Within the scope of this research, Li 2 Mg 6 TiO 9 -based ceramics were prepared by a traditional solid-state sintering technique. The research analyzed the influence of lithium (Li) volatilization during the sintering process, on the phase composition, and resultant microwave dielectric performances (MIDP) of the Li 2 Mg 6 TiO 9 -based ceramics, employing advanced analytical techniques. X-ray diffraction and Raman spectroscopy analyses indicated the emergence of a second phase Mg 2 TiO 4 within the sample when the sintering temperature attained 1550 °C due to Li volatilization. The generated Mg 2 TiO 4 could effectively tune the MIDP of the ceramics. Optimal MIDP of Li 2 Mg 6 TiO 9 -based ceramics were derived from a sintering temperature of 1650 °C: dielectric constant ( ε r ) = 12.78, quality factor ( Q × f ) = 129,010 GHz, temperature coefficient of resonant frequency ( τ f ) = − 46.2 ppm/°C. Low ε r and ultrahigh Q × f indicate that the current ceramics have potential application prospects in millimeter wave communication as substrate materials.
Qi Yuan,Yutong Meng,Sen Wang,Gaobin Liu,Qiyao Wang,Kuoming Song,He Zhao,Shuai Yan,Xin Li
The effects of different contents of B 2 O 3 -Bi 2 O 3 on the sintering temperature and dielectric properties of MgO-12%TiO 2 (w) ceramics were investigated. B 2 O 3 -Bi 2 O 3 addition effectively reduced the sintering temperature and improved the dielectric properties of ceramic samples; however, an excessive amount of B 2 O 3 -Bi 2 O 3 led to the deterioration of dielectric properties. This is because Bi 2 O 3 participated in the chemical reaction between MgO and TiO 2 and generated a high-dielectric-loss Bi 2 Ti 2 O 7 phase, resulting in an increased dielectric loss in the ceramic samples. In contrast, B 2 O 3 formed a liquid phase to fill the grain gaps and pores during sintering, improving the densities of the ceramic samples. An appropriate amount of B 2 O 3 -Bi 2 O 3 accelerated the reaction between MgO and TiO 2 and formed ultralow-dielectric-loss phases—MgTiO 3 and Mg 2 TiO 4 , and the dielectric losses of the ceramic samples decreased to an order of 10 −5 .
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