Soft-chemical reaction of layered perovskite Na2Nd2Ti3O10 and its microwave dielectric properties

The mechanism of soft-chemical reaction of Na2Nd2Ti3O10 has been investigated in terms of the structure and composition. The Na0.21Nd0.60TiO3 was prepared by soft-chemical reaction using layered perovskite Na2Nd2Ti3O10 through protonated layered perovskite H1.37Na0.63Nd2Ti3O10 with HNO3 solution. The ion-exchange ratio of the Na+/Ti4+ in Na2Nd2Ti3O10 was estimated by using inductively coupled plasma spectrometry (ICP), and the weight loss of H2O were changed from 0.70 to 0.21. The products; the protonated H1.37Na0.63Nd2Ti3O10 was transferred from layered perovskite to three-dimensional perovskite at around 400–600 °C as following topochemical condensation and dispersion the interlayer Na into Nd site. The crystal structure of Na0.21Nd0.60TiO3 was assigned to a double perovskite structure with orthorhombic space group Pmmm. The dielectric properties of the specimen showed an ɛr = 86, a Qf = 1500 GHz and a τf = +270 ppm/°C. the sintered ceramics containing Na0.21Nd0.60TiO3 plate-like particles by spark plasma sintering (SPS) exhibited a {0 0 l} orientation degree of 9.9%. The obtained samples showed anisotropy in the dielectric properties according to the different directions parallel and perpendicular to c-axis.