Characterization of Calcium Titanate–Magnesium Titanate Eutectic by Scanning Microwave Microscopy

Microstructure and dielectric properties in a CaTiO₃ (CT)–MgTiO₃ (MT) diffusion couple were studied by scanning electron microscopy (SEM) and near-field scanning microwave microscopy (SMM). Complex microstructures containing Mg₂TiO₄ (M2T) and MgTi₂O₅ (MT2) phases as well as eutectic structures of CT–MT and MT2–CT developed during cooling from the melt. Variations in the local dielectric properties observed in SMM images are correlated with the microstructures characterized by SEM/EDS. The SMM characterization clearly distinguished low-dielectric-constant MT and high-dielectric-constant CT phases. The M2T, MT, and MT2 phases have similar dielectric properties, and were more difficult to distinguish in the SMM. The phase development during melting and solidification, and SMM imaging limitations are discussed.