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

A pressure-induced phase transformation in the lithium aluminum silicate beta-eucryptite was studied with in situ Raman spectroscopy. Dense beta-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 (similar to 520 cm(-1)) at a contact stress of about 3 GPa likely corresponds to the reversible phase transformation of beta-eucryptite to the orthorhombic phase epsilon-eucryptite. Loading and unloading in situ Raman indentation experiments are discussed with regards to this transformation.