Effects of A-site configuration entropy on the dielectric properties in tetragonal tungsten bronze ceramics

A series of Sr4.5Ca0.5MTi3Nb7O30 [M = La0.5Nd0.5 (LN), La1/3Nd1/3Sm1/3 (LNS) and La0.25Nd0.25Sm0.25Eu0.25 (LNSE)] ceramics with different A-site configuration entropy were prepared, and the effects of the A-site configuration entropy on the dielectric and ferroelectric properties were investigated. Due to the combined effect of high entropy and solid solution, the best dielectric performance was achieved in the LNS composition, where the dielectric constant remained around 650 in the temperature range of 269–515 K with a change rate of less than 15%. Under the DC high voltage field up to 67 kV/cm, each component's polarization characteristics and dielectric constants obtained good electric field stability and temperature stability under a high electric field.