KLu 2 F 7 single crystals were grown by micro-pulling-down method. KLu 2 F 7 has phase transition around 730°C, which is between melting temperature and room temperature. The high-temperature phase is monoclinic and the low temperature phase is orthorhombic. To keep the temperature of as-grown crystal above the phase transition temperature, the conventional carbon hot zone was modified, and its temperature gradient was investigated. Using the modified setup, KLu 2 F 7 crystal with monoclinic (high temperature) phase was grown. After the growth procedure, the as-grown crystal was quenched to room temperature and it was found that the crystal keeps the monoclinic (high temperature) phase at room temperature.