Structure and microwave dielectric properties of Li(Al1-xLix)SiO4-x ceramics

• Published in: Ceramics international Vol. 49; no. 3; pp. 4290 - 4297
• Main Authors: Wang, Yarong, Ding, Shihua, Hou, Zhengpeng, Xiao, Junwen, Zhang, Yun, Song, Tianxiu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2023
• Subjects: First-principle; LAS; Low-permittivity; Microwave dielectric properties; Low-permittivity; First-principle; LAS; Microwave dielectric properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2022.09.313

Li(Al1-xLix)SiO4-x (x = 0.005, 0.01, 0.015, and 0.02) ceramics were synthesized via a traditional solid phase reaction method with different sintering temperatures. To determine the positions occupied by Li+ in the lattice, the defect formation energies and total energies of various sites of LiAlSiO4 (LAS) occupied by Li+ were examined, and the energy of LAS systems were calculated using density functional theory of first-principle with the CASTEP module. The results demonstrated that the Al-sites occupied by Li+ had the lowest formation energies and total energy, so Li + should substitute Al3+. The impacts of replacing Al3+ with Li+ on the bulk density, sintering properties, phase composition, microstructure, and microwave dielectric properties of Li(Al1-xLix)SiO4-x (0 = x ≤ 0.02) ceramics were thoroughly studied. With Li+-doping, the sintering temperature decreased from 1300 °C (x = 0) to 1175 °C (x = 0.02), while the Q × f and τf values of LAS ceramics significantly increased. The Li(Al0.99Li0.01)SiO3.99 ceramic was fully sintered at 1250 °C for 10 h to obtain excellent microwave dielectric properties: εr = 3.49, Q × f = 51,358 GHz, and τf = −51.48 × 10−6 °C−1.