Low-temperature co-fired LiMnPO4–TiO2 ceramics with near-zero temperature coefficient of resonant frequency

• Published in: Journal of materials science. Materials in electronics Vol. 28; no. 18; pp. 13970 - 13975
• Main Authors: Xia, C. C., Chen, G. H., Yuan, C. L., Zhou, C. R.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2017; Springer Nature B.V
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemical compatibility; Chemistry and Materials Science; Dielectric properties; Lithium compounds; Low temperature; Materials Science; Materials selection; Optical and Electronic Materials; Permittivity; Phosphates; Q factors; Resonant frequencies; Sintering; Titanium dioxide; Zero temperature coefficient
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-7246-2

The microwave dielectric properties and the microstructures of LiMnPO 4 -TiO 2 composite ceramics prepared by solid-state reaction method have been investigated. The results show that the pure LiMnPO 4 (LMP) ceramic can be sintered at 750 °C for 4 h and has a relative permittivity (ε r ) of 6.7 and high quality factor (Q ×  f ) of 41,696 GHz (at 11.2 GHz) with a temperature coefficient of resonant frequency (τ f ) of −55 ppm/°C. The relatively large negative τ f value is lowered by preparing LMP-TiO 2 composite ceramics. Adding TiO 2 lowers τ f from −55 to +26.8 ppm/°C, and does not induce much degradation of dielectric properties. Typically, the 19 wt% TiO 2 -added ceramic sintered at 875 °C for 4 h exhibits excellent properties of ε r  = 12.3, Q ×  f  = 38,671 GHz, τ f  = 6.7 ppm/°C. Moreover, this material has a chemical compatibility with silver, making it a very promising candidate material for LTCC applications.