Delafossite

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Delafossite
Cuprite-Delafossite-133433.jpg
Discrete, wine-red cuprite crystals on matrix covered by brightly reflective delafossite microcrystals
General
Category Oxide minerals
Formula
(repeating unit)		CuFeO2
IMA symbol Del [1]
Strunz classification 4.AB.15
Crystal system Trigonal
Crystal class Hexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space group R3m
Unit cell a = 3.04, c = 17.12 [Å]; Z = 3
Identification
ColorBlack
Crystal habit Tabular to equant crystals; botryoidal crusts, spherulitic, powdery, massive
Twinning Contact twins on {0001}
Cleavage Imperfect on {1011}
Tenacity Brittle
Mohs scale hardness5.5
Luster Metallic
Streak Black
Diaphaneity Opaque
Specific gravity 5.41
Optical propertiesUniaxial
Pleochroism Distinct; O = pale golden brown; E = rose-brown
Other characteristicsWeakly magnetic
References [2] [3] [4]

Delafossite is a copper iron oxide mineral with formula CuFeO2 or Cu1+Fe3+O2. It is a member of the delafossite mineral group, which has the general formula ABO2, a group characterized by sheets of linearly coordinated A cations stacked between edge-shared octahedral layers (BO6). [5] Delafossite, along with other minerals of the ABO2 group, is known for its wide range of electrical properties, its conductivity varying from insulating to metallic. [5] Delafossite is usually a secondary mineral that crystallizes in association with oxidized copper and rarely occurs as a primary mineral. [5]

Contents

Composition

The chemical formula for delafossite is CuFeO2, which was first determined through chemical analysis of the pure mineral by G. S. Bohart. [6] The ratio he determined was very close to Cu:Fe:O=1:1:2, with slightly more iron than copper. Rogers. [6] attributed this fact to a small amount of hematite in the sample. In order to determine the composition of delafossite Rogers used the Ziervogel process. The Ziervogel process is used to test for the presence of cuprous oxides by looking for the "spangle reaction" which produces thin flakes of metallic silver when cuprous oxide is mixed with silver sulfate. When Rogers heated powdered delafossite with silver sulfate solution, the spangle reaction occurred. The only oxides possibilities to consider for delafossite are cuprous copper and ferrous iron. Rogers concluded that the iron was combining with the oxygen as a radical and that it only acted as a radical. This indicated that the copper in delafossite was in the cuprous rather than the cupric form. Hence he concluded that the composition of delafossite was probably cuprous metaferrite, CuFe3+O2. This composition was later confirmed by Pabst by the determination of interionic distances in the crystal lattice. [7]

Structure

The atomic structure of delafossite and the delafossite group consists of a sheet of linearly coordinated A cations stacked between edge-shared octahedral layers (BO6). In the delafossite atomic structure there are two alternating planar layers. The two layers consist of one layer triangular-patterned A cations and a layer of edge-sharing BO6 octahedra compacted with respect to the c axis. The delafossite structure can have two polytypes according to the orientation of the planar layer stacking. Hexagonal 2H types that have a space group of P63/mmc are formed when two A layers are stacked with each layer rotated 180° in relation to one another. Alternatively, when the layers are stacked each layer in the same direction in relation to one another, it makes a rhombohedral 3R type with a space group of R3m. [5]

Physical properties

The color of delafossite is black, with a hardness of 5.5, and imperfect cleavage in the {1011} direction. [2] Pabst [8] calculated the density of delafossite to be 5.52. Contact twinning has been observed in the {0001} direction. [2] The unit cell parameters were calculated to be a = 3.0351 Å, c = 17.166 Å, V = 136.94 Å3. [9] Delafossite is tabular to equidimensional in habit and has a black streak and a metallic luster. [6] Delafossite has hexagonal symmetry that can have the space groups R3m or P63/mmc depending on the stacking of A cation layers. Delafossite compounds can have magnetic properties when magnetic ions are in the B cation position. [5] Delafossite compounds also have properties dealing with electric conductivity such as insulation and/or metallic conduction. Delafossite compounds can exhibit p- or n-type conductivity based on their composition. [5]

Rhombohedral (3R), CuFeO2 properties:

Hexagonal (2H), CuFeO2 properties:

Synthesis

3R CuFeO2 is often synthesized by solid state reactions, sol gel methods, and hydrothermal synthesis.

Pure 2H CuFeO2 and other 2H delafossite-type oxides are difficult to synthesize. The only pure 2H CuFeO2 crystals were pure 2H CuFeO2 nanoplates with a thickness of about 100 nm which were synthesized at temperatures as low as 100 °C from CuI and FeCl3·6H2O. [10]

Application

Solar cells: 2H CuFeO2 has a band gap of 1.33 eV and a high absorption coefficient of 3.8×104 cm−1 near the band gap edge at 700 nm. It demonstrated a photovoltaic effect when placed into thin film structures composed of ITO/ZnO/2H CuFeO2/graphite/carbon black. [10]

Other applications: CuFeO2 is made of earth abundant elements and has good stability in aqueous environments, and as such was investigated as photocathodes for photoelectrochemical reduction of CO2, solar water reduction, and as a cathode material in lithium batteries. Whereas the 3R phase was somewhat characterized, only X-ray diffraction and theoretical calculation of eg and t2g occupancies of the Fe3+ are available for 2H CuFeO2. [10]

Geologic occurrence

In 1873, delafossite was discovered by Charles Friedel in a region of Ekaterinbug, Siberia. [11] Since its discovery it has been identified as a fairly common mineral found in such places as the copper mines of Bisbee, Arizona. [6] Delafossite is usually a secondary mineral often found in oxidized areas of copper deposits although it can be a primary mineral as well. [2] [5] Delafossite can be found as massive, relatively distinct crystals on hematite. [6] Delafossite has since been found in mines around the world from Germany to Chile. [2]

Origin of the name

Delafossite was first noted by Charles Friedel in 1873 and given the composition Cu2O·Fe2O3. [6] The mineral was given the name delafossite in honor of the French mineralogist and crystallographer Gabriel Delafosse (1796–1878). [5] Delafosse is known for noting the close relationship between crystal symmetry and physical properties. [12]

See also

Related Research Articles

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Mineral Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

High-temperature superconductivity Superconductive behavior at temperatures much higher than absolute zero

High-temperature superconductors are operatively defined as materials that behave as superconductors at temperatures above 77 K, the boiling point of liquid nitrogen, one of the simplest coolants in cryogenics. All materials currently known to conduct at ordinary pressures become superconducting at temperatures far below ambient, and therefore require cooling. The majority of high-temperature superconductors are ceramic materials. On the other hand, Metallic superconductors usually work below 73.15 K : they are then called low-temperature superconductors. Metallic superconductors are also ordinary superconductors, since they were discovered and used before the high-temperature ones.

Chalcopyrite Copper iron sulfide mineral

Chalcopyrite ( KAL-kə-PY-ryte, -⁠koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.

Perovskite (structure) Type of crystal structure

A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two ions, often of very different sizes, and X is an ion (frequently oxide) that bonds to both ions. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where either/both the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in their oxidation states.

Yttrium barium copper oxide Chemical compound

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Copper(I) oxide Chemical compound - an oxide of copper with formula Cu2O

Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu2O. It is one of the principal oxides of copper, the other being or copper(II) oxide or cupric oxide (CuO). This red-coloured solid is a component of some antifouling paints. The compound can appear either yellow or red, depending on the size of the particles. Copper(I) oxide is found as the reddish mineral cuprite.

Covellite Sulfide mineral

Covellite is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is commonly a secondary mineral in limited abundance and although it is not an important ore of copper itself, it is well known to mineral collectors.

Sperrylite

Sperrylite is a platinum arsenide mineral with the chemical formula PtAs2 and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits. It has a Mohs hardness of 6 - 7 and a very high specific gravity of 10.6.

Copper monosulfide Chemical compound

Copper monosulfide is a chemical compound of copper and sulfur. It was initially thought to occur in nature as the dark indigo blue mineral covellite. However, it was later shown to be rather a cuprous compound, formula Cu+3S(S2). CuS is a moderate conductor of electricity. A black colloidal precipitate of CuS is formed when hydrogen sulfide, H2S, is bubbled through solutions of Cu(II) salts. It is one of a number of binary compounds of copper and sulfur (see copper sulfide for an overview of this subject), and has attracted interest because of its potential uses in catalysis and photovoltaics.

Birnessite Manganese hydroxide mineral

Birnessite (nominally MnO2.nH2O) is a hydrous manganese dioxide mineral with a chemical formula of Na0.7Ca0.3Mn7O14·2.8H2O. It is the main manganese mineral species at the Earth's surface, and commonly occurs as fine-grained, poorly crystallized aggregates in soils, sediments, grain and rock coatings (e.g., desert varnish), and marine ferromanganese nodules and crusts. It was discovered at Birness, Aberdeenshire, Scotland.

Djurleite

Djurleite is a copper sulfide mineral of secondary origin with formula Cu31S16 that crystallizes with monoclinic-prismatic symmetry. It is typically massive in form, but does at times develop thin tabular to prismatic crystals. It occurs with other supergene minerals such as chalcocite, covellite and digenite in the enriched zone of copper orebodies. It is a member of the chalcocite group, and very similar to chalcocite, Cu2S, in its composition and properties, but the two minerals can be distinguished from each other by x-ray powder diffraction. Intergrowths and transformations between djurleite, digenite and chalcocite are common. Many of the reported associations of digenite and djurleite, however, identified by powder diffraction, could be anilite and djurleite, as anilite transforms to digenite during grinding.

Arthurite

Arthurite is a mineral composed of divalent copper and iron ions in combination with trivalent arsenate, phosphate and sulfate ions with hydrogen and oxygen. Initially discovered by Sir Arthur Russell in 1954 at Hingston Down Consols mine in Calstock, Cornwall, England, arthurite is formed as a resultant mineral in the oxidation region of some copper deposits by the variation of enargite or arsenopyrite. The chemical formula of Arthurite is CuFe23+(AsO4,PO4,SO4)2(O,OH)2•4H2O.

Copper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both minerals and synthetic materials comprise these compounds. Some copper sulfides are economically important ores.

Campigliaite is a copper and manganese sulfate mineral with a chemical formula of Cu4Mn(SO4)2(OH)6·4H2O. It has a chemical formula and also a crystal structure similar to niedermayrite, with Cd(II) cation replacing by Mn(II). The formation of campigliaite is related to the oxidation of sulfide minerals to form sulfate solutions with ilvaite associated with the presence of manganese. Campigliaite is a rare secondary mineral formed when metallic sulfide skarn deposits are oxidized. While there are several related associations, there is no abundant source for this mineral due to its rare process of formation. Based on its crystallographic data and chemical formula, campigliaite is placed in the devillite group and considered the manganese analogue of devillite. Campigliaite belongs to the copper oxysalt minerals as well followed by the subgroup M=M-T sheets. The infinite sheet structures that campigliaite has are characterized by strongly bonded polyhedral sheets, which are linked in the third dimension by weaker hydrogen bonds.

Cuprospinel is a mineral that occurs naturally in Baie Verte, Newfoundland, Canada. The mineral was found in an exposed ore dump, on the property of Consolidated Rambler Mines Limited near Baie Verte, Newfoundland. The mineral was first characterized by Ernest Henry Nickel, a mineralogist with the Department of Energy, Mines and Resources in Australia, in 1973.

Copper(I) sulfate, also known as cuprous sulfate, is the inorganic compound with the chemical formula Cu2SO4. It is a white solid that has attracted little attention, in contrast to copper(II) sulfate. It is an unusual example of a copper(I) compound derived from an oxyanion, illustrated also by the non- or fleeting existence of cuprous nitrate and cuprous perchlorate.

Hidalgoite Mineral of the beudantite group

Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.

Oxyselenide Class of chemical compounds

Oxyselenides are a group of chemical compounds that contain oxygen and selenium atoms. Oxyselenides can form a wide range of structures in compounds containing various transition metals, and thus can exhibit a wide range of properties. Most importantly, oxyselenides have a wide range of thermal conductivity, which can be controlled with changes in temperature in order to adjust their thermoelectric performance. Current research on oxyselenides indicates their potential for significant application in electronic materials.

Buserite is a hydrated layered Mn-oxide mineral with nominal chemical formula MnO2.nH2O. It was named after Swiss chemist professor W. Buser, who first identified it in 1952 in deep-sea manganese nodules. Buser named it 10 Å manganate because the periodicity in the layer stacking direction was 10 Å. It was renamed buserite in 1970 by the nomenclature commission of the International Mineralogical Association (IMA).

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID   235729616.
  2. 1 2 3 4 5 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1997). "Delafossite". Handbook of Mineralogy (PDF). Vol. III (Halides, Hydroxides, Oxides). Chantilly, VA, US: Mineralogical Society of America. ISBN   0962209724.
  3. ↑ Delafossite. Mindat.org
  4. ↑ Delafossite. Webmineral
  5. 1 2 3 4 5 6 7 8 Marquardt, M. A.; Ashmore, N. A.; Cann, D. P. (2006). "Crystal chemistry and electrical properties of the delafossite structure". Thin Solid Films. 496 (1): 146–156. Bibcode:2006TSF...496..146M. doi:10.1016/j.tsf.2005.08.316.
  6. 1 2 3 4 5 6 Rogers, A. (1913). "Delafossite, a Cuprous Metaferrite from Bisbee, Arizona". American Journal of Science. 35 (207): 290–294. Bibcode:1913AmJS...35..290R. doi:10.2475/ajs.s4-35.207.290.
  7. ↑ Pabst, A. (1946). "Notes on the Structure of Delafossite" (PDF). American Mineralogist. 23 (539–546).
  8. ↑ Pabst, Adolf (1938). "Crystal Structure and Density of Delafossite". American Mineralogist. 20: 175–176.
  9. ↑ Shannon, R. D.; Rogers, D. B.; Prewitt, C. T. (1971). "Chemistry of noble metal oxides. I. Syntheses and properties of ABO2 delafossite compounds". Inorganic Chemistry. 10 (4): 713. doi:10.1021/ic50098a011.
  10. 1 2 3 4 Jin, Yi; Chuamanov, George (2016). "Solution Synthesis of Pure 2H CuFeO2 at Low Temperatures". RSC Advances. 6 (31): 26392–26397. Bibcode:2016RSCAd...626392J. doi:10.1039/C6RA01901C.
  11. ↑ Rogers, A. (1922). "Delafossite from Kimberly, Nevada" (PDF). American Mineralogist. 7: 102–104.
  12. ↑ 1839: Gabriel Delafosse et Alfred Des Cloizeaux Archived 2012-04-26 at the Wayback Machine . Institut de minéralogie et de physique des milieus condensés, 19 March 2009.
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