Structure characterization and microwave dielectric properties of LiGa5O8 ceramic with low-εr and low loss

LiGa5O8 ceramics with inverse spinel structure were prepared in a temperature range of 1200-1300 degrees C by solidstate reaction method. LiGa5O8 ceramics crystallized in cubic structure with space group P4332, in which Li+ and Ga3+ distributed in the octahedral B sites with 1:3 ordering. The optimal microwave dielectric properties with epsilon(r) =10.51, Q x f = 127,040 GHz, and tau(f) = -60.16 ppm/degrees C were achieved at 1260 degrees C for 6 h. Microwave dielectric properties were discussed in combination with the intrinsic characteristics of crystal structure by packing fraction, Raman spectra, and infrared reflectivity spectrum. Additionally, CaTiO3 was used to suppress if of LiGa5O8 ceramics to near zero, and optimized performances of epsilon(r) = 12.79, Q x f = 109,752 GHz and tau(f) = +4.07 ppm/degrees C were obtained for 0.94LiGa(5)O(8)-0.06CaTiO(3) ceramics at 1260 degrees C. These bright spots make LiGa5O8 ceramic a potential candidate for 5 G and millimeter wave technology.