In situ Raman indentation of β-eucryptite: Characterization of the pressure-induced phase transformation

A pressure-induced phase transformation in the lithium aluminum silicate β-eucryptite was studied with in situ Raman spectroscopy. Dense β-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 β-eucryptite to the orthorhombic phase ε-eucryptite. Loading and unloading in situ Raman indentation experiments are discussed with regards to this transformation.