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 ABO3, AB2O6, and A2B2O7 types. Properties of the systems NaNbO3-BaTiO3, NaNbO3–SrTiO3, and NaNbO3-Sr2Ta2O7 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 NaNbO3-SrTiO3 undergoes a phase transition from orthorhombic to cubic symmetry at 15 to 20 mole % SrTiO3 accompanied by a change from NaNbO3-type behavior to para-electric behavior. Results on some mixed-crystal systems are also reported.