Sn Se emerges as one of the most promising Te-free thermoelectric materials due to its strong anharmonicity and multiple valence bands structure.Recently,compositing has been proven effective in optimizing thermoelect...Sn Se emerges as one of the most promising Te-free thermoelectric materials due to its strong anharmonicity and multiple valence bands structure.Recently,compositing has been proven effective in optimizing thermoelectric performance of various metal chalcogenides.Herein,a series of Sn Se-x Cu_(2)S(x=0,0.5%,1%,3%,5%)materials have been fabricated via solution synthesis,particle blending,and spark plasma sintering in sequence.After incorporating Cu_(2)S,the materials become Sn Se based composites with Cu doping,S substitution and Cu_(2)Sn Se_(3)secondary phase.We elucidate that the power factor of polycrystalline Sn Se can be tuned and enhanced at varied temperature ranges through adjusting the addition amount of Cu_(2)S.Additionally,the composites achieve suppressed lattice thermal conductivity when compared to Sn Se itself,as the introduced point defects and Sn Se/Cu_(2)Sn Se_(3)interfaces intensify phonon scattering.Consequently,Sn Se-0.5%Cu_(2)S and Sn Se-3%Cu_(2)S achieve a peak z T of 0.70 at 830 K(intermediate temperature range)and a highly increased z T of 0.28 at 473 K(low temperature range),respectively,which are~130%and 200%of values reached by Sn Se at the corresponding temperatures.The study demonstrates that our approach,which combines compositing with elemental doping and substitution,is effective in optimizing the thermoelectric performance of Sn Se at varied temperature ranges.展开更多
This review covers the major reactions involved in the solution synthesis of nanomaterials.It was designed to classify the traditional strategies such as precipitation,reduction,seed growth,etching,and so on into two ...This review covers the major reactions involved in the solution synthesis of nanomaterials.It was designed to classify the traditional strategies such as precipitation,reduction,seed growth,etching,and so on into two basic processes which are termed as bottom-up and top-down routines.The discussion is focused on the basic mechanism and principles during the nudeation and growth of nanocrystals,especially in the solution system.This review also presents a prediction for how to utilize these intrinsic processes to artificially construct the desired specific and functional nanostructures.We try to describe the most directive and effective way to control the structures of nanocrystals for researchers who can master the major reaction mechanism and grasp the basic technologies in synthetic nanoscience.展开更多
Ni-Y2O3 nanocomposite powder with uniform distribution of fine oxide particles in the metal matrix was successfully fabricated via solution combustion process followed by hydrogen reduction. The combustion behavior wa...Ni-Y2O3 nanocomposite powder with uniform distribution of fine oxide particles in the metal matrix was successfully fabricated via solution combustion process followed by hydrogen reduction. The combustion behavior was investigated by DTA-TG analysis. The influence of urea to nickel nitrate（U/Ni） ratio on the combustion behavior and morphology evolution of the combusted powder was investigated. The morphological characteristics and phase transformation of the combusted powder and the reduced powder were characterized by FESEM, TEM and XRD. The HRTEM image of Ni-Y2O3 nanocomposite powder indicated that Y2O3 particles with average particle size of about 10 nm dispersed uniformly in the nickel matrix.展开更多
The Cu/CeO_(2)nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis(SCS).The phase composition,surface morphology and optical characteristics of Cu/CeO_(2)...The Cu/CeO_(2)nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis(SCS).The phase composition,surface morphology and optical characteristics of Cu/CeO_(2)were studied.The results show that the SCS products are composed of cubic fluorite CeO_(2)and Cu.Due to the generation and escape of gas during the synthetic reaction,the SCS CeO_(2)shows porous structure,in which the mesopores(diameter 10-17 nm)nest in the wall of large pores(diameter80-300 nm).X-ray photoelectron spectroscopy(XPS)outcomes indicate that the oxygen vacancy concentration of CeO_(2)increases(18.97%-30.93%)with the increase of Cu concentration.The decoration of Cu greatly enhances the catalytic activity of CeO_(2)nanomaterials.30 wt%Cu/CeO_(2)composite material shows the best photocatalytic activities for the degradation of methyl orange(MO)(95.99%),which is about 4.3times that of CeO_(2)at the same time(120 min).UV-vis diffuse reflectance spectroscopy(DRS)results show that the semiconductor band gap is reduced with the addition of metallic Cu,which leads to the enhancement of photocatalytic activity.The free radical trapping experiments demonstrate that·O_(2)-and h+are the main active species in the photocatalytic degradation of MO.Based on the above results,a hypothesized mechanism for enhanced photocatalysis of Cu/CeO_(2)nanomaterials was proposed:the porous structure provides more reactive sites and channels for mass transfer,and the presence of metallic Cu improves the oxygen vacancy concentration of CeO_(2)and then promotes charge-carrier separation,which helps enhance the photocatalytic performance of Cu/CeO_(2).展开更多
Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating ...Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.展开更多
This paper describes a combinatorial Synthesis of the Mannich Bases in Solution through the Mannich reaction using 3 ketones, 5 amines and formaldehyde in solution and hydrochloride as a catalyst and then using a macr...This paper describes a combinatorial Synthesis of the Mannich Bases in Solution through the Mannich reaction using 3 ketones, 5 amines and formaldehyde in solution and hydrochloride as a catalyst and then using a macroporous quarterized ammonium resin (CO32- form) as a scavenge agent to remove the acid catalyst when the Mannich reaction is completed. It was found by GC/MS analysis that the symmetrical ketone, such as acetone, in the Mannich reaction mainly produces one Mannich base; while the asymmetrical ketone, such as 2-pentanone, gives two Mannich bases. The reactivity depends on the tereo-hinder of both ketones and amines.展开更多
The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studie...The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.展开更多
Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characterist...Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.展开更多
Ultrafine Fe3O4 powder was successfully synthesized via a novel ageing process from a precursor FeO（OH）, which was the hydrolysate of FeCl3 in the urea solution. The structure of as-synthesized powder was characteri...Ultrafine Fe3O4 powder was successfully synthesized via a novel ageing process from a precursor FeO（OH）, which was the hydrolysate of FeCl3 in the urea solution. The structure of as-synthesized powder was characterized by X-ray diffraction （XRD）, and the morphology of these nanoparticles was investigated using a transmission electron microscope （TEM）. Pure phase Fe3O4 was obtained and the mean diameter of these nanoparticles was about 21 nm.Furthermore, the study indicated that the precursor FeO（OH） played an important role in the formation of Fe3O4 nanoparticles. The mechanism was also discussed.展开更多
The synthesis of active electrode materials at room temperature is one of the effective strategies to reduce the fabrication cost of sodium ion batteries(SIBs).Herein,a layered material(Na_(2)[(VO)_(2)(HPO_(4))_(2)C_(...The synthesis of active electrode materials at room temperature is one of the effective strategies to reduce the fabrication cost of sodium ion batteries(SIBs).Herein,a layered material(Na_(2)[(VO)_(2)(HPO_(4))_(2)C_(2)O_(4)]·2H_(2)O,abbreviated as NVPC followingly)with open-framework structures has been successfully prepared at room temperature under ambient conditions and is evaluated as a cathode for SIBs.It is revealed that NVPC cathode can deliver a maximum reversible capacity of ca.70 mAh/g at 10 mA/g,and exhibit superior rate capability and cycling performance:at 50 mA/g,maximum reversible capacity ca.50 m Ah/g with capacity retention of 88.4%over 250 cycles corresponds to only 0.046%capacity decay per cycle;at 100 mA/g,a maximum reversible capacity of 35 mAh/g with capacity retention of60.9%over 500 cycles.This study demonstrates a practical example of a low-cost synthesis of the cathode materials for SIBs.At the same time,the systematic electrochemical research results also show promising prospects for long lifespan low-cost SIBs.展开更多
In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nan...In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nanopowders with different La_(2)O_(3) doping amount(0.5~5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La_(2)O_(3) addition,the product synthesized by SCS changed from needle-like W_(18) O_(49) to irregularly granulated H0.53 WO3 and the complete reduction temperature also increased form 700°C to 850°C. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La_(2)O_(3) was enhanced as the La_2O_3 addition increased. Nevertheless, due to the optimal size and distribution of La_(2)O_(3) particles,the sample with 2.0 wt% La_(2)O_(3) addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv0.2, which are the best compared with the literature.展开更多
Porous LiNiVO4 powder was synthesized via solution combustion synthesis method using lithium nitrate, nickel nitrate,ammonium metavanadate and citric acid as raw materials. Thermogravimetry (TG) and differential scann...Porous LiNiVO4 powder was synthesized via solution combustion synthesis method using lithium nitrate, nickel nitrate,ammonium metavanadate and citric acid as raw materials. Thermogravimetry (TG) and differential scanning calorimetry (DSC),X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) were used toevaluate the structures and morphologies of samples. The results show that the calcination temperature has significant effect on thecrystallinity and morphologies. Pure LiNiVO4 flaky nanoparticles with a mean particle size around 20 nm can be readily prepared bycalcining the precursor in air at 500 °C for 2 h. As a cathode material for lithium-ion batteries, the porous LiNiVO4 powder exhibits agood structural reversibility.展开更多
As the most important nanoporous material, zeolites, which have intricate micropores, are essential heterogeneous catalysts in industrial processes. Zeolites are generally synthesized with organic templates under hydr...As the most important nanoporous material, zeolites, which have intricate micropores, are essential heterogeneous catalysts in industrial processes. Zeolites are generally synthesized with organic templates under hydrothermal conditions; however, this method is environmentally unfriendly and costly due to the formation of harmful gases and polluted water. This article briefly summarizes the role of organic templates and describes designed routes for the organotemplate-free synthesis of zeolites, aided by zeolite seeds and zeolite seeds solution. Furthermore, this review explicates that the micmpore volume decreases with an increase of the Si/Al ratios in the organotemplate-free synthesis of zeolite products, where Na^＋ exists as an alkali cation. This feature is very important in directing the synthesis of zeolite catalysts with controllable Si/AI ratios under organotemplate-free conditions, and is thus important for the efficient design of zeolites.展开更多
Nano-pelletα-Al_(2)O_(3) was prepared using aluminum nitrate as precursor and urea as fuel by a fast method of solution combustion synthesis.The formation of the nano material was dependent on the molar ratio of fuel...Nano-pelletα-Al_(2)O_(3) was prepared using aluminum nitrate as precursor and urea as fuel by a fast method of solution combustion synthesis.The formation of the nano material was dependent on the molar ratio of fuel/oxidant,calcination temperature,and foreign metallic ions.The prerequisite conditions of the formation were a suitable fuel/oxidant molar ratio larger than two and calcination temperature higher than 673 K.Foreign ions,Ce^(4+) or Co^(2+),hindered this formation via promoting the generation of stable penta-coordinated Al^(3+) ions due to strong interaction with alumina,were revealed by ^(27)Al NMR spectra.Such Al^(3+) ions were recognized as a critical intermediate state for the phase transformation of alumina and their presence deterred the transformation.The nano-pellet morphology of the product demonstrated a specific surface area of 69 m^(2)/g,of which the external surface area occupied 59 m^(2)/g.It was found that the supported cobalt acetate on such nano-pellets existed as nanoparticles attached to the external surface,evidenced by the TEM characterization.The prepared catalyst could efficiently catalyze the selective oxidation of cyclohexane under the reaction condition of pressure under 0.8 MPa,temperature at 373 K,and time for 4 hours.The conversion of the reaction achieved up to 7.9%;while the cyclohexanone selectivity was 42.7%and the cyclohexanone and cyclohexanol selectivity was 91.6%.This catalytic performance recommends the supported cobalt acetate on the inert nano-pellet a-Al_(2)O_(3) as a promising catalyst for the selective oxidation of cyclohexane.展开更多
The calcium-doped ZnO nanoparticles,Zn1-xCaxO(x=0,0.025,0.05,0.075)were prepared by the solution combustion method.The synthesized nanoparticles were characterized by various techniques such as XRD,FTIR,Raman,FE...The calcium-doped ZnO nanoparticles,Zn1-xCaxO(x=0,0.025,0.05,0.075)were prepared by the solution combustion method.The synthesized nanoparticles were characterized by various techniques such as XRD,FTIR,Raman,FESEM-EDX,PL,Impedance,and UV-Vis.The Rietveld refinement of the X-ray diffractogram yields the crystalline structure and lattice parameters.Also,the XRD analysis shows that the substitution of Ca into ZnO does not alter the Wurtzite structure of ZnO.The crystallite size of the samples,calculated using the Scherer equation,was found to be between 46 nm and 92 nm.FTIR spectra detect the ZnO-related vibration modes of the samples.The FESEM morphological images suggest the spherical shape of the synthesized nanoparticles.The EDAX spectra identify the presence of Zn,Ca,and O atoms in the samples.The Raman active modes of the ZnO phase were identified by Raman spectral analysis.The analysis of Photoluminescence(PL)spectra gives information about the UV emission and other visible bands corresponding to violet,blue,and green emission representing different intrinsic defects in synthesized nanoparticles.Using UV-vis spectroscopy,the optical transparency and band gap values were examined.The energy band gap obtained by Tauc’s plot was decreased with the increase in Ca doping.Impedance analysis shows that the grain conductivity increased with the increase in dopant concentration.Contrarily,the total conductivity decreased with the increasing doping concentration due to increased grain boundary resistance.The proposed work demonstrates the changes in microstructure,electrical conductivity,and optical bandgap energy with Ca-doping.These synthesized Ca-doped ZnO nanoparticles could be promising materials for photocatalytic applications.展开更多
Composition/structure-dependent superconductivity for FeSe-based superconductors attracted great attention not only due to their high superconducting transition temperatures(TC),but also for understanding the origin o...Composition/structure-dependent superconductivity for FeSe-based superconductors attracted great attention not only due to their high superconducting transition temperatures(TC),but also for understanding the origin of iron-based superconductivity.Here,we report a new Fe-poor organic-inorganic hybrid material Fe_(14)Se_(16)(tepa)0.8 with a paramagnetic-diamagnetic transition at∼42 K grown by a high-temperature organic-solution-phase method with soluble iron/selenium sources in a tepa solution,alternative to previous intercalation strategies.The Fe_(14)Se_(16)(tepa)0.8 phase is in a tetragonal layered hybrid structure with a nanoplate shape.Composition analyses reveal a Fe-poor characteristic of the hybrid in contrast to previous FeSe-intercalated superconductor,and selected area electron diffraction pattern is featured by Fe_(3)Se_(4) superstructures with a√2×√2 of Fe vacancy order.Ab initio density functional calculations show that minus Fe_(3)Se_(4) ions are stable in the hybrid and∼0.25e-/Fe_(0.75)Se is obviously larger than the reported values of approximately 0.2e-/FeSe in other FeSe-intercalated superconductors.Typical hysteresis loops and temperature dependence of dc/ac susceptibilities of the Fe_(14)Se_(16)(tepa)0.8 measured below∼42 K suggest a presence of the Meissner effect in this material.Effects of synthesis conditions on structures and magnetic properties of the hybrids show a magnetic evolution from a long-range ferrimagnetic(FIM)order of Fe_(14)Se_(16)(tepa)to a coexistence of FIM and superconducting(SC)orders of Fe_(14)Se_(16)(tepa)0.9 and an SC order of Fe_(14)Se_(16)(tepa)0.8.X-ray absorption spectrum(XAS)confirms the presence of ferric/ferrous irons.Mössbauer studies reveal that the high-TC superconductivity originates from a suppression of the FIM order through tuning the spin states of irons from high-spin Fe^(3+)(S=5/2)and Fe^(2+)(S=2)in the Fe_(14)Se_(16)(tepa)to low-spin Fe^(3+)(S=1/2)and Fe^(2+)(S=0)in the Fe_(14)Se_(16)(tepa)0.8.Although no zero resistance is detected even at a temperature of 2 K,the resistivity at 2 K decreases by more than 1600 times compared to that in a normal state calculated by a variable range hopping(VRH)model,suggesting that the high-TC superconductivity of Fe_(14)Se_(16)(tepa)0.8 is possible.展开更多
CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS acti...CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.展开更多
Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. I...Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.展开更多
A comparative study was conducted by using solution combustion synthesis with three different doping routes(liquid-liquid(WL10), liquid-solid(WLNO) and solid-solid(WLO)) to produce nanoscale powders and further fabric...A comparative study was conducted by using solution combustion synthesis with three different doping routes(liquid-liquid(WL10), liquid-solid(WLNO) and solid-solid(WLO)) to produce nanoscale powders and further fabricate the ultrafine-grained W-1.0 wt.%La2O3 alloys by pressureless sintering. Compared with pure tungsten, W-1.0 wt.%La2O3 alloys exhibit ultrafine grains and excellent mechanical properties. After sintering, the average grain size of the WLO sample is larger than that of WL10 and WLNO samples;the microhardness values of WL10 and WLNO samples are similar but larger than the value of WLO sample. The optimized La2O3 particles are obtained in the WL10 sample after sintering at 1500 ℃ with the minimum mean size by comparing with WLNO and WLO samples, which are uniformly distributed either at grain boundaries or in the grain interior with the sizes of(57±29.7) and(27±13.1) nm, respectively. This study exhibits ultrafine microstructure and outperforming mechanical properties of the W-1.0 wt.%La2O3 alloy via the liquid-liquid doping route, as compared with conventionally-manufactured tungsten materials.展开更多
Ce-substituted lithium ferrite, Li0.5CexFe2.5-x04 （x = 0, 0.05 and 0.1 ） compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at ...Ce-substituted lithium ferrite, Li0.5CexFe2.5-x04 （x = 0, 0.05 and 0.1 ） compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at unity. The thermal decomposition process was investigated by thermogravimetry-differential thermal analysis, which showed a stable phase formation above 600 ℃. The phase composition and molecular bonding of Li0.5CexFe2.5_x04 were characterized by X-ray powder diffraction analysis and Fourier transform infrared spectroscopy, respectively. An extensive study of electrical relaxation process has been represented with impedance and modulus as a function of frequency at different temperatures. The activation energy obtained from both the formalisms was found to be equal within the error. The dc conductivity and hopping frequency were thermally activated and their activation energies were found to be in the range of 0.69-0.64 eV for x = 0.05. The scaling of modulus and impedance were used to understand the electrical relaxation behaviour of the compositions and they suggest the time temperature superposition principle.展开更多
基金the National Natural Science Foundation of China(Nos.51802034,11674040,51672270,11904039)the Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2018jcyj AX0346)+1 种基金the Chongqing Entrepreneurship and Innovation Program for the Returned Overseas Chinese Scholars(No.cx2018020)the Fundamental Research Funds for the Central Universities(No.2019CDQYCL003)。
文摘Sn Se emerges as one of the most promising Te-free thermoelectric materials due to its strong anharmonicity and multiple valence bands structure.Recently,compositing has been proven effective in optimizing thermoelectric performance of various metal chalcogenides.Herein,a series of Sn Se-x Cu_(2)S(x=0,0.5%,1%,3%,5%)materials have been fabricated via solution synthesis,particle blending,and spark plasma sintering in sequence.After incorporating Cu_(2)S,the materials become Sn Se based composites with Cu doping,S substitution and Cu_(2)Sn Se_(3)secondary phase.We elucidate that the power factor of polycrystalline Sn Se can be tuned and enhanced at varied temperature ranges through adjusting the addition amount of Cu_(2)S.Additionally,the composites achieve suppressed lattice thermal conductivity when compared to Sn Se itself,as the introduced point defects and Sn Se/Cu_(2)Sn Se_(3)interfaces intensify phonon scattering.Consequently,Sn Se-0.5%Cu_(2)S and Sn Se-3%Cu_(2)S achieve a peak z T of 0.70 at 830 K(intermediate temperature range)and a highly increased z T of 0.28 at 473 K(low temperature range),respectively,which are~130%and 200%of values reached by Sn Se at the corresponding temperatures.The study demonstrates that our approach,which combines compositing with elemental doping and substitution,is effective in optimizing the thermoelectric performance of Sn Se at varied temperature ranges.
基金supported by the Fundamental Research Funds for the Central Universities(WK2060190043 and WK2060190053)the National Natural Science Foundation of China(21521091,21131004,21390393,U1463202 and 21522107)
文摘This review covers the major reactions involved in the solution synthesis of nanomaterials.It was designed to classify the traditional strategies such as precipitation,reduction,seed growth,etching,and so on into two basic processes which are termed as bottom-up and top-down routines.The discussion is focused on the basic mechanism and principles during the nudeation and growth of nanocrystals,especially in the solution system.This review also presents a prediction for how to utilize these intrinsic processes to artificially construct the desired specific and functional nanostructures.We try to describe the most directive and effective way to control the structures of nanocrystals for researchers who can master the major reaction mechanism and grasp the basic technologies in synthetic nanoscience.
基金Project(2132046)supported by the Beijing Natural Science Foundation,ChinaProject(51104007)supported by the National Natural Science Foundation of China
文摘Ni-Y2O3 nanocomposite powder with uniform distribution of fine oxide particles in the metal matrix was successfully fabricated via solution combustion process followed by hydrogen reduction. The combustion behavior was investigated by DTA-TG analysis. The influence of urea to nickel nitrate（U/Ni） ratio on the combustion behavior and morphology evolution of the combusted powder was investigated. The morphological characteristics and phase transformation of the combusted powder and the reduced powder were characterized by FESEM, TEM and XRD. The HRTEM image of Ni-Y2O3 nanocomposite powder indicated that Y2O3 particles with average particle size of about 10 nm dispersed uniformly in the nickel matrix.
基金Project supported by the Fundamental Research Funds for the Central Universities(2019ZDPY20)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21_2199)。
文摘The Cu/CeO_(2)nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis(SCS).The phase composition,surface morphology and optical characteristics of Cu/CeO_(2)were studied.The results show that the SCS products are composed of cubic fluorite CeO_(2)and Cu.Due to the generation and escape of gas during the synthetic reaction,the SCS CeO_(2)shows porous structure,in which the mesopores(diameter 10-17 nm)nest in the wall of large pores(diameter80-300 nm).X-ray photoelectron spectroscopy(XPS)outcomes indicate that the oxygen vacancy concentration of CeO_(2)increases(18.97%-30.93%)with the increase of Cu concentration.The decoration of Cu greatly enhances the catalytic activity of CeO_(2)nanomaterials.30 wt%Cu/CeO_(2)composite material shows the best photocatalytic activities for the degradation of methyl orange(MO)(95.99%),which is about 4.3times that of CeO_(2)at the same time(120 min).UV-vis diffuse reflectance spectroscopy(DRS)results show that the semiconductor band gap is reduced with the addition of metallic Cu,which leads to the enhancement of photocatalytic activity.The free radical trapping experiments demonstrate that·O_(2)-and h+are the main active species in the photocatalytic degradation of MO.Based on the above results,a hypothesized mechanism for enhanced photocatalysis of Cu/CeO_(2)nanomaterials was proposed:the porous structure provides more reactive sites and channels for mass transfer,and the presence of metallic Cu improves the oxygen vacancy concentration of CeO_(2)and then promotes charge-carrier separation,which helps enhance the photocatalytic performance of Cu/CeO_(2).
基金Project supported bythe National Natural Science Foundation of China (50306008) and the Fund fromthe Preli minary Research Project of General Equipment Ministry (41328030507)
文摘Perovskite LaMnO3 powders with an average crystallite size of 12.5 nm were rapidly synthesized via a microwave-induced autocombustion reaction using glycine as a fuel and nitrate as an oxidant. After self-propagating combustion, the desired nanocrystalline perovskite LaMnO3 was obtained and no further calcination was carried out. The possible processes of combustion reaction were discussed according to the principle of propellant chemistry. The autocombustion and thermal decomposition of the precursor were investigated using the TG-DTA and FT-IR techniques. The influences of glycine-nitrate molar ratio and heat-treatment temperature on the perovskite phase formation and crystallite size of as-burnt powder were studied by XRD. The morphology and size of the as-burnt powder before and after milling were characterized and compared by TEM.
基金National Natural Science Foundation of China (29674915, 29844001).
文摘This paper describes a combinatorial Synthesis of the Mannich Bases in Solution through the Mannich reaction using 3 ketones, 5 amines and formaldehyde in solution and hydrochloride as a catalyst and then using a macroporous quarterized ammonium resin (CO32- form) as a scavenge agent to remove the acid catalyst when the Mannich reaction is completed. It was found by GC/MS analysis that the symmetrical ketone, such as acetone, in the Mannich reaction mainly produces one Mannich base; while the asymmetrical ketone, such as 2-pentanone, gives two Mannich bases. The reactivity depends on the tereo-hinder of both ketones and amines.
文摘The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.
基金Project(51104007)supported by the National Natural Science Foundation of ChinaProject(2132046)supported by Beijing Natural Science Foundation,China
文摘Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.
文摘Ultrafine Fe3O4 powder was successfully synthesized via a novel ageing process from a precursor FeO（OH）, which was the hydrolysate of FeCl3 in the urea solution. The structure of as-synthesized powder was characterized by X-ray diffraction （XRD）, and the morphology of these nanoparticles was investigated using a transmission electron microscope （TEM）. Pure phase Fe3O4 was obtained and the mean diameter of these nanoparticles was about 21 nm.Furthermore, the study indicated that the precursor FeO（OH） played an important role in the formation of Fe3O4 nanoparticles. The mechanism was also discussed.
基金financially supported by the National Natural Science Foundation of China(No.21805278)。
文摘The synthesis of active electrode materials at room temperature is one of the effective strategies to reduce the fabrication cost of sodium ion batteries(SIBs).Herein,a layered material(Na_(2)[(VO)_(2)(HPO_(4))_(2)C_(2)O_(4)]·2H_(2)O,abbreviated as NVPC followingly)with open-framework structures has been successfully prepared at room temperature under ambient conditions and is evaluated as a cathode for SIBs.It is revealed that NVPC cathode can deliver a maximum reversible capacity of ca.70 mAh/g at 10 mA/g,and exhibit superior rate capability and cycling performance:at 50 mA/g,maximum reversible capacity ca.50 m Ah/g with capacity retention of 88.4%over 250 cycles corresponds to only 0.046%capacity decay per cycle;at 100 mA/g,a maximum reversible capacity of 35 mAh/g with capacity retention of60.9%over 500 cycles.This study demonstrates a practical example of a low-cost synthesis of the cathode materials for SIBs.At the same time,the systematic electrochemical research results also show promising prospects for long lifespan low-cost SIBs.
基金financially supported by the National Key R&D Program of China (2017YFB0306000 and 2017YFB0305600)the National Natural Science Foundation Program of China (51574031,51604239,51604240 and 51674095)+2 种基金the Natural Science Foundation Program of Beijing (2162027)the General Project of the Education Department of Hunan Province (15C1308)the Fundamental Research Funds for the Central Universities(JZ2017HGBZ0920)。
文摘In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nanopowders with different La_(2)O_(3) doping amount(0.5~5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La_(2)O_(3) addition,the product synthesized by SCS changed from needle-like W_(18) O_(49) to irregularly granulated H0.53 WO3 and the complete reduction temperature also increased form 700°C to 850°C. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La_(2)O_(3) was enhanced as the La_2O_3 addition increased. Nevertheless, due to the optimal size and distribution of La_(2)O_(3) particles,the sample with 2.0 wt% La_(2)O_(3) addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv0.2, which are the best compared with the literature.
文摘Porous LiNiVO4 powder was synthesized via solution combustion synthesis method using lithium nitrate, nickel nitrate,ammonium metavanadate and citric acid as raw materials. Thermogravimetry (TG) and differential scanning calorimetry (DSC),X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) were used toevaluate the structures and morphologies of samples. The results show that the calcination temperature has significant effect on thecrystallinity and morphologies. Pure LiNiVO4 flaky nanoparticles with a mean particle size around 20 nm can be readily prepared bycalcining the precursor in air at 500 °C for 2 h. As a cathode material for lithium-ion batteries, the porous LiNiVO4 powder exhibits agood structural reversibility.
基金This work was supported by the National Natural Science Foundation of China （21273197 and 21333009）.
文摘As the most important nanoporous material, zeolites, which have intricate micropores, are essential heterogeneous catalysts in industrial processes. Zeolites are generally synthesized with organic templates under hydrothermal conditions; however, this method is environmentally unfriendly and costly due to the formation of harmful gases and polluted water. This article briefly summarizes the role of organic templates and describes designed routes for the organotemplate-free synthesis of zeolites, aided by zeolite seeds and zeolite seeds solution. Furthermore, this review explicates that the micmpore volume decreases with an increase of the Si/Al ratios in the organotemplate-free synthesis of zeolite products, where Na^＋ exists as an alkali cation. This feature is very important in directing the synthesis of zeolite catalysts with controllable Si/AI ratios under organotemplate-free conditions, and is thus important for the efficient design of zeolites.
基金Funded by the Yangfan Project of Guangdong Province(No.2015YT02C089)the Natural Science Foundation of Shandong Province(No.ZR2020MB113)。
文摘Nano-pelletα-Al_(2)O_(3) was prepared using aluminum nitrate as precursor and urea as fuel by a fast method of solution combustion synthesis.The formation of the nano material was dependent on the molar ratio of fuel/oxidant,calcination temperature,and foreign metallic ions.The prerequisite conditions of the formation were a suitable fuel/oxidant molar ratio larger than two and calcination temperature higher than 673 K.Foreign ions,Ce^(4+) or Co^(2+),hindered this formation via promoting the generation of stable penta-coordinated Al^(3+) ions due to strong interaction with alumina,were revealed by ^(27)Al NMR spectra.Such Al^(3+) ions were recognized as a critical intermediate state for the phase transformation of alumina and their presence deterred the transformation.The nano-pellet morphology of the product demonstrated a specific surface area of 69 m^(2)/g,of which the external surface area occupied 59 m^(2)/g.It was found that the supported cobalt acetate on such nano-pellets existed as nanoparticles attached to the external surface,evidenced by the TEM characterization.The prepared catalyst could efficiently catalyze the selective oxidation of cyclohexane under the reaction condition of pressure under 0.8 MPa,temperature at 373 K,and time for 4 hours.The conversion of the reaction achieved up to 7.9%;while the cyclohexanone selectivity was 42.7%and the cyclohexanone and cyclohexanol selectivity was 91.6%.This catalytic performance recommends the supported cobalt acetate on the inert nano-pellet a-Al_(2)O_(3) as a promising catalyst for the selective oxidation of cyclohexane.
文摘The calcium-doped ZnO nanoparticles,Zn1-xCaxO(x=0,0.025,0.05,0.075)were prepared by the solution combustion method.The synthesized nanoparticles were characterized by various techniques such as XRD,FTIR,Raman,FESEM-EDX,PL,Impedance,and UV-Vis.The Rietveld refinement of the X-ray diffractogram yields the crystalline structure and lattice parameters.Also,the XRD analysis shows that the substitution of Ca into ZnO does not alter the Wurtzite structure of ZnO.The crystallite size of the samples,calculated using the Scherer equation,was found to be between 46 nm and 92 nm.FTIR spectra detect the ZnO-related vibration modes of the samples.The FESEM morphological images suggest the spherical shape of the synthesized nanoparticles.The EDAX spectra identify the presence of Zn,Ca,and O atoms in the samples.The Raman active modes of the ZnO phase were identified by Raman spectral analysis.The analysis of Photoluminescence(PL)spectra gives information about the UV emission and other visible bands corresponding to violet,blue,and green emission representing different intrinsic defects in synthesized nanoparticles.Using UV-vis spectroscopy,the optical transparency and band gap values were examined.The energy band gap obtained by Tauc’s plot was decreased with the increase in Ca doping.Impedance analysis shows that the grain conductivity increased with the increase in dopant concentration.Contrarily,the total conductivity decreased with the increasing doping concentration due to increased grain boundary resistance.The proposed work demonstrates the changes in microstructure,electrical conductivity,and optical bandgap energy with Ca-doping.These synthesized Ca-doped ZnO nanoparticles could be promising materials for photocatalytic applications.
基金supported by the National Natural Science Foundation of China(Nos.52371203,51971221 and 52031014).
文摘Composition/structure-dependent superconductivity for FeSe-based superconductors attracted great attention not only due to their high superconducting transition temperatures(TC),but also for understanding the origin of iron-based superconductivity.Here,we report a new Fe-poor organic-inorganic hybrid material Fe_(14)Se_(16)(tepa)0.8 with a paramagnetic-diamagnetic transition at∼42 K grown by a high-temperature organic-solution-phase method with soluble iron/selenium sources in a tepa solution,alternative to previous intercalation strategies.The Fe_(14)Se_(16)(tepa)0.8 phase is in a tetragonal layered hybrid structure with a nanoplate shape.Composition analyses reveal a Fe-poor characteristic of the hybrid in contrast to previous FeSe-intercalated superconductor,and selected area electron diffraction pattern is featured by Fe_(3)Se_(4) superstructures with a√2×√2 of Fe vacancy order.Ab initio density functional calculations show that minus Fe_(3)Se_(4) ions are stable in the hybrid and∼0.25e-/Fe_(0.75)Se is obviously larger than the reported values of approximately 0.2e-/FeSe in other FeSe-intercalated superconductors.Typical hysteresis loops and temperature dependence of dc/ac susceptibilities of the Fe_(14)Se_(16)(tepa)0.8 measured below∼42 K suggest a presence of the Meissner effect in this material.Effects of synthesis conditions on structures and magnetic properties of the hybrids show a magnetic evolution from a long-range ferrimagnetic(FIM)order of Fe_(14)Se_(16)(tepa)to a coexistence of FIM and superconducting(SC)orders of Fe_(14)Se_(16)(tepa)0.9 and an SC order of Fe_(14)Se_(16)(tepa)0.8.X-ray absorption spectrum(XAS)confirms the presence of ferric/ferrous irons.Mössbauer studies reveal that the high-TC superconductivity originates from a suppression of the FIM order through tuning the spin states of irons from high-spin Fe^(3+)(S=5/2)and Fe^(2+)(S=2)in the Fe_(14)Se_(16)(tepa)to low-spin Fe^(3+)(S=1/2)and Fe^(2+)(S=0)in the Fe_(14)Se_(16)(tepa)0.8.Although no zero resistance is detected even at a temperature of 2 K,the resistivity at 2 K decreases by more than 1600 times compared to that in a normal state calculated by a variable range hopping(VRH)model,suggesting that the high-TC superconductivity of Fe_(14)Se_(16)(tepa)0.8 is possible.
基金The research was carried out within the State Assignment of the Ministry of Science and Higher Education of the Russian Federation(project No.FFUG-2024-0036)。
文摘CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.
基金financially supported by the National Natural Science Foundation of China (Nos. 51672064 and U1435206)
文摘Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.
基金Projects(2017YFB0306000,2017YFB0305600)supported by the National Key Research and Development Program of ChinaProjects(51774035,51604025,51574031,51574030,51574029,51604240)supported by the National Natural Science Foundation of China+2 种基金Project(2019JZZY010327)supported by the Shandong Key Research and Development Plan Project,ChinaProjects(2174079,2162027)supported by the Natural Science Foundation Program of Beijing,ChinaProjects(FRF-IDRY-19-025,FRF-TP-17-034A2,FRF-TP-19-015A3,FRF-IDRY-19-003C2)supported by the Fundamental Research Funds for the Central Universities of China。
文摘A comparative study was conducted by using solution combustion synthesis with three different doping routes(liquid-liquid(WL10), liquid-solid(WLNO) and solid-solid(WLO)) to produce nanoscale powders and further fabricate the ultrafine-grained W-1.0 wt.%La2O3 alloys by pressureless sintering. Compared with pure tungsten, W-1.0 wt.%La2O3 alloys exhibit ultrafine grains and excellent mechanical properties. After sintering, the average grain size of the WLO sample is larger than that of WL10 and WLNO samples;the microhardness values of WL10 and WLNO samples are similar but larger than the value of WLO sample. The optimized La2O3 particles are obtained in the WL10 sample after sintering at 1500 ℃ with the minimum mean size by comparing with WLNO and WLO samples, which are uniformly distributed either at grain boundaries or in the grain interior with the sizes of(57±29.7) and(27±13.1) nm, respectively. This study exhibits ultrafine microstructure and outperforming mechanical properties of the W-1.0 wt.%La2O3 alloy via the liquid-liquid doping route, as compared with conventionally-manufactured tungsten materials.
基金Financial support from the UGC-SAP F.530/15/DRS/2009
文摘Ce-substituted lithium ferrite, Li0.5CexFe2.5-x04 （x = 0, 0.05 and 0.1 ） compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at unity. The thermal decomposition process was investigated by thermogravimetry-differential thermal analysis, which showed a stable phase formation above 600 ℃. The phase composition and molecular bonding of Li0.5CexFe2.5_x04 were characterized by X-ray powder diffraction analysis and Fourier transform infrared spectroscopy, respectively. An extensive study of electrical relaxation process has been represented with impedance and modulus as a function of frequency at different temperatures. The activation energy obtained from both the formalisms was found to be equal within the error. The dc conductivity and hopping frequency were thermally activated and their activation energies were found to be in the range of 0.69-0.64 eV for x = 0.05. The scaling of modulus and impedance were used to understand the electrical relaxation behaviour of the compositions and they suggest the time temperature superposition principle.
