Superconductivity is a phenomenon arising from cooperative electron behavior.However,correlations among(1)the minimum tuning parameter required for emergence,(2)the superconducting transition temperature resulting fro...Superconductivity is a phenomenon arising from cooperative electron behavior.However,correlations among(1)the minimum tuning parameter required for emergence,(2)the superconducting transition temperature resulting from minimal tuning,and(3)the host’s physical/chemical properties still elude the scientific community.Recent empirical investigations,such as those revealing ideal gas-like correlations at the onset of superconductivity in intercalated superconductors,motivate this study.Our investigation reports similar findings in systems(>170 compounds)exhibiting superconductivity through other perturbative means,such as single-element doping.In general,statistical measures,including distance correlation analyses(≠linear regression fit)of thermodynamic variables,indicate the presence of empirical relationships near the superconducting onset of systematically tuned compounds.These relations involve unit cell volume(V),the number of valence electrons(N),and the superconducting transition temperature(T_(c)).Note:The author’s primary aim is not to validate or challenge BCS theory;it is instead to focus on leveraging methodology led by available data to enhance the exploration and development of innovative and cost-effective superconductors.展开更多
稀磁半导体(Diluted Magnetic Semiconductor,DMS)是一种兼具半导体性与磁性且具有优异独特磁光、磁电功能的新型半导体材料。首先介绍了DMS的研究进展及其分类,重点阐述了Ⅰ-Ⅱ-Ⅴ族基DMS的磁电性质,在实验方面和理论计算方面所取得的...稀磁半导体(Diluted Magnetic Semiconductor,DMS)是一种兼具半导体性与磁性且具有优异独特磁光、磁电功能的新型半导体材料。首先介绍了DMS的研究进展及其分类,重点阐述了Ⅰ-Ⅱ-Ⅴ族基DMS的磁电性质,在实验方面和理论计算方面所取得的研究进展,包括Ⅰ-Ⅱ-Ⅴ族DMS的制备方法、基本磁性质、磁性起源、输运性质及光学性质等。目前已经证实了某些DMS材料的铁磁性起源机制,一些新型DMS材料的最高居里温度(Curie temperature,Tc)已经可以与(Ga,Mn)As相比拟,并克服了传统稀磁半导体难以解决的问题。最后对Ⅰ-Ⅱ-Ⅴ族DMS的发展和应用前景进行了展望。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
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 structural and electrophysical characteristics of a number of solid solutions of layered oxides of the perovskite-type Bi_(7)Ti_(4+x)WxNb_(1-2x-0.1)V_(0.1)O_(21)(x=0.1-0.4)are studied.According to X-ray powder dif...The structural and electrophysical characteristics of a number of solid solutions of layered oxides of the perovskite-type Bi_(7)Ti_(4+x)WxNb_(1-2x-0.1)V_(0.1)O_(21)(x=0.1-0.4)are studied.According to X-ray powder diffraction data,all the compounds studied are single-phase and have the structure of Aurivillius phases(m=2.5)with a rhombic crystal lattice(space group I2 cm,Z=2).Changes in tetragonal and rhombic distortions of perovskite-like layers in compounds were considered depending on their chemical composition.The temperature dependences of the relative permittivityε(T)were measured.It was shown that the Curie temperature T_(C) of the perovskite-type oxides Bi_(7)Ti_(4+x)WxNb_(1-2x-0.1)V_(0.1)O_(21)(x=0.1-0.4)linearly decreases with increasing parameter x.The activation energies of charge carriers were obtained in different temperature ranges.It was found that there are three temperature regions with very different activation energies due to the different nature of the charge carriers in the studied compounds.The effect of substitution of Nb^(5+) ions by V^(5+) ions is investigated.It was found that for a number of compounds,the substitution of niobium ions by vanadium ions led to an increase in the dielectric constant and a decrease in the dielectric loss tangent.展开更多
基金The National High Magnetic Field Laboratory is supported by the National Science Foundation through NSF/DMR-2128556,NSF/DMR-1644779,and the State of Florida.
文摘Superconductivity is a phenomenon arising from cooperative electron behavior.However,correlations among(1)the minimum tuning parameter required for emergence,(2)the superconducting transition temperature resulting from minimal tuning,and(3)the host’s physical/chemical properties still elude the scientific community.Recent empirical investigations,such as those revealing ideal gas-like correlations at the onset of superconductivity in intercalated superconductors,motivate this study.Our investigation reports similar findings in systems(>170 compounds)exhibiting superconductivity through other perturbative means,such as single-element doping.In general,statistical measures,including distance correlation analyses(≠linear regression fit)of thermodynamic variables,indicate the presence of empirical relationships near the superconducting onset of systematically tuned compounds.These relations involve unit cell volume(V),the number of valence electrons(N),and the superconducting transition temperature(T_(c)).Note:The author’s primary aim is not to validate or challenge BCS theory;it is instead to focus on leveraging methodology led by available data to enhance the exploration and development of innovative and cost-effective superconductors.
文摘稀磁半导体(Diluted Magnetic Semiconductor,DMS)是一种兼具半导体性与磁性且具有优异独特磁光、磁电功能的新型半导体材料。首先介绍了DMS的研究进展及其分类,重点阐述了Ⅰ-Ⅱ-Ⅴ族基DMS的磁电性质,在实验方面和理论计算方面所取得的研究进展,包括Ⅰ-Ⅱ-Ⅴ族DMS的制备方法、基本磁性质、磁性起源、输运性质及光学性质等。目前已经证实了某些DMS材料的铁磁性起源机制,一些新型DMS材料的最高居里温度(Curie temperature,Tc)已经可以与(Ga,Mn)As相比拟,并克服了传统稀磁半导体难以解决的问题。最后对Ⅰ-Ⅱ-Ⅴ族DMS的发展和应用前景进行了展望。
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.
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(State assignment in the field of scientific activity,Southern Federal University,2020).
文摘The structural and electrophysical characteristics of a number of solid solutions of layered oxides of the perovskite-type Bi_(7)Ti_(4+x)WxNb_(1-2x-0.1)V_(0.1)O_(21)(x=0.1-0.4)are studied.According to X-ray powder diffraction data,all the compounds studied are single-phase and have the structure of Aurivillius phases(m=2.5)with a rhombic crystal lattice(space group I2 cm,Z=2).Changes in tetragonal and rhombic distortions of perovskite-like layers in compounds were considered depending on their chemical composition.The temperature dependences of the relative permittivityε(T)were measured.It was shown that the Curie temperature T_(C) of the perovskite-type oxides Bi_(7)Ti_(4+x)WxNb_(1-2x-0.1)V_(0.1)O_(21)(x=0.1-0.4)linearly decreases with increasing parameter x.The activation energies of charge carriers were obtained in different temperature ranges.It was found that there are three temperature regions with very different activation energies due to the different nature of the charge carriers in the studied compounds.The effect of substitution of Nb^(5+) ions by V^(5+) ions is investigated.It was found that for a number of compounds,the substitution of niobium ions by vanadium ions led to an increase in the dielectric constant and a decrease in the dielectric loss tangent.
