Single crystal growth of CuFe1−Ga O2 by the optical floating-zone method

Song, Jiangluqi; Wu, Jie; Rao, Xin; Li, S.J.; Zhao, Zhuan; Liu, X.G.; Zhao, Xinguo; Sun, Xiaofeng

doi:10.1016/j.jcrysgro.2016.04.046

Cited by 11 publications

(5 citation statements)

References 32 publications

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“…If stoichiometric source material would be used, the peritectic Cu 2 O–Fe 2 O 3 phase diagram (Figure a in ref. []) reveals that the liquidus temperature is about 1400 °C, and due to the increase of the stability range with temperature, Fe 2 O 3 is favored to crystalize. CuFeO 2 melts incongruently, but the growth window is larger than in the case of CuAlO 2 (Figure in ref.…”

Section: Resultsmentioning

confidence: 99%

“…Fe 2 O 3 addition acts as a sintering agent and improves the conductivity for x < 0.2 by increasing the grain size . The only paper known to us with the aim to grow bulk ternary delafossites was the systematic study on OFZ growth of CuFe 1–x Ga x O 2 in Ar flow under normal pressure and with a pulling rate of 0.5 mm h −1 published by Song et al . The feed and seed rods were rotated at a rate of 15 rpm in opposite directions to homogenize the molten zone.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Investigation of Ternary Delafossite Crystals

Wolff

Klimm

Ganschow

et al. 2019

Crystal Research and Technology

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The ternary phase diagram of copper-iron-aluminium delafossite is established with FactSage calculations to improve the conditions for solution growth and the electrical conductivity of the transparent p-type semiconductor copper-aluminium delafossite by addition of iron oxide. Initial growth experiments with the optical float zone method show that the growth of single crystals with commercially relevant dimensions is not expected in the near future.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamic Investigation of Ternary Delafossite Crystals

Wolff

Klimm

Ganschow

et al. 2019

Crystal Research and Technology

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“…Typically the melting behavior is described to be peritectic, which means that upon heating in addition to melt with different composition some higher melting solid phase is formed. For CuAlO 2 , α-Al 2 O 3 is the higher melting phase, and in some recent publications Fe 2 O 3 is claimed to play this role for CuFeO 2 [25,26]. This assumption is, however, incorrect because Fe 2 O 3 decomposes to Fe 3 O 4 and cannot be treated as a stable component of the system.…”

Section: Discussionmentioning

confidence: 99%

“…The melting points of iron oxides (Fe 2 O 3 decomposes to Fe 3 O 4 , which melts at 1597 • C) are significantly lower than for Al 2 O 3 (T f = 2054 • C [24]), and consequently a larger growth window for CuFeO 2 (R 3m, a = 3.0351 Å, c = 17.166 Å) can be expected. (Some CuO-Fe 2 O 3 phase diagrams [25,26] in the literature neglect the decomposition of Fe 2 O 3 and show the congruent melting point of Fe 3 O 4 instead.) CuFeO 2 is the only delafossite compound, that has already be grown with reasonable quality in diameters up to 5-8 mm by the optical floating zone (OFZ) technique [25,27,28].…”

Section: While Examining the Mineralogical Collection Of The éCole Na...mentioning

confidence: 99%

“…Our prior thermodynamic investigations have shown that growth methods involving crucibles are unsuitable as the aggressive copper melt attacks all crucible materials [22]. In addition to pure CuFeO 2 , CuFe 1−x Ga x O 2 with x ≤ 12% have been grown by Song et al by the OFZ method [26]. For CuCr 1−x Al x O 2 it was shown that solid solution formation with mixed occupancy on the B-site seems to stabilize the delafossite phase thermodynamically [29], but CuFeO 2 with high (≈ 30%) Al 3+ content only grew in polycrystalline form, presumably as a result of severe segregation in the CuFeO 2 -CuAlO 2 solid solution system.…”

Section: While Examining the Mineralogical Collection Of The éCole Na...mentioning

confidence: 99%

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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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