Dielectric, pyroelectric and piezoelectric properties of bismuth-modified 0.69PMT–0.31PT ceramics

Abstract

The dielectric, pyroelectric and piezoelectric properties of relaxor ferroelectric in the 0.69(Pb_(1–3x/2)Bi_x)(Mg_1/3Ta_2/3)O₃-0.31PbTiO₃ ceramics have been investigated. The dielectric constant and loss of poled ceramic samples were determined. The pyroelectric coefficient and the spontaneous polarization were measured by the static Byer-Roundy method as a function of temperature. The piezoelectric d₃₃ and coupling factor (k_p) were measured by using the Berlincourt d₃₃ meter and resonance-antiresonance method, respectively. The Curie temperature and pyroelectric peak temperature decreased gradually with the addition of Bi₂O₃. The maximum dielectric and pyroelectric constant increase sharply with addition of 1 mole% Bi₂O₃ and then decrease gradually with further addition of Bi₂O₃. The PMT-PT specimen modified 3 mole% Bi₂O₃ showed a large voltage responsivity (F_v ∽ 0.1m²/C). The dissipation factor and piezoelectric constant could be improved by small additions of Bi₂O₃.

Key Words:

• relaxor ferroelectrics
• dielectric
• piezoelectric
• pyroelectric properties
• solid solutions