In situ Diamond Anvil Cell–Raman Spectroscopy and Nanoindentation Study of the Pressure‐Induced Phase Transformation in Pure and Zinc‐Doped β‐Eucryptite

Abstract

b-eucryptite (LiAlSiO 4 ), a member of the family of lithium aluminum silicates, is known to undergo a reversible pressureinduced phase transformation at~0.8 GPa to e-eucryptite. This study correlates the results between two techniques, in situ diamond anvil cell-Raman spectroscopy and nanoindentation experiments, to explore how doping (substituting Zn for Li) influences this pressure-induced phase transformation. Diamond anvil cell tests carried up to 3 GPa hydrostatic stress under Raman spectroscopy were compared with nanoindentation results, which provide a more localized, multiaxial stress state. The results indicate that the magnitude of hysteresis observed (difference between the pressures required for the forward and reverse transformation) is lower for Zn-doped b-eucryptite; however, the onset of the phase transformation is unchanged by doping with Zn. Furthermore, calculations of activation volume from nanoindentation experiments yield similar values (~0.1 nm 3 ) for pure and Zn-doped b-eucryptite, suggesting that the nucleation event that establishes the onset of the phase transformation is the same for both materials.

Atomic-scale mechanism for pressure-induced amorphization of β-eucryptite

“…In their recent high-pressure X-ray diffraction (XRD) experiments, Zhang amorphize at pressures of 3-5 GPa via reconstructive transformations with significant changes in atomic coordinations, 18,41 and suggested that PIA in b-eucryptite is possibly assisted by mechanical instability and kinetic hindrance of equilibrium phase transformations owing to reduced atomic mobility at 300 K. 18 Furthermore, recent nano-indentation studies have revealed that the pressure-induced transition in b-eucryptite is associated with an activation volume similar to that of SiO 4 and AlO 4 tetrahedra. 42,43 However, the atomic-scale mechanisms that govern PIA in b-eucryptite and the detailed structural characteristics of the amorphous phase are still unclear.…”

Pressure-induced phase transformation in β-eucryptite: An X-ray diffraction and density functional theory study

“…13,[16][17][18][19] In addition, βeucryptite (a LiAlSiO 4 polymorph) exhibits a pressureinduced phase transformation at pressures that are low enough to be exploited technologically. 20,21 The crystal structure of β-eucryptite (space group P6 4 22 or P6 2 22) can be described as a stuffed derivative of β-quartz. 10,[12][13][14] For this structure, Morosin et al 15 reported a phase transformation occurring at pressures as low as ∼ 0.8GPa.…”