Morphological control of Sn2+ doped calcium carbonate phosphors by crystallizing amorphous calcium carbonate and its fluorescence property

Morphological control of Sn2+ doped calcium carbonate phosphors by crystallizing amorphous calcium carbonate formed from aqueous solution reaction of CaCl2-(NH4)(2)CO3-SnCl2 system and its fluorescence property were investigated. Amorphous calcium carbonate changed into spherical and platelike vaterites at 15-50 degrees C and needlelike aragonite above 60 degrees C. In order to obtain calcite, a suspension of vaterite formed at 20 degrees C by crystallizing amorphous calcium carbonate was kept at 90 degrees C for 120 min. The content of Sn2+ in platelike vaterite crystal was Sn/CaCO3 mol% of approximately 0.4 and was about 4 times as compared with that of rhombohedral calcite crystal. The emission spectrum of rhombohedral calcite phosphors with Sn2+ of 0.04 mol% showed bright blue fluorescence at 465 nm. Its optimum excitation wavelength was wavelength of ultraviolet irradiation at 255 nm.