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.
Runze Geng,Jin Hu,Youwen Zhai,Juemin Yan,Kaijun Wang,Weijun Zhang,Qingming Chen,Xiang Liu,Kaizhao Wang
The tritium breeder's primary research focus is to inhibit lithium's volatilization during sintering and improve the mechanical properties of tritium breeder ceramic pebbles. In this study, ceramic pebbles were prepared by wet method using lithium alginate as a lithium supplement and polyvinyl alcohol. The effects of different contents of lithium alginate (LA) and polyvinyl alcohol (PVA) on ceramic pebbles were systematically studied. The results show that the lithium content in Li 4 SiO 4 pebbles after sintering can be increased to 27.6wt% by adding 3wt% lithium alginate, which effectively inhibits the volatilization of lithium. In addition, when the sintering temperature is 1000℃ and the duration is 6 h, the crush load of ceramic pebbles can be increased to 50.9 N, and the density can reach 2.01 g/cm 3 . The above results indicate that Li 4 SiO 4 ceramic pebbles rich in lithium, which can meet the demand for tritium breeding ceramics, can be prepared by adding LA.
LiCoO2 is widely used in lithium-ion batteries. Innovatively, this study reveals that by employing a synergistic strategy of Li volatilization and anion doping, LiCoO2-based materials demonstrate exceptional performance as solid oxide fuel cell (SOFC) cathodes. At high temperatures, Li volatilization forms a Co3O4 phase. Concurrently, anionic doping is achieved by substituting F ions for O ions. The synergy of these two strategies increases the concentration of oxygen vacancies and the formation of heterogeneous interfaces, effectively enhancing the adsorption, dissociation, and diffusion rates of oxygen, thereby significantly improving the oxygen reduction reaction (ORR) of LiCoO2 (LCO). LCOF1 (LiCoO1.9F0.1+Co3O4) exhibits an oxygen diffusion coefficient (Dchem) and surface exchange coefficient (Kchem) of 8.85 × 10–5 cm2 s–1 and 7.61 × 10–3 cm s–1, respectively, which are 45% and 26% higher than those of undoped LCO. Furthermore, at 800 °C, LCOF1 achieves a PPD of 0.86 W cm–2 and an Rp as low as 0.012 Ω cm2, representing improvements of 110% in PPD and a reduction of 78.6% in Rp compared to LCO. These findings indicate that the synergistic effect of Li volatilization and F doping is an effective strategy for enhancing the performance of Li-containing cathodes, offering valuable perspectives for the development of high-performance SOFC cathodes.
危险品化学品经营许可证（带存储）