A Fe K-edge XAS study of amethyst

Benedetto, Francesco Di; d’Acapito, Francesco; Fornaciai, Gabriele; Innocenti, Massimo; Montegrossi, Giordano; Pardi, Luca; Tesi, Silvia; Romanelli, Marco

doi:10.1007/s00269-009-0332-0

Cited by 31 publications

(29 citation statements)

References 38 publications

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“…5b), with the estimated energy positions of L1 (7112.8 eV), L2 (7114.2 eV), the centroid (7113.5 eV), and FWHM (1.2 eV). These results are in good agreement with those for octahedral Fe(III) in hematite [28,31], confirming that Fe in the title compound is trivalent with octahedral coordination. The lineshapes of the 3 non 1s-3d lines converge to quasi-Gaussian (i.e., 80% Guassian in average), consistent with those reported by Wikle et al [28] as well.…”

Section: Fe K-edge Xanes Spectrasupporting

confidence: 90%

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

Wang

Chen

et al. 2010

Journal of Solid State Chemistry

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Section: Fe K-edge Xanes Spectrasupporting

confidence: 90%

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

Wang

Chen

et al. 2010

Journal of Solid State Chemistry

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“…and/or Fe 4? (Cox 1976;Dedushenko et al 2004;Di Benedetto et al 2010). Unfortunately, direct EPR detection of Fe 2?…”

Section: Calculation Of Absolute Number Of Spins and Thermodynamic Prmentioning

confidence: 91%

“…is the dominant iron species in natural quartz and is expected to oxidize, migrate, and cluster to form surface Fe 3? species during pulverization in air (Cressey et al 1993;Di Benedetto et al 2010). Interestingly, the EPR spectrum of the same amethyst sample pulverized in acetone does not contain any signal in the magnetic field below g = 4.28 ( Fig.…”

Section: Introductionmentioning

confidence: 90%

“…This peak does not correspond to any known lattice-bound Fe 3? centers in quartz (Barry and Moore 1964;Matarrese et al 1969;Mombourquette et al 1986;Halliburton et al 1989;Minge et al 1989Minge et al , 1990Weil 1994;Balitsky et al 2000;Di Benedetto et al 2010) and was interpreted to represent surface Fe 3? species formed during sample preparation (SivaRamaiah et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic and magnetic properties of surface Fe3+ species on quartz: effects of gamma-ray irradiation and implications for aerosol–radiation interactions

Sivaramaiah

Pan

2012

Phys Chem Minerals

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Samples of a natural amethyst, pulverized in air, and irradiated for gamma-ray doses from 0.14 to 70 kGy, have been investigated by powder electron paramagnetic resonance (EPR) spectroscopy from 90 to 294 K. The powder EPR spectra show that the surface Fe 3? species on the gamma-ray-irradiated quartz differ from its counterpart without irradiation in both the effective g value and the observed line shape, suggesting marked radiation effects. This suggestion is supported by quantitatively determined thermodynamic properties, magnetic susceptibility, relaxation times, and geometrical radius. In particular, the surface Fe 3? species on gamma-ray-irradiated quartz has larger Gibbs and activation energies than its non-irradiated counterpart, suggesting radiation-induced chemical reactions. The shorter phase-memory time (T m ) but longer spin-lattice relaxation time (T 1 ) of the surface Fe 3? species on the gamma-ray-irradiated quartz than that without irradiation indicate stronger dipolar interactions in the former. Moreover, the calculated geometrical radius of the surface Fe 3? species on the gamma-ray-irradiated quartz is three orders of magnitude larger than that of its counterpart on the as-is sample. These results provide new insights into radiation-induced aerosol nucleation, with relevance to atmospheric cloud formation and global climate changes.

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“…This is especially true for sample MT-09, where a couple of mineral inclusions (e.g., mica) have been detected by microscopy. Second, Fe is known to occur as both Fe 2+ and Fe 3+ in quartz [15,29]. However, Fe 2+ is not detectable by EPR at X-band frequencies [14].…”

Section: Trace Element Incorporation Into Quartzmentioning

confidence: 99%

Trace Element Compositions and Defect Structures of High-Purity Quartz from the Southern Ural Region, Russia

et al. 2017

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Abstract:Quartz samples of different origin from 10 localities in the Southern Ural region, Russia have been investigated to characterize their trace element compositions and defect structures. The analytical combination of cathodoluminescence (CL) microscopy and spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and trace-element analysis by inductively coupled plasma mass spectrometry (ICP-MS) revealed that almost all investigated quartz samples showed very low concentrations of trace elements (cumulative concentrations of <50 ppm with <30 ppm Al and <10 ppm Ti) and low abundances of paramagnetic defects, defining them economically as "high-purity" quartz (HPQ) suitable for high-tech applications. EPR and CL data confirmed the low abundances of substitutional Ti and Fe, and showed Al to be the only significant trace element structurally bound in the investigated quartz samples. CL microscopy revealed a heterogeneous distribution of luminescence centres (i.e., luminescence active trace elements such as Al) as well as features of deformation and recrystallization. It is suggested that healing of defects due to deformation-related recrystallization and reorganization processes of the quartz lattice during retrograde metamorphism resulted in low concentrations of CL activator and other trace elements or vacancies, and thus are the main driving processes for the formation of HPQ deposits in the investigated area.

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A Fe K-edge XAS study of amethyst

Cited by 31 publications

References 38 publications

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

Thermodynamic and magnetic properties of surface Fe3+ species on quartz: effects of gamma-ray irradiation and implications for aerosol–radiation interactions

Trace Element Compositions and Defect Structures of High-Purity Quartz from the Southern Ural Region, Russia

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