采用快速液相烧结法制备Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)(x=0.00、0.03、0.06、0.12)系列多铁陶瓷样品,研究Pr-Ti共掺杂对BiFe O_(3)结构、缺陷、电学和磁学特性的影响。XRD分析结果表明:所有样品均为菱方钙钛矿结构,Pr-Ti共掺杂可...采用快速液相烧结法制备Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)(x=0.00、0.03、0.06、0.12)系列多铁陶瓷样品,研究Pr-Ti共掺杂对BiFe O_(3)结构、缺陷、电学和磁学特性的影响。XRD分析结果表明:所有样品均为菱方钙钛矿结构,Pr-Ti共掺杂可有效抑制杂相生成,当掺杂量高于0.06时杂相基本消失,共掺杂引起结构畸变。正电子湮没寿命谱测试结果表明:所有样品中均存在阳离子空位型缺陷,空位尺寸和浓度均随Pr-Ti掺杂量增加而增大。电学和磁学性能测试结果表明:适量Pr-Ti共掺杂可有效提高Bi Fe O_(3)的介电、铁电和磁学性能。综合上述结果,认为BiFeO_(3)多铁性能的改善可能是由于Pr-Ti共掺杂引起晶格畸变、减少氧空位浓度、改变阳离子空位浓度等多种原因引起。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
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
We experimentally investigate the stabilization of the anatase phase of Ti_(1-x)Sn_(x)O_(2)(x<0.5)nanofibers when synthesized by an electrospinning method.The as-spun nanofibers became nano-grained,polycrystalline ...We experimentally investigate the stabilization of the anatase phase of Ti_(1-x)Sn_(x)O_(2)(x<0.5)nanofibers when synthesized by an electrospinning method.The as-spun nanofibers became nano-grained,polycrystalline nanofibers after calcination and the diameters of the nanofibers depend on Sn content.Stabilization of the anatase phase in Ti-rich compositions and incorporation of Sn ions were confirmed by X-ray diffraction,Raman,X-ray absorption near-edge structure,and photoluminescence(PL)spectroscopies.Results from the PL study also demonstrated the tunable nature of the optical properties,with the emission maximum shifting towards higher wavelength with increasing Sn concentration.展开更多
The electronic structure and optical properties of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7)(x¼0,1/8,2/8,3/8,4/8)were studied by first-principle calculations within the generalized gradient approximation approaches(GGA).Th...The electronic structure and optical properties of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7)(x¼0,1/8,2/8,3/8,4/8)were studied by first-principle calculations within the generalized gradient approximation approaches(GGA).The lattice constants of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) increase with the increase of Ti^(4+)content caused by the substitution of Ti^(4+)with larger ionic radius for Mn^(4+).Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) is a direct band gap semiconductor,and the band gap(Eg)increases with the increase of Ti^(4+)content.From the density of states,the introduction of Ti-3d states can weaken the effects of Mn-3d states on the bottom of conduction band and has little influence on O-2p states on the top of valence band.The introduction of nonmagnetic Ti^(4+)ions can weaken the magnetism of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7).According to the Mulliken population analysis,it is found that the introduction of Ti^(4+)enhances the electronic accepting capacity of oxygen ions and enhances the electronic losing capacity of manganese ions.The bond strength of Ti–O covalent bond is stronger than that of Mn–O covalent bond.Furthermore,the optical properties of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) was calculated.As Ti^(4+)content increases,the absorption edge of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) has a blue shift,the static refractive index n0 decreases,the static dielectric constant"1(0)decreases,the position of loss peak moves to higher energy.展开更多
Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal ...Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering.The reaction mechanism of Li_(4)Si_(1-x)Ti_(x)O_(4) was put forward.XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion,which promotes the grain growth and changes the fracture mode.The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2.However,the thermal conductivity and ionic conductivity are the best when x=0.05 and x=0.1,respectively.Thermal cycling stability of Li_(4)Si_(1-x)Ti_(x)O_(4) pebbles was further appraised through investigating the changes of microstructure and crush load.After undergoing thermal cycling,the Li_(4)Si_(1-x)Ti_(x)O_(4) still show higher crush load compared with Li_(4)SiO_(4),despite Ti segregation in some samples.The x=0.05 sample exhibits excellent thermal cycling stability.In summary,proper amount of Ti doping can improve the crush load,thermal and ionic conductivity,and thermal cycling stability of Li_(4)SiO_(4).展开更多
NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定...NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定性好,但其立方相结构不稳定,影响其实际应用。采用溶液浇筑法,制备纯PVDF-LiTFSI电解质膜和以PVDF为基、3种不同质量比的Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)的固态电解质膜,并探讨纯PVDF-LiTFSI电解质膜和3种不同质量比的活性无机电解质填料对复合固态电解质离子电导率的影响。结果表明,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时,电解质膜的XRD图谱的衍射峰比纯PVDF-LiTFSI下降更为明显,电化学窗口为3.9 V左右,表现出更好的稳定性。在不同温度下分别测量其离子电导率发现,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时的电解质膜均高于纯PVDF-LiTFSI电解质膜和Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为2∶1和3∶1时的电解质膜。将其装配成电池后发现,0.1C下电池首次充放电比容量分别为90 m A·h/g和87 m A·h/g。以0.5C的电流循环25圈,放电比容量从57 mA·h/g衰减至51mA·h/g,容量保持率为99.7%。所以,以PVDF为基、Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1的固态电解质膜有优良的倍率性能和循环稳定性能。展开更多
文摘在LiNO_3/SiO_2/Si基板上制备了Li_(1-x)Bi_(4+x)Ti_4O_(15)系列薄膜(x=0.3、0.4、0.5、0.6),并系统分析了这些薄膜的微观结构以及铁电、介电及漏电等电学特性。研究结果表明,在氮气气氛中以600℃持温30 min制备的单一相薄膜中Li0.5Bi4.5Ti4O15薄膜的结晶效果最好,且在其表面可成长出独立晶粒分布状态;x为0.5时薄膜的剩余极化强度2Pr=53.5μC/cm2、矫顽场2Ec=144.2 k V/cm,此时薄膜的铁电性能相对最佳;该系列薄膜的介电常数介于37~100,介电损失相对偏高,介于0.7~1.0;所有薄膜的漏电流均随外加电压的增加而逐渐增大,其中Li0.5Bi4.5Ti4O15薄膜漏电流最小,外加电压为10 V时其值约为3.88×10-6A。
文摘采用快速液相烧结法制备Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)(x=0.00、0.03、0.06、0.12)系列多铁陶瓷样品,研究Pr-Ti共掺杂对BiFe O_(3)结构、缺陷、电学和磁学特性的影响。XRD分析结果表明:所有样品均为菱方钙钛矿结构,Pr-Ti共掺杂可有效抑制杂相生成,当掺杂量高于0.06时杂相基本消失,共掺杂引起结构畸变。正电子湮没寿命谱测试结果表明:所有样品中均存在阳离子空位型缺陷,空位尺寸和浓度均随Pr-Ti掺杂量增加而增大。电学和磁学性能测试结果表明:适量Pr-Ti共掺杂可有效提高Bi Fe O_(3)的介电、铁电和磁学性能。综合上述结果,认为BiFeO_(3)多铁性能的改善可能是由于Pr-Ti共掺杂引起晶格畸变、减少氧空位浓度、改变阳离子空位浓度等多种原因引起。
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 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This work was supported by the Korea Science and Engineering Foundation(KOSEF)grant funded by the Ministry of Education,Science,and Technology(MEST)(No.M2AN01)One of the authors(K.A.)appreciates the support of the Brainpool Program during his stay in Inha University.
文摘We experimentally investigate the stabilization of the anatase phase of Ti_(1-x)Sn_(x)O_(2)(x<0.5)nanofibers when synthesized by an electrospinning method.The as-spun nanofibers became nano-grained,polycrystalline nanofibers after calcination and the diameters of the nanofibers depend on Sn content.Stabilization of the anatase phase in Ti-rich compositions and incorporation of Sn ions were confirmed by X-ray diffraction,Raman,X-ray absorption near-edge structure,and photoluminescence(PL)spectroscopies.Results from the PL study also demonstrated the tunable nature of the optical properties,with the emission maximum shifting towards higher wavelength with increasing Sn concentration.
基金This work was supported by the Excellent Talent Project in University of Chongqing(Grant No.2017-35)the Program for Innovation Teams in University of Chongqing(Grant No.CXTDX201601032)+1 种基金he Science and Technology Innovation Project of Social Undertakings and People’s Livelihood Guarantee of Chongqing(Grant No.CSTC2017 shmsA90015)the Chongqing Research Program of Basic Research and Frontier Technology(Grant Nos.CSTC2018 jcyjAX0416,CSTC2016jcyjA0175 and CSTC2016jcyjA0349).
文摘The electronic structure and optical properties of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7)(x¼0,1/8,2/8,3/8,4/8)were studied by first-principle calculations within the generalized gradient approximation approaches(GGA).The lattice constants of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) increase with the increase of Ti^(4+)content caused by the substitution of Ti^(4+)with larger ionic radius for Mn^(4+).Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) is a direct band gap semiconductor,and the band gap(Eg)increases with the increase of Ti^(4+)content.From the density of states,the introduction of Ti-3d states can weaken the effects of Mn-3d states on the bottom of conduction band and has little influence on O-2p states on the top of valence band.The introduction of nonmagnetic Ti^(4+)ions can weaken the magnetism of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7).According to the Mulliken population analysis,it is found that the introduction of Ti^(4+)enhances the electronic accepting capacity of oxygen ions and enhances the electronic losing capacity of manganese ions.The bond strength of Ti–O covalent bond is stronger than that of Mn–O covalent bond.Furthermore,the optical properties of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) was calculated.As Ti^(4+)content increases,the absorption edge of Ca_(3)(Mn_(1-x)Ti_(x))_(2)O_(7) has a blue shift,the static refractive index n0 decreases,the static dielectric constant"1(0)decreases,the position of loss peak moves to higher energy.
基金supported by National Natural Science Foundation of China(No.51802257)Natural Science Foundation of Shaanxi Provincial Department of Education(18JK0570)China Postdoctoral Science Foundation(2019M663788).
文摘Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering.The reaction mechanism of Li_(4)Si_(1-x)Ti_(x)O_(4) was put forward.XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion,which promotes the grain growth and changes the fracture mode.The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2.However,the thermal conductivity and ionic conductivity are the best when x=0.05 and x=0.1,respectively.Thermal cycling stability of Li_(4)Si_(1-x)Ti_(x)O_(4) pebbles was further appraised through investigating the changes of microstructure and crush load.After undergoing thermal cycling,the Li_(4)Si_(1-x)Ti_(x)O_(4) still show higher crush load compared with Li_(4)SiO_(4),despite Ti segregation in some samples.The x=0.05 sample exhibits excellent thermal cycling stability.In summary,proper amount of Ti doping can improve the crush load,thermal and ionic conductivity,and thermal cycling stability of Li_(4)SiO_(4).
文摘NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定性好,但其立方相结构不稳定,影响其实际应用。采用溶液浇筑法,制备纯PVDF-LiTFSI电解质膜和以PVDF为基、3种不同质量比的Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)的固态电解质膜,并探讨纯PVDF-LiTFSI电解质膜和3种不同质量比的活性无机电解质填料对复合固态电解质离子电导率的影响。结果表明,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时,电解质膜的XRD图谱的衍射峰比纯PVDF-LiTFSI下降更为明显,电化学窗口为3.9 V左右,表现出更好的稳定性。在不同温度下分别测量其离子电导率发现,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时的电解质膜均高于纯PVDF-LiTFSI电解质膜和Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为2∶1和3∶1时的电解质膜。将其装配成电池后发现,0.1C下电池首次充放电比容量分别为90 m A·h/g和87 m A·h/g。以0.5C的电流循环25圈,放电比容量从57 mA·h/g衰减至51mA·h/g,容量保持率为99.7%。所以,以PVDF为基、Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1的固态电解质膜有优良的倍率性能和循环稳定性能。
