Single-crystal elasticity of Zn2TiO4-spinel up to 18 GPa

Abstract

Abstract The single-crystal elastic constants of the spinel phase of Zn2TiO4 have been studied for the first-time using Brillouin scattering up to 18 GPa at room temperature in a diamond anvil cell. The three independent elastic constants of Zn2TiO4 spinel at ambient conditions were calculated: C 11 = 226(3), C 12 = 137(4) and C 44 = 88(2). The bulk modulus (K S0) is 167(3) GPa, with pressure derivative K ′ s = 5.3 ( 2 ) , and the shear modulus (G 0) is 67(1) GPa, with pressure derivative G ′ = 0.06 ( 5 ) . On basis of previous studies, our results suggest a possibility of the general law of elastic constants with pressure derivative ( C ′ ijs ) for spinel structure minerals: C ′ 11 ≈ C ′ 12 and C ′ 44 << C ′ 11 C ′ 12 . In addition, Zn2TiO4 have the lowest velocities and V S gradient compared with the spinel type minerals in Earth’s mantle. Our results indicate the incorporation of Zn and Ti in the structure of ringwoodite may have a negative effect on the sound velocities and V S gradient of Earth’s mantle transition zone.