Thermal conductivity and phonon anharmonicity of chemical vapor transport grown and mineral–FeS ₂ single crystals: An optothermal Raman study

In this work, thermal conductivity and anharmonic properties of chemical vapor transport (CVT)-grown pyrite-FeS2 mineral single crystals have been investigated compared. It has shown that optothermal Raman technique is able to capture the large difference between CVT samples at low temperatures. This attributed point defects such as sulfur vacancies or impurity doping CVT-grown FeS2 crystals. Balkanski–Klemens model analysis three-phonon scattering Ag Eg modes lattice expansion are dominant contributors while four-phonon negligible in pyrite-FeS2. Thus, materials difficult measure by conventional methods (i.e., flash method) can be measured their most native form using spectroscopy (RS) without rigorous sample preparation.