Identification of the Bravais lattice and cell parameters through quantitative model-based transmission electron microscopy and Niggli cell reduction theory: the case of intermetallic Ni5Pb2Te3

Abstract

This article demonstrates a simple and effective way to accurately determine the Bravais lattice type and cell parameters of an unknown phase by combining quantitative model-based high-resolution (scanning) transmission electron microscopy and Niggli cell reduction theory. This method was applied to the Ni5Pb2Te3 phase in the Ni–Pb–Te ternary system, which exists at high temperatures and forms from the interaction of Ni contacts with PbTe thermoelectric materials. The structure was identified to be triclinic with the space group P1 and cell parameters a = 5.43 ± 0.09 Å, b = 3.93 ± 0.03 Å, c = 3.75 ± 0.01 Å, α = 115.4 ± 0.2°, β = 93.4 ± 0.6° and γ = 91.1 ± 0.1°. The methodology is particularly beneficial for the class of problems where the phase under study coexists in a multiphase environment.