An x‐ray photoelectron spectroscopy (XPS) study was conducted to: (i) compare the Si (2p) and O (1s) peaks of selected Si‐containing minerals, and (ii) evaluate the application of XPS in identifying probable Si‐bonding environments in Si‐containing ferrihydrites. For silica gel, the Si (2p) and O (1s) XPS peaks occurred at 104.0 and 534.2 eV, respectively; with biotite, these peaks occurred at 102.8 and 532.4 eV. The difference in the Si (2p) binding energies between silica gel and biotite was attributed to differences in the Si‐bonding environment and the number of ‐Si‐O‐Si‐ linkages at corners of the SiO4 tetrahedron, and the charge deficit in the tetrahedral layer of biotite. The Si (2p) XPS peak for silicate adsorbed on ferrihydrite occurred at 100.9 eV, which indicated the probable presence of ligand‐bound silicate or small units of polymerized silica at the ferrihydrite surface. For ferrihydrite samples treated with an excess of Si (≥75 g kg−1), peaks attributable to a separate Si‐rich phase were identified on decomposition of the Si (2p) and O (1s) XPS peaks. In the case of ferrihydrite coprecipitated with silicate at Si/Fe molar ratios ≥0.10, the Si (2p) peak occurred at approximately 102.8 eV, which is a position similar to that observed for layer silicates, indicating the possible presence of Si, i.e., the presence of ‐Fe‐O‐Sl‐ bonds, within the ferrihydrite structure.

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Method for investigating threshold field of charge injection at electrode/dielectric interfaces by space charge observation Appl. Phys. Lett. 101, 172902 (2012) Low contact resistivity of metals on nitrogen-doped cuprous oxide (Cu2O) thin-films J. Appl. Phys. 112, 084508 (2012) Preserving stable 100% spin polarization at (111) heterostructures of half-metallic Heusler alloy Co2VGa with semiconductor PbS J. Appl. Phys. 112, 083710 (2012) Thermal conduction properties of Mo/Si multilayers for extreme ultraviolet optics A Si/Pd ohmic contact scheme to n-GaP ͑nϳ5ϫ10 17 cm Ϫ3 ͒ was investigated using Rutherford backscattering spectrometry, transmission electron microscopy, energy dispersive x-ray spectrometry, and the Cox-Strack measurement. Contact resistivities of ϳ2ϫ10 Ϫ4 ⍀ cm 2 are obtained for annealing temperatures ranging from 350 to 650°C. This contact is thermally stable at 550°C. The ohmic contact formation mechanism is rationalized in terms of the solid phase regrowth of an n ϩ layer and the solid phase epitaxy of a Si layer.