ESR spectrum of Fe<sup>+3</sup> in topaz. II. Superhyperfine structure

Holuj, F.; Quick, Stuart M.

doi:10.1139/p68-137

Cited by 7 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The valence states of Ti 3+ , Cr 3+ , Mn 3+ and Fe 3+ in imperial topaz were confirmed by EPR (Schott et al (2003). In agreement with the studies carried out by Thyer et al (1967), Holuj and Quick (1968) and Schott et al (2003), all based on EPR results, Fe 3+ substitutes for Al 3+ in the crystal structure of topaz. The replacement of Al 3+ by Ga 3+ was described by Northrup and Reeder (1994) and Breiter et al (2013).…”

Section: Discussionsupporting

confidence: 92%

The fingerprint of imperial topaz from Ouro Preto region (Minas Gerais state, Brazil) based on cathodoluminescence properties and composition

et al. 2018

View full text Add to dashboard Cite

A study of the cathodoluminescence (CL) properties of imperial topaz from Ouro Preto region (Minas Gerais state, Brazil) and its relation with trace-element composition was conducted, using scanning electron microscope cathodoluminescence (SEM-CL), optical microscope cathodoluminescence (OM-CL), cathodoluminescence-spectrometry (CL-spectrometry), electron microprobe analysis (EMPA), laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectrometry. Each analytical technique allowed characterization of the imperial topaz fingerprint. SEM-CL panchromatic images show different crystal growth and resorption events in imperial topaz crystals. Colour CL images indicate only blue to violet emissions. The CL-spectra indicate a broad emission band with low intensity peak at ~417 nm and a broad emission band with high intensity and major peaks at 685, 698, 711 and 733 nm. The EMPA indicates high OH content, in which the OH/(OH + F) ratio ranges between 0.35–0.43 (0.72 ≤ OH ≤ 0.86 apfu). High Cu and Zn concentrations (LA-ICP-MS) were measured in the high luminescence areas of SEM-CL images, suggesting both elements as CL-activators in imperial topaz. Raman and CL-spectra indicate high Cr concentrations, corroborated by EMPA and LA-ICP-MS results. The high Cr caused strong luminescence intensities that enabled their superimposition over the OH stretching mode (~3650 cm–1) of topaz in all Raman spectra. Among trace elements, the concentrations of Ti, V, Cr, Mn, Fe, Cu, Zn, Ga and Ge provide the fingerprint of imperial topaz.

show abstract

Section: Discussionsupporting

confidence: 92%

The fingerprint of imperial topaz from Ouro Preto region (Minas Gerais state, Brazil) based on cathodoluminescence properties and composition

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The presence of Fe 3+ impurity at A13+ sites in topaz has been reported (Thyer et al, 1967). All crystals of topaz are also known to have a concentration of F-up to about 20 % by weight (Thyer et al, 1967) and replacement of F-by OH-has been demonstrated by the OH absorption peak at 2.745 pm (Holuj & Quick, 1968). Substitution of OH-for F-has also been predicted by Rosenberg (1967) from X-ray and optical studies.…”

Section: (A) General Structurementioning

confidence: 97%

“…Since the F-content (20 % by weight) of topaz can be replaced by OH- (Rosenberg, 1967;Holuj & Quick, 1968) and the AI a+ content can be replaced by Fe a+, it is possible that the planar faults are thin layers of an exsolved phase involving OH-and/or Fe 3÷.…”

Section: (I) Planar Faultsmentioning

confidence: 99%

See 1 more Smart Citation

On the nature of grown-in defects in topaz

Phakey¹,

Horney²

1976

Acta Cryst Sect A

View full text Add to dashboard Cite

A study has been made of crystals of topaz by optical and interference microscopy, X-ray topography, and scanning and transmission electron microscopy. Most of the samples show a nearly perfect region with dislocation density ~ 102 cm -2 surrounded by a highly defective narrow rim containing dislocations (density ~ 107 cm -2 and higher), low-angle boundaries, networks and planar faults. The Burgers vectors of the dislocations observed in both regions of the crystal have been determined by means of diffraction contrast experiments and the nature of other defects is considered in detail. The relevance of the defects to the anomalous optical properties of the rim is discussed. A direct correlation between etch pits and dislocations in (001) sections of topaz is shown and evidence is presented that screw dislocations or even those with an appreciable screw component are not required for the formation of curl-bottomed pits. The origin of curl-bottomed pits is explained. It is suggested that the sudden increase in the density of dislocations in the rim is due to heterogeneous nucleation of dislocations by local internal stresses in growth layers which have been poisoned by increased impurity concentrations during growth.

show abstract