Phase evolution and microwave dielectric properties of BaTi4O9 ceramics prepared by reaction sintering method

BaTi₄O₉ microwave dielectric ceramics were prepared by reaction sintering method using BaCO₃ and TiO₂ as raw materials. The phase evolution and the chemical reactions were proposed based on the X-ray diffraction results with sintering temperature. The microstructure characteristics were observed using scanning electron microscopy and energy dispersive spectrometer. The compact ceramics with a single phase of BaTi₄O₉ could be prepared successfully by reaction sintering method, exhibiting optimum microwave dielectric properties: a dielectric constant of 36.9, a high quality factor of 52 735 (at 7.5GHz), and a near zero temperature coefficient of resonant frequency of 5.8 ppm/°C, after sintering at 1200°C for 6 hours.