In the paper, the results of investigations of temperature and frequency dependences of dielectric permeability and dielectric loss of compositions LDPE + xvol%Bi<sub>2</sub>Te<sub>3</sub> are ...In the paper, the results of investigations of temperature and frequency dependences of dielectric permeability and dielectric loss of compositions LDPE + xvol%Bi<sub>2</sub>Te<sub>3</sub> are stated. The investigations were carried out at frequency 10 – 10<sup>5</sup> Hz and temperature 20°C - 150°C intervals, respectively. It was revealed that increase of percentage of the filler Bi<sub>2</sub>Te<sub>3</sub> in the matrix, reduces to increase of dielectric permeability and dielectric loss of composites LDPE + xvol%Bi<sub>2</sub>Te<sub>3</sub> in connection with the change reducing to Maxwell-Wagner’s volume polarization and emergence of comparative strong inner field in semiconductor clusters.展开更多
The main focus of the research was to correlate the microstructure with dielectric and magnetic properties of Bi1-xBaxFeO3 samples. Bi1-xBaxFeO3 samples（x = 0.1, 0.2 and 0.3） were synthesized by the conventional sol...The main focus of the research was to correlate the microstructure with dielectric and magnetic properties of Bi1-xBaxFeO3 samples. Bi1-xBaxFeO3 samples（x = 0.1, 0.2 and 0.3） were synthesized by the conventional solid-state reaction method using nano-powders of Bi2O3, Fe2O3, and BaCO3. Thereafter, field emission scanning electron microscope and X-ray diffraction（XRD） techniques were used to examine the structure and phase of the samples. Phase analysis by XRD indicated that the single-phase perovskite structure was formed with possible increment in lattice parameter with increasing Ba doping. Complex permeability（u＇iand u＇＇i） measured using impedance analyzer confirmed the increase in magnetic property with increasing Ba doping. Finally, dielectric constant（k） was analyzed as a function of temperature at different frequencies. Dielectric constant as high as 2900 was attained in this research for Bi0.8Ba0.2FeO3 sample due to reduction in leakage current at this composition.展开更多
The dielectric breakdown（DB） model for a penny-shaped crack under a semipermeable boundary condition in a three-dimensional piezoelectric medium is studied.An approximate analytical solution is derived by using the ...The dielectric breakdown（DB） model for a penny-shaped crack under a semipermeable boundary condition in a three-dimensional piezoelectric medium is studied.An approximate analytical solution is derived by using the boundary integral equation with extended displacement discontinuity,and the corresponding boundary element method with double iterative approaches is developed to analyze the semi-permeable crack.The effect of electric boundary conditions on crack faces is discussed on the basis of DB model.By comparing the DB model with the polarization saturation（PS） model for different piezoelectric materials,some interesting phenomena related to the electric yielding zone and local J-integral are observed.展开更多
文摘In the paper, the results of investigations of temperature and frequency dependences of dielectric permeability and dielectric loss of compositions LDPE + xvol%Bi<sub>2</sub>Te<sub>3</sub> are stated. The investigations were carried out at frequency 10 – 10<sup>5</sup> Hz and temperature 20°C - 150°C intervals, respectively. It was revealed that increase of percentage of the filler Bi<sub>2</sub>Te<sub>3</sub> in the matrix, reduces to increase of dielectric permeability and dielectric loss of composites LDPE + xvol%Bi<sub>2</sub>Te<sub>3</sub> in connection with the change reducing to Maxwell-Wagner’s volume polarization and emergence of comparative strong inner field in semiconductor clusters.
文摘The main focus of the research was to correlate the microstructure with dielectric and magnetic properties of Bi1-xBaxFeO3 samples. Bi1-xBaxFeO3 samples（x = 0.1, 0.2 and 0.3） were synthesized by the conventional solid-state reaction method using nano-powders of Bi2O3, Fe2O3, and BaCO3. Thereafter, field emission scanning electron microscope and X-ray diffraction（XRD） techniques were used to examine the structure and phase of the samples. Phase analysis by XRD indicated that the single-phase perovskite structure was formed with possible increment in lattice parameter with increasing Ba doping. Complex permeability（u＇iand u＇＇i） measured using impedance analyzer confirmed the increase in magnetic property with increasing Ba doping. Finally, dielectric constant（k） was analyzed as a function of temperature at different frequencies. Dielectric constant as high as 2900 was attained in this research for Bi0.8Ba0.2FeO3 sample due to reduction in leakage current at this composition.
基金Project supported by the National Natural Science Foundation of China(Nos.11102186 and 11272290)the Science and Technology Key Project of Henan(No.132102210412)
文摘The dielectric breakdown（DB） model for a penny-shaped crack under a semipermeable boundary condition in a three-dimensional piezoelectric medium is studied.An approximate analytical solution is derived by using the boundary integral equation with extended displacement discontinuity,and the corresponding boundary element method with double iterative approaches is developed to analyze the semi-permeable crack.The effect of electric boundary conditions on crack faces is discussed on the basis of DB model.By comparing the DB model with the polarization saturation（PS） model for different piezoelectric materials,some interesting phenomena related to the electric yielding zone and local J-integral are observed.
