Phase stability and structural properties of Ni7 ± δS6 and Ni9S8 Heat capacity and thermodynamic properties of Ni7S6 at temperatures from 5 K to 970 K and of Ni9S8 from 5 K to 673 K

Stølen, Svein; Fjellvåg, Helmer; Grønvold, Fredrik; Seim, Helene; Westrum, Edgar F.

doi:10.1006/jcht.1994.1116

Cited by 28 publications

(18 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An additional effect is due to the very high thermal expansivity of Ni 9 S 8 ; with V/V = 120 * 10 −6 K −1 (Stoelen et al 1994) it is c. three times that of NiS. This causes strong relative shrinking of the Ni 9 S 8 part on cooling, making the inclusion at ambient temperature significantly smaller than it would be if it would only be NiS.…”

Section: (A) X Liquid < 1: Under-stoichiometric Inclusionsmentioning

confidence: 99%

Spontaneous cracking of thermally toughened safety glass. Part one: Properties of nickel sulphide inclusions

Kasper

2018

Glass Struct Eng

View full text Add to dashboard Cite

Spontaneous breakage of glass in facades is under control today, due to application of a very effective prevention method, namely the Heat Soak Test (HST) following EN 14179-1 (2006/2016). Nevertheless, details of the latter are still subject to discussion, mainly due to the fact that some years ago, it was discovered in an R&D project that it's holding temperature is too high, and it was reduced to 260 ± 10 • C at the recent review. In the present paper we investigate the properties of nickel sulphide inclusions in order to show that there's a huge difference in their comportment, and therewith their "criticality", in the HST or on the façade. Namely, not only the expansivity difference between nickel sulphide and the glass plays a role. Nickel sulphide inclusions show a spectrum of possible compositions, and we approach this fact systematically, showing how the breakage probability under both conditions changes depending on the detailed composition of the inclusions. The result of this comparison is that, out of all nickel sulphide inclusions leading to breakage in HST, only 40% also lead to breakage at ambient. Another aspect is the time-to-breakage curve in the HST. By the example of a dataset where nearly only SiO 2 stones cause breakages therein, we show that

show abstract

Section: (A) X Liquid < 1: Under-stoichiometric Inclusionsmentioning

confidence: 99%

Spontaneous cracking of thermally toughened safety glass. Part one: Properties of nickel sulphide inclusions

Kasper

2018

Glass Struct Eng

View full text Add to dashboard Cite

show abstract

“…Thermodynamic properties of godlevskite (Ni 9 S 8 ) were obtained from heat capacity measurements by StÖlen et al (1994) for Ni 7 S 6 and Ni 3 S 2 . A iH8 f of^802Á92 kJ/mol was calculated from H 298Á15 À H 0 (74920 J/mol) using the standard enthalpy of formation of NiS given by Robie & Hemingway (1995).…”

Section: Godlevskitementioning

confidence: 99%

Fe-Ni-Co-O-S Phase Relations in Peridotite-Seawater Interactions

Klein

Bach

2009

Journal of Petrology

224

160

View full text Add to dashboard Cite

Serpentinization of abyssal peridotites is known to produce extremely reducing conditions as a result of dihydrogen (H 2 ,aq) release upon oxidation of ferrous iron in primary phases to ferric iron in secondary minerals by H 2 O. We have compiled and evaluated thermodynamic data for Fe^Ni^Co^O^S phases and computed phase relations in fO 2 ,g^fS 2 ,g and aH 2 ,aq^aH 2 S,aq diagrams for temperatures between 150 and 4008C at 50 MPa. We use the relations and compositions of Fe^Ni^Co^O^S phases to trace changes in oxygen and sulfur fugacities during progressive serpentinization and steatitization of peridotites from the Mid-Atlantic Ridge in the 15820 0 N Fracture Zone area (Ocean Drilling Program Leg 209). Petrographic observations suggest a systematic change from awar-uite^magnetite^pentlandite and heazlewoodite^magnetite^pentlandite assemblages forming in the early stages of serpentinization to millerite^pyrite^polydymite-dominated assemblages in steatized rocks. Awaruite is observed in all brucite-bearing partly serpentinized rocks. Apparently, buffering of silica activities to low values by the presence of brucite facilitates the formation of large amounts of hydrogen, which leads to the formation of awaruite. Associated with the prominent desulfurization of pentlandite, sulfide is removed from the rock during the initial stage of serpentinization. In contrast, steatitization indicates increased silica activities and that highsulfur-fugacity sulfides, such as polydymite and pyrite^vaesite solid solution, form as the reducing capacity of the peridotite is exhausted and H 2 activities drop. Under these conditions, sulfides will not desulfurize but precipitate and the sulfur content of the rock increases. The co-evolution of fO 2 ,g^fS 2 ,g in the system follows an isopotential of H 2 S,aq, indicating that H 2 S in vent fluids is buffered. In contrast, H 2 in vent fluids is not buffered by Fe^Ni^Co^O^S phases, which merely monitor the evolution of H 2 activities in the fluids in the course of progressive rock alteration.The co-occurrence of pentlan-dite^awaruite^magnetite indicates H 2 ,aq activities in the interacting fluids near the stability limit of water. The presence of a hydrogen gas phase would add to the catalyzing capacity of awaruite and would facilitate the abiotic formation of organic compounds.

show abstract

“…Many forms of nickel sulfide have been reported in the literature, each one having its own solubility product (Table 1) [22][23][24][25][26]. However, correct and consistent solubility data is very difficult to assess and compare due to discussions regarding the conditions of formation and the existence of some polymorphs [27][28][29][30], to the variation in the available thermodynamic data [22,[24][25][26]31,32] and to the definition of solubility product [8,22,31]. Despite the many discussions on this topic concerning phase transition behaviour and some of the high temperature phases, most of the low temperature forms of nickel sulfide, namely millerite (␤-NiS), vaesite (NiS 2 ), polydymite (Ni 3 S 4 ) and heazlewoodite (Ni 3 S 2 ), are better characterized [27,[33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%