In view of the question about the vortex glass theory of the freezing of disordered vortex matter raised by recent experimental observations, we reinvestigate the critical scaling of high Tc superconductors. It is fou...In view of the question about the vortex glass theory of the freezing of disordered vortex matter raised by recent experimental observations, we reinvestigate the critical scaling of high Tc superconductors. It is found that the dc current-voltage characteristic of mixed state superconductors has a general form of extended power law which is based on the Ginzburg-Landau （GL） functional in the similar way as the vortex glass theory. Isotherms simulated from this nonlinear equation fit the experimental I- V data of Strachan et al. [Phys. Rev. Left. 87（2001） 067007]. The puzzling question of the derivative plot for the I - V curves and the controversy surrounding the values of critical exponents are discussed.展开更多
用自燃烧法低温合成了单相 (Sr,Pb) Ti O3陶瓷粉末 ,研究和确定了自燃烧反应的 p H值条件 ,分析了自燃烧反应历程。测量了 (Sr,Pb) Ti O3的居里温度及 Y掺杂陶瓷阻 -温特性。结果表明 ,(Sr,Pb) Ti O3的居里温度较理论计算值稍有偏移。...用自燃烧法低温合成了单相 (Sr,Pb) Ti O3陶瓷粉末 ,研究和确定了自燃烧反应的 p H值条件 ,分析了自燃烧反应历程。测量了 (Sr,Pb) Ti O3的居里温度及 Y掺杂陶瓷阻 -温特性。结果表明 ,(Sr,Pb) Ti O3的居里温度较理论计算值稍有偏移。典型陶瓷样品的电阻升阻比为 4.2 ,V型特性明显。Y掺杂陶瓷样品的电阻率与 Y掺杂量之间关系符合一般稀土掺杂规律。展开更多
The Aurivillius phases(APs)[Bi_(2)O_(2)]2t[A_(m-1)B_(m)O_(3m+1)]2-are well-known ferroelectrics with high Curie temperatures.Hightemperature piezoceramics Bi_(3-x)Gd_(x)TiNbO_(9)(BiGdTiNb,x=0,0.1,0.2,0.3)were prepared...The Aurivillius phases(APs)[Bi_(2)O_(2)]2t[A_(m-1)B_(m)O_(3m+1)]2-are well-known ferroelectrics with high Curie temperatures.Hightemperature piezoceramics Bi_(3-x)Gd_(x)TiNbO_(9)(BiGdTiNb,x=0,0.1,0.2,0.3)were prepared by a solid-state reaction method.The structural and electrophysical characteristics of BiGdTiNb ceramics have been studied.According to the data of powder X-ray diffraction,all the compounds are single-phase with the structures of two-layer APs(m=2)with the orthorhombic crystal lattice(space group A21am).The temperature dependence of the relative permittivityε/ε_(0)(T)of the compounds was measured and showed that the Curie temperature of perovskite-like oxides Bi_(3-x)Gd_(x)TiNbO_(9) increases linearly with an increase in the substitution parameter x to T_(C)=950℃.The activation energies of charge carriers have been found in different temperature ranges.展开更多
The Aurivillius phases[Bi_(2)O_(2)][A_(n−1)B_(n)O3_(n+1)]are well-known ferroelectrics with high Curie temperatures T_(C).High-temperature piezoceramics Bi_(3-x)Gd_(x)TiTaO_(9)(BGdTTa,x=0.0,0.1,0.2,0.3)were prepared b...The Aurivillius phases[Bi_(2)O_(2)][A_(n−1)B_(n)O3_(n+1)]are well-known ferroelectrics with high Curie temperatures T_(C).High-temperature piezoceramics Bi_(3-x)Gd_(x)TiTaO_(9)(BGdTTa,x=0.0,0.1,0.2,0.3)were prepared by a solid-state reaction method.The structural and electrophysical characteristics of BGdTTa ceramics have been studied.According to the data of powder X-ray diffraction,all the compounds are single-phase with the structures of two-layer Aurivillius phases(m=2)with the orthorhombic crystal lattice(space group A2_(1)am).The temperature dependence of the relative permittivity ε/ε_(o)(T)of the compounds was measured and showed that the Curie temperature T_(C) of perovskite-like oxides Bi_(3-x)Gd_(x)TiTaO_(9)increases linearly with an increase in the substitution parameter x to TC=925℃.The activation energies of charge carriers have been found in different temperature ranges.展开更多
基金Supported by the National Key Basic Research Special Foundation of China under Grant No G1999064602, and the Natlonal Natural Science Foundation of China under Grant Nos 10174003, 50377040 and 90303008.
文摘In view of the question about the vortex glass theory of the freezing of disordered vortex matter raised by recent experimental observations, we reinvestigate the critical scaling of high Tc superconductors. It is found that the dc current-voltage characteristic of mixed state superconductors has a general form of extended power law which is based on the Ginzburg-Landau （GL） functional in the similar way as the vortex glass theory. Isotherms simulated from this nonlinear equation fit the experimental I- V data of Strachan et al. [Phys. Rev. Left. 87（2001） 067007]. The puzzling question of the derivative plot for the I - V curves and the controversy surrounding the values of critical exponents are discussed.
文摘用自燃烧法低温合成了单相 (Sr,Pb) Ti O3陶瓷粉末 ,研究和确定了自燃烧反应的 p H值条件 ,分析了自燃烧反应历程。测量了 (Sr,Pb) Ti O3的居里温度及 Y掺杂陶瓷阻 -温特性。结果表明 ,(Sr,Pb) Ti O3的居里温度较理论计算值稍有偏移。典型陶瓷样品的电阻升阻比为 4.2 ,V型特性明显。Y掺杂陶瓷样品的电阻率与 Y掺杂量之间关系符合一般稀土掺杂规律。
基金This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation,2020.
文摘The Aurivillius phases(APs)[Bi_(2)O_(2)]2t[A_(m-1)B_(m)O_(3m+1)]2-are well-known ferroelectrics with high Curie temperatures.Hightemperature piezoceramics Bi_(3-x)Gd_(x)TiNbO_(9)(BiGdTiNb,x=0,0.1,0.2,0.3)were prepared by a solid-state reaction method.The structural and electrophysical characteristics of BiGdTiNb ceramics have been studied.According to the data of powder X-ray diffraction,all the compounds are single-phase with the structures of two-layer APs(m=2)with the orthorhombic crystal lattice(space group A21am).The temperature dependence of the relative permittivityε/ε_(0)(T)of the compounds was measured and showed that the Curie temperature of perovskite-like oxides Bi_(3-x)Gd_(x)TiNbO_(9) increases linearly with an increase in the substitution parameter x to T_(C)=950℃.The activation energies of charge carriers have been found in different temperature ranges.
基金This work was supported by the Ministry of Science and Higher Education of the Russian Federation.“Features of crystalline systems with local structural disturbances at meso-and nanoscale scale levels,experiencing successive structural and magnetic phase transitions”,hands.I.P.Raevsky.,2020-2022.
文摘The Aurivillius phases[Bi_(2)O_(2)][A_(n−1)B_(n)O3_(n+1)]are well-known ferroelectrics with high Curie temperatures T_(C).High-temperature piezoceramics Bi_(3-x)Gd_(x)TiTaO_(9)(BGdTTa,x=0.0,0.1,0.2,0.3)were prepared by a solid-state reaction method.The structural and electrophysical characteristics of BGdTTa ceramics have been studied.According to the data of powder X-ray diffraction,all the compounds are single-phase with the structures of two-layer Aurivillius phases(m=2)with the orthorhombic crystal lattice(space group A2_(1)am).The temperature dependence of the relative permittivity ε/ε_(o)(T)of the compounds was measured and showed that the Curie temperature T_(C) of perovskite-like oxides Bi_(3-x)Gd_(x)TiTaO_(9)increases linearly with an increase in the substitution parameter x to TC=925℃.The activation energies of charge carriers have been found in different temperature ranges.
