Characterization of structure and chemical bond in high-Q microwave dielectric ceramics LiM2GaTi2O8 (M = Mg, Zn). Issue 11 (September 2022)

• Record Type: Journal Article
• Authors: Tang, Ying; Shen, Shiyao; Li, Jie; Zhao, Xiangguang; Xiang, Huaicheng; Su, Heping; Zhou, Di; Fang, Liang
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 11(2022)
• Page Start: 4573
• Page End: 4579
• Publication Date: 2022-09
• Subjects: Spinel structure -- Microwave dielectric properties -- High Q×f value -- Chemical bond theory; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2022.04.039
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: LiM2 GaTi2 O8 (M = Mg, Zn) ceramics with the Fd -3 m space group were synthesized using the solid-state method. In comparison with Mg 2+ that fully occupied the tetrahedral (A) site in LiMg2 GaTi2 O8, LiZn2 GaTi2 O8 was jointly occupied by Zn 2+ and Li + at the A site. Excellent microwave dielectric properties of Q × f = 133, 400 ± 500 GHz, 101, 800 ± 500 GHz, ε r = 17.1 ± 0.2, 15.8 ± 0.2, and τ f = −60.1 ± 3.0 ppm/°C, − 42.2 ± 3.0 ppm/°C for LiZn2 GaTi2 O8 and LiMg2 GaTi2 O8 were obtained, respectively. The large deviations (30.3% for LiMg2 GaTi2 O8 and 19.6% for LiZn2 GaTi2 O8 ) between the corrected ε corr and theoretical ε th were observed, which might be attributed to the underestimated Shannon's ionic polarizability of Ti 4+ in Ti-containing spinels. Their intrinsic microwave dielectric properties were discussed based on bond valence, lattice energy ( U ), and B-site bond energy ( E ). Besides, their large negative τ f values were compensated to near-zero by CaTiO3 .