Goethite, α-FeO(OH), from single-crystal data

Yang, Hexiong; Ren, Lu; Downs, Robert T.; Costin, Gelu

doi:10.1107/s1600536806047258

Cited by 97 publications

(96 citation statements)

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“…Microscopic observations have also clarified the thermal decomposition of goethite into hematite through the formation mechanism of slit-like micropores [12]. In this case, the slits are generated along the goethite [001] G direction, where the crystal is defined by the orthorhombic space group Pbnm, with lattice constants of a G = 4.5979 Å, b G = 9.9510 Å, and c G = 3.0175 Å [12][13][14]. Structural investigation on the thermal decomposition of goethite was carried out using X-ray and electron diffraction with high-resolution transmission electron microscope (TEM) imaging.…”

Section: Introductionmentioning

confidence: 99%

Twin formation in hematite during dehydration of goethite

et al. 2016

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Twin formation in hematite during dehydration was investigated using X-ray diffraction, electron diffraction, and high-resolution transmission electron microscopy (TEM).When synthetic goethite was heated at different temperatures between 100 and 800 °C, a phase transformation occurred at temperatures above 250 °C. The electron diffraction patterns showed that the single-crystalline goethite with a growth direction of [001] G was transformed into hematite with a growth direction of [100] H . Two non-equivalent structures emerged in hematite after dehydration, with twin boundaries at the interface between the two variants. As the temperature was increased, crystal growth occurred. At 800 °C, the majority of the twin boundaries disappeared; however, some hematite particles remained in the twinned variant. The electron diffraction patterns and high-resolution TEM observations indicated that the twin boundaries consisted of crystallographically equivalent prismatic (100), (010), and (11 � 0) planes. According to the total energy calculations based on spin-polarized density functional theory, the twin boundary of prismatic (100) screw had small interfacial energy (0.24 J/m 2 ). Owing to this low interfacial energy, the prismatic (100) screw interface remained after higher-temperature treatment at 800 °C.

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Section: Introductionmentioning

confidence: 99%

Twin formation in hematite during dehydration of goethite

et al. 2016

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“…Proper phase identification requires calibration of the instrumental geometry; in this case, this was accomplished through the diffraction patterns of Si and Al 2 O 3 . Table 4 shows the main crystalline phases observed in the corrosion layer and the d-spacing and Miller indices of their high-intensity finger-print reflections that were used to identify them [40,41]. Other phases usually found as corrosion products display only high angle, low d-spacing reflections, which are difficult to use phase identification due to strong peak overlap at low d-spacings.…”

Section: Phase Distributionmentioning

confidence: 99%

“…8(a) and (b), which were obtained by integration over the full range of 2θ measured]. This was done using the (101) reflection at d-spacing 4.20 Å for goethite [40] and (512) reflection at d-spacing 1.63 Å for akaganeite [41]. Fig.…”

Section: Phase Distributionmentioning

confidence: 99%

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

Serdar

Meral

Kunz

et al. 2015

Cement and Concrete Research

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The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel highchromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide-hydroxides formed during the chlorideinduced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel.

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“…The atomic radii of Tc(IV) and Fe(III) are also closely related in size (78.5 vs. 69 to 78.5 pm, (a) respectively), and both are octahedral (6-fold) coordinated (Huheey et al 1993), so a coupled substitution scheme is possible. The atomic structure of goethite, recently determined by Yang et al (2006), is shown in Figure 2.5. On the other hand, examining the reduced run products with X-ray absorption spectroscopy (XAS) methods (briefly described in Appendix A) has revealed that the 99 Tc-bearing phase is a separate, reduced Tc(IV) oxide phase and may not be substituting for Fe(III)-O in the host ferric oxyhydroxide phase (Burke et al 2006, Fredrickson et al 2004, Fredrickson et al 2009, Morris et al 2008, Peretyazhko et al 2008a, Watson et al 2001, Wharton et al 2000, Zachara et al 2007).…”

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confidence: 99%

“…On the one hand, substituting Tc(IV) for Fe(III) in goethite, for example, is plausible because the Tc(IV)-O and Fe(III)-O bond lengths are similar (1.99 and 2.026 Å, respectively) (Yang et al 2006). The atomic radii of Tc(IV) and Fe(III) are also closely related in size (78.5 vs. 69 to 78.5 pm, (a) respectively), and both are octahedral (6-fold) coordinated (Huheey et al 1993), so a coupled substitution scheme is possible.…”

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confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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Goethite, α-FeO(OH), from single-crystal data

Abstract: Key indicatorsSingle-crystal X-ray study T = 273 K Mean (e-O) = 0.001 Å R factor = 0.019 wR factor = 0.052 Data-to-parameter ratio = 21.0 For details of how these key indicators were automatically derived from the article, see

Cited by 97 publications

References 15 publications

Twin formation in hematite during dehydration of goethite

Twin formation in hematite during dehydration of goethite

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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