INVESTIGATION OF GaN BEHAVIOR IN CONTACT WITH FE, Fe2-4N AND Co/Cr AT HIGH PRESSURES AND HIGH TEMPERATURES

Abstract

In this work behavioral features of gallium nitride (GaN) being in contact with Fe, Fe_2-4N and (Co/Cr)_eut under high-pressure (6–8 GPa) high-temperature (up to 2000 °C) conditions (HP-HT) have been described. Preparatory stages of experimental research including thermobaric calibration of the toroidal HP apparatus using thermocouple method considering some melting results of a number of metals and alloys such as Pt, (Mo-C)_eut, Fe, Fe_2-4N, (Co/Cr)_eut, Cu and Pr under pressure are highlighted in detail. The gallium nitride was found to dissolve in the Fe, Fe_2-4N and (Co/Cr)_eut melts as evidenced by increasing of sample weights (non GaN part). As a rule, changes of mass took place starting from temperatures below the melting point of a pure material (sample) that is obviously due to contact melting at the GaN-sample interface. At a fixed pressure and isochronous experimental conditions the degree of GaN dissolution strongly depends from temperature for all systems under consideration. For temperature region of 1800–2000 °С a mass increasing of  the second component in GaN-Fe, GaN-Fe_2-4N and GaN-(Co/Cr)_eut pairs due to GaN dissolving reach 20–30 wt. %. There was a tendency to decreasing of GaN solubility coursed by pressure reducing as it was noted on example of the GaN-(Co/Cr)_eut pair. Regarding the equilibrium concentrations of Ga and N in melts of Fe, Fe_2-4N and (Co/Cr)_eut alloy the final conclusion will be received after examination of quenched samples by EDX, XRD, Raman spectroscopy and other methods.