Structural phase transition and microwave dielectric properties of Ca_(1-x)Sr_xTiO_3 (x = 0.1-0.9) ceramics

摘要

Single phase Ca_(1-x)Sr_xTiO_3 (x = 0.1, 0.25, 0.5, 0.75 and 0.9) bulk ceramics samples were prepared through a mixed oxide solid state sintering route. All the samples were characterized using synchrotron X-ray diffraction, Raman spectroscopy, scanning electron microscopy and vector network analyzer. Structural analysis revealed structural phase transition from orthorhombic (Pbnm) to tetragonal (14/mcm) at x＞ 0.5, consistent with the present Raman spectroscopy results. There was no evidence of orthorhombic Bmmb symmetry in the range x = 0.1-0.9. Relative permittivity varied from 148 to 241, quality factor from 7,427 to 1,487 GHz and temperature coefficient of resonance frequency from +320 to +479 ppm/℃ with an increase in x from 0.1 to 0.9.