Needlelike Crystal Growth and Anisotropic Photochemical Reactivity of Ta3N5 Synthesized in Vacuo

A new method is introduced to synthesize Ta3N5 crystal by reaction of TaCl5 and NH4Cl powders in vacuo at 850 degrees C. The synthesized Ta3N5 has a needlelike morphology with preferential growth in the [100] direction. It is possible that adsorption of chloride on the surfaces of the growing crystal inhibits growth in all but this preferential direction. A low photochemical reactivity for water splitting on the needlelike Ta3N5 suggests photochemical reductive sites on (100) surfaces of the Ta3N5 crystal.