Preparation of gallium oxynitride in the presence of iron through a citrate route

Gallium oxynitrides were prepared in the copresence of various amounts of Fe3+ by ammonia nitridation of oxide precursors. Their crystallinity reduced in a compositional range up to 3 mol% and improved again above 4 mol% with an appearance of a nitride impurity. The product with 2 mol% of Fe3+ showed the maximum oxygen content of 21 mol% and minimum nitrogen content of 24 mol%. X-ray absorption spectroscopy, Mössbauer and magnetic measurements suggested a small amount of Fe3O4-like clusters in the oxynitride products. Density-functional calculations supported that the Fe-O-clustered system is more preferable than the statistical distribution of iron in the hexagonal gallium oxynitride structure.