Preparation of gallium oxynitride powder and its nanofibers by the nitridation of a gallium oxide precursor doped with nickel or cobalt obtained via the citrate route

Abstract

Acicular crystals were grown in gallium oxynitride powder prepared by ammonia nitridation of amorphous gallium oxide precursors containing less than 5 at% of either Ni or Co, via the citrate route. The crystals were several tens of nanometres wide, several micrometres long, and grown in the temperature range 750 to 850 degrees C in a flow of ammonia of less than 200 mL min(-1). The crystal structure of the gallium oxynitride was a highly disordered 2H wurtzite-type with some 3C zinc blende-type stacking faults. The crystals grew in their basal plane changing their aspect ratio with the supplying method of small amounts of Ni or Co and an amount of residual carbon. The acicular crystals were grown by the catalytic behavior of Ni or Co to enhance one-dimensional growth in the hexagonal c-plane.

Crystal growth and characterization of gallium oxynitride nanowires grown on seed crystals

“…4(b)). At 750 °C, the nanowires grow parallel to the c-plane of the seed crystals [24]. The preferred orientation observed in the XRD patterns obtained from nanowires grown at 750 and 800 °C is caused by long nanowires grown parallel to the c-plane lying on the substrate.…”

“…3(a) shows the XRD pattern of GaON containing nanowires and agglomerated grains prepared by nitridation of a GaNi oxide precursor at 750 °C). GaON obtained by nitridation with Ni additives crystallizes with a highly disordered 2H wurtzite structure with some 3C zinc blende stacking faults [24]. XRD patterns for the GaON nanowires grown at 750 and 800 °C exhibit remarkable preferred orientation (Figs.…”

“…Gallium oxynitride products consisting of nanowires and agglomerated grains were prepared by ammonolysis of an amorphous oxide precursor prepared from Ga(NO 3 ) 3 •9H 2 O and Ni(NO 3 ) 2 •6H 2 O mixture in a molar ratio of Ga:Ni = 0.97:0.03 dissolved in 20 mL of distilled water with citric acid in an equimolar amounts to the total metal nitrates [24]. These reagents were purchased from Wako Pure Chemicals and had purities of 99.9%.…”

“…A similar method has been used to dope 3d transition metals into GaON [2023]. GaON nanowires were grown with GaON particles in the ammonolysis of an amorphous gallium oxide precursor containing a few percent of Ni or Co additives [24]. GaON nanowires grown in the temperature range 750 to 850 °C were several micrometers long and several tens of nanometers wide.…”

Processing of dielectric oxynitride perovskites for powders, ceramics, compacts and thin films

“…The thermal instability have proved useful for the preparation of magnetic granular thin films exhibiting useful properties such as magnetoresistance and microwave absorption 17 . The unstable nature was also effective for obtaining gallium oxynitride nanowire prepared through the citrate route 18 . Thermal stability of Ta-N chemical bond needs to be studied to overcome the thermal decomposition of SrTaO 2 N. The thermal stability reported for SrTaO 2 N in an Ar atmosphere is not consistent with the result of a study on the crystal structure against temperature.…”