Sc Modification Induced Short-range Ordering in ZnGa2O4 Spinel Leading to High Microwave Dielectric Performance

Abstract

Sc3+ (0,0.1,0.3,0.5,0.7mol%) modified ZnGa2O4 (abbreviated Sc-ZGO) ceramics were synthesized by solid-state method. The relationship between microwave dielectric performance and bonds vibration of Sc-ZGO as a function of Sc3+ modification has been systematically investigated. With Sc3+ modification, the εr of Sc-ZGO ceramics keeps steady (~10). While the τf of Sc-ZGO shows linear correlation with Sc3+ concentration increasing from -71ppm/℃ to -39ppm/℃, and the Q×f value climbs up to a maximum value (5Sc-ZGO) and then ramp down. 5Sc-ZGO sintered at 1350oC for 2 h exhibits the best microwave dielectric properties with εr = 9.9, Q×f = 124,147 GHz, tanδ = 7.98×10-5, and τf = -56 ppm/°C (@9.9 GHz). Q×f value of Sc modified ZGO increased by almost 45% compared with normal spinel ZnGa2O4 ceramics. The enhancement of τf and Q×f on Sc modified ZnGa2O4 can be attributed to higher densification, however, further Raman and FT-IR analysis elucidated that short-range cation ordering degree is another governing factor. The influence of Sc3+ modification on ZnGa2O4 bonds vibration has been discussed in detail.