Growth of well-developed sodium tantalate crystals from a sodium chloride flux

Well-developed cubic crystals of NaTaO3 and NaTaO3 : La were successfully grown by cooling an NaCl flux at 650-1000 degrees C. Colourless and transparent NaTaO3 and NaTaO3 : La crystals were obtained from relatively low-temperature solutions containing 20 mol% solute, with a smallest average size of 0.18 mm. The crystal sizes and forms were highly dependent on the holding temperature, cooling rate, and starting composition. In particular, when La2O3 powders were added to the starting compositions, NaTaO3 : La crystals with a very unique surface morphology were grown from the NaCl flux. Additionally, the average size of the NaTaO3 : La crystals decreased dramatically when compared with that of the NaTaO3 crystals prepared under the same conditions. Furthermore, the NaTaO3 and NaTaO3 : La crystals exhibited high dye photodegradation activity. These results demonstrate that NaCl is adequate for synthesizing high quality and well-developed tantalate crystals.