Microstructural variation and dielectric properties of KTiNbO5 and K3Ti5NbO14 ceramics

KTiNbO5 (KTN) and K3Ti5NbO14 (3K5TN) ceramics sintered at 1150 °C and 1125 °C, respectively, exhibited a dense, homogeneous microstructure with a high relative density (≥96% of the theoretical density). Abnormal grain growth occurred in both specimens during sintering, and large (002) and (001) grains developed in KTN and 3K5TN ceramics, respectively. A dielectric constant (εr) of 13 and a dielectric loss of 2.9% at 10 MHz were obtained from KTN ceramics sintered at 1150 °C. The 3K5TN ceramics sintered at 1125 °C showed an εr of 15 and a dielectric loss of 12% at 10 MHz. The resistivity of KTN and 3K5TN ceramics was low and their εr and dielectric loss values displayed low-frequency dispersion (LFD); the presence of K+ ions between the layers could be responsible for their low resistivity and LFD.