The electrophysical and structural characteristics of bismuth titanate oxides of a number of phases of solid solutions of the Aurivillius phases Bi_(7−2x)Nd_(2x)Ti_(4)NbO_(21)(x=0.0,0.2,0.4,0.6,0.8,1.0)having a layere...The electrophysical and structural characteristics of bismuth titanate oxides of a number of phases of solid solutions of the Aurivillius phases Bi_(7−2x)Nd_(2x)Ti_(4)NbO_(21)(x=0.0,0.2,0.4,0.6,0.8,1.0)having a layered structure of the perovskite type have been investigated.According to the XRD data,all studied compounds are single-phase and have a mixed-layer structure of Aurivillius phases(m=2.5)with a rhombic crystal lattice(space group I2cm,Z=2).A relationship has been established between changes in the chemical composition of solid solutions and orthorhombic and tetragonal distortions of perovskite-like layers.The temperature dependences of the relative permittivityε/ε_(o)(T)are measured.It was found that the change in the phase transition temperature-Curie temperature T_(C)synthesized Aurivillius phases Bi_(7−x)Nd_(2x)Ti_(4)NbO_(21)(x=0.0,0.2,0.4,0.6,0.8,1.0)has a close to linear dependence on the change in the parameter x.The activation energies of charge carriers in different temperature ranges were calculated.It was found that three clearly defined temperature ranges with different activation energies can be distinguished,which is associated with the different nature of charge carriers in the studied solid solutions of the perovskite type.The effect of substitution of Nd^(3+)ions for Bi3+ions is investigated.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 study was financially supported by the Ministry of Science and Higher Education of the Russian Federation[State task in the field of scientific activity,scientific project No.0852-2020-0032(BAS0110/20-3-08IF)].
文摘The electrophysical and structural characteristics of bismuth titanate oxides of a number of phases of solid solutions of the Aurivillius phases Bi_(7−2x)Nd_(2x)Ti_(4)NbO_(21)(x=0.0,0.2,0.4,0.6,0.8,1.0)having a layered structure of the perovskite type have been investigated.According to the XRD data,all studied compounds are single-phase and have a mixed-layer structure of Aurivillius phases(m=2.5)with a rhombic crystal lattice(space group I2cm,Z=2).A relationship has been established between changes in the chemical composition of solid solutions and orthorhombic and tetragonal distortions of perovskite-like layers.The temperature dependences of the relative permittivityε/ε_(o)(T)are measured.It was found that the change in the phase transition temperature-Curie temperature T_(C)synthesized Aurivillius phases Bi_(7−x)Nd_(2x)Ti_(4)NbO_(21)(x=0.0,0.2,0.4,0.6,0.8,1.0)has a close to linear dependence on the change in the parameter x.The activation energies of charge carriers in different temperature ranges were calculated.It was found that three clearly defined temperature ranges with different activation energies can be distinguished,which is associated with the different nature of charge carriers in the studied solid solutions of the perovskite type.The effect of substitution of Nd^(3+)ions for Bi3+ions is investigated.
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.
