_(6).A complete stress relief at interfaces between phases in solid solutions with...An analysis of heterophase states was carried out for ferro-active solid solutions of the system(1-x-y)NaNbO_(3)-x KNbO_(3)-y CdNb_(2)O_(6).A complete stress relief at interfaces between phases in solid solutions with y=0.05 and x=0.10,0.40,and 0.45 is realized at the single-domain state of the tetragonal and orthorhombic phases.In solid solutions with y=0.05 and x=0.05 and 0.20,as well as with y=0.075 and 0.10,and x=0.15,the formation of a planar interphase boundary being parallel to a zero-net-strain plane occurs at the elastic matching of the single-domain tetragonal and polydomain orthorhombic phases.In contrast to this,at y=0.05 and x=0.25,0.30,and 0.35,the complete stress relief is associated with a co-existence of the single-domain orthorhombic and polydomain tetragonal phases,however in some cases,the tetragonal phase aims at a monodomainization.展开更多
The gas-liquid phase coexistence in a two-dimensional Lennard-Jones system is investigated using Maxwell construction method together with molecular dynamics simulations.The results of phase coexistence in different t...The gas-liquid phase coexistence in a two-dimensional Lennard-Jones system is investigated using Maxwell construction method together with molecular dynamics simulations.The results of phase coexistence in different truncations of the potential are compared with data obtained from the literature,and the corresponding critical properties calculated.The crossover from Ising-like to mean field behavior is observed and confirmed as the temperature approaches the critical point from below.Performing simulations on systems with different sizes,we find that a finite size effect is more significant than those shown in most of the previous results,and a lower critical temperature is obtained when the full extent of this finite size effect is considered.展开更多
A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single pa...A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei.展开更多
In this work,dielectric ultracapacitors were designed and fabricated using a combination of phase boundary and nanograin strategies.These ultracapacitors are based on submicron-thick Ba(Zr_(0.2)Ti_(0.8))O_(3) ferroele...In this work,dielectric ultracapacitors were designed and fabricated using a combination of phase boundary and nanograin strategies.These ultracapacitors are based on submicron-thick Ba(Zr_(0.2)Ti_(0.8))O_(3) ferroelectric films sputterdeposited on Si at 500℃.With a composition near a polymorphic phase boundary(PPB),a compressive strain,and a high nucleation rate due to the lowered deposition temperature,these films exhibit a columnar nanograined microstructure with gradient phases along the growth direction.Such a microstructure presents three-dimensional polarization inhomogeneities on the nanoscale,thereby significantly delaying the saturation of the overall electric polarization.Consequently,a pseudolinear,ultraslim polarization(P)-electric field(E)hysteresis loop was obtained,featuring a high maximum applicable electric field(~5.7 MV/cm),low remnant polarization(~5.2μC/cm^(2))and high maximum polarization(~92.1μC/cm^(2)).This P-E loop corresponds to a high recyclable energy density(W_(rec)~208 J/cm^(3))and charge‒discharge efficiency(~88%).An indepth electron microscopy study revealed that the gradient ferroelectric phases consisted of tetragonal(T)and rhombohedral(R)polymorphs along the growth direction of the film.The T-rich phase is abundant near the bottom of the film and gradually transforms into the R-rich phase near the surface.These films also exhibited a high Curie temperature of~460℃and stable capacitive energy storage up to 200℃.These results suggest a feasible pathway for the design and fabrication of high-performance dielectric film capacitors.展开更多
Received 26 June 2014;Revised 13 October 2014;Accepted 20 October 2014;Published 12 November 2014 Inhomogeneous states caused by the coexistence of the ferroelectric(FE)and antiferroelectric(AFE)phases in lead–zircon...Received 26 June 2014;Revised 13 October 2014;Accepted 20 October 2014;Published 12 November 2014 Inhomogeneous states caused by the coexistence of the ferroelectric(FE)and antiferroelectric(AFE)phases in lead–zirconate–titanate based solid solutions have been investigated.It has been found that the domains of the FE and AFE phases with sizes of the order of 20 nm to 30 nm coexist in the bulk of the samples due to a small difference in the free energies of these phases.The coherent character of the interphase boundaries(IPBs)leads to the concentration of the elastic stresses along these boundaries.These elastic stresses cause the local decomposition of the solid solution and formation of segregates near the IPBS due to the condition that equivalent positions of the crystal lattice are occupied by the ions with different sizes.The sizes of the segregates formed in this way are of the order 8 nm to 15 nm.Some physical effects caused by the presence of these segregate nanostructures are analyzed and discussed.展开更多
Barium titanate is a classical ferroelectric material that exhibits a jump-like behavior in the order parameter,spontaneous polarization,near the temperature of its transition to the paraelectric phase.This serves as ...Barium titanate is a classical ferroelectric material that exhibits a jump-like behavior in the order parameter,spontaneous polarization,near the temperature of its transition to the paraelectric phase.This serves as a textbook example of a first-order phase transition,marked by the coexistence of polar and non-polar phase regions.Despite compelling evidence of the gradual phase transformation across Curie temperature(TC)and partial retention of ferroelectric properties above TC,the microscopic mechanisms of the phase retention remain unclear.Current study explains temperature anomalies in the macroscopic characteristics of polycrystalline barium titanate by employing complementary macroscopic and local techniques.Our findings reveal that retention of the polar phase regions is driven by the charged defects,which act as the origin of the spatially non-uniform internal electric fields.The insights from this research offer a deeper understanding of the fundamental mechanisms governing ferroelectric behavior and open new possibilities for tailoring materials with phase coexistence for a wide range of technological applications.展开更多
Presented results demonstrate importance of taking into account such a phenomenon as the solid solution decomposition at the boundaries separating coexisting phases in lead zirconate-titanate-based solid solutions wit...Presented results demonstrate importance of taking into account such a phenomenon as the solid solution decomposition at the boundaries separating coexisting phases in lead zirconate-titanate-based solid solutions with compositions belonging to the morphotropic boundary region of the"temperature–composition"phase diagram.It is shown that in the local decomposition of solid solutions in the vicinity of the boundaries separating the tetragonal and rhombohedral phases in lead zirconate-titanate-based solid solutions lead to the changes of the solid solution's chemical composition and to the formation of segregates.It is also shown that the proper thermoelectric treatment of samples containing these segregates can give substantially higher values of piezoelectric parameters in the lead zirconate-titanate-based compounds.展开更多
InMarkov ChainMonte Carlo(MCMC)simulations,thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples.These samples are selected in accordance wit...InMarkov ChainMonte Carlo(MCMC)simulations,thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples.These samples are selected in accordance with the probability distribution function,known from the partition function of equilibrium state.As the stochastic error of the simulation results is significant,it is desirable to understand the variance of the estimation by ensemble average,which depends on the sample size(i.e.,the total number of samples in the set)and the sampling interval(i.e.,cycle number between two consecutive samples).Although large sample sizes reduce the variance,they increase the computational cost of the simulation.For a given CPU time,the sample size can be reduced greatly by increasing the sampling interval,while having the corresponding increase in variance be negligible if the original sampling interval is very small.In this work,we report a few general rules that relate the variance with the sample size and the sampling interval.These results are observed and confirmed numerically.These variance rules are derived for theMCMCmethod but are also valid for the correlated samples obtained using other Monte Carlo methods.The main contribution of this work includes the theoretical proof of these numerical observations and the set of assumptions that lead to them.展开更多
The phase behavior and evolution of self-organized assembling structures in the sodium alkylcarboxylate/fatty alcohol systems were investigated by TEM. With increasing concentration of fatty alcohol, the micells trans...The phase behavior and evolution of self-organized assembling structures in the sodium alkylcarboxylate/fatty alcohol systems were investigated by TEM. With increasing concentration of fatty alcohol, the micells transform into lamellar La phase, sponge L3 phase, multilamellar vesicle, and transform back to lamellar La phase. At higher alcohol concentration, a stable two aqueous phase coexisting region has been observed in this kind of systems after aged two months. Unilamellar vesicles were found both in two separated phases but the vesicle density of the upper phase is much higher than that of me bottom phase.展开更多
文摘The thermophysical properties of expanded liquid mercury have been investigated along the liquid-vapor coexistence curve by using Monte Carlo and Molecular Dynamic simulations. For the purpose, an empirical state dependent interatomic potential for the region of dense metallic liquid is used, while the state dependence is not necessary near the cliffcal point. In order to test the validity of this potential, we determine the surface layering and the sound velocity, two properties very sensitive to the choice of the potential. Our results are in quite good agreement with other theoretical results and to the experimental data available in the literature.
文摘Non-equilibrium phases formed in melt-quenched CuIn（SexTe1-x）2 system, where x = 0.1, 0.2, 0.4, 0.5, 0.6, 0.8 and 0.9, have been studied using Rietveld refinement of the crystal structure and Raman spectroscopy. Results of structure refinement have showed that all the samples, except the CuIn（Se0.1Te0.9）2, are heterogeneous. All the observed non-equilibrium phases are quaternary system and are found to have chalcopyrite structure （I42d）, in accordance with the CuInTe2-CuInSe2 phase diagram. The lattice constants deduced from the refinement have showed linear variation with Se content. A detailed analysis of the characteristic Al modes present in the Raman spectrum of individual sample has corroborated the results obtained from the structure analysis. The position of Al mode of individual phase is found to vary linearly with Se content, which suggests that CuIn（SexTe1-x）2 system exhibits single-mode behaviour.
基金National Natural Science Foundation of China，the Foundation of Harbin Institute of Technology
文摘The transport properties of gluon in color space in a system of coexistence of both hadronic and QGP phases are investigated from the quantum transport equation of gluon.
基金supported by the National Natural Science Foundation of China(11402185)
文摘The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.
基金sponsored by the National Natural Science Founda-tion of China(Nos.52072239 and 52234010)the Natural Science Foundation of Chongqing,China(No.cstc2021jcyj-msxmX0720)the EPSRC(No.EP/L027348/1).
文摘Solid solutions of Na_(0.5) Bi_(0.5) TiO_(3)(NBT)and BiNi_(0.5) Ti_(0.5) O_(3)(BNiT)were prepared by a solid-state reaction route,and their electrical properties investigated by a combination of impedance spectroscopy and electromotive force measurements to explore the possibility of developing mixed ionic-electronic conductors based on NBT.Phase analysis showed that BNiT has a large solid solution limit in NBT(60 mol%based on X-ray diffraction),and the room temperature crystal structure changes from rhombohedral to pseudo-cubic with increasing BNiT content.Neutron diffraction revealed the coexistence of rhombohedral and tetragonal phases when the BNiT content≥40 mol%.Electrically,incorporation of BNiT induces p-type electronic conduction into NBT by hopping of holes between Ni^(2+)(Ni_(Ni)^(x))and Ni^(3+)(Ni·Ni),and therefore changes the electrical conduction mechanism systematically from predominant oxide-ion conduction to mixed ionic-electronic conduction and then to predominant p-type electronic conduction.The total conductivity of the solid solutions showed a“V-shape”variation with increasing BNiT content.Possible mechanisms for the phase evolution and the conductivity-composition relationships are discussed.Achieving high levels of ionic and electronic conductivity simultaneously in NBT by introducing elements with variable oxidation states remains challenging due to the competition between an enhanced electronic component and a suppressed ionic component.Low levels of BNiT incorporation are,however,beneficial to reducing the dielectric loss of NBT for dielectric applications.
文摘In the framework of nonperturbative quantum field theory, the critical phenomena of one-dimensionalextended Hubbard model (EHM) at half-filling are discussed from weak to intermediate interactions. After the EHMbeing mapped into two decoupled sine-Gordon models, the ground state phase diagram of the system is derived in anexplicit way. It is confirmed that the coexisting phases appear in different interaction regimes which cannot be foundby conventional theoretical methods. The diagram shows that there are seven different phase regions in the groundstate, which seems not to be the same as previous discussions, especially the boundary between the phase separationand condensed phase regions. The phase transition properties of the model between various phase regions are studied indetail.
基金Project supported by the National Natural Science Foundation of China (10774097,10875107)the Science & Technology Committee of Shanghai Municipality (08dj1400202)+1 种基金the Natural Science Foundation of Henan Province (092300410138,102300410108)the Doctoral Innovation Fund of Zhengzhou University of Light Industry (2010BSJJ027)
文摘The temperature dependence of the magnetic properties was systemically studied by dc/ac magnetization and specific heat measurement for heavy rare earth HoCrO3 chromites.The results revealed the existence of complex phase coexistence and competitive magnetic behavior in HoCrO3 chromites.It was found that,in the region of higher temperature above 141.0 K,HoCrO3 behaved as a typical Curie-Weiss paramagnetic（PM）.And in the region of low temperature,a novel magnetization behavior was observed with negative magnetization（diamagnetism-like） characteristics under an external field of 100 Oe and M-T curves exhibited two symmetrical branches for field cooling（FC） and zero field cooling（ZFC） modes.This behavior indicated the coexistence of canted antiferromagnetic（CAFM） and weak ferromagnetic（FM） phase.These also exhibited the existence of competition mechanism below characteristic temperature TN1=141.0 K and the magnetic order of Ho ion below 7.5 K.The current complex magnetization might be attributed to the interaction between paramagnetic Ho3＋ moments and canted Cr3＋ moments.
基金Project supported by State Key Laboratory of Rare Earth Permanent Magnetic Materials (SKLREPM17OF06)National Natural Science Foundation of China (U1802254+1 种基金51871201)Xinmiao Talent Planning of Zhejiang Province (2019R403055)。
文摘Replacement of samarium(Sm) with abundant yttrium(Y) can help solve the potential shortage of Sm in the preparation of promising Sm2 Fe17 Nx magnets.In this article,phase composition,microstructure and magnetic properties of(Sm1-yYy)2 Fe17Nx(y=0,0.2,0.4,0.6,0.8,1.0) were investigated.Maximum energy product(BH)max is improved when less than 40 at% Y is doped in(Sm1-yYy)2 Fe17Nx powder.In particular,when 20 at% Y replaces Sm,(BH)max of(Sm1-yYy)2 Fe17Nx powder increases by 15.1% from 131.7 to151.6 kJ/m3.The effect of annealing temperature on the structural properties of high Y doping(Sm0.6Y0.4)2 Fe17 and the magnetic properties of the corresponding nitrides were subsequently investigated.In the RE2 Fe17 phase grain combination process,the interlaced structure of the rhombohedral Th2 Zn17-type structural phase and the hexagonal Th2 Ni17-type structural phase is formed.Due to shortrange exchange coupling,the nitride with the highest content of two interlaced RE2 Fe17 phases has the highest magnetic properties:Br=1.23 T,HcJ=443.9 kA/m and(BH)max=197.6 kJ/m3.
基金supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 200983512)Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2013R1A6A3A03063900)the Brain Korea 21
文摘We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-based atomic force microscope in ambient conditions, and the stacking particles form Au nanoparticle-aggregated nanowire while the nozzle retracts from the surface. Their mechanical properties with relatively low elastic modulus are in situ investigated by using the same apparatus.
基金support of the Ministry of Science and Higher Education of the Russian Federation(State task in the field of scientific activity in 2023)Project No.FENW-2023-0010/(GZ0110/23-11-IF).
文摘An analysis of heterophase states was carried out for ferro-active solid solutions of the system(1-x-y)NaNbO_(3)-x KNbO_(3)-y CdNb_(2)O_(6).A complete stress relief at interfaces between phases in solid solutions with y=0.05 and x=0.10,0.40,and 0.45 is realized at the single-domain state of the tetragonal and orthorhombic phases.In solid solutions with y=0.05 and x=0.05 and 0.20,as well as with y=0.075 and 0.10,and x=0.15,the formation of a planar interphase boundary being parallel to a zero-net-strain plane occurs at the elastic matching of the single-domain tetragonal and polydomain orthorhombic phases.In contrast to this,at y=0.05 and x=0.25,0.30,and 0.35,the complete stress relief is associated with a co-existence of the single-domain orthorhombic and polydomain tetragonal phases,however in some cases,the tetragonal phase aims at a monodomainization.
基金supported by the National Natural Science Foundation of China(20903112,10972217)the Knowledge Innovation Program of Chinese Academy of Sciences(KJCX2-YW-L08)
文摘The gas-liquid phase coexistence in a two-dimensional Lennard-Jones system is investigated using Maxwell construction method together with molecular dynamics simulations.The results of phase coexistence in different truncations of the potential are compared with data obtained from the literature,and the corresponding critical properties calculated.The crossover from Ising-like to mean field behavior is observed and confirmed as the temperature approaches the critical point from below.Performing simulations on systems with different sizes,we find that a finite size effect is more significant than those shown in most of the previous results,and a lower critical temperature is obtained when the full extent of this finite size effect is considered.
基金Supported by National Natural Science Foundation of China(11375005)
文摘A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei.
基金the financial support from the Natural Science Foundation of Shandong Province(Nos.ZR2022ZD39,ZR2022ME031,ZR2023QB119,ZR2023QE138,ZR2020QE042,and ZR2022QB138)the National Natural Science Foundation of China(No.52002192)+3 种基金the Science,Education and Industry Integration Pilot Projects of Qilu University of Technology(Shandong Academy of Sciences)(Nos.2022GH018,2023PX062,and 2023PX041)the Training Plan Project of Qilu University of Technology(Nos.2023RCKY093 and 2023RCKY095)the support from the Jinan City Science and Technology Bureau(No.2021GXRC055)the Education Department of Hunan Province/Xiangtan University(No.KZ0807969)。
文摘In this work,dielectric ultracapacitors were designed and fabricated using a combination of phase boundary and nanograin strategies.These ultracapacitors are based on submicron-thick Ba(Zr_(0.2)Ti_(0.8))O_(3) ferroelectric films sputterdeposited on Si at 500℃.With a composition near a polymorphic phase boundary(PPB),a compressive strain,and a high nucleation rate due to the lowered deposition temperature,these films exhibit a columnar nanograined microstructure with gradient phases along the growth direction.Such a microstructure presents three-dimensional polarization inhomogeneities on the nanoscale,thereby significantly delaying the saturation of the overall electric polarization.Consequently,a pseudolinear,ultraslim polarization(P)-electric field(E)hysteresis loop was obtained,featuring a high maximum applicable electric field(~5.7 MV/cm),low remnant polarization(~5.2μC/cm^(2))and high maximum polarization(~92.1μC/cm^(2)).This P-E loop corresponds to a high recyclable energy density(W_(rec)~208 J/cm^(3))and charge‒discharge efficiency(~88%).An indepth electron microscopy study revealed that the gradient ferroelectric phases consisted of tetragonal(T)and rhombohedral(R)polymorphs along the growth direction of the film.The T-rich phase is abundant near the bottom of the film and gradually transforms into the R-rich phase near the surface.These films also exhibited a high Curie temperature of~460℃and stable capacitive energy storage up to 200℃.These results suggest a feasible pathway for the design and fabrication of high-performance dielectric film capacitors.
文摘Received 26 June 2014;Revised 13 October 2014;Accepted 20 October 2014;Published 12 November 2014 Inhomogeneous states caused by the coexistence of the ferroelectric(FE)and antiferroelectric(AFE)phases in lead–zirconate–titanate based solid solutions have been investigated.It has been found that the domains of the FE and AFE phases with sizes of the order of 20 nm to 30 nm coexist in the bulk of the samples due to a small difference in the free energies of these phases.The coherent character of the interphase boundaries(IPBs)leads to the concentration of the elastic stresses along these boundaries.These elastic stresses cause the local decomposition of the solid solution and formation of segregates near the IPBS due to the condition that equivalent positions of the crystal lattice are occupied by the ions with different sizes.The sizes of the segregates formed in this way are of the order 8 nm to 15 nm.Some physical effects caused by the presence of these segregate nanostructures are analyzed and discussed.
基金support of the Ministry of Science and Higher Education of the Russian Federation(state task FEUZ-2023-0017).
文摘Barium titanate is a classical ferroelectric material that exhibits a jump-like behavior in the order parameter,spontaneous polarization,near the temperature of its transition to the paraelectric phase.This serves as a textbook example of a first-order phase transition,marked by the coexistence of polar and non-polar phase regions.Despite compelling evidence of the gradual phase transformation across Curie temperature(TC)and partial retention of ferroelectric properties above TC,the microscopic mechanisms of the phase retention remain unclear.Current study explains temperature anomalies in the macroscopic characteristics of polycrystalline barium titanate by employing complementary macroscopic and local techniques.Our findings reveal that retention of the polar phase regions is driven by the charged defects,which act as the origin of the spatially non-uniform internal electric fields.The insights from this research offer a deeper understanding of the fundamental mechanisms governing ferroelectric behavior and open new possibilities for tailoring materials with phase coexistence for a wide range of technological applications.
文摘Presented results demonstrate importance of taking into account such a phenomenon as the solid solution decomposition at the boundaries separating coexisting phases in lead zirconate-titanate-based solid solutions with compositions belonging to the morphotropic boundary region of the"temperature–composition"phase diagram.It is shown that in the local decomposition of solid solutions in the vicinity of the boundaries separating the tetragonal and rhombohedral phases in lead zirconate-titanate-based solid solutions lead to the changes of the solid solution's chemical composition and to the formation of segregates.It is also shown that the proper thermoelectric treatment of samples containing these segregates can give substantially higher values of piezoelectric parameters in the lead zirconate-titanate-based compounds.
基金supported in part by the King Abdullah University of Science and Technology(KAUST)Center for Numerical Porous Media.In addition,S.Sun would also like to acknowledge the support of this study by a research award from King Abdulaziz City for Science and Technology(KACST)through a project entitled”Study of Sulfur Solubility using Thermodynamics Model and Quantum Chemistry”.
文摘InMarkov ChainMonte Carlo(MCMC)simulations,thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples.These samples are selected in accordance with the probability distribution function,known from the partition function of equilibrium state.As the stochastic error of the simulation results is significant,it is desirable to understand the variance of the estimation by ensemble average,which depends on the sample size(i.e.,the total number of samples in the set)and the sampling interval(i.e.,cycle number between two consecutive samples).Although large sample sizes reduce the variance,they increase the computational cost of the simulation.For a given CPU time,the sample size can be reduced greatly by increasing the sampling interval,while having the corresponding increase in variance be negligible if the original sampling interval is very small.In this work,we report a few general rules that relate the variance with the sample size and the sampling interval.These results are observed and confirmed numerically.These variance rules are derived for theMCMCmethod but are also valid for the correlated samples obtained using other Monte Carlo methods.The main contribution of this work includes the theoretical proof of these numerical observations and the set of assumptions that lead to them.
基金Project (Nos. 29773004, 29733110) supported by the National Natural Science Foundation of China
文摘The phase behavior and evolution of self-organized assembling structures in the sodium alkylcarboxylate/fatty alcohol systems were investigated by TEM. With increasing concentration of fatty alcohol, the micells transform into lamellar La phase, sponge L3 phase, multilamellar vesicle, and transform back to lamellar La phase. At higher alcohol concentration, a stable two aqueous phase coexisting region has been observed in this kind of systems after aged two months. Unilamellar vesicles were found both in two separated phases but the vesicle density of the upper phase is much higher than that of me bottom phase.
