Effect of temperature on structural expansion for Bi0.8−xPrxBa0.2FeO3 (x ≤ 0.1) ceramics

• Thermal expansions of Bi0.8−xPrxBa0.2FeO3 (x ≤ 0.1) are studied by HT-XRD.
• No phase decomposition and structural phase transition detected.
• The unit cell thermal expansion and thermal expansion coefficients are positive.
• The thermal expansion coefficients abnormal around the Néel temperature are observed.

At temperature range of 25–800 °C, in situ X-ray diffraction studies on Bi0.8−xPrxBa0.2FeO3 (x ≤ 0.1) ceramics are performed. The unit cell symmetry remains unchanged, while temperature dependence of lattice parameters and unit-cell volumes vary. There are no phase decomposition and structural phase transition detected in the system, which indicate that Pr, Ba co-doping may stabilize the structure of BiFeO3 ceramic. The unit cell thermal expansion and thermal expansion coefficients are positive. However, for sample with x = 0.1, i.e., Bi0.7Pr0.1Ba0.2FeO3, the unit cell structural stability decreases, and the thermal expansion coefficient increases. The thermal expansion coefficients abnormal around the Néel temperature are observed, which may suggest a possible antiferromagnetic–paramagnetic transition. It is probably the explanation for their low thermal expansion coefficient during the heating process.