Ferroelectricity in Tl2MoO4 and Tl2WO4

Ferroelectric behavior has been discovered in Tl2MoO4, Tl2WO4, and their solid solutions. The Curie temperature is 38 °C for the molybdate and 11 °C for the tungstate. Transitions at intermediate temperature are observed in the solid solution. This is a first‐order transition of the type 6/mmmFmm2(s); thus, it is fully ferroelectric and partially ferroelastic. Other transitions in Tl2MoO4 and Tl2WO4 at higher temperatures were also examined.