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Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y)

Tuxworth, Andrew J.; Wang, Chun-Hai; Evans, John S.O.

Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) Thumbnail


Authors

Andrew J. Tuxworth

Chun-Hai Wang



Abstract

Rare earth oxyselenides A4O4Se3 (A = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) were synthesised using solid state reactions and three new structure types (β, γ, and δ) were observed. A4O4Se3 materials adopt either the α (A = Nd, Sm), β (A = Eu), γ (A = Gd, Tb) or δ (A = Dy, Ho, Er, Yb, Y) structure depending on the rare earth radius. Each structure type contains alternating [A2O2]2+ and Se2−/Se22− layers. Different ordered and disordered arrangements of Se2− and [Se–Se]2− give the Se layer flexibility and lead to the four different structure types observed. The volume coefficients of expansion for A4O4Se3 ranged from +1.746(9) × 10−5 to +2.237(3) × 10−5 K−1 from 12 to 300 K; no structural phase transitions were observed in this temperature range. Diffuse reflection spectra show A4O4Se3 are semiconductors with band gap Eg 1.02–1.46 eV. Gd4O4Se3, Dy4O4Se3, and Tb4O4Se3 samples show antiferromagnetic ordering with Néel temperature, TN, of 7–9 K. DFT calculations confirm the two different valence states of Se2− and Se22− in Eu4O4Se3.

Citation

Tuxworth, A. J., Wang, C., & Evans, J. S. (2015). Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y). Dalton Transactions, 44(7), 3009-3019. https://doi.org/10.1039/c4dt03336a

Journal Article Type Article
Publication Date Feb 21, 2015
Deposit Date May 4, 2015
Publicly Available Date May 6, 2015
Journal Dalton Transactions
Print ISSN 1477-9226
Electronic ISSN 1477-9234
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 44
Issue 7
Pages 3009-3019
DOI https://doi.org/10.1039/c4dt03336a

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