In-Situ Raman Indentation of ??-Eucryptite: Characterization of the Pressure Induced Phase Transformation...

A pressure-induced phase transformation in the lithium aluminum silicate ��-eucryptite was studied with in-situ Raman spectroscopy. Dense ��-eucryptite composites were made via powder synthesis followed by sintering. The specimens were then subjected to diamond indentation up to applied contact stresses of about 8 GPa, while collecting Raman spectra. The appearance of a Raman peak (~520 cm-1) at a contact stress of about 3 GPa likely corresponds to the reversible phase transformation of ��-eucryptite to the orthorhombic phase ��-eucryptite. Loading and unloading in-situ Raman indentation experiments are discussed with regards to this transformation.