The magnetic phase diagram (x,T) of the SmMn2(Ge1-xSix)2 system has been studied by susceptibility and magnetization measurement. With increasing silicon concentration the temperature region of ferromagnetic ordering ...The magnetic phase diagram (x,T) of the SmMn2(Ge1-xSix)2 system has been studied by susceptibility and magnetization measurement. With increasing silicon concentration the temperature region of ferromagnetic ordering decreases on the phaae diagram.展开更多
Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibri...Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.展开更多
Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(x=0.1-1.0)ceramics were prepared via a conventional solid-state method,the dependence of crystal structure and bond characteristics on microwave dielectric properties was invest...Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(x=0.1-1.0)ceramics were prepared via a conventional solid-state method,the dependence of crystal structure and bond characteristics on microwave dielectric properties was investigated systemically.The X-ray diffraction patterns indicated that the single-phase Pr_(2)Zr_(3)(MoO_(4))_(9)structure was formed in all the specimens.As the Ti^(4+)content increased,the lattice volume gradually decreased,which was ascribed to the fact that the ionic radius of Ti^(4+)was smaller than that of Zr^(4+).Notably,outstanding microwave dielectric properties withεr of 10.73-16.35,Q·f values of 80,696-18,726 GHz and minorτ_(f) values−14.1-−2.6 ppm/℃were achieved in Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)ceramics.Theε_(r) increased with the rising x values,which was associated with the increase ofα/Vm values.The decreasing Q·f was affected by the decline of lattice energy of[Zr/TiO_(6)]octahedral.Theτf value was dominated by[Zr/TiO_(6)]octahedral distortion,Mo-O bond energy,bond strength and B-site bond valence.Furthermore,infrared reflection spectra suggested that the properties were mainly caused by the absorption of phonon,and the dielectric loss could be further reduced by optimizing the experimental process.展开更多
The replacement of liquid organic electrolytes with solid-state electrolytes(SSEs)is a feasible way to solve the safety issues and improve the energy density of lithium batteries.Developing SSEs materials that can wel...The replacement of liquid organic electrolytes with solid-state electrolytes(SSEs)is a feasible way to solve the safety issues and improve the energy density of lithium batteries.Developing SSEs materials that can well match with high-voltage cathodes and lithium metal anode is quite significant to develop high-energy-density lithium batteries.Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)SSE with NASICON structure exhibits high ionic conductivity,low cost and superior air stability,which enable it as one of the most hopeful candidates for all-solidstate batteries(ASSBs).However,the high interfacial impedance between LATP and electrodes,and the severe interfacial side reactions with the lithium metal greatly limit its applications in ASSBs.This review introduces the crystal structure and ion transport mechanisms of LATP and summarizes the key factors affecting the ionic conductivity.The side reaction mechanisms of LATP with Li metal and the promising strategies for optimizing interfacial compatibility are reviewed.We also summarize the applications of LATP including as surface coatings of cathode particles,ion transport network additives and inorganic fillers of composite polymer electrolytes.At last,this review proposes the challenges and the future development directions of LATP in SSBs.展开更多
Non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)(x=-0.07-0.45)magneto-optical ceramics were fabricated by solid-state reactive sintering in vacuum combined with hot isostatic pressing(HIP)posttreatment without any...Non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)(x=-0.07-0.45)magneto-optical ceramics were fabricated by solid-state reactive sintering in vacuum combined with hot isostatic pressing(HIP)posttreatment without any sintering aids.The phase composition,densification process,microstructure,optical transmittance,and Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics were investigated.The in-line transmittance of(Tb_(0.93)Hf_(0.04))_(2)Hf_(2)O_(7.07)ceramics with a thickness of 2.0 mm reaches 74.6%at 1064 nm.The Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics is-153.4,-155.8,and-181.2 rad/(T-m)at the wavelength of 633 nm when x=-0.07,0,and 0.1,respectively.The Verdet constant increases with the increase of Tb content,and these values are higher than that of the commercial Tb_(3)Ga_(5)O_(12) crystal,indicating that non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics have a great potential for the application in Faraday isolators.展开更多
Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline...Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5d_(1) level of Ce^(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_(x))_(2)Si_(2)O_(7):Ce scintillator by adjusting La/Gd ratio.展开更多
Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigat...Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials.The results show that ceramics are compact with regular-shaped grains of 1-5μm size.(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)has a pyrochlore structure mainly determined by ionic radius ratio,but the ordering degree decreases with increase of the Er_(2)O_(3)content.There is no phase transformation from 1000 to 1200℃,and the(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics exhibit excellent phase stability during thermal treatment at 1200℃for 100 h and 1400℃for 50 h.The thermal conductivities of dense(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics range from 1.52 to 1.59 W/(m·K),which is lower than that of Sm_(2)Zr_(2)O_(7),and decrease as the Er2O3content increases.Besides,the thermal expansion coefficient of(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)is higher than that of Sm_(2)Zr_(2)O_(7).展开更多
文摘The magnetic phase diagram (x,T) of the SmMn2(Ge1-xSix)2 system has been studied by susceptibility and magnetization measurement. With increasing silicon concentration the temperature region of ferromagnetic ordering decreases on the phaae diagram.
基金financially supported by the National Natural Science Foundation of China(No.51904250)the China Postdoctoral Science Foundation(No.2021M692254)+2 种基金the Sichuan Science and Technology Program(No.2022YFG0098)the Fundamental Research Funds for the Central Universities(Nos.2021CDSN-02,2022SCU12002,2022CDZG-17,2022CDSN-08,2022CDZG-9)the Hohhot Science and Technology Program(No.2023-Jie Bang Gua Shuai-Gao-3)。
文摘Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.
基金supported by the National Natural Science Foundation of China(No.51972143)supported by State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KFZD202101)。
文摘Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(x=0.1-1.0)ceramics were prepared via a conventional solid-state method,the dependence of crystal structure and bond characteristics on microwave dielectric properties was investigated systemically.The X-ray diffraction patterns indicated that the single-phase Pr_(2)Zr_(3)(MoO_(4))_(9)structure was formed in all the specimens.As the Ti^(4+)content increased,the lattice volume gradually decreased,which was ascribed to the fact that the ionic radius of Ti^(4+)was smaller than that of Zr^(4+).Notably,outstanding microwave dielectric properties withεr of 10.73-16.35,Q·f values of 80,696-18,726 GHz and minorτ_(f) values−14.1-−2.6 ppm/℃were achieved in Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)ceramics.Theε_(r) increased with the rising x values,which was associated with the increase ofα/Vm values.The decreasing Q·f was affected by the decline of lattice energy of[Zr/TiO_(6)]octahedral.Theτf value was dominated by[Zr/TiO_(6)]octahedral distortion,Mo-O bond energy,bond strength and B-site bond valence.Furthermore,infrared reflection spectra suggested that the properties were mainly caused by the absorption of phonon,and the dielectric loss could be further reduced by optimizing the experimental process.
基金Key-Area Research and Development Program of Guangdong Province,Grant/Award Number:2020B090919001National Natural Science Foundation of China,Grant/Award Number:U2001220+1 种基金Shenzhen All-Solid-State Lithium Battery Electrolyte Engineering Research Center,Grant/Award Number:XMHT20200203006Shenzhen Technical Plan Project,Grant/Award Number:JCYJ20180508152210821,JCYJ20170817161221958,JCYJ20180508152135822。
文摘The replacement of liquid organic electrolytes with solid-state electrolytes(SSEs)is a feasible way to solve the safety issues and improve the energy density of lithium batteries.Developing SSEs materials that can well match with high-voltage cathodes and lithium metal anode is quite significant to develop high-energy-density lithium batteries.Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)SSE with NASICON structure exhibits high ionic conductivity,low cost and superior air stability,which enable it as one of the most hopeful candidates for all-solidstate batteries(ASSBs).However,the high interfacial impedance between LATP and electrodes,and the severe interfacial side reactions with the lithium metal greatly limit its applications in ASSBs.This review introduces the crystal structure and ion transport mechanisms of LATP and summarizes the key factors affecting the ionic conductivity.The side reaction mechanisms of LATP with Li metal and the promising strategies for optimizing interfacial compatibility are reviewed.We also summarize the applications of LATP including as surface coatings of cathode particles,ion transport network additives and inorganic fillers of composite polymer electrolytes.At last,this review proposes the challenges and the future development directions of LATP in SSBs.
基金supported by the National Key R&D Program of China(Grant No.2021YFE0104800)the NSFC-RFBR Cooperative Research Project(Grant No.61911530135)the Key Research Project of the Frontier Science of the Chinese Academy of Sciences(No.QYZDB-SSWJSC022)。
文摘Non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)(x=-0.07-0.45)magneto-optical ceramics were fabricated by solid-state reactive sintering in vacuum combined with hot isostatic pressing(HIP)posttreatment without any sintering aids.The phase composition,densification process,microstructure,optical transmittance,and Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics were investigated.The in-line transmittance of(Tb_(0.93)Hf_(0.04))_(2)Hf_(2)O_(7.07)ceramics with a thickness of 2.0 mm reaches 74.6%at 1064 nm.The Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics is-153.4,-155.8,and-181.2 rad/(T-m)at the wavelength of 633 nm when x=-0.07,0,and 0.1,respectively.The Verdet constant increases with the increase of Tb content,and these values are higher than that of the commercial Tb_(3)Ga_(5)O_(12) crystal,indicating that non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics have a great potential for the application in Faraday isolators.
基金Project supported by the National Natural Science Foundation of China(11975220,51972291)the National Key Research and Development Program of China(2016YFB0700204)Natural Science Foundation of Shanghai(16ZR1441100)。
文摘Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_(2)Si_(2)O_(7):Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5d_(1) level of Ce^(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_(x))_(2)Si_(2)O_(7):Ce scintillator by adjusting La/Gd ratio.
基金Project supported by the National High Technology Research and Development Program of China(2015AA034403)National Natural Science Foundation of China(51762036)The Science and Technology Program of Inner Mongolia(2019)。
文摘Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials.The results show that ceramics are compact with regular-shaped grains of 1-5μm size.(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)has a pyrochlore structure mainly determined by ionic radius ratio,but the ordering degree decreases with increase of the Er_(2)O_(3)content.There is no phase transformation from 1000 to 1200℃,and the(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics exhibit excellent phase stability during thermal treatment at 1200℃for 100 h and 1400℃for 50 h.The thermal conductivities of dense(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics range from 1.52 to 1.59 W/(m·K),which is lower than that of Sm_(2)Zr_(2)O_(7),and decrease as the Er2O3content increases.Besides,the thermal expansion coefficient of(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)is higher than that of Sm_(2)Zr_(2)O_(7).
