Mössbauer study on microwave synthesized (Cu,Fe) sulfide composites and correlation with natural mineral—cubanite

Pareek, S. P.; Rais, Anwar; Tripathi, Amita; Chandra, Usha

doi:10.1007/978-3-540-78697-9_136

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…Intriguingly, Vaughan and Burns (1972) measured Mössbauer spectra of several sulfides containing four-coordinated Fe atoms, including cubanite, sternbergite, and argentopyrite. They noted that, while the Mössbauer spectra of both cubanite and sternbergite consist of only one single hyperfine set of six-lines, as have also been observed by others (Greenwood and Whitfield 1968;Wintenberger et al 1974Wintenberger et al , 1990McCammon 1994McCammon , 1995Rozenberg et al 1997;Pareek et al 2008), the spectrum of argentopyrite is clearly characterized by two overlapping six-line sub-spectra, A and B, of equal intensity, suggesting that Fe in argentopyrite may occur in two distinct tetrahedral positions. This observation is evidently supported by our structural data.…”

Section: Resultssupporting

confidence: 55%

“…Ternary sulfides with a general chemical formula MFe 2 S 3 , where M represents a monovalent cation, such as Cu + , Ag + , K + , Cs + , Rb + , or Tl + , are characterized by Fe with a nominal valency of +2.5, due to rapid electron exchange between Fe 2+ and Fe 3+ ions (Greenwood and Whitfield 1968;Vaughan and Burns 1972;Amthauer and Bente 1983;Wintenberger et al 1990;McCammon 1994;Reissner et al 2004;Pareek et al 2008). These materials exhibit numerous interesting electronic-magnetic properties (Sleight and Gillson 1973;Wintenberger et al 1990;Reissner et al 2006), as well as polymorphism at different temperatures or pressures (e.g., Putnis 1977;Miyamoto et al 1980;McCammon 1994McCammon , 1995Rozenberg et al 1997;Pruseth et al 1999).…”

Section: Introductionmentioning

confidence: 99%

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Crystal structure of argentopyrite, AgFe2S3, and its relationship with cubanite

Yang

Pinch

Downs

2009

American Mineralogist

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The structure of argentopyrite, AgFe 2 S 3 , was determined for the first time with single-crystal X-ray diffraction. In contrast to the previously reported orthorhombic symmetry, our data show that argentopyrite is monoclinic with space group P112 1 /n (non-standard setting) and unit-cell parameters a = 6.6902(2), b = 11.4497(4), c = 6.4525(2) Å, γ = 90.2420(8)°, and V = 494.26(3) Å 3 . Similar to cubanite (CuFe 2 S 3 ), the structure of argentopyrite is also based on approximately hexagonal closepacked S atoms, with cations ordered over one half of the tetrahedral sites, forming corner-shared AgS 4 and FeS 4 tetrahedral sheets parallel to (001). The two structures differ chiefly in the linkage between the two adjacent tetrahedral sheets and the ordering patterns of cations within a tetrahedral sheet. Topologically, the structure of argentopyrite can be obtained by a displacement of a tetrahedral sheet in the cubanite structure along the (a/2 + b/6) direction relative to the sheet beneath, giving rise to a cluster of four edge-shared FeS 4 tetrahedra in argentopyrite, as compared to two in cubanite. There are two distinct Fe sites (Fe1 and Fe2) in argentopyrite, rather than only one, as in other MFe 2 S 3 sulfide minerals (M = monovalent cations). Together with published Mössbauer data, we suggest that there exists some degree of Fe 2+ -Fe 3+ order-disorder in argentopyrite, with Fe 2+ favoring the more distorted Fe2 tetrahedral site. Argentopyrite appears to possess all the features proposed by Putnis (1977) for a high-temperature ordered form of cubanite.

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Section: Resultssupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Crystal structure of argentopyrite, AgFe2S3, and its relationship with cubanite

Yang

Pinch

Downs

2009

American Mineralogist

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“…The characterization of CuFe 2 S 3 prepared under controlled conditions (Pareek et al 2008) indicates the importance of methods of preparation to achieve an abundant yield of cubanite. We found that the quenching process results in the formation of pyrrhotite in abundance.…”

Section: Resultsmentioning

confidence: 99%

“…The temperature was slowly raised to 800°C under controlled rate of heating and kept at the same temperature for 12 hours. The samples thus prepared were then cooled down to room temperature in various steps described elsewhere (Pareek et al 2008). The sample was characterized and analyzed by recording X-ray-diffraction patterns using a Philips diffractometer with CuKa radiation.…”

Section: Methodsmentioning

confidence: 99%

SYNTHETIC CUBANITE CuFe2S3: PRESSURE-INDUCED TRANSFORMATION TO ISOCUBANITE

Chandra¹,

Parthasarathy²,

Sharma³

2010

The Canadian Mineralogist

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Cubanite, the orthorhombic polymorph of CuFe 2 S 3 , is very sensitive to temperature, pressure and compositional variations. This sensitivity has prevented its successful synthesis in a controlled laboratory environment. We report here the first successful synthesis of cubanite and its high-pressure Mössbauer spectroscopic and electrical properties up to 7 GPa. We also compare the Mössbauer spectroscopic and electrical resistivity results on our synthetic cubanite with the behavior of naturally occurring cubanite under identical conditions. The magnetic hyperfine field, a sensitive Mössbauer parameter of the synthetic sample, corresponds to that of orthorhombic cubanite. We report here the pressure-induced transformation of the magnetic sextet (cubanite) to a paramagnetic doublet (isocubanite) at ~4 GPa at room temperature. This transformation has been confirmed independently by our electrical resistivity measurements up to 7 GPa. The present results could be useful in estimating the metamorphic pressure conditions of cubanite-bearing carbonaceous chondrites. soMMaiRe La cubanite, polymorphe orthorhombique de CuFe 2 S 3 , est très sensible aux variations en température, pression et composition. A cause de cette sensibilité, il a été jusqu'à maintenant impossible de la synthétiser au laboratoire sous conditions contrôlées. Nous avons réussi cette synthèse pour la première fois, et nous avons déterminé son spectre Mössbauer et ses propriétés électriques à pression élevée, jusqu'à 7 GPa. Aussi, nous comparons nos résultats avec le comportement de la cubanite naturelle à conditions identiques. Le champ magnétique hyperfin, un paramètre Mössbauer sensible de l'échantillon synthétique, correspond à celui de la cubanite. Nous avons découvert une transformation sensible à la pression du sextet magnétique (cubanite) au doublet paramagnétique (isocubanite) à ~4 GPa à température ambiante. Cette transformation a été confirmée de façon indépendante par nos mesures de la résistivité électrique jusqu'à 7 GPa. Nos résultats pourraient s'avérer utiles pour estimer la pression du métamorphisme des chondrites carbonacées porteuses de cubanite. (Traduit par la Rédaction)Mots-clés: cubanite, isocubanite, transition à haute pression, cellule à enclume de diamant, spectroscopie de Mössbauer, propriétés électriques. §

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“…In this direction, synthesis of this rarely found mineral, cubanite (CuFe 2 S 3 ) was successfully attempted using conventional as well as microwave heating. The rapid microwave heating seems to be advantageous over conventional technique showing a characteristic peak of cubanite at d= 3.22 Å (Pareek et al 2008, Chandra et al 2010,2011. It is reported that synthesis of orthorhombic cubanite depends not only on the preparatory conditions (controlled heating and cooling rate) but also on compositional variation.…”

Section: Examples Of Microwave Synthesismentioning

confidence: 99%