Growth of shaped 12CaO×7Al2O3 crystals by the micro-pulling down method

12CaO×7Al2O3 (C12A7) single crystals have been successfully grown by the micro-pulling down method for the first time. Single and transparent C12A7 crystal was obtained with radio-frequency heating μ-PD system. Phase stability is discussed as a function of oxygen concentration in the growth atmosphere. A minimum 1.0 Vol% O2 with nitrogen atmosphere yields C12A7 phase. The distribution of Ca, Al and O elements at cross-section part was investigated by the electron probe microanalysis. The crystal composition deviation could be controlled by reducing O2 gas concentration to 1.0 Vol%.