Preparation of Gallium Nitride Powders and Nanowires from a Gallium(III) Nitrate Salt in Flowing Ammonia

Abstract

Gallium nitride (GaN) powders were prepared by calcining a gallium(III) nitrate salt in flowing ammonia in the temperature ranging from 500 to 1050 °C. The process of conversion of the salt to GaN was monitored by X-ray diffraction and 71 Ga MAS (magic-angle spinning) NMR spectroscopy. The salt decomposed to γ-Ga 2 O 3 and then converted to GaN without γ-β Ga 2 O 3 phase transition. It is most likely that the conversion of γ-Ga 2 O 3 to GaN does not proceed through Ga 2 O but stepwise via amorphous gallium oxynitride (GaO x N y ) as intermediates. The GaN nanowires and microcrystals were obtained by calcining the pellet containing a mixture of γ-Ga 2 O 3 and carbon in flowing ammonia at 900 °C for 15 h. The growth of the nanowire might be explained by the vapor-solid (VS) mechanism in a confined reactor. Room-temperature photoluminescence spectra of as-synthesized GaN powders obtained showed the emission peak at 363 nm.

Chemical Synthesis and Characterization of γ-Co2NiGa Nanoparticles with a Very High Curie Temperature

“…The precursors for the Co 2 NiGa NPs were CoCl 2 ·6H 2 O (99.9%), Ni­(NO 3 ) 2 ·6H 2 O (99.999%), and Ga­(NO 3 ) 3 · x H 2 O (99.9%). The value of x in Ga­(NO 3 ) 3 · x H 2 O was set to 8 for calculations based on the literature . In a typical preparation of γ-Co 2 NiGa NPs, CoCl 2 ·6H 2 O (0.117 g, 0.4912 mmol), Ni­(NO 3 ) 2 ·6H 2 O (0.075 g, 0.2579 mmol), and Ga­(NO 3 ) 3 · x H 2 O (0.116 g, 0.2900 mmol) were dispersed in methanol (46 mL) and sonicated for 10 min.…”