Width of zone forbidden to complex sulfides (sulfo-salts) as determined by their crystollochemical characteristics

Platonov, A. N.; Mozgova, N. N.

doi:10.1080/00206817509471638

Cited by 3 publications

(4 citation statements)

References 7 publications

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“…The width of the forbidden zone to isostructural sulfosalts is sensitive to a variety of factors that are related to the composition and structure. [33] Thus, in Ag 3 As x Sb 1Àx S 3 compounds band gap decreases with increase in atomic number of pnictogen and the antimony load (Table 1). In binary compounds [for example, As 2 S 3 (E g = 2.50 eV) and Sb 2 S 3 (E g = 1.72 eV)], [34] isomorphous substitution of As by Sb causes a greater drop in energy gap values than in ternary compounds [Ag 3 AsS 3 (E g = 2.14 eV) and Ag 3 SbS 3 (E g = 1.97 eV)].…”

Section: Spectroscopic Measurementsmentioning

confidence: 96%

On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

2010

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The reactivity of the ruby silver minerals proustite (3Ag(2)S⋅As(2)S(3)) and pyrargyrite (3Ag(2)S⋅Sb(2)S(3)) was studied with two types of electrodes: a carbon-paste electroactive electrode (CPEE) and a paraffin-impregnated graphite electrode (PIGE). Polycrystalline samples of α-Ag(2)S (acanthite), As(2)S(3) (orpiment), Sb(2)S(3) (stibnite), Ag(3)AsS(3) (proustite), Ag(3)SbS(3) (pyrargyrite), and three samples of the proustite-pyrargyrite solid solution series were synthesized from pure elements by a solid-state reaction method. Phase identification of samples was carried out by XRD and chemical homogeneity was checked by SEM-EDS. Besides, sulfosalts were characterized by diffuse reflectance spectroscopy (DRS). Flat-band and formal potentials of sulfosalts were determined by the Mott-Schottky method and differential pulse abrasive stripping voltammetry, respectively. Band structure, bonding and solid-state structure are considered to investigate the oxidation and reduction of the solids. A ligand-to-metal charge transfer (LMCT) transition from the AsS(3) (or SbS(3)) group to Ag is related to ease of reducing the pyrargyrite-proustite series. Despite the increase in the amount of As (Sb) in Ag(3)SbS(3) (Ag(3)AsS(3)), reactivity is similar due to the similarity of the solid-state structures, and the same oxidation states of S, As, Sb and Ag species in the lattice. However, the nature of the pnictogen (As or Sb) changes the position of the conduction and valence band edges and modulates the reactivity of the pyrargyrite-proustite series. Anodic dissolution occurs by hole transfer from the top of the valence band that is formed mainly by the states of the AsS(3) and SbS(3) groups. Meanwhile, silver reduction occurs by electron transfer from the Ag 5s orbitals located at the bottom of the conduction band. The difficulty in dissolving proustite and pyrargyrite in cyanide is related to the presence of pyramidal AsS(3) and SbS(3) groups in these sulfosalts.

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Section: Spectroscopic Measurementsmentioning

confidence: 96%

On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

2010

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“…Thus whereas N and P are typical non-metals, As and Sb are semi-metals and Bi is a true metal (18). Hence, even though the Z-S (Z: As or Sb) bonding has a predominantly covalent character, the presence of Sb increases the metallization degree of covalent bonds in the SbS 3 groups (17). On the other hand, it is well known that metals tend to be more easily oxidized than nonmetals.…”

Section: Dissolution Of Ag 3 Sbs 3 In Sulfuric Acidmentioning

confidence: 99%

Electrochemical Aspects of Silver Sulfosalts Dissolution in Acid Thiourea Solution

2011

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Electro-oxidation of synthetic pyrargyrite (Ag 3 SbS 3 ) and proustite (Ag 3 AsS 3 ) powders in sulfate acid medium with thiourea has been studied. Two different types of electrodes were used for characterization of dissolution process. On one hand, thiourea oxidation was investigated on a paraffin-impregnated graphite electrode (PIGE) in order to determine the potential range to produce formamidine disulfide (protonated form, FDSH 2 2+ ). On other hand, electro-oxidized thiourea (FDSH 2 2+ ) was used to dissolve the sulfosalts particles at the PIGE and carbon paste electrodes (CPEs) surfaces. The chemical bond between sulfur and arsenic or antimony in the crystal structure of sulfosalts has an important role in the dissolution process of the solids. The results obtained herein agree with one previous study on the oxidation of sulfosalts in cyanide media [ChemPhysChem 11 (2010) 2879], and these demonstrate that structural, electronic, and bonding properties of sulfosalts mainly determine their reactivity regulating the extent of the reaction.

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“…(1.97 eV) son similares a aquéllas reportados en la literatura, (2.11, 2.13) eV y (1.93, 2.01) eV a temperatura ambiente, respectivamente. 39,67 Las brechas de energía se incrementan de manera no lineal con el aumento en el contenido de As (Figura 3.4).…”

Section: Sbsunclassified

“…De acuerdo a Platonov y Mozgova, 39 en sulfosales que son isoestructurales, la amplitud de la brecha de energía está relacionada a diferencias en la estructura electrónica y el número atómico de los elementos que forman al cristal. Así, la brecha de energía de la serie Ag3AsS3-Ag3AsS3 aumenta con la disminución del número atómico y la proporción del pnicógeno (Tabla 3.1, Figura 3.4).…”

Section: Sbsunclassified

Estudio fisicoquímico de las sulfosales isoestructurales Ag₃AsS₃ (proustita) y Ag₃SbS₃ (pirargirita) en soluciones de cianuro: extracción de plata

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Width of zone forbidden to complex sulfides (sulfo-salts) as determined by their crystollochemical characteristics

Cited by 3 publications

References 7 publications

On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

Electrochemical Aspects of Silver Sulfosalts Dissolution in Acid Thiourea Solution

Estudio fisicoquímico de las sulfosales isoestructurales Ag₃AsS₃ (proustita) y Ag₃SbS₃ (pirargirita) en soluciones de cianuro: extracción de plata

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