Theoretical investigation of mechanical and thermal properties of MPO4 (M = Al, Ga)

Minimum lattice thermal conductivities and mechanical properties of polymorphous MPO4 (M = Al, Ga) are investigated by first principles calculations. The theoretical minimum thermal conductivities are found to be 1.02W (m K)(-1) for alpha-AlPO4, 1.20W (m K)(-1) for beta-AlPO4, 0.87W (m K)(-1) for alpha-GaPO4 and 0.88W (m K)(-1) for beta-GaPO4. The lower thermal conductivities in comparison to YSZ can be attributed to the lattice phonon scattering due to the framework of heterogeneous bonds. In addition, the low shear-to-bulk modulus ratio for both beta-AlPO4 (0.38) and beta-GaPO4 (0.30) is observed. Our results suggest their applications as light-weight thermal insulator and damage-tolerant/machinable ceramics. (C) 2013 Elsevier Ltd. All rights reserved.