Effect of Ion Substitution for Nd 3+ Based on Structural Characteristic on the Microwave Dielectric Properties of NdNbO 4 Ceramic System

NdNbO 4 ceramics with substituted Nd 3+ were prepared by conventional mixed oxide route. The solid solubility limits of Sr , Ca , Mn , and Co in NdNbO 4 were discussed. The generated second phases had a direct affect on the quality factors of NdNbO 4 ceramic. The effects of ionic substitution on the microstructures and microwave dielectric properties based on structural characteristics of NdNbO 4 ceramics were investigated systematically. The specimens presented single NdNbO 4 phase that were used to explain the microwave dielectric properties of NdNbO 4 based on the structural characteristics. From microscopy and phase analysis, it was determined the microwave dielectric properties were strongly dependent on structural characteristics. The dielectric constants were related to the relative density and ion polarizabilities, the temperature coefficients of the resonant frequency τ ƒ were effected by the octahedral structures, and the quality factors Q × ƒ was dependent on, and increased monotonically with, packing fraction.