To enhance the thermoelectric performance of Cu2GeSe3, a series of Te-alloyed samples Cu2Ge(Se(1-x)Tex)3 are synthesized and investigated in this work. It is found that the lattice thermal conductivity is reduced ...To enhance the thermoelectric performance of Cu2GeSe3, a series of Te-alloyed samples Cu2Ge(Se(1-x)Tex)3 are synthesized and investigated in this work. It is found that the lattice thermal conductivity is reduced drastically for x = 0.1 sample, which may be attributed to the point defects introduced by alloying. However, for samples with x ≥ 0.2, the lattice thermal conductivity increases with increasing x, which is related to a less distorted structure. The structure evolution,together with the change in carrier concentration, also leads to a systemically change in electrical properties. Finally, a z T of 0.55@750 K is obtained for the sample with x = 0.3, about 62% higher than that for the pristine sample.展开更多
The crystal structure of a Ni(II) complex with 1,7-diaminoethyl-4,10-dimethyl,4,7,10-tetraazacyclododecane has been determined by X-ray diffraction method. Crystal data for NiC14H36Br2N6O: monoclinic, space group P21/...The crystal structure of a Ni(II) complex with 1,7-diaminoethyl-4,10-dimethyl,4,7,10-tetraazacyclododecane has been determined by X-ray diffraction method. Crystal data for NiC14H36Br2N6O: monoclinic, space group P21/n, a=0.8848(3), b=1.4656(3), c=1.5828(3) nm, β=90.47(3)°, V=2.0525 nm3, Z=4. The two pendant primary amino groups are located in cis positions in the complex, their nitrogen atoms and the four nitrogen donors of the fold tetraaza-macrocycle coordinate Ni(II) ion, forming a distorted octahedral geometry.展开更多
基于密度泛函理论的广义梯度近似对畸形钙钛矿DyMnO3的基态电子结构及光学性质进行计算和分析.结果表明优化的晶体结构参数与实验结果相符合,DyMnO3具有非间接带隙大小为0.91 e V的能带结构,结合态密度分析了各元素价电子态的分布.计算...基于密度泛函理论的广义梯度近似对畸形钙钛矿DyMnO3的基态电子结构及光学性质进行计算和分析.结果表明优化的晶体结构参数与实验结果相符合,DyMnO3具有非间接带隙大小为0.91 e V的能带结构,结合态密度分析了各元素价电子态的分布.计算分析包括介电常数,吸收系数,反射率等光学性质.展开更多
A unified theoretical method is established to determine the charge-compensated C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals by simulating the electron paramagnetic resonance(EPR)parameters and Stark energy le...A unified theoretical method is established to determine the charge-compensated C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals by simulating the electron paramagnetic resonance(EPR)parameters and Stark energy levels.The potential(Er^(3+)–F^(−)–O_(4)^(2−))and(Er^(3+)-F_(7)^(−)-O_(4)^(2−))structures for theC3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals are checked by diagonalizing 364×364 complete energy matrices in the scheme of superposition model.Our studies indicate that the C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 may be ascribed to the local(Er^(3+)-F^(−)-O_(4)^(2−))structure,where the upper ligand ion F−undergoes an off-center displacement by∆Z≈0.3˚A for CdF2 and∆Z≈0.29˚A for the CaF2 along the C3 axis.Meanwhile,a local compressed distortion of the(ErFO4)6−cluster is expected to be∆R≈0.07˚A for CdF2:Er3+and∆R≈0.079˚A for CaF2:Er3+.The considerable g-factor anisotropy for Er3+ions in each of both crystals is explained reasonably by the obtained local parameters.Furthermore,our studies show that a stronger covalent effect exists in the C3v(Ⅱ)center for Er3+in CaF2 or CaF2,which may be due to the stronger electrostatic interaction and closer distance between the central Er3+ion and ligand O2−with the(Er^(3+)-F^(−)-O_(4)^(2−))structure.展开更多
目的:探讨乳腺内结构扭曲病变采用数字乳腺体层合成(digital breast tomosynthesis,DBT)联合超声诊断的价值。方法:回顾性分析2021年1月—2022年4月滨州医学院附属医院收治的行DBT、超声检查的78例患者的临床资料,以病理学结果为金标准...目的:探讨乳腺内结构扭曲病变采用数字乳腺体层合成(digital breast tomosynthesis,DBT)联合超声诊断的价值。方法:回顾性分析2021年1月—2022年4月滨州医学院附属医院收治的行DBT、超声检查的78例患者的临床资料,以病理学结果为金标准,对单一诊断与联合诊断的诊断效能进行比较。结果:78例患者中良性病变30例,恶性病变48例;超声诊断灵敏度、特异度、阳性预测值、阴性预测值、准确率分别为64.58%、56.67%、70.45%、50.00%、61.54%,DBT检查分别为79.17%、76.67%、84.44%、69.70%、78.21%,DBT联合超声检查分别为95.83%、96.67%、97.87%、93.55%、96.15%,DBT联合超声诊断灵敏度、特异度、阳性预测值、阴性预测值、准确率均显著高于超声、DBT检查(P<0.01)。结论:DBT联合超声用于检查乳腺内结构扭曲病变可提高诊断效能。展开更多
The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of whic...The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of which x (wt%)=2,5, 10, 15, 20,25, and 30. The samples were sintered at 1400℃ for an hour in air. The Ce element in SrTiO3 ceramics is used as an impurity donor. The scanning electron microscopic (SEM) analysis and X-ray diffractive examination of SrTiO3 ceramics containing CeO2 indicated that there exists a Ce2O3 secondary phase (viz. glass phase) and it had solid solution solubility for impurities which decrease the semiconductive property of SrTiO3 ceramics , and weaken the oxidation of the surface of grain and thus increase the conductivity of the grains. The semiconducting ceramics process lightly distorted cubic structure at room temperature. This paper mainly gives a study of the conductivity of CeO2 modified SrTiO3 ceramics.展开更多
The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with M...The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51672270,11674040,and 11404044)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH016)the Project for Fundamental and Frontier Research in Chongqing City(Grant No.CSTC2015JCYJBX0026)
文摘To enhance the thermoelectric performance of Cu2GeSe3, a series of Te-alloyed samples Cu2Ge(Se(1-x)Tex)3 are synthesized and investigated in this work. It is found that the lattice thermal conductivity is reduced drastically for x = 0.1 sample, which may be attributed to the point defects introduced by alloying. However, for samples with x ≥ 0.2, the lattice thermal conductivity increases with increasing x, which is related to a less distorted structure. The structure evolution,together with the change in carrier concentration, also leads to a systemically change in electrical properties. Finally, a z T of 0.55@750 K is obtained for the sample with x = 0.3, about 62% higher than that for the pristine sample.
文摘The crystal structure of a Ni(II) complex with 1,7-diaminoethyl-4,10-dimethyl,4,7,10-tetraazacyclododecane has been determined by X-ray diffraction method. Crystal data for NiC14H36Br2N6O: monoclinic, space group P21/n, a=0.8848(3), b=1.4656(3), c=1.5828(3) nm, β=90.47(3)°, V=2.0525 nm3, Z=4. The two pendant primary amino groups are located in cis positions in the complex, their nitrogen atoms and the four nitrogen donors of the fold tetraaza-macrocycle coordinate Ni(II) ion, forming a distorted octahedral geometry.
基金Supported by National Natural Science Foundation of China(11547265)Natural Science Foundation of Shandong Province(ZR2015AM025)Doctoral Research Program of Heze University(XY14BS003)
文摘基于密度泛函理论的广义梯度近似对畸形钙钛矿DyMnO3的基态电子结构及光学性质进行计算和分析.结果表明优化的晶体结构参数与实验结果相符合,DyMnO3具有非间接带隙大小为0.91 e V的能带结构,结合态密度分析了各元素价电子态的分布.计算分析包括介电常数,吸收系数,反射率等光学性质.
基金Project supported by the National Natural Science Foundation of China(Grant No.1170513)the Natural Science Foundation of Shaanxi Province,China(Grant No.Z20200051)+1 种基金the Foundation of the Education Department of Shaanxi Provincial Government,China(Grant No.16JK1461)the Scientific Research Foundation of Xi’an University of Architecture and Technology,China(Grant No.QN1729).
文摘A unified theoretical method is established to determine the charge-compensated C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals by simulating the electron paramagnetic resonance(EPR)parameters and Stark energy levels.The potential(Er^(3+)–F^(−)–O_(4)^(2−))and(Er^(3+)-F_(7)^(−)-O_(4)^(2−))structures for theC3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals are checked by diagonalizing 364×364 complete energy matrices in the scheme of superposition model.Our studies indicate that the C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 may be ascribed to the local(Er^(3+)-F^(−)-O_(4)^(2−))structure,where the upper ligand ion F−undergoes an off-center displacement by∆Z≈0.3˚A for CdF2 and∆Z≈0.29˚A for the CaF2 along the C3 axis.Meanwhile,a local compressed distortion of the(ErFO4)6−cluster is expected to be∆R≈0.07˚A for CdF2:Er3+and∆R≈0.079˚A for CaF2:Er3+.The considerable g-factor anisotropy for Er3+ions in each of both crystals is explained reasonably by the obtained local parameters.Furthermore,our studies show that a stronger covalent effect exists in the C3v(Ⅱ)center for Er3+in CaF2 or CaF2,which may be due to the stronger electrostatic interaction and closer distance between the central Er3+ion and ligand O2−with the(Er^(3+)-F^(−)-O_(4)^(2−))structure.
文摘目的:探讨乳腺内结构扭曲病变采用数字乳腺体层合成(digital breast tomosynthesis,DBT)联合超声诊断的价值。方法:回顾性分析2021年1月—2022年4月滨州医学院附属医院收治的行DBT、超声检查的78例患者的临床资料,以病理学结果为金标准,对单一诊断与联合诊断的诊断效能进行比较。结果:78例患者中良性病变30例,恶性病变48例;超声诊断灵敏度、特异度、阳性预测值、阴性预测值、准确率分别为64.58%、56.67%、70.45%、50.00%、61.54%,DBT检查分别为79.17%、76.67%、84.44%、69.70%、78.21%,DBT联合超声检查分别为95.83%、96.67%、97.87%、93.55%、96.15%,DBT联合超声诊断灵敏度、特异度、阳性预测值、阴性预测值、准确率均显著高于超声、DBT检查(P<0.01)。结论:DBT联合超声用于检查乳腺内结构扭曲病变可提高诊断效能。
文摘The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of which x (wt%)=2,5, 10, 15, 20,25, and 30. The samples were sintered at 1400℃ for an hour in air. The Ce element in SrTiO3 ceramics is used as an impurity donor. The scanning electron microscopic (SEM) analysis and X-ray diffractive examination of SrTiO3 ceramics containing CeO2 indicated that there exists a Ce2O3 secondary phase (viz. glass phase) and it had solid solution solubility for impurities which decrease the semiconductive property of SrTiO3 ceramics , and weaken the oxidation of the surface of grain and thus increase the conductivity of the grains. The semiconducting ceramics process lightly distorted cubic structure at room temperature. This paper mainly gives a study of the conductivity of CeO2 modified SrTiO3 ceramics.
文摘The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).