WEB Synchrotron radiation X-ray powder diffraction and magnetometric study of natural and synthetic terms of the stannite-kesterite pseudobinary system in the low temperature regime (5-275 K)Friday (28.02.2020) 08:04 - 08:04 Poster Room Part of:
Stannite and kesterite are minerals considered as promising p-type semiconductor materials for the thin film photovoltaic technology. Nowadays, the research is still unravelling the way to optimise performance in this task. This proposal is aimed at realising a temperature dependent X-ray Powder Diffraction (XRPD) investigation of synthetic and natural samples, to ascertain the occurrence and the relevance of a new low temperature polymorph. Accordingly, the temperature dependence of the structural features of four samples belonging to pseudobinary system stannite-kesterite Cu2Fe1-xZnxSnS4 (with x=0.1, 0.3, 0.5, 1) has been investigated using high quality synchrotron XRPD in the temperature range 5 - 275 K. Experimental measurements were carried out at the ID22 beamline of ESRF (Grenoble, France).
The lattice parameters, the free positional atomic parameters and the thermal parameters were determined by means of Rietveld analysis and compared with the local structural information let available by the study of the pair distribution function (PDF) carried out at both 5 and 275 K.
The kesterite sample (x=1) has been refined in both space groups I4 ̅2m and I4 ̅ but a careful analysis suggested a preference for the I4 ̅ model. The unit-cell volume, for all samples but the sample with x=0.3, continuously decreases on cooling, exhibiting an overall elastic and thermodynamic behaviour well modelled by the Grüneisen fit.
Conversely, the sample with x=0.3 undergoes an abrupt contraction at ~50-60 K, where an iso-structural transition takes place. The SQUID measurements on sample x=0.1 put in evidence important results and identified an antiferromagnetic transition at 7.3 K.