Growth and Characterization of KMgF3 Single Crystals by the Czochralski Technique under CF4 Atmosphere

KMgF3 (KMF) single crystals were grown by the Czochralski technique as a new candidate of vacuum-ultra-violet optical materials. The absorption edge of KMF single crystals was 115 nm. The distribution of birefringence in the radial direction was of the order of 10-7. The thermal expansion coefficient of KMF single crystals along the <111> orientation was 1.98×10-5 K-1. Together with its excellent mechanical properties, these characteristics show KMF to be superior to the current materials.