Pressure-induced volume anomaly and structural phase transition in nanocrystalline SnO2

High-pressure behavior of tetragonal rutile structured, nanocrystalline SnO2, with an average grain size of 5 nm is investigated by in situ synchrotron based angle dispersive powder X-ray diffraction technique up to 34 GPa at ambient temperature. Results indicate that the tetragonal structure remains stable up to 18 GPa. Beyond 18 GPa a first order phase transformation to a cubic phase with large volume discontinuity is observed. Co-existence of both ambient and high pressure phases is observed till the highest pressure investigated. On pressure release, the high pressure daughter phase is retained. The bulk modulus for ambient rutile phase and high pressure daughter phase is 217 (+/- 10) and 202 (+/- 5) GPa respectively with the value of pressure derivative of bulk modulus fixed at 4. The observed phase transition sequence in nanomaterial is different from the bulk compound. It is concluded that the anomaly in the pressure-volume data in present studies and electrical transport data seen near 3 GPa in previous [38] work is of electronic in nature since material is structurally stable in this pressure region. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim