Rare earth radii in the iron garnets

Geller, S.; Mitchell, Dale W.

doi:10.1107/s0365110x59002602

Cited by 23 publications

(16 citation statements)

References 2 publications

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“…400 Most notably, however, AgBiS 2 has seen a massive stride in photovoltaic efficiency very recently, much more so than its copper analogues. Also unlike CuBiS 2 , nanocrystalline-and high temperature bulk-AgBiS 2 occupies a 3D cubic disordered rocksalt structure, 401,402 which has seen previous interest due to its high temperature order-disorder transition and its effect on thermoelectric behaviour. 403,404 While the bulk has been recorded to have an optical band gap of 0.9 eV, 405 strong quantum confinement effects have meant that quantum dot thin-films have band gaps reported at 1.0-1.3 eV, although with one study reporting 2.67 eV; that study also reports a very strong absorption coefficient above 10 5 for low frequencies.…”

Section: Noble Metal Bismuth Chalcogenides and Halidesmentioning

confidence: 99%

Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

2017

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The field of photovoltaics is undergoing a surge of interest following the recent discovery of the lead hybrid perovskites as a remarkably efficient class of solar absorber. Of these, methylammonium lead iodide (MAPI) has garnered significant attention due to its record breaking efficiencies, however, there are growing concerns surrounding its long-term stability. Many of the excellent properties seen in hybrid perovskites are thought to derive from the 6s electronic configuration of lead, a configuration seen in a range of post-transition metal compounds. In this review we look beyond MAPI to other ns solar absorbers, with the aim of identifying those materials likely to achieve high efficiencies. The ideal properties essential to produce highly efficient solar cells are discussed and used as a framework to assess the broad range of compounds this field encompasses. Bringing together the lessons learned from this wide-ranging collection of materials will be essential as attention turns toward producing the next generation of solar absorbers.

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Section: Noble Metal Bismuth Chalcogenides and Halidesmentioning

confidence: 99%

Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

2017

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“…In AgSbTe 2 , on the other hand, Ag and Sb are randomly disordered. The extremely low thermal conductivity of LiPbSb 3 S 6 appears to be similar in origin to AgSbTe 2 and likely results from the inherent Li/Sb and Li/Pb disorder in the metal sites of the structure. ,, …”

mentioning

confidence: 92%

LiPbSb₃S₆: A Semiconducting Sulfosalt with Very Low Thermal Conductivity

Agha

Malliakas

et al. 2014

Inorg. Chem.

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The new semiconductor LiPbSb3S6 crystallizes in the space group P21/c. The structure is a member of the lillianite homologous series and is composed of layers of PbS archetype Sb/Li-S separated by trigonal-prismatic-coordinated Pb/Li. Electronic band structure calculations indicate an indirect band gap, with direct gaps lying very close in energy. LiPbSb3S6 has one of the lowest thermal conductivities seen in a crystalline material, ∼0.24 W m(-1) K(-1) at room temperature, and a high resistivity, ∼4 × 10(9) Ω·cm, and exhibits strong light absorption with a nearly direct band gap of 1.6 eV.

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“…AgBiS 2 , a member of the I−V−VI 2 family, is a polymorphic semiconductor and shows structural phase transition as a function of the temperature. 22,28 In the bulk phase, AgBiS 2 crystallizes in a trigonal crystal structure (space group, P3̅ m1) at room temperature, which transforms to a cation disordered rock salt structure (space group, Fm3̅ m) at ∼473 K. 22,28 Previously, we demonstrated that the high-temperature cubic phase of AgBiS 2 was stabilized in the form of nanocrystals with ordered structure at room temperature by the solution-based kinetically controlled synthesis. 22 We observed the existence of an unforeseen order−disorder transition with an anomalous change in thermopower at ∼610 K in these nanocrystals.…”

Section: ■ Introductionmentioning

confidence: 99%

Origin of the Order–Disorder Transition and the Associated Anomalous Change of Thermopower in AgBiS₂ Nanocrystals: A Combined Experimental and Theoretical Study

Guin¹,

Banerjee²,

Sanyal

et al. 2016

Inorg. Chem.

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Bulk AgBiS2 crystallizes in a trigonal crystal structure (space group, P3̅m1) at room temperature, which transforms to a cation disordered rock salt structure (space group, Fm3̅m) at ∼473 K. Surprisingly, at room temperature, a solution-grown nanocrystal of AgBiS2 crystallizes in a metastable Ag/Bi ordered cubic structure, which transforms to a thermodynamically stable disorded cubic structure at 610 K. Moreover, the order-disorder transition in nanocrystalline AgBiS2 is associated with an unusual change in thermopower. Here, we shed light on the origin of a order-disorder phase transition and the associated anomalous change of thermopower in AgBiS2 nanocrystals by using a combined experimental, density functional theory based first-principles calculation and ab initio molecular dynamics simulations. Positron-annilation spectroscopy indicates the presence of higher numbers of Ag vacancies in the nanocrystal compared to that of the bulk cubic counterpart at room temperature. Furthermore, temperature-dependent two-detector coincidence Doppler broadening spectroscopy and Doppler broadening of the annihilation radiation (S parameter) indicate that the Ag vacancy concentration increases abruptly during the order-disorder transition in nanocrystalline AgBiS2. At high temperature, a Ag atom shuttles between the vacancy and interstitial sites to form a locally disordered cation sublattice in the nanocrystal, which is facilitated by the formation of more Ag vacancies during the phase transition. This process increases the entropy of the system at higher vacancy concentration, which, in turn, results in the unusual rise in thermopower.

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Rare earth radii in the iron garnets

Cited by 23 publications

References 2 publications

Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

LiPbSb₃S₆: A Semiconducting Sulfosalt with Very Low Thermal Conductivity

Origin of the Order–Disorder Transition and the Associated Anomalous Change of Thermopower in AgBiS₂ Nanocrystals: A Combined Experimental and Theoretical Study

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Rare earth radii in the iron garnets

Cited by 23 publications

References 2 publications

Beyond methylammonium lead iodide: prospects for the emergent field of ns2containing solar absorbers

Beyond methylammonium lead iodide: prospects for the emergent field of ns2containing solar absorbers

LiPbSb3S6: A Semiconducting Sulfosalt with Very Low Thermal Conductivity

Origin of the Order–Disorder Transition and the Associated Anomalous Change of Thermopower in AgBiS2 Nanocrystals: A Combined Experimental and Theoretical Study

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Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

Beyond methylammonium lead iodide: prospects for the emergent field of ns²containing solar absorbers

LiPbSb₃S₆: A Semiconducting Sulfosalt with Very Low Thermal Conductivity

Origin of the Order–Disorder Transition and the Associated Anomalous Change of Thermopower in AgBiS₂ Nanocrystals: A Combined Experimental and Theoretical Study