Cubic Perovskite Pb(Mg_1/3Nb_2/3)O₃: A Damage Tolerant, Machinable, and Thermal barrier coating material

Abstract

Abstract In this article, we use first-principles density functional theory (DFT), with plane-wave pseudopotentials, to calculate the structural, mechanical, thermal, electronic, and bonding properties of the cubic perovskite Pb(Mg 1/3 Nb 2/3 )O 3 . The results are compared with those of some isostructural compounds. The optimised lattice constant agrees fairly well with the experimental value. Mechanical stability is verified for this compound. This perovskite is damage-tolerant, as it is ductile according to all indicators. The machinability level of this substance is similar to that of the well-known MAX phases. Low thermal conductivity, better thermal shock resistance, low Debye temperature, and high melting temperature of Pb(Mg 1/3 Nb 2/3 )O 3 should favour its use as thermal barrier coating (TBC) material. Dual characteristics of a weak metal and a semiconductor are expected for this material. Covalent bonding is significant in this cubic perovskite. The Fermi surface is very complex and contains a Fermi pocket around each X-point.