Gallium oxonitrides

the manufacturers of chemical compounds provide Ga203 at different levels of purity, produced by a variety of (usually unspecified) methods. Such commercially available samples often contain mixtures of polymorphs, especially of the P-Ga203 and a-Ga203 phases, although pure samples of P-Ga203 can be obtained by heating the mixture, for example, at a temperature of 800 °C for 10-12 h [163]. Yet, the different materials obtained from the same supplier can correspond to different polymorphs. For example, the Aldrich 99.99 + % sample studied by Machon et al. corresponded to a 70 30 mixture of the P- and a-phases, whereas a sample purchased from the same supplier with 99.999 + % purity consisted mainly of the 8-Ga203 polymorph (D. Machon et al., unpublised work). 

---

The theoretical search for new gallium oxonitride compounds was initiated following the observation of spinel-type structured materials that formed as side products... 

During the past thirty years several reports have been published on the synthesis of gallium oxonitride phases. The first of these was mentioned by Verdier and Marchand in 1976 as a side product during the reaction of ammonia with gallium oxide, whenaphase with the composition Gai x 3nxpNi xO withx 0.1 and as vacancies was isolated under low-temperature conditions [213]. The authors did not report any detailed crystal structure data, but did note that the XRD pattern was... 

Figure 3.10 Photoluminescence measurement of gallium oxonitride in comparison to two...

Figure 3.11 In spinel-type structured gallium oxonitrides the lattice parameter Oq increases with higher nitrogen contents. The considered compositions are theoretically calculated regarding charge neutrality and considering a fllled-anion model.

The Li-doped gallium oxonitride with hexagonal w-GaN structure displayed a yellow photoluminescence following excitation at 254nm. 

---