Crystal structural and microwave dielectric properties of Ba4B′Nb3O12 (B′=Yb, Tm, Er, Y, Ho, Dy, Gd) ceramics

Abstract The influence of substitution of rare-earth ion (RE = Yb, Tm, Er, Y, Ho, Dy, Gd) for B′-site on phase composition, crystal structure, micromorphology, and microwave dielectric properties of Ba4RENb3O12 ceramics are investigated. The results of XRD and Rietveld refinement indicate that the Ba4RENb3O12 ceramic is composed of Ba(RE1/12Nb9/12)O3 and Ba (RE1/2Nb1/2)O3 phases. Porosity analysis shows that the relative density of Ba4RENb3O12 ceramics can reach more than 95.25%. The variations of permittivity and temperature coefficient are associated with ionic polarization and cell polarization, respectively. The A1g Raman‐active modes at 754 cm−1 are oxygen-octahedron stretch vibration, reflecting the variation of the structure. Optimal microwave dielectric properties (er = 38.75, Q × f = 41251 GHz, τf = 71.57 ppm/°C) of Ba4RENb3O12 ceramics for RE = Yb are obtained at 1425 °C for 6 h.