PHASE-STABILITY OF CHEMICALLY DERIVED ENSTATITE (MGSIO3) POWDERS

A modified Pechini chemical preparation technique was used to produce enstatite (MgSiO3) powder. By this method, low-temperature stable orth oenstatite (OE) was obtained at 850-degrees-C after 2 h of calcination . The effects of annealing temperature/time, initial particle size, ch emical dopants, and shear stress on the conversion of protoenstatite ( PE) to clinoenstatite (CE) on the powder have been studied. The result s indicated that the transformation of orthorhombic PE to monoclinic C E was sensitive to the initial powder particle size as well as to the type and amount of chemical dopant used. Sodium ions (Na+), which were found to cause the formation of a glassy phase around the PE grains, destabilized the PE phase physically. In comparison, manganese ions (M n2+), were found to preferentially substitute for the smaller Mg2+ ion s in solid solution and stabilized the PE phase chemically. The powder s with different chemical dopants were examined by TEM and EDS.