High-pressure electrical resistivity, Mossbauer, thermal analysis, and micro-Raman spectroscopic investigations on microwave synthesized orthorhombic cubanite (CuFe2S3)

We present here the powder X-ray diffraction, micro-Raman, thermal, Mossbauer and high-pressure electrical resistivity properties of microwave synthesized orthorhombic cubanite CuFe2S3. The unique physico-chemical conditions required for the formation of orthorhombic cubanite CuFe2S3 prevents its successful synthesis under the normal laboratory conditions. However, in natural occurrence, the mineral occurs in orthorhombic structure along with chalcopyrite (CuFeS2) and pyrrhotite (Fe1-xS). A successful attempt to synthesize orthorhombic CuFe2S3 is reported using microwave heating. The DTA and Micro-Raman and Mossbauer spectroscopic measurements on the synthesized sample confirm that the synthetic sample is orthorhombic cubanite. High pressure electrical resistivity measurements on the sample show an irreversible first order phase transformation of orthorhombic cubanite to NiAs structure at similar to 4 GPa. The high-pressure recovered sample has been characterized by micro-Raman spectroscopy and exhibits Raman bands at 349 and 387 cm(-1), characteristic of isocubanite phase. The present high-pressure and temperature studies on the orthorhombic cubanite may be useful in understanding the thermodynamic behavior of cubanite and its paragenesis in carbonaceous chondrite. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.