Bi1/2Na1/2TiO3–BaTiO3 based thick-film capacitors for high-temperature applications

Thick films with compositions (1 − x)(0.94Bi1/2Na1/2TiO3–0.06BaTiO3)–x(K0.5Na0.5NbO3) (x = 0, 0.03, 0.09 and 0.18) have been prepared and their structural and electrical properties have been investigated. Dielectric properties show that these films are well suited for high-temperature applications due to their low variance in permittivity (<15%) over large temperature ranges. The thick film with x = 0.18 offers an operational temperature range from room temperature to 350 °C. Films with x = 0.03 and 0.09 also possess a stabile permittivity up to 400 °C. The improvement in the thermal stability of the permittivity is attributed to the addition of K0.5Na0.5NbO3 which leads to breaking of the long-range order in the materials. However, the polarizability of the materials was found to decrease possibly due to the clamping effect of the substrate. The characteristics of each film are discussed based on dielectric and electrical properties.