Effect of raw material pretreatment and ionic radius on the preparation and microwave dielectric properties of Re2TiO5 ceramics

Abstract

The present study focuses on the synthesis and characterization of rare-earth titanates, specifically Re2TiO5 (ReLa, Nd, Sm), with a particular emphasis on their microwave dielectric properties. The factors influencing the synthesis of La2TiO5 compound through the traditional solid-state method were thoroughly investigated, with a significant finding being the notable impact of moisture absorption in La2O3. The impact of variations in rare-earth cation radii on the structure and dielectric properties was systematically analyzed. Re2TiO5 (ReLa, Nd, Sm) ceramics crystallized into an orthorhombic structure with space group Pnam, which was confirmed through Rietveld refinement. The resulting materials demonstrated exceptional microwave dielectric properties characterized by a low permittivity range of 13.72–17.39, high-quality factors ranging from 8331 to 17,795 GHz, and a significantly reduced temperature coefficient of resonance frequency (−33.2∼-12.6 ppm/°C). The correlation between microwave dielectric properties and structural characteristics (including ionic polarizability, packing fraction, and bond valence) was investigated. The exceptional potential of these rare-earth titanates lies in their ability to meet the stringent requirements for low signal transmission delay in wireless communication systems, owing to their advantageous low permittivity within the microwave frequency spectrum.