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arXiv · 1806.00587

Structural, dielectric and ferroelectric studies of thermally stable and efficient energy storage ceramic material: (Na0.5-xKxBi0.5-xLax)TiO3

Anita Verma·Arun Kumar Yadav·Nasima Khatun·Sunil Kumar·Ravindra Jangir·Velaga Srihari·V. Raghavendra Reddy·Shun Wei Liu·Sajal Biring·Somaditya Sen
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Abstract

The structural, dielectric and ferroelectric properties of lead-free (Na0.5-xKxBi0.5-xLax)TiO3 powders synthesized by sol-gel self-combustion method were investigated. Rietveld refinement of Synchrotron x-ray diffraction data confirms pure single phase rhombohedral crystal structure with R3c space group for all the compositions and anti-phase octahedral tilting angle decreased with increase in composition x. Homogeneity and elemental proportions were confirmed by Energy dispersive x-ray spectrometry. The temperature-dependent dielectric study has shown two diffuse type of dielectric anomaly for all the samples, due to A-site disorder in the lattice, which has been assigned to two-has transitions: ferroelectric to anti-ferroelectric and anti-ferroelectric to the paraelectric phase transition. The transition temperature of these phase transitions is found to decrease as a function of composition. Thermal stability range of dielectric constant increases from ~100C to 220C as a function of composition. Stable dielectric constant first increases, from 1557 10 % for parent compound, with the composition, highest for 6 % composition with emid ~ 2508 10 % for the temperature range ~180 C to 340C and after that decreases to 1608 10 % for 12 % but remain higher than the parent compound Na0.5Bi0.5TiO3. Ferroelectric measurements have shown monotonously decreasing coercive field as a function of the composition due to a decrease in grain size, confirmed by microstructural studies using Field Emission Scanning Electron Microscope. Exponential increases in the energy storage efficiency from ~ 17 % to 87 % as a function of composition have also observed. These types of materials, with stable high dielectric constant and low tan delta, have a vast scope in the field of the thermally stable dielectric constant materials and energy storage applications.

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Anita Verma, Arun Kumar Yadav, Nasima Khatun, Sunil Kumar, Ravindra Jangir, Velaga Srihari, V. Raghavendra Reddy, Shun Wei Liu, Sajal Biring, Somaditya Sen. 2018-06-02. Structural, dielectric and ferroelectric studies of thermally stable and efficient energy storage ceramic material: (Na0.5-xKxBi0.5-xLax)TiO3. https://arxiv.org/abs/1806.00587

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