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

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(Mg1/3Nb2/3)O3. 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(Mg1/3Nb2/3)O3 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.

Semiconductor to metallic transition under induced pressure in Cs2AgBiBr6 double halide perovskite: a theoretical DFT study for photovoltaic and optoelectronic applications

“…Pugh used the bulk to shear modulus value ratio (B/G) (brittle/ductile) to identify defects in crystal solids. 39,40 According to this idea, ductile materials have a B/G ratio higher than the critical value of 2.46, which is distributed as a broad line between the brittle and ductile natures in crystalline solid samples. A material will exhibit a ductile nature, if its Pugh's ratio has a value greater than the broader line value shown in Fig.…”

The effect of metal substitution in CsSnI3 perovskites with enhanced optoelectronic and photovoltaic properties

“…25 Transition metal Ni-doping in CsGeCl 3 increases its band gap energy and shrinkage the optical absorption due to the Moss-Burstein effect. [27][28][29] In this manuscript, we are addressing the effects of Cu-doped CsSnI 3 for optoelectronic and photovoltaic applications. We have applied density functional theory (DFT) to calculate electronic, mechanical, and optical properties.…”

Semiconductor to metallic transition in double halide perovskites Cs2AgBiCl6 through induced pressure: A DFT simulation for optoelectronic and photovoltaic applications

“…The simulated elastic constants of Cs 2 AgBiCl 6 justified the cubic symmetry criterion under the condition of Eq. (10) [ 24 ]: C 11 + 2C 12 > 0, C 44 > 0 and C 11 – C 44 > 0 …”

“…The unit cell structure and atomic relaxation of Cs 2 AgBiCl 6 have been accomplished under the residual forces 0.03 eV/Å. To calculate the elastic modulus C ij, the finite strain theory was applied [ 16 , 23 , 24 ]. The stress tensor has six independent stress parameters σij, and each strain δj corresponds to a unit cell.…”