Mineralogy under extreme conditions

Shu, Jinfu

doi:10.1016/j.gsf.2011.10.002

Cited by 3 publications

References 51 publications

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Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study

Kuzmin

Anspoks

Kalinko³

et al. 2018

Physica Status Solidi (b)

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High‐pressure (0–26.7 GPa) Cu K‐edge X‐ray absorption spectroscopy is used to study possible structural modifications of anti‐perovskite‐type copper nitride (Cu3N) crystal lattice. The analysis of X‐ray absorption near‐edge structure (XANES) and extended X‐ray absorption fine structure (EXAFS), based on theoretical full‐multiple‐scattering and single‐scattering approaches, respectively, suggests that at all pressures the local atomic structure of Cu3N remains close to that in cubic Pmtrue3¯m phase. Therefore, the transition to metal state above 5 GPa, observed previously using pressure‐dependent electrical resistance and optical absorption measurements, is explained by the band gap collapse due to a decrease of the unit cell volume. We found that the lattice parameter of Cu3N is reduced by ≈2% upon increasing pressure up to 26.7 GPa, and the structure is restored upon pressure release.

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Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study

Kuzmin

Anspoks

Kalinko³

et al. 2018

Physica Status Solidi (b)

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Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes

et al. 2013

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Abstract:The investigation of the contamination in soil, plants and groundwater revealed a spatial evolution, with an increasing trend in the Cr, Fe, Ni, Mn and Co contents in soils from the Assopos to Thiva basin, followed by C. Evia and Ni-laterite deposits, suggesting that the latter and their parent ophiolites are a potential source for these metals. In contrast, the contamination in groundwater by Cr(VI), ranging from 2 to 360 μg/L Cr, and a varying degree of salinization is probably due to both human activities and natural processes. A diverse source for the contamination of soil and groundwater in the Assopos-Thiva basins is consistent with the increasing trend of the Mg/Si ratio and Cr(VI) concentration in water. The use of deep karst-type aquifer instead of the shallow-Neogene one may provide a solution to the crucial environmental problem. The selective extraction by EDTA and alkaline solution showed that Cr and Fe are less available than Mn. The Cr contents in plants range from <1 to tens of mg/kg, due probably to the high resistance of chromite. However, the average Cr total contents in plants/crops are higher than normal or sufficient values, whilst Cr total accumulation [(% metals in plants × 100)/metal in soil] and Cr(VI) accumulation are relatively low. There is a very good positive correlation between accumulation factors for Cr and Fe (R 2 = 0.92), suggesting a similarity concerning their uptake.

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Is there a layer deep in the Earth that uncouples heat from mechanical work?

Burns

2014

Preprint

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Abstract. The thermal expansion coefficient is presented as the coupling between heat energy and mechanical work. It is shown that when heat and work are uncoupled then very unusual material properties occurs: for example, acoustic p waves are not damped and heat is not generated from mechanical motion. It is found that at pressures defined by the bulk modulus divided by the Anderson–Grüneisen parameter, then the thermal expansion coefficient approaches zero in linear-elastic models. Very large pressures always reduce thermal expansion coefficients; the importance of a very small or even negative thermal expansion coefficient is discussed in relation to physical processes deep in the core and mantle of Earth. Models of the thermal expansion coefficients based on interatomic potentials which are always relegated to isometric conditions preclude any changes in volume due to temperature changes. However, it is known that the pressures in the Earth are large enough to effectively reduce thermal expansion coefficients to near zero which decouples heat from mechanical work.

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Mineralogy under extreme conditions

Cited by 3 publications

References 51 publications

Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study

Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study

Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes

Is there a layer deep in the Earth that uncouples heat from mechanical work?

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Mineralogy under extreme conditions

Cited by 3 publications

References 51 publications

Origin of Pressure‐Induced Metallization in Cu3N: An X‐ray Absorption Spectroscopy Study

Origin of Pressure‐Induced Metallization in Cu3N: An X‐ray Absorption Spectroscopy Study

Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes

Is there a layer deep in the Earth that uncouples heat from mechanical work?

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Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study

Origin of Pressure‐Induced Metallization in Cu₃N: An X‐ray Absorption Spectroscopy Study