0.5BiDyxFe1-xO3-0.5PbTiOa（0.5BDxF1-x-0.5PT） （x=0.00, 0.05, 0.10, 0.15, 0.20） multiferroic composites were pre- pared by conventional solid state reaction method. Structural characterization was performed by X-ray ...0.5BiDyxFe1-xO3-0.5PbTiOa（0.5BDxF1-x-0.5PT） （x=0.00, 0.05, 0.10, 0.15, 0.20） multiferroic composites were pre- pared by conventional solid state reaction method. Structural characterization was performed by X-ray diffraction and the mate- rials showed tetragonal structure at room temperature. Surface morphology of the composites was studied by a scanning electron microscope （SEM）. Frequency and temperature dependence of dielectric constant （er） and dielectric loss （tan~） of 0.5BDxF1_x- 0.5PT were measured in a wide range of frequency （100 Hz to 1 MHz） and temperature （25 to 400 ~C）. The analysis of the study showed that the er and tang decreased with increasing frequency in the given range for all the samples which could be explained through the occurrence of dipole relaxation process. The effect of substitution of rare earth element dysprosium （Dy） showed increase in er in all the samples prepared for different concentrations from 0.00 to 0.20. An explanation for high value of er for Dy modified 0.5BiFeO3-0.5PbTiO3 （0.5BF-0.5PT） compared to Gd modified 0.5BF-0.5PT was provided. The variation of AC conductivity with inverse temperature found to obey the Arrhenius equation and the composites showed negative temperature coefficient of resistance （NTCR） behavior. The activation energy was found to be in the range from 0.25 to 0.40 eV for all the studied samples.展开更多
The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 ...The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 Hz)at different temperatures(28-500℃).Nyquist plot reveals the presence of bulk effect only.The bulk resistance of the compound decreases with rise in temperature which shows the negative temperature coefficient of resistance(NTCR)like a semiconductor.The ac conductivity spectrum was found to obey Jonscher’s universal power law.DC conductivity(bulk)with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity and the activation energy found to be 0.97 eV.展开更多
Polycrystalline samples of Bi_(1-x)La_(x)FeO_(3)[x=0.5,0.6,0.7 and 0.8]were synthesized through high temperature solid state reaction method.The structural studies of the compounds were done using X-ray diffraction te...Polycrystalline samples of Bi_(1-x)La_(x)FeO_(3)[x=0.5,0.6,0.7 and 0.8]were synthesized through high temperature solid state reaction method.The structural studies of the compounds were done using X-ray diffraction technique.Dielectric constant and dielectric loss were studied for various frequencies(100 Hz–10^(4)Hz)at different temperatures.The temperature-dependent non-Debye type relaxation process was suggested in the materials from the analysis of frequency-dependent electrical data at different temperatures.Temperature dependence of dc and ac conductivity at various frequencies showed negative temperature coefficient of resistance(NTCR)behavior.The frequency dependence of ac conductivity at different temperatures obeyed Jonscher’s universal power law.The temperature dependence of dc and ac conductivity was fitted to Arrhenius equation.The activation energies at different temperature ranges were calculated to know the charge species involved in the conduction process.展开更多
The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5（Bi LaxFe1-xO3）–0.5（Pb Ti O3）（x = 0.05,0.10,0.15,0.20）（BLxF1-x-PT） were prepared by mixed oxide method.Structural characterization was per...The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5（Bi LaxFe1-xO3）–0.5（Pb Ti O3）（x = 0.05,0.10,0.15,0.20）（BLxF1-x-PT） were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La（x = 0.05–0.20） concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range（102–106Hz） at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures（200–300 ℃）.展开更多
基金the SERB under DST Fast Track Scheme for Young Scientist (Project No. SR/FTP/PS-036/2011) New Delhi, IndiaCSIR for sanction of Emeritus Scientist scheme (Project No. 21(0944)/12/EMR-II)
文摘0.5BiDyxFe1-xO3-0.5PbTiOa（0.5BDxF1-x-0.5PT） （x=0.00, 0.05, 0.10, 0.15, 0.20） multiferroic composites were pre- pared by conventional solid state reaction method. Structural characterization was performed by X-ray diffraction and the mate- rials showed tetragonal structure at room temperature. Surface morphology of the composites was studied by a scanning electron microscope （SEM）. Frequency and temperature dependence of dielectric constant （er） and dielectric loss （tan~） of 0.5BDxF1_x- 0.5PT were measured in a wide range of frequency （100 Hz to 1 MHz） and temperature （25 to 400 ~C）. The analysis of the study showed that the er and tang decreased with increasing frequency in the given range for all the samples which could be explained through the occurrence of dipole relaxation process. The effect of substitution of rare earth element dysprosium （Dy） showed increase in er in all the samples prepared for different concentrations from 0.00 to 0.20. An explanation for high value of er for Dy modified 0.5BiFeO3-0.5PbTiO3 （0.5BF-0.5PT） compared to Gd modified 0.5BF-0.5PT was provided. The variation of AC conductivity with inverse temperature found to obey the Arrhenius equation and the composites showed negative temperature coefficient of resistance （NTCR） behavior. The activation energy was found to be in the range from 0.25 to 0.40 eV for all the studied samples.
基金The authors(PN and BB)acknowledge the financial support through DRS-I under SAP of UGC for the development of research work in the School of Physics,SU.
文摘The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 Hz)at different temperatures(28-500℃).Nyquist plot reveals the presence of bulk effect only.The bulk resistance of the compound decreases with rise in temperature which shows the negative temperature coefficient of resistance(NTCR)like a semiconductor.The ac conductivity spectrum was found to obey Jonscher’s universal power law.DC conductivity(bulk)with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity and the activation energy found to be 0.97 eV.
文摘Polycrystalline samples of Bi_(1-x)La_(x)FeO_(3)[x=0.5,0.6,0.7 and 0.8]were synthesized through high temperature solid state reaction method.The structural studies of the compounds were done using X-ray diffraction technique.Dielectric constant and dielectric loss were studied for various frequencies(100 Hz–10^(4)Hz)at different temperatures.The temperature-dependent non-Debye type relaxation process was suggested in the materials from the analysis of frequency-dependent electrical data at different temperatures.Temperature dependence of dc and ac conductivity at various frequencies showed negative temperature coefficient of resistance(NTCR)behavior.The frequency dependence of ac conductivity at different temperatures obeyed Jonscher’s universal power law.The temperature dependence of dc and ac conductivity was fitted to Arrhenius equation.The activation energies at different temperature ranges were calculated to know the charge species involved in the conduction process.
基金support through DRS-I of UGC under SAP,School of Physics,Sambalpur University,UGC-Rajiv Gandhi National Fellowship scheme,UGCBSR fellowship scheme,SERB under DST Fast Track Scheme for Young Scientist (Project No.SR/FTP/PS-036/2011)New Delhi,India,and CSIR for sanction of Emeritus Scientist scheme (Project No.21(0944)/12/EMR-Ⅱ)
文摘The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5（Bi LaxFe1-xO3）–0.5（Pb Ti O3）（x = 0.05,0.10,0.15,0.20）（BLxF1-x-PT） were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La（x = 0.05–0.20） concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range（102–106Hz） at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures（200–300 ℃）.
