Browsing by Subject "High pressure study"
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Item High pressure study of gamma iron oxide up to 52 GPa by x-ray diffraction(Texas Tech University, 2005-12) Sandhu, Jagdev S.; Ma, Yanzhang; Ertas, Atila; Levitas, ValeryThe high pressure behavior of ã- Fe2O3 has been investigated up to 52 GPa using X-ray diffraction techniques and a diamond anvil cell. We are reporting phase transformation of bulk and nanocrystalline ã- Fe2O3 samples. The behavior of bulk sample has been carried out to 31.9 GPa and nano sample has been examined to 51.8 GPa. The phase transformation pressure of nanocrystalline sample is about 20.8 GPa. The bulk modulus of bulk sample is KOT = 172.5 ± 5.6 GPa, and its pressure derivative, K’OT = 20.6 ± 1.0 and in case of nano sample, KOT =135.21 ± 6.38 GPa, and its pressure derivative is K’OT = 28.01 ± 1.91.Item High pressure study of spinel chromite(Texas Tech University, 2005-05) White, Allen D. C.; Ma, Yanzhang; Levitas, Valery; Ertas, AtilaChromite has one of the most important crystal structures, the spinel structure; therefore its high pressure behavior has significant implications to the foundation of a wide range of materials. It is also found throughout our Earthfs interior. These facts make its high pressure studies important to materials science, physics, geosciences, and crystallography. Synchrotron X-ray diffraction measurements of chromite were performed using a symmetrical diamond anvil cell to 41.2 GPa. The data was fit using the third order Birch-Murnaghan equation of state, and the bulk modulus KOT was determined to be 197}19 GPa with KŒOT=66}12 when fitting data to 16 GPa. Further investigation revealed a pressure induced phase transformation at 28.2 GPa.