E. Soignard et al., High pressure-high temperature investigation of the stability of nitride spinels in the systems Si3N4-Ge3N4, SOL ST COMM, 120(5-6), 2001, pp. 237-242
In this study, we used laser-heated diamond anvil cell techniques coupled w
ith synchrotron X-ray diffraction to investigate the synthesis and stabilit
y of nitride spinels in the Si3N4-Ge3N4 system, at pressures close to 20 GP
a and at temperatures up to > 2000 degreesC. The newly discovered nitride s
pinels were found to be stable over the entire pressure and temperature ran
ge studied. There is little incorporation Of Si3N4 component in gamma -Ge3N
4, but we observed formation of a new ternary nitride spinel (SixGe1-x)(3)N
-4, with x similar to 0.6. The analysis of the X-ray patterns indicates tha
t Si4+, normally considered to be the smaller ion, is strongly partitioned
into the octahedral sites in the spinel phase. Excess Ge4+ ions may also oc
cupy these octahedral sites in the experimental synthesis at high pressure
and temperature. (C) 2001 Elsevier Science Ltd. All rights reserved.