Solid Solution Dielectrics Based on Sodium Niobate

The dielectric properties of some twenty solid solution systems based on sodium niobate are described, the additives being classified into ABO 3 , AB 2 O 6 , and A 2 B 2 O 7 types. Properties of the systems NaNbO 3 ‐BaTiO 3 , NaNbO 3 –SrTiO 3 , and NaNbO 3 ‐Sr 2 Ta 2 O 7 are described in some detail. A composition in the last system has permittivity and loss tangent values at 1600 cycles per second of 2600 and 0.003, respectively, at 20°C. and 1600 and 0.025, respectively, at 200OC. The system NaNbO 3 ‐SrTiO 3 undergoes a phase transition from orthorhombic to cubic symmetry at 15 to 20 mole % SrTiO 3 accompanied by a change from NaNbO 3 ‐type behavior to para‐electric behavior. Results on some mixed‐crystal systems are also reported.