Crystal structure and XANES investigation of petzite, Ag<sub>3</sub>AuTe<sub>2</sub>

Hongu, Hidetomo; Yoshiasa, Akira; Nespolo, M.; Tobase, Tsubasa; Tokuda, Makoto; Sugiyama, Kazumasa

doi:10.1107/s2052520619002166

Cited by 5 publications

(6 citation statements)

References 25 publications

(23 reference statements)

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“…[ 40 ] The irreducible representations for the modulated structure were obtained using the superspace group method. [ 40,44–48 ] The results of the analysis of the optical activity of the modes were presented in van Loosdrecht et al [ 40 ] The relative strong bands are observed in the 80–109 cm −1 region in polarized Raman spectra. We have registered depolarized spectra in which all modes will appear.…”

Section: Resultsmentioning

confidence: 99%

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Palyanova

Beliaeva

Кох

et al. 2022

J Raman Spectroscopy

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Electron microprobe analysis (EMPA), X-ray powder diffraction (XRD), and Raman spectroscopy (RS) were applied to characterize the synthetic gold chalcogenides of the Au-Te-Se-S system and natural analogs from the Gaching deposit (Central Kamchatka, Russia). The EPMA results showed that the synthetic chalcogenides have different Te/Se/S and Au/X (X = Te + Se + S) ratios: AuX 2 , Au 3 X 10 , and AuX. They are similar in composition to natural compoundscalaverite (AuTe 2 ), maletoyvayamite (Au 3 Te 6 Se 4 ), and unnamed minerals AuTe 0.7 Se 0.3 and AuSe 0.7 S 0.3 . It was established that chalcogenides AuX, Au 3 X 10 , and AuX 2 have a specific Raman spectra with characteristic peaks. The position of the peaks and the character of the spectra of the synthetic phases and their natural analogs from the Gaching deposit coincide within the limits of accuracy. Different ratios of chalcogenes Te/Se/S in compounds influence the Raman peak positions. The positions of the peaks for natural compounds AuX differ depending on the predominance of Te (AuTe 0.7 Se 0.3 ) or Se (AuSe 0.7 S 0.3 ). AuSe synthetic phases consist of a mixture of αand β-polymorphs. Raman spectroscopy can be used for the identification of natural gold chalcogenides worldwide, which are difficult to diagnose by other methods due to the microscopic grain sizes and close intergrowths with other ore minerals. The similarity of the Raman spectra upon changing the concentrations of Se and S suggests identical structures and possible isomorphism in the composition range of AuTe 0.

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Section: Resultsmentioning

confidence: 99%

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Palyanova

Beliaeva

Кох

et al. 2022

J Raman Spectroscopy

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“…Calaverite shows incommensurate super-structure ordering only in certain compositional regions (Bindi et al, 2009), whereas sylvanite and krennerite do not in any region. On the other hand, petzite Ag 3 AuTe 2 is a compound with a defined silver-to-gold ratio (Thompson, 1949;Hongu et al, 2019a), with distinct ordered positions for the silver and gold atoms, unlike calaverite, krennerite and sylvanite.…”

Section: Real Structures Of Telluridesmentioning

confidence: 99%

“…The XANES patterns of gold and of period V and VI elements in compounds vary depending on the chemical bonding state and structure (Hongu et al, 2019a,b;Yoshiasa et al, 2019). Clear differences in peak shape have been observed in gold minerals such as petzite, aurostibite (AuSb 2 ) and nagyagite (Hongu et al, 2019a). The patterns of the Au L III -edge and Te K-edge XANES spectra are very similar for calaverite, krennerite and sylvanite.…”

Section: Description Of the Crystal Structure And Bonding Distancesmentioning

confidence: 99%

“…The electron configuration of Au + and Au 3+ are [Xe] 4f 14 5d 10 and [Xe] 4f 14 5d 8 , respectively. Linear covalent coordination is formed by sp hybridization and observed in several Au + 5d 10 compounds (Pauling, 1931;Elliott & Pauling, 1938;Cotton & Wilkinson, 1980;Hongu et al, 2019a). Au 3+ tends to form square planar covalent coordination, corresponding to the use of bonding orbitals formed by dsp 2 hybridization (Elliott & Pauling, 1938).…”

Section: Introductionmentioning

confidence: 99%

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Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au_1–xAg_xTe₂ group minerals

Kitahara¹,

Yoshiasa²,

Tokuda³

et al. 2022

Acta Crystallogr B Struct Sci Cryst Eng Mater

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The structure refinement and XANES study of two gold–silver–tellurides [Au1+x Ag x Te2, krennerite (x = 0.11–0.13) and sylvanite (x = 0.29–0.31)] are presented and the structures are compared with the prototype structure of calaverite (x = 0.08–0.10). Whereas the latter is well known for being incommensurately modulated at ambient conditions, neither krennerite nor sylvanite present any modulation. This is attributed to the presence of relatively strong Te—Te bonds (bond distances < 2.9 Å) in the two minerals, which are absent in calaverite (bond distances > 3.2 Å). In both tellurides, trivalent gold occurs in slightly distorted square planar coordination, whereas monovalent gold, partly substituted by monovalent silver, presents a 2+2+2 coordination, corresponding to distorted rhombic bipyramids. The differentiation between bonding and non-bonding contacts is obtained by computation of the Effective Coordination Number (ECoN). The CHARge DIstribution (CHARDI) analysis is satisfactory for both tellurides but suggests that the Te—Te bond in the [Te3]2− anion is not entirely homopolar. Both tellurides can therefore be described as Madelung-type compounds, despite the presence of Te–Te in both structures.

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“…The D correlates with the melting temperature and physical properties, such as the hardness of crystals. The D for each atom can be estimated using the dynamic component in the Debye-Waller factor based on the Debye approximation (Willis & Pryor, 1975;Wood et al, 2002;Christensen et al, 2006;Nakatsuka et al, 2011Nakatsuka et al, , 2015Yoshiasa et al, 2016;Tokuda et al, 2019;Hongu et al, 2019). We estimated D for each atom using the values of U eq (Table 3) under the assumption that there are no static disorder components of atoms.…”

Section: Mean-square Displacement and Estimated Debye Temperature (H D )mentioning

confidence: 99%

Crystal structure refinements of stoichiometric Ni₃Se₂ and NiSe

et al. 2021

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Single crystals of Ni3Se2 (trinickel diselenide) and NiSe (nickel selenide) with stoichiometric chemical compositions were grown in evacuated silica-glass tubes. The chemical compositions of the single crystals of Ni3Se2 and NiSe were determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). The crystal structures of Ni3Se2 [rhombohedral, space group R32, a = 6.02813 (13), c = 7.24883 (16) Å, Z = 3] and NiSe [hexagonal, space group P63/mmc, a = 3.66147 (10), c = 5.35766 (16) Å, Z = 2] were analyzed by single-crystal X-ray diffraction and refined to yield R values of 0.020 and 0.018 for 117 and 85 unique reflections, respectively, with F o > 4σ(F o). R32 is a Sohncke type of space group where enantiomeric structures can exist; the single-domain structure obtained by the refinement was confirmed to be correct by a Flack parameter of −0.05 (2). The existence of Ni—Ni bonds was confirmed in both compounds, in addition to the Ni—Se bonds. The value of the atomic displacement parameter (mean-square displacement) of each atom in NiSe was larger than that in Ni3Se2. The larger amplitude of the atoms in NiSe corresponds to longer Ni—Se and Ni—Ni bond lengths in NiSe than in Ni3Se2. The Debye temperatures, θD, estimated from observed mean-square displacements for Ni and Se in Ni3Se2, were 322 and 298 K, respectively, while those for Ni and Se in NiSe were 246 and 241 K, respectively. The existence of large cavities in the structure and the weak bonding force are likely responsible for the brittle and soft nature of the NiSe crystal.

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Crystal structure and XANES investigation of petzite, Ag₃AuTe₂

Cited by 5 publications

References 25 publications

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au_1–xAg_xTe₂ group minerals

Crystal structure refinements of stoichiometric Ni₃Se₂ and NiSe

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Crystal structure and XANES investigation of petzite, Ag3AuTe2

Cited by 5 publications

References 25 publications

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au1–x Ag x Te2 group minerals

Crystal structure refinements of stoichiometric Ni3Se2 and NiSe

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Crystal structure and XANES investigation of petzite, Ag₃AuTe₂

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au_1–xAg_xTe₂ group minerals

Crystal structure refinements of stoichiometric Ni₃Se₂ and NiSe