| Popis: |
Crystals of chromium-rich phases of fair diffraction quality synthesized in experiments on the investigation of phase relations in the SiO2–MgO–Cr2O3 system, have been studied by means of single-crystal X-ray diffraction. For the selected phases (majorite-knorringite garnet, akimotoite, bridgmanite, MgCr2O4 with calcium-titanate-type structure, Mg(Mg,Si,Cr)2O4 with distorted calcium-titanate structure, anhydrous phase B, olivine, wadsleyite and ringwoodite), we determined the unit-cell parameters, the space group, and the mechanism of chromium incorporation in their structures. Also, we compare the influence of two minor elements (aluminum and chromium) on the unit-cell parameters of deep minerals (garnet, akimotoite and bridgmanite). |
