Structure-property relations in xCaTiO3-(1-x)SrMg1/3Nb2/3O3 based microwave dielectrics

• Published in: Journal of the European Ceramic Society Vol. 23; no. 14; pp. 2435 - 2441
• Main Authors: BAGSHAW, H, IDDLES, D, QUIMBY, R, REANEY, I. M
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Oxford Elsevier 2003
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electrotechnical and electronic ceramics; Exact sciences and technology; Permittivity (dielectric function); Physics; Technical ceramics; Perovskite type compound; Binary system; Microwave; Magnesium Niobium Strontium Oxides Mixed; Solid solution; Oxide ceramics; Dielectric ceramics; Chemical preparation; Manufacturing; Permittivity; Magnesium Oxides; Electroceramics; Oxides Mixed; Scanning electron microscopy; Q factor; Electrical properties; Dielectric materials; Dielectric properties; Calcium Titanates; Experimental study; X ray diffraction; Niobium Oxides; Property structure relationship; Microstructure; Strontium Oxides
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/s0955-2219(03)00132-8

Solid solutions of the system (x)CaTiO3-(1-x)Sr(Mg1/3Nb2/3)O3 (CTSMN) were prepared by the mixed oxide route. All compositions were found to be single phase by X-ray diffraction; pellets had densities > 95% of the theoretical X-ray density. Scanning electron microscopy coupled with energy dispersive X-ray analysis revealed a homogeneous distribution of cations within instrument sensitivity in all samples except for pure SMN which showed evidence of some unreacted MgO. SMN is reported as a 1:2 ordered trigonal/hexagonal complex perovskite structure in the X-ray data files but electron diffraction revealed superlattice reflections characteristic of both in-phase and anti-phase rotations of octahedra arising from further structural phase transitions on cooling. These reflections were retained throughout the solid solution range but #+1/3{hkl} ordered superlattice reflections were absent in samples where x > 0.1. In general, the microwave quality factor (Qu*fo) decreased as x increased and the temperature coefficient of resonant frequency (TCf) was approximately linearly proportional to the permittivity; at x~0.20: TCf~0, *er ~45 and Qu*fo ~9000.