A new case configuration in R^3, the conjugate-nest consisted of one regular tetrahedron and one regular octahedron is discussed. If the configuration is a central configuration, then all masses of outside layer are e...A new case configuration in R^3, the conjugate-nest consisted of one regular tetrahedron and one regular octahedron is discussed. If the configuration is a central configuration, then all masses of outside layer are equivalent, the masses of inside layer are also equivalent. At the same time the following relation between ρ（r =√3/3ρ is the radius ratio of the sizes） and mass ratio τ=~↑m/m must be satisfied τ=~↑m/m=ρ（ρ＋3）（3＋2ρ＋ρ^2）^-3/2＋ρ（-ρ＋3）（3-2ρ＋ρ^2）^-3/2-4.2^-3/2ρ^-2-^-1ρ^-2/2（1＋ρ）（3＋2ρ＋ρ^2）^-3/2＋2（ρ-1）（3-2ρ＋ρ^2）^-3/2-4（2√2）^-3ρ, and for any mass ratio τ, when mass ratio r is in the open interval （0, 0.03871633950 ... ）, there exist three central configuration solutions（the initial configuration conditions who imply hamagraphic solutions） corresponding radius ratios are r1, r2, and r3, two of them in the interval （2.639300779… , ＋∞） and one is in the interval （0.7379549890…, 1.490942703… ）. when mass ratio τ is in the open interval （130.8164950… , ＋∞）, in the same way there have three corresponding radius ratios, two of them in the interval （0, 0.4211584789... ） and one is in the interval （0.7379549890…, 1.490942703…）. When mass ratio τ is in the open interval （0.03871633950…, 130.8164950…）, there has only one solution r in the interval （0.7379549890…, 1.490942703… ）.展开更多
It is a challenge to obtain highly tunable multifunctional performances in one ferroelectric system by a simple approach to meet the miniaturization,integration,and functionalization requirements of advanced electroni...It is a challenge to obtain highly tunable multifunctional performances in one ferroelectric system by a simple approach to meet the miniaturization,integration,and functionalization requirements of advanced electronic components.Herein,rare earth erbium(Er)modulated 0.9K_(0.5)Na_(0.5)NbO_(3)-0.1Sr(1-x)Er_(x)Ti_((1-x/4))O_(3),(0.9KNN-0.1ST:xEr)transparent-photoluminescent-ferroelectric energy storage multifunctional ceramics are prepared to solve this problem.The effect of lattice distortion and oxygen vacancies by Er doping on the optical and electrical properties is systematically investigated.The Er^(3+)ions can introduce a large distortion of the NbO_(6) octahedron by replacing the A-site in KNN-based ceramics.Thanks to the higher c/a ratio and lower oxygen vacancy content are simultaneously obtained in 0.9KNN-0.1ST:0.1Er ceramics.The effective energy storage density(Wrec)of 0.86 J/cm^(3),excellent near-infrared transmittance of 51.7%(1100 nm)and strong green upconversion photoluminescence are achieved in this multifunctional ceramic.This study provides a solid basis for rare earth ions doped ferroelectric ceramics with tunable multifunctional properties and has significant potential for applications in optoelectronic devices.展开更多
Three-dimensional （3D） porous V2O5 octahedrons have been successfully fabricated via a solid-state conversion process of freshly prepared ammonium vanadium oxide （AVO） octahedrons. The formation of AVO octahedrons...Three-dimensional （3D） porous V2O5 octahedrons have been successfully fabricated via a solid-state conversion process of freshly prepared ammonium vanadium oxide （AVO） octahedrons. The formation of AVO octahedrons is a result of the selective adsorption of capping reagents and the favourable supersaturation of growth species. Subsequently, 3D porous V2O5 octahedrons were obtained by simple thermolysis of the AVO octahedrons via a calcination treatment. As cathode material for lithium batteries, the porous V2O5 octahedron cathode exhibits a capacity of 96 mAh·g^-1 at high rate up to 2 A·g^-1 in the rang of 2.4 4 V and excellent cyclability with little capacity loss after 500 cycles, which can be ascribed to its high specific surface area and tunable pore architecture. Importantly, this facile solid-state thermal conversion strategy can be easily extended to controllably fabricate other porous metal oxide micro/nano materials with specific surface textures and morphologies.展开更多
Phase-change memory(PCM)has been developed for three-dimensional(3D)data storage devices,posing huge challenges to the thermal stability and reliability of PCM.However,the low thermal stability of Ge2Sb2Te5(GST)limits...Phase-change memory(PCM)has been developed for three-dimensional(3D)data storage devices,posing huge challenges to the thermal stability and reliability of PCM.However,the low thermal stability of Ge2Sb2Te5(GST)limits further application.Here,we demonstrate PCM based on In0.9Ge2Sb2Te5(IGST)alloy,showing 180C 10-years data retention,6 ns set speed,one order of magnitude longer life time,and 75%reduced power consumption compared to GST-based device.The In can occupy the cationic positions and the In-Te octahedrons with good phase-change properties can geometrically match well with the host Ge-Te and Sb-Te octahedrons,acting as nucleation centers to boost the set speed and enhance the endurance of IGST device.Introducing stable matched phase-change octahedrons can be a feasible way to achieve practical PCMs.展开更多
Multiferroic BiFeO_(3)-based ceramics were synthesized using the rapid liquid-phase sintering method.The rare-earth ion(Sm^(3+),Gd^(3+),Y^(3+))doping causes structural distortion without changing the intrinsic rhomboh...Multiferroic BiFeO_(3)-based ceramics were synthesized using the rapid liquid-phase sintering method.The rare-earth ion(Sm^(3+),Gd^(3+),Y^(3+))doping causes structural distortion without changing the intrinsic rhombohedral perovskite structure.Raman analysis shows that the effect of doping on E modes is greater than A1 modes,and the microstructure of FeO_(6) octahedron can be regulated by ion doping.A-site trivalent ion doped ceramics exhibit improved magnetism compared with pure BiFeO_(3) ceramic,which originated from the suppressed spiral spin structure of Fe ions.The tilt of FeO_(6) octahedron as a typical structure instability causes the anomalous change of the imaginary part of permittivity at high frequency,and doped ceramics exhibit natural resonance around 16-17 GHz.展开更多
Since the historical discovery of high Tc superconductivity(HTS)of La2CuO4 in 1986[1],the superconductivity me chanism of copper oxides remains one of the biggest mysteries in the field of condensed matter physics[2-1...Since the historical discovery of high Tc superconductivity(HTS)of La2CuO4 in 1986[1],the superconductivity me chanism of copper oxides remains one of the biggest mysteries in the field of condensed matter physics[2-10].High-Tc cuprates crystallize into layered perovskite structure,as well as copper oxygen octahedron coordination.In octahedron symmetry,the 3d orbitals of Cu^2+with a 3d^9 configuration degenerate into two top eg and three lower t2g orbitals.展开更多
We employ advanced first principles methodology,merging self-consistent phonon theory and the Boltzmann transport equation,to comprehensively explore the thermal transport and thermoelectric properties of KCdAs.Notabl...We employ advanced first principles methodology,merging self-consistent phonon theory and the Boltzmann transport equation,to comprehensively explore the thermal transport and thermoelectric properties of KCdAs.Notably,the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon lifetimes.Through various methodologies,including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes,the article unveils microphysical mechanisms contributing to the lowκL within KCdAs.Key features include significant anisotropy in Cd atoms,pronounced anharmonicity in K atoms,and relative vibrations in non-equivalent As atomic layers.Cd atoms,situated between As layers,exhibit rattling modes and strong lattice anharmonicity,contributing to the observed lowκL.Remarkably flat bands near the valence band maximum translate into high PF,aligning with ultralowκL for exceptional thermoelectric performance.Under optimal temperature and carrier concentration doping,outstanding ZT values are achieved:4.25(a(b)-axis,p-type,3×10^(19)cm^(−3),500 K),0.90(c-axis,p-type,5×10^(20)cm^(−3),700 K),1.61(a(b)-axis,n-type,2×10^(18)cm^(−3),700 K),and 3.06(c-axis,n-type,9×10^(17)cm^(−3),700 K).展开更多
In2O3 octahedrons were synthesized by carbothermal reduction using In2O3 nanoparticles as the source material. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray(...In2O3 octahedrons were synthesized by carbothermal reduction using In2O3 nanoparticles as the source material. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray(EDX), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis(SAED) and Room-temperature photoluminescence(PL) spectroscopy. The results show that the products are single-crystalline In2O3 octahedrons, the length of the octahedrons is in the range of 400~3 000 nm; the PL patterns display two peaks located at 447nm and 555 nm upon excitation at 380 nm, and the other two peaks located at 444 nm and 550 nm upon excitation at 325 nm; the excitation pattern shows two peaks located at 274 nm and 371 nm, respectively. The growth mechanism of the In2O3 octahedrons is discussed, and the high supersaturation ratio is considered as the key factor.展开更多
Spinel structure ferrites MFe2O4(M = Co,Ni,Mn,Zn) nano-octahedrons have been fabricated by a simple hydrothermal route under mild conditions,using sodium citrate as addition agent.The products were characterized in de...Spinel structure ferrites MFe2O4(M = Co,Ni,Mn,Zn) nano-octahedrons have been fabricated by a simple hydrothermal route under mild conditions,using sodium citrate as addition agent.The products were characterized in detail by XRD,TEM and ED.The growth process was also monitored by NaOH concentration,temperature and citrate-dependent observations.It was found that the reaction temperature had no obvious influence on the morphology of the products,while NaOH concentration had great effect on the morphology of the final products.The edge size of octahedral ferrites was estimated to 100-200 nm at the hydrothermal temperature of 180 ℃.Vibrating sample magnetometer was used to characterize magnetic properties of octahedral ferrites at room temperature.Magnetic measurements showed that these ferrites exhibited obvious ferromagnetic behaviors.展开更多
基金NSF of China(10231010)NSF of Chongqing EducationCommittee(071105)NSF of SXXYYB(070X)
文摘A new case configuration in R^3, the conjugate-nest consisted of one regular tetrahedron and one regular octahedron is discussed. If the configuration is a central configuration, then all masses of outside layer are equivalent, the masses of inside layer are also equivalent. At the same time the following relation between ρ（r =√3/3ρ is the radius ratio of the sizes） and mass ratio τ=~↑m/m must be satisfied τ=~↑m/m=ρ（ρ＋3）（3＋2ρ＋ρ^2）^-3/2＋ρ（-ρ＋3）（3-2ρ＋ρ^2）^-3/2-4.2^-3/2ρ^-2-^-1ρ^-2/2（1＋ρ）（3＋2ρ＋ρ^2）^-3/2＋2（ρ-1）（3-2ρ＋ρ^2）^-3/2-4（2√2）^-3ρ, and for any mass ratio τ, when mass ratio r is in the open interval （0, 0.03871633950 ... ）, there exist three central configuration solutions（the initial configuration conditions who imply hamagraphic solutions） corresponding radius ratios are r1, r2, and r3, two of them in the interval （2.639300779… , ＋∞） and one is in the interval （0.7379549890…, 1.490942703… ）. when mass ratio τ is in the open interval （130.8164950… , ＋∞）, in the same way there have three corresponding radius ratios, two of them in the interval （0, 0.4211584789... ） and one is in the interval （0.7379549890…, 1.490942703…）. When mass ratio τ is in the open interval （0.03871633950…, 130.8164950…）, there has only one solution r in the interval （0.7379549890…, 1.490942703… ）.
基金supported by the National Natural Science Foundation of China(Grants No.52162019,No.51802140,No.52202136,No.12174174)the Natural Science Foundation of Jiangxi Province(Grant No.20212ACB214011).L.S.expresses thanks for the support from Nanchang University.
文摘It is a challenge to obtain highly tunable multifunctional performances in one ferroelectric system by a simple approach to meet the miniaturization,integration,and functionalization requirements of advanced electronic components.Herein,rare earth erbium(Er)modulated 0.9K_(0.5)Na_(0.5)NbO_(3)-0.1Sr(1-x)Er_(x)Ti_((1-x/4))O_(3),(0.9KNN-0.1ST:xEr)transparent-photoluminescent-ferroelectric energy storage multifunctional ceramics are prepared to solve this problem.The effect of lattice distortion and oxygen vacancies by Er doping on the optical and electrical properties is systematically investigated.The Er^(3+)ions can introduce a large distortion of the NbO_(6) octahedron by replacing the A-site in KNN-based ceramics.Thanks to the higher c/a ratio and lower oxygen vacancy content are simultaneously obtained in 0.9KNN-0.1ST:0.1Er ceramics.The effective energy storage density(Wrec)of 0.86 J/cm^(3),excellent near-infrared transmittance of 51.7%(1100 nm)and strong green upconversion photoluminescence are achieved in this multifunctional ceramic.This study provides a solid basis for rare earth ions doped ferroelectric ceramics with tunable multifunctional properties and has significant potential for applications in optoelectronic devices.
文摘Three-dimensional （3D） porous V2O5 octahedrons have been successfully fabricated via a solid-state conversion process of freshly prepared ammonium vanadium oxide （AVO） octahedrons. The formation of AVO octahedrons is a result of the selective adsorption of capping reagents and the favourable supersaturation of growth species. Subsequently, 3D porous V2O5 octahedrons were obtained by simple thermolysis of the AVO octahedrons via a calcination treatment. As cathode material for lithium batteries, the porous V2O5 octahedron cathode exhibits a capacity of 96 mAh·g^-1 at high rate up to 2 A·g^-1 in the rang of 2.4 4 V and excellent cyclability with little capacity loss after 500 cycles, which can be ascribed to its high specific surface area and tunable pore architecture. Importantly, this facile solid-state thermal conversion strategy can be easily extended to controllably fabricate other porous metal oxide micro/nano materials with specific surface textures and morphologies.
基金Genetic Engineering of Precious Metal Materials in Yunnan Province(I)-Construction and Application of Precious Metal Materials Professional Database(I),Grant/Award Number:202002AB080001-1National Natural Science Foundation of China,Grant/Award Numbers:91964204,61874129,61874178,61904189+2 种基金Science and Technology Council of Shanghai,Grant/Award Numbers:20501120300,18DZ2272800Shanghai Sailing Program,Grant/Award Number:19YF1456100the National Key Research and Development Program of China,Grant/Award Numbers:2017YFA0206101,2018YFB0407500。
文摘Phase-change memory(PCM)has been developed for three-dimensional(3D)data storage devices,posing huge challenges to the thermal stability and reliability of PCM.However,the low thermal stability of Ge2Sb2Te5(GST)limits further application.Here,we demonstrate PCM based on In0.9Ge2Sb2Te5(IGST)alloy,showing 180C 10-years data retention,6 ns set speed,one order of magnitude longer life time,and 75%reduced power consumption compared to GST-based device.The In can occupy the cationic positions and the In-Te octahedrons with good phase-change properties can geometrically match well with the host Ge-Te and Sb-Te octahedrons,acting as nucleation centers to boost the set speed and enhance the endurance of IGST device.Introducing stable matched phase-change octahedrons can be a feasible way to achieve practical PCMs.
基金supported by the National Natural Science Foundation of China(51502054)the Postdoctoral Science Foundation of China(2014M551236)the Postdoctoral Science Foundation of Heilongjiang Province(LBH-Z14083).
文摘Multiferroic BiFeO_(3)-based ceramics were synthesized using the rapid liquid-phase sintering method.The rare-earth ion(Sm^(3+),Gd^(3+),Y^(3+))doping causes structural distortion without changing the intrinsic rhombohedral perovskite structure.Raman analysis shows that the effect of doping on E modes is greater than A1 modes,and the microstructure of FeO_(6) octahedron can be regulated by ion doping.A-site trivalent ion doped ceramics exhibit improved magnetism compared with pure BiFeO_(3) ceramic,which originated from the suppressed spiral spin structure of Fe ions.The tilt of FeO_(6) octahedron as a typical structure instability causes the anomalous change of the imaginary part of permittivity at high frequency,and doped ceramics exhibit natural resonance around 16-17 GHz.
基金supported by the National Natural Science Foundation of China(Grant No.11820101003)the Ministry of Science&Technology(Grant Nos.2018YFA0305701,2017YFA0302901,and 2016YFA0300301)
文摘Since the historical discovery of high Tc superconductivity(HTS)of La2CuO4 in 1986[1],the superconductivity me chanism of copper oxides remains one of the biggest mysteries in the field of condensed matter physics[2-10].High-Tc cuprates crystallize into layered perovskite structure,as well as copper oxygen octahedron coordination.In octahedron symmetry,the 3d orbitals of Cu^2+with a 3d^9 configuration degenerate into two top eg and three lower t2g orbitals.
基金supported by the Natural Science Foundation of Shandong Province for Major Basic Research under Grant No.ZR2023ZD09the National Natural Science Foundation of China under Grant Nos.12174327,11974302,and 92270104.
文摘We employ advanced first principles methodology,merging self-consistent phonon theory and the Boltzmann transport equation,to comprehensively explore the thermal transport and thermoelectric properties of KCdAs.Notably,the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon lifetimes.Through various methodologies,including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes,the article unveils microphysical mechanisms contributing to the lowκL within KCdAs.Key features include significant anisotropy in Cd atoms,pronounced anharmonicity in K atoms,and relative vibrations in non-equivalent As atomic layers.Cd atoms,situated between As layers,exhibit rattling modes and strong lattice anharmonicity,contributing to the observed lowκL.Remarkably flat bands near the valence band maximum translate into high PF,aligning with ultralowκL for exceptional thermoelectric performance.Under optimal temperature and carrier concentration doping,outstanding ZT values are achieved:4.25(a(b)-axis,p-type,3×10^(19)cm^(−3),500 K),0.90(c-axis,p-type,5×10^(20)cm^(−3),700 K),1.61(a(b)-axis,n-type,2×10^(18)cm^(−3),700 K),and 3.06(c-axis,n-type,9×10^(17)cm^(−3),700 K).
文摘In2O3 octahedrons were synthesized by carbothermal reduction using In2O3 nanoparticles as the source material. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray(EDX), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis(SAED) and Room-temperature photoluminescence(PL) spectroscopy. The results show that the products are single-crystalline In2O3 octahedrons, the length of the octahedrons is in the range of 400~3 000 nm; the PL patterns display two peaks located at 447nm and 555 nm upon excitation at 380 nm, and the other two peaks located at 444 nm and 550 nm upon excitation at 325 nm; the excitation pattern shows two peaks located at 274 nm and 371 nm, respectively. The growth mechanism of the In2O3 octahedrons is discussed, and the high supersaturation ratio is considered as the key factor.
文摘Spinel structure ferrites MFe2O4(M = Co,Ni,Mn,Zn) nano-octahedrons have been fabricated by a simple hydrothermal route under mild conditions,using sodium citrate as addition agent.The products were characterized in detail by XRD,TEM and ED.The growth process was also monitored by NaOH concentration,temperature and citrate-dependent observations.It was found that the reaction temperature had no obvious influence on the morphology of the products,while NaOH concentration had great effect on the morphology of the final products.The edge size of octahedral ferrites was estimated to 100-200 nm at the hydrothermal temperature of 180 ℃.Vibrating sample magnetometer was used to characterize magnetic properties of octahedral ferrites at room temperature.Magnetic measurements showed that these ferrites exhibited obvious ferromagnetic behaviors.
