Structural, dielectric and impedance properties of NaCa2V5O15 ceramics

Banarji Behera,P. Nayak,R.N.P. Choudhary 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Polycrystalline sample of NaCa2V5O15 (NCV) with tungsten bronze structure was prepared by a mixed oxide method at relatively low temperature (i.e. 630℃). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Microstructural study showed that the grains are uniformly and densely distributed over the surface of the sample. Detailed studies of dielectric properties showed that the compound has dielectric anomaly above the room temperature (i.e. 289 ℃), and shows hysteresis in polarization study. The electrical parameters of the compound were studied using complex impedance spectroscopy technique in a wide temperature (23–500 ℃) and frequency (102–106 Hz) ranges. The impedance plots showed only bulk (grain) contributions, and there is a non-Debye type of dielectric dispersion. Complex modulus spectrum confirms the grain contribution only in the compound as observed in the impedance spectrum. The activation energy, calculated from the ac conductivity of the compound, was found to be 0.20–0.30 eV. These values of activation energy suggest that the conduction process is of mixed type (i.e. ionic–polaronic). Polycrystalline sample of NaCa2V5O15 (NCV) with tungsten bronze structure was prepared by a mixed oxide method at relatively low temperature (i.e. 630℃). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Microstructural study showed that the grains are uniformly and densely distributed over the surface of the sample. Detailed studies of dielectric properties showed that the compound has dielectric anomaly above the room temperature (i.e. 289 ℃), and shows hysteresis in polarization study. The electrical parameters of the compound were studied using complex impedance spectroscopy technique in a wide temperature (23–500 ℃) and frequency (102–106 Hz) ranges. The impedance plots showed only bulk (grain) contributions, and there is a non-Debye type of dielectric dispersion. Complex modulus spectrum confirms the grain contribution only in the compound as observed in the impedance spectrum. The activation energy, calculated from the ac conductivity of the compound, was found to be 0.20–0.30 eV. These values of activation energy suggest that the conduction process is of mixed type (i.e. ionic–polaronic).

Dielectric, Electrical and Conduction Mechanism Study of 0.6BiFeO3–0.4PbTiO3

Truptimayee Sahu,Banarji Behera 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.5

0.6BiFeO 3 –0.4PbTiO 3 sample was prepared using conventional solid state reaction route. The X-ray diff raction confi rmedthe formation of the sample. The microstructure study was carried out using fi eld emission scanning electron microscope. Agood dielectric value was observed at room temperature. The impedance study showed the non-Debye type of behaviour andthe Nyquist plot fi t confi rmed the contribution of both grain and grain boundary eff ect in the material. The ac conductivityobeyed Jonscher’s power law. The temperature variation of frequency exponent suggested that overlapping large polarontunnelling model was appropriate to understand the conduction mechanism within the temperature range (250–350 °C). Thetemperature variation of ac conductivity followed Arrhenius equation.

Structural and dielectric properties of Ba3V2O8 ceramics

Praveen Khatri,V. Srinivas,Banarji Behera,R.N.P. Choudhary 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Polycrystalline sample of Ba3V2O8 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) analysis confirms the formation of single-phase compound of hexagonal (rhombohedral) crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compound has well defined grains, which are distributed uniformly throughout the surface of the sample. The dielectric properties of the compound studied in a wide frequency range (102– 106 Hz) at different temperatures (25–400 ℃), exhibits that they are temperature dependent. Detailed analysis of impedance spectra showed that the electric properties of the material are strongly dependent on frequency and temperature. The activation energy, calculated from the temperature dependence of ac conductivity (dielectric data), was found to be 0.23 eV at 50 kHz in the higher temperature region. Polycrystalline sample of Ba3V2O8 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) analysis confirms the formation of single-phase compound of hexagonal (rhombohedral) crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compound has well defined grains, which are distributed uniformly throughout the surface of the sample. The dielectric properties of the compound studied in a wide frequency range (102– 106 Hz) at different temperatures (25–400 ℃), exhibits that they are temperature dependent. Detailed analysis of impedance spectra showed that the electric properties of the material are strongly dependent on frequency and temperature. The activation energy, calculated from the temperature dependence of ac conductivity (dielectric data), was found to be 0.23 eV at 50 kHz in the higher temperature region.

Electrical and Magnetic Properties of Rare Earth Doped Pb0.8R0.2Fe0.1Cr0.1Ti0.8O3 Ceramics

Amrita Nayak,S. K. Patri,Banarji Behera 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.5

Rare earth doped Pb 0.8 R 0.2 Fe 0.1 Cr 0.1 Ti 0.8 O 3 (R = La, Nd, Sm) ceramics were prepared by solid state reaction method. The formation of the materials was confi rmed using X-ray diffraction. A meticulous investigation of dielectric properties was carried out in order to evaluate the macroscopic effect and ensuing incorporation of rare earth ions over a wide range of frequency and temperature. The phase transition temperatures of these ceramics were in the range of 75–115 °C and 325–365 °C. The ac conductivity of the samples was found to be frequency and temperature dependent. Charge transport through short as well as long range conduction contributions were indicated in different temperature regions of conductivity studies. The ferroelectric, magnetic hysteresis and magnetoelectric measurements were conducted to affirm the multiferroic properties in these materials.

Investigation on Structural, Dielectric, Thermistor Parameters and Negative Temperature Coefficient Behaviour of Nd, Gd, and La-Doped Bismuth Ferrite

Priyambada Mallick,A. K. Sahu,Susanta Ku. Biswal,S. K. Satpathy,Banarji Behera 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.5

Synthesis of polycrystalline samples of Bi 1–x R x FeO 3 (R = Nd, Gd and La) with x = 0.5, 0.6, 0.7 and 0.8 were demonstrated through solid-state reaction method at high temperature. The X-ray diffraction technique confirmed the orthorhombic phase of the samples and structural parameters like microstrain, crystallinity percentage, and dislocation density of the composites were calculated using an approximation method from XRD data. A negative temperature coefficient of resistance (NTCR) behavior of all the samples at various temperatures was confi rmed from the variation of resistance with temperature. The inverse dependence of dielectric constant with a doping concentration of rare earth metal was identified. Bismuth ferrite with dopants Nd, La, and Gd was found to have the potential to be used as an NTC Thermistor by enhancing the value of thermistor constant (β), sensitivity factor (α), and stability factor.

Dielectric and Frequency Dependent Transport Properties of Gadolinium Doped Bismuth Ferrite

A. K. Sahu,S. K. Satpathy,S.K. Rout,Banarji Behera 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.2

Ceramics of (Bi 1−x Gd x FeO 3 ) [x = 0.5, 0.6 and 0.7] were synthesized through mixed oxide method. Structural studies of the ceramics were done using X-ray diff raction technique. At high frequency, nearly flat response in the dielectric constant and dielectric loss with temperature up to 200 °C were observed. Dielectric constant found to increase with decrease in Gadolinium concentration. Frequency dependent electrical data analysis at diff erent temperatures suggested a temperature dependent non-Debye type relaxation process in the ceramics. Frequency dependence AC conductivity at different temperatures obeyed Jonscher’s universal power law. The temperature dependence of DC and AC conductivity was fitted with Arrhenius equation. The activation energies at different temperature ranges were calculated to understand the conduction process.