We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

Infinitely adaptive transition metal oxychalcogenides : the modulated structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2.

Wang, Chun-Hai and Ainsworth, Chris M. and Gui, Dong-Yun and McCabe, Emma E. and Tucker, Matthew G. and Evans, Ivana R. and Evans, John S. O. (2015) 'Infinitely adaptive transition metal oxychalcogenides : the modulated structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2.', Chemistry of materials., 27 (8). pp. 3121-3134.


This article reports the syntheses, structures, and physical properties of the oxychalcogenides (Ce1–xLax)2O2MnSe2 with x = 0–0.7. These materials have a layered structure related to that of the LaOFeAs-derived superconductors but with the transition metal sites 50% occupied. Ce2O2MnSe2 contains alternating layers of composition: [Ce2O2]2+ and [MnSe2]2–. The size mismatch between the layers leads to an incommensurate structure with a modulation vector of q = αa*+ 0b*+0.5c* with α = 0.158(1), which can be described with a (3 + 1)D superspace structural model in superspace group Cmme(α,0,1/2)0s0 [67.12]. There is a strong modulation of Mn site occupancies, leading to a mixture of corner- and edge-sharing MnSe4/2 tetrahedra in the [MnSe2]2– layers. The modulation vector can be controlled by partial substitution of Ce3+ for larger La3+, and a simple commensurate case was obtained for (Ce0.78La0.22)2O2MnSe2 with α = 1/6. The materials respond to the change in relative size of the oxide and chalcogenide blocks by varying the ratio of corner- to edge-sharing tetrahedra. The superspace model lets us unify the structural description of the five different ordering patterns reported to date for different Ln2O2MSe2 (Ln = lanthanide) materials. Mn moments in Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2 order antiferromagnetically below TN = 150 K, and Ce moments order below ∼70 K. The magnetic structures of both materials have been determined using neutron diffraction. Both materials are semiconductors; Ce2O2MnSe2 has σ = 9 × 10–6 Ω–1 cm–1 at room temperature and an activation energy for charge carrier mobility from RT to 170 °C of ∼0.4 eV.

Item Type:Article
Full text:(AM) Accepted Manuscript
Download PDF
Publisher Web site:
Publisher statement:This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, copyright © 2015 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
Date accepted:No date available
Date deposited:06 May 2015
Date of first online publication:02 April 2015
Date first made open access:10 April 2016

Save or Share this output

Look up in GoogleScholar