An evaluation of the impact of crystal structure on microwave dielectric properties of novel titanite-type CaMGeO5 ceramics. Issue 16 (December 2022) - Du, Kang
Abstract: Novel titanite-type Ca M GeO5 ( M = Ge, Hf, Zr) microwave dielectric ceramics were prepared using solid-state reaction. A CaGe2 O5 single-phase ceramic with a triclinic structure was obtained, and the main phase compositions and crystal structure of Ca M GeO5 ( M = Hf, Zr) ceramics were confirmed. The CaGe2 O5 single-phase ceramic exhibited a high Q × f value (92, 400 GHz), and its Q × f values were controlled by the r c (Ge-O) and the packing fraction. For Ca M GeO5 ( M = Hf, Zr) multi-phase ceramics, the Q × f values were deteriorated by the second phase. The τ f and τ ε values of the Ca M GeO5 ceramics were directly controlled by the ε r anomaly peaks, and the phase transitions were controlled by − δ . The τ f values of the Ca M GeO5 ( M = Ge, Hf, Zr) ceramics were mainly related to − δ, and the small − δ corresponded to the nearer-zero τ f values for the titanite-type Ca M GeO5 ceramic with negative τ f values. The optimal microwave dielectric properties ( ε r = 10.57, Q × f = 92, 400 GHz at 13.22 GHz, and τ f = 68.3 ppm/°C) were obtained by the CaGe2 O5 ceramic.