Due to the purity of texture, Fluorophlogopite has high bulk resistivity (about 1000 times higher than natural mica), and the safe use temperature can reach 1100℃. The electrical breakdown strength of fluoro-crystalline mica decreases with the increase of mica sheet thickness. Natural mica contains a lot of impurities, and its electrical properties are unstable, and its electrical properties are worse at high temperature and high frequency. When the temperature is above 500℃, it will gradually lose its mica properties due to dehydration.