Thermodynamic Assessment of the Cu-Fe-O System

Khvan, Alexnadra V.; Fabrichnaya, Olga; Savinykh, G.; Adam, Robert; Seifert, Hans Jürgen

doi:10.1007/s11669-011-9951-5

Cited by 32 publications

(17 citation statements)

References 34 publications

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“…The authors of reference [33] include several of the authors of the FactSage [24] thermodynamic system, and consequently the FactSage calculations that are used in the present paper are in good agreement with both prior assessments [32,33] -except the circumstance that FactSage so far contains no data for Cu 2+ (CuO) in the melt. Nevertheless, under the growth conditions for CuFeO 2 the CuO content was found to be low, < 10% [2], which agrees well with the literature (see Fig.…”

Section: Discussionsupporting

confidence: 74%

Growth of CuFeO2 single crystals by the optical floating-zone technique

Wolff

Schwaigert

Siche

et al. 2020

Journal of Crystal Growth

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CuFeO 2 single crystals up to 50 mm in length and up to 10 mm in diameter were grown by the optical floating-zone method. Stoichiometric polycrystalline rods with a diameter of 6-12 mm were used as feed materials to produce crystals of sufficient size to be used as substrates for the growth of thin films of delafossites.For stable growth along the c-axis, low growth rates of 0.4 mm/h are necessary.Due to the incongruent melting behavior of CuFeO 2 , a stable melt zone requires adjustment of the lamp power during growth. The melting of CuFeO 2 is not simply incongruent because the thermodynamic equilibrium includes more than two solid phases and the melt; the gas phase is also involved. The crystals were characterized by X-ray diffraction and X-ray fluorescence measurements. from Catherinebourgh, Sibiria" -which instead he reported in the year 1873 to be composed from equimolar quantities of Cu + 2 O with the combination of Fe 3+ 2 O 3 , about 3.5% Al 2 O 3 [1]. This chemical composition can be written as Cu(Fe,Al)O 2 . The new mineral was given the name delafossite. In the years since Friedel's discovery a large number of other A + B 3+ O 2 compounds have become known that show basically the same structural features: BO 6 octahedra form layers that are stacked parallel to (001), and these edge-sharing octahedral sheets are connected along the [001] direction by linear O -A + -O bonds. Depending on details of the stacking sequence, the structures are usually either hexagonal or trigonal [2]. As an exception, Cu + Mn 3+ O 2 is monoclinic with space group C2/m [3]. Shannon et al. [4] revealed that not only copper and silver can acts as the A + element, but also other quite noble metals like palladium or even platinum. This is surprising because oxides of the platinum group metals are not only scarce and often unstable, but also the known platinum group binary oxides show oxidation states of 2+ or higher, e.g. PdO, PdO 2 , PtO, PtO 2 , PtO 3 , and not Pt 1+ as occours in Pt-containing delafossites.Oxide materials based on the ABO 2 delafossite structure are of particular interest due to the novel properties that accompany their cation variation at A and B sites. These properties are of interest to fundamental science [5,6,7,8,9] as well as applications [10]. Usually, the semiconductor delafossites consist of Ag or Cu at the A-site and several trivalent cations like Al, Fe or Ga at the B-site. Important among the semiconducting delafossites is CuAlO 2 with its relatively high mobility for a p-type transparent conducting oxide [11]. Pd-and Pt-based compounds (for A + ) are metallic delafossite oxides where B-site cations are transition metals like Co, Cr or Rh [4,12,13]. Among these, the growth of single crystalline PdCoO 2 has become of interest due to its ultra-high conductivity at room temperature. Recently an in-plane resistivity ρ ab = 2.6 µΩ·cm at 295 K was measured for sub-mm-sized PdCoO 2 crystals, which makes this material the most conductive oxide known, comparable to the best metallic conductors Ag, Cu, Au a...

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Section: Discussionsupporting

confidence: 74%

Growth of CuFeO2 single crystals by the optical floating-zone technique

Wolff

Schwaigert

Siche

et al. 2020

Journal of Crystal Growth

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“…Delafossite has typically needle-like structure [21] when it precipitates homogeneously in the glassy slag matrix or nucleates on spinel crystals below about 1170-1100 °C, depending on the prevailing oxygen partial pressure [22].…”

Section: Discussionmentioning

confidence: 99%

Freeze-lining Formation and Microstructure in a Direct-to-blister Flash Smelting Slag

Taskinen¹,

Kaskiala

Miettinen

et al. 2013

Journal for Manufacturing Science &Amp; Production

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Copper smelting in one processing step directly from concentrates to blister copper has been realized on an industrial scale in a few smelters, using concentrates with a high Cu/Fe-ratio. The fluxing of any direct-to-blister slag is demanding task as it must be fluid and maintain suitable properties in the oxidising conditions of copper making, and the reducing conditions of slag cleaning. The smelting slags in the direct-to-blister furnaces contain much more chemically dissolved copper than typical matte making slags. In this investigation, an industrial direct-to-blister slag was used in a freeze lining growth kinetics study. The freeze lining was formed on a water cooled metal finger at typical smelting temperatures using different dipping times from 5 to 120 min. The growth kinetics of the lining was very fast in the initial stage of the slag contact with the cooled metal surface. The quenched samples showed characteristic solidification zones from the cold end towards the hot side of the freeze lining and the molten slag shown already in other freeze linings and different slag types. The slag chemistry modifies the solidification pattern very much and thus the crystalline phases in the lining included also phases created by the high copper oxide concentration as well as the specific gangue assay of the smelters feed mixture. The thermal stability of the freeze lining in high-in-copper DB slags is discussed as well as the mechanism of delafossite precipitation.

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“…Fe þ 3 was later replaced by neutral FeO 1.5 species [6], resulting in the (Fe þ 2 ,) P (O -2 , FeO 1.5 , Va -Q ) Q formula unit of the solution. In this form the model was accepted by several authors and used to optimize higher-order systems [18][19][20].…”

Section: Liquidmentioning

confidence: 99%