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Tuxworth AJ, Wang CH, Evans JS. Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y). Dalton Trans. 2015;44(7):3009-19doi: 10.1039/c4dt03336a.
Tuxworth, A. J., Wang, C. H., & 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 (Cambridge, England : 2003), 44(7), 3009-19. https://doi.org/10.1039/c4dt03336a
Tuxworth, Andrew J, et al. "Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y)." Dalton transactions (Cambridge, England : 2003) vol. 44,7 (2015): 3009-19. doi: https://doi.org/10.1039/c4dt03336a
Tuxworth AJ, Wang CH, Evans JS. Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y). Dalton Trans. 2015 Feb 21;44(7):3009-19. doi: 10.1039/c4dt03336a. PMID: 25581725.
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Dalton Trans. 2015 Feb 21;44(7):3009-19. doi: 10.1039/c4dt03336a.

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

Dalton transactions (Cambridge, England : 2003)

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

Affiliations

  1. Department of Chemistry, University Science Site, Durham University, South Road, Durham, DH1 3LE, UK. [email protected].

PMID: 25581725 DOI: 10.1039/c4dt03336a

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 Se(2-)/Se2(2-) layers. Different ordered and disordered arrangements of Se(2-) 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 Se(2-) and Se2(2-) in Eu4O4Se3.

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