Temperature-driven structural phase transitions in 0.05(Na_0.50Bi_0.50)TiO₃-0.95NaNbO₃ solid solution via amplitude mode analysis

Solid State Physics Division, Bhabha Atomic Research Centre - Mumbai 400085, India and Homi Bhabha National Institute - Anushaktinagar, Mumbai 400094, India

^(a) E-mail: skmsspd@barc.gov.in (corresponding author)
^(b) E-mail: psastry@barc.gov.in

Received: 21 April 2023
Accepted: 7 August 2023

Abstract

Structural phase transitions in the ABO₃-type lead-free eco-friendly piezoelectric (05NBT) have been studied as a function of temperature using dielectric and X-ray diffraction techniques. Below 300 K, we observed dispersion in dielectric permittivity with the frequency, which confirmed relaxor behaviour in 05NBT. Using detailed analysis of temperature-dependent powder X-ray diffraction data of 05NBT, four phase transitions were identified across 600 K, 773 K, 823 K and 923 K. We found that on doping 5% NBT in pure sodium niobate, the low-temperature rhombohedral ferroelectric (N) phase and the high-temperature (S) phase of the sodium niobate get suppressed. To get a better insight about the temperature-driven structural phase transitions, various antiferrodistortive and additional distortive mode as well as the mode amplitude relative to high-symmetry cubic phase were computed and results are discussed.