Phase Transitions Of The Ferroelectric Na0.5Bi0.5TiO3 By Dielectric And Internal Friction Measurements

Venkata Ramana Mudinepalli1*, N. Ramamanohar Reddy2, Wen-Chin Lin1, K.V. Siva Kumar3, B.S. Murty

1Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan

2Department of Materials Science and Nanotechnology, Yogi Vemana University, Kadapa, 516 227, India

3Ceramic Composite Materials Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515003, India

4Nanotechnology Laboratory, Department of Metallurgical and Materials Engineering, Indian Institute of Technology- Madras, Chennai, 600 036, India

Adv. Mater. Lett., 2015, 6 (1), pp 27-32

DOI: 10.5185/amlett.2015.5620

Publication Date (Web): Dec 28, 2014

E-mail: materialphysics.ramana@gmail.com

Abstract


This work focuses on the high temperature dielectric and mechanical spectroscopic properties of lead free relaxor Sodium Bismuth Titanate (NBT) ceramics, fabricated by conventional ceramic double sintering method. Systematic measurements of dielectric and mechanical properties have been performed as a function of temperature. A sequence of phase transitions has been studied by both dielectric and anelastic measurements. Three internal friction peaks were observed near 350, 200 and 120 °C. The 350 °C-peak corresponds to a transition associated with the tetragonal (P4bm) to rhombohedral (R3c) phase, and the 200 °C-peak is related to the ferroelectric to antiferroelectric phase transition. The 120 °C-peak could be ascribed to the interaction between the domain walls and the diffusion of oxygen vacancies in the domains.

Keywords

Internal friction, ferroelectric, elastic modulus, dielectric, phase transition, Curie transition temperature.

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