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Ray A.,Nayak B.,Elorika P.,Barman R.,Sharmistha A.,Badapanda T.,Anwar S. 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5
In the current work, the structural, dielectric, and electrocaloric performance of Ba0.7Ca0.3TiO3 ceramic synthesized by solid-state reaction route is presented. The structural analysis was examined by X-ray diffraction and Rietveld refinement, which confirms the existence of a combined phase of tetragonal structure with P4mm symmetry and orthorhombic structure with Amm2 symmetry. The scanning electron micrograph shows well-defined and pore-free grains. The temperature-dependent dielectric performance shows diffuse phase transition behavior. The temperature-dependent ferroelectric hysteresis behavior was examined under the application of various amplitudes of an applied electric field. The energy storage density, energy loss density, and energy storage efficiency of the composition at different temperature were calculated using the standard formula. The thermal energy potential has been calculated by employing the Olsen cycle. Also, pyroelectric figures of merit (FOMs) for voltage responsivity (Fv), current responsivity (Fi), energy harvesting (Fe), new energy harvesting (F*e), and detective (Fd) were calculated. Adiabatic temperature change, isothermal entropy change, and electrocaloric strength are evaluated using an indirect technique based on the thermodynamic Maxwell's relation.
Ankush Thakur,R. R. Singh,P. B. Barman 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.6
Citrate precursor technique has been used to synthesize strontium hexaferrite and reported here. The crystallization process for ferrite phase formation has been investigated by TG/DTG/DTA for three different heating rates in air atmosphere. The thermal process mainly consists of three essential steps; first removal of water residues; second decomposition of organic compound and the third step is crystallization of SrF12O19. The activation energy of reaction is, 157 KJ/mole, evaluated using non-isothermal kinetic model. The precursor and crystallized SrF12O19 samples have been characterized for structural, chemical, morphological, dielectric and magnetic properties using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), inductance capacitance resistance (LCR) meter bridge and vibrating sample magnetometer (VSM) respectively. The degree of crystallization of SrF12O19 is the key factor for the dilution and enhancement of morphological and magnetic properties. The thermal, morphological and magnetic analysis confirms the formation of single phase of magnetoplumbite strontium ferrite at 1200°C.
Neha Sharma,Sunanda Sharda,Dheeraj Sharma,Vineet Sharma,P. B. Barman,S.C. Katyal,Pankaj Sharma,S. K. Hazra 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5
Steady state current-voltage characteristics of the amorphous (Se80Te20)98Y2 (Y = Ag, Bi, Ge, Cd) semiconductors at different temperatures are reported. The measurements were performed using direct-current voltage bias to understand the basic conductivity mechanism and to evaluate the impact of each substituent on electrical response. The space charge limited conduction mechanism, and the density of states near Fermi level have been calculated. The difference in electrical response due to different substitutions in the glassy matrix is analyzed.