. (2015) 'Innitely adaptive transition metal oxychalcogenides : the modulated structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2.', Chemistry of materials., 27 (8). pp. 3121-3134. Further information on publisher's website:http://dx.doi.org/10.1021/acs.chemmater.5b00666 Publisher's copyright statement: This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Chemistry of Materials, copyright c 2015 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acs.chemmater.5b00666. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 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(α0 cm -1 at room temperature and an activation energy for charge carrier mobility from RT to 170 °C of ~0.4 eV. INTRODUCTIONInorganic materials built from the stacking of well-defined sublayers form a large, diverse and technologically important family. Exploitable behaviour exhibited by such layered systems includes high-temperature superconductivity,

. (2016) '3D transition metal ordering and Rietveld stacking fault quantication in the new oxychalcogenides La2O2Cu24xCd2xSe2.', Chemistry of materials., 28 (9). pp. 3184-3195. Further information on publisher's website:http://dx.doi.org/10.1021/acs.chemmater.6b00924 Publisher's copyright statement: This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Chemistry of Materials, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acs.chemmater.6b00924].Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 1+ and Cd 2+ ions segregate into distinct fully occupied and half occupied checkerboard-like layers respectively, leading to complex long-range superstructures in the 3rd (stacking) dimension. To understand the structure and microstructure of these new materials we have developed and implemented a new methodology for studying low and high probability stacking faults using a Rietveldcompatible supercell approach capable of analyzing systems with thousands of layers. We believe this method will be widely applicable.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT: The quaternary transition metal oxyselenide Ce 2 O 2 ZnSe 2 has been shown to adopt a ZrCuSiAs-related structure with Zn 2+ cations in a new ordered arrangement within the [ZnSe 2 ] 2-layers. The color of the compound changes as a function of cell volume, which can vary by ~0.4%. under different synthetic conditions. At the highest, intermediate and lowest cell volumes the color is yellow-ochre, brown and black respectively. The volume decrease is attributed to oxidation of the Ce from +3 to +4, the extent of which can be controlled by the synthetic conditions. Ce 2 O 2 ZnSe 2 is a semiconductor at all cell volumes with experimental optical band gaps of 2.2, 1.4 and 1.3 eV for high, intermediate and low cell volume samples respectively. SQUID measurements show Ce 2 O 2 ZnSe 2 to be paramagnetic from 2-300 K with a negative Weiss temperature of θ = -10 K suggesting weak antiferromagnetic interactions.

A number of Ln2O2MSe2 (Ln = La and Ce; M = Fe, Zn, Mn, and Cd) compounds, built from alternating layers of fluorite-like [Ln2O2](2+) sheets and antifluorite-like [MSe2](2-) sheets, have recently been reported in the literatures. The available MSe4/2 tetrahedral sites are half-occupied, and different compositions display different ordering patterns: [MSe2](2-) layers contain MSe4/2 tetrahedra that are exclusively edge-sharing (stripe-like), exclusively corner-sharing (checkerboard-like), or mixtures of both. This paper reports 60 new compositions in this family. We reveal that the transition-metal arrangement can be systematically controlled by either Ln or M doping, leading to an "infinitely adaptive" structural family. We show how this is achieved in La2O2Fe1-xZnxSe2, La2O2Zn1-xMnxSe2, La2O2Mn1-xCdxSe2, Ce2O2Fe1-xZnxSe2, Ce2O2Zn1-xMnxSe2, Ce2O2Mn1-xCdxSe2, La2-yCeyO2FeSe2, La2-yCeyO2ZnSe2, La2-yCeyO2MnSe2, and La2-yCeyO2CdSe2 solid solutions.

Polycrystalline samples of La2O2Cu2‐4xCd2xSe2 (x = 0—0.5) are prepared by solid state reaction of La2O3 and the elements in the presence of Al powder as O2 getter (Al2O3 crucible in evacuated silica tubes, 1100 °C, 12 h).