Vibrational spectroscopic and crystal chemical analyses of double perovskite Y2MgTiO6 microwave dielectric ceramics

Structure-property relationships of Y2MgTiO6, a type of double perovskite materials, were investigated systematically. Rietveld refinement of XRD patterns confirmed that Y2MgTiO6 belongs to the P2(1)/c space group and has a structure analogous to that of monoclinic Dy2MgTiO6. In accordance with the observed number of vibrational bands and group theoretical predictions, O and Y ions at the 4e site dominated the Raman peaks. The IR reflectivity spectrum indicated that the major contributions to the relative permittivity and intrinsic loss were modes lower than 500 cm(-1). The measured relative permittivity closely approached the calculated values determined according to P-V-L theory, the Clausius-Mossotti equation and IR fitted results. The larger bond energy for Mg-O bonds than for Ti-O bonds corresponds to a more stable octahedron of [MgO6], as verified by the octahedral distortion. Satisfactory microwave dielectric properties of Y2MgTiO6 ceramics were as follows: epsilon(r) = 20.4 +/- 0.8, Q x f = 42 060 +/- 310 GHz, tau(f )= -52 +/- 3 ppm/degrees C, sintered at 1450 degrees C.