Synthesis and characterization of polycrystalline KAlSi3O8 hollandite [liebermannite]

Abstract

A polycrystalline specimen of liebermannite [KAlSi3O8 hollandite]was synthesized at 14.5 GPa and 1473 K using glass starting material in a uniaxial split-sphere apparatus. The recovered specimen is pure tetragonal hollandite [SG: I4/m]with bulk density of within 98% of the measured X-ray value. The specimen was also characterized by Raman spectroscopy and nuclear magnetic resonance spectroscopy. Sound velocities in this specimen were measured by ultrasonic interferometry to 13 GPa at room T in a uniaxial split-cylinder apparatus using Al2O3 as a pressure marker. Finite strain analysis of the ultrasonic data yielded KS0 = 145(1)GPa, K0′ = 4.9(2), G0 = 92.3(3)GPa, G0′ = 1.6(1)for the bulk and shear moduli and their pressure derivatives, corresponding to VP0 = 8.4(1)km/s, VS0 = 4.9(1)km/s for the sound wave velocities at room temperature. These elasticity data are compared to literature values obtained from static compression experiments and theoretical density functional calculations. Show more