Sc modification induced short-range cation ordering and high microwave dielectric performance in ZnGa2O4 spinel ceramics

Sc3+ (0,0.1,0.3,0.5,0.7 mol%) modified ZnGa2O4 (abbreviated Sc-ZGO) ceramics were synthesized by solid-state method. The relationship between microwave dielectric performance and bonds vibration has been systematically investigated. With Sc3+ modification, the epsilon(r) of Sc-ZGO keeps steady (similar to 10). While tau(f) values (increasing from -71 ppm/degrees C to -39 ppm/degrees C) show linear correlation with Sc3+ concentration. And Qxf values climb up to a maximum value and then ramp down. The Qxf value of Sc-ZGO increased by almost 45% compared with normal spinel ZnGa2O4 ceramics. The enhancement of tau(f) and Qxf on Sc modified ZnGa2O4 can be attributed to higher densification, however, further analysis elucidated that short-range cation or-dering degree is another governing factor. The influence of Sc3+ modification on ZnGa2O4 bonds vibration has been discussed in detail. 5Sc-ZGO sintered at 1350 degrees C for 2 h exhibits the best microwave dielectric properties: epsilon(r) = 9.9, Qxf = 124,147 GHz, tan delta = 7.98 x 10(-5), and tau(f)= -56 ppm/degrees C (@9.9 GHz). (c) 2021 Elsevier B.V. All rights reserved.