Cation distribution and bond energy of intermediate spinel Mg(Zn0.5Ti0.5)2xGa(2−2x)O4 microwave dielectric ceramics. Issue 23 (1st December 2021)

• Record Type: Journal Article
• Authors: Shen, Shiyao; Tang, Ying; Li, Jie; Fang, Weishuang; Ao, LaiYuan; Zhao, Xiangguang; Fang, Liang
• Is Part Of: Ceramics international. Volume 47:Issue 23(2021)
• Page Start: 33731
• Page End: 33737
• Publication Date: 2021-12-01
• Subjects: Intermediate spinel -- MgGa2O4 -- Substitution -- Bond energy -- Microwave dielectric properties; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.08.283
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Substitution of Ga 3+ by [Zn0.5 Ti0.5 ] 3+ in MgGa2 O4 improved the comprehensive properties of the resultant spinel. A continuous solid solution with a spinel structure was formed in Mg(Zn0.5 Ti0.5 )2 x Ga(2−2 x ) O4 (0 ≤ x ≤ 1); here, Zn 2+ occupied the tetrahedral 8 a site while Ti 4+ occupied the octahedral 16 d site, resulting in a decrease in the degree of inversion λ from 0.86 to 0. The optimal sintering temperature decreased from 1460 °C to 1220 °C, and the dielectric constant ( ε r ) increased from 8.8 to 14.9; these changes could be ascribed to the greater polarizability of [Zn0.5 Ti0.5 ] 3+ relative to that of Ga 3+ . The temperature coefficient of resonant frequency ( τ f ) of the material remarkably increased from −64.1 ppm/°C to −16.8 ppm/°C, which may be attributed to the increase in dielectric polarizability/molecular volume, bond energy, and bond valence in B-sites. The high-quality factor ( Q × f ) slightly decreased from 89, 253 GHz to 73, 432 GHz with decreasing λ and packing fraction. Optimal microwave dielectric properties were obtained from the sample with x = 1 and sample sintered at 1220 °C; in this case, ε r = 14.9, Q × f = 73, 432 GHz, and τ f = −16.8 ppm/°C.