(Ba, Sr)TiO₃ system under DC-bias field: I. Improvement on the thermostability of pyroelectric response by Zr-substitution

Abstract

(Ba, Sr)TiO₃ (BST) is being actively investigated as a prime candidate material for thermal imaging sensor that utilizes the dielectric bolometer (DB) mode. However, strong temperature-dependent pyroelectric properties of BST severely limit its widespread applications. In the present study, we have attempted to improve the thermostability of pyroelectric response by narrowing the temperature intervals between the three consecutive rhombohedral-orthorhombic-tetragonal-cubic phase transitions. For this purpose, we have partially substituted Zr ions for Ti ions in the B-site of perovskite structure. It was observed that the three pyroelectric peaks associated with the structural phase transitions coalesced together at near room temperature, exhibiting a broad pyroelectric response at higher Zr concentrations (≥ 10 at.% Zr). It was shown that the broadness of pyroelectric response under the DC-bias field was closely correlated with the broadness of pyroelectric response in the absence of DC-bias field. Therefore, the thermostability of pyroelectric response under the DC-bias field was also significantly improved by the Zr-substitution.

Keywords:

• (Ba, Sr)TiO₃ (BST)
• pyroelectric coefficient
• dielectric bolometer (DB) mode
• spontaneous polarization
• ferroelectric-paraelectric transition