Microwave dielectric properties of Re 3Ga 5O 12 (Re: Nd, Sm, Eu, Dy and Yb) ceramics and effect of TiO 2 on the microwave dielectric properties of Sm 3Ga 5O 12 ceramics

Abstract

Re 3Ga 5O 12 (Re: Nd, Sm, Eu, Dy and Yb) garnet ceramics sintered at 1350–1500 °C had a high quality factor ( Q × f) ranging from 40,000 to 192,173 GHz and a low dielectric constant ( ɛ r) of between 11.5 and 12.5. They also exhibited a relatively stable temperature coefficient of resonant frequency ( τ f ) in the range of −33.7 to −12.4 ppm/°C. In order to tailor the τ f value, TiO 2 was added to the Sm 3Ga 5O 12 ceramics, which exhibited good microwave dielectric properties. The relative density and grain size increased with addition of TiO 2, resulting in the enhancement of Q × f value. The τ f increased with the addition of TiO 2. Excellent microwave dielectric properties of ɛ r = 12.4, Q × f = 240,000 GHz and τ f = −16.1 ppm/°C were obtained from the Sm 3Ga 5O 12 ceramics sintered at 1450 °C for 6 h with 1.0 mol% TiO 2. Therefore, Re 3Ga 5O 12 ceramics, especially TiO 2-added Sm 3Ga 5O 12 ceramics are good candidates for advanced substrate materials in microwave integrated circuits (MICs) applications.