Converison of diaspore to corundum: A new α-alumina transformation sequence

摘要

A new two-step transformation sequence has been identi- fied for the conversion of diaspore (α-ray diffraction pattern of the intermediate phase, designated α'-Al_2O_3, has been indexed to a monoclinic (P2) cell, with a=9.566(5) A, b= 5.124(2) A,c=9.15(4) A, and β=91.76(3). Nuclear mag- netic resonance of α'-Al_2O_3 indicates that 15-20/100 of the aluminum is on tetrahedral sites, with the remainder in octahedral coordination.