. (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).

Infinitely Adaptive Transition-Metal Ordering in Ln 2O2MSe2-Type Oxychalcogenides. -A range of Ln 2O2 Se2 and La2-yCeyO2M 1 Se2 (Ln: La, Ce, M 1 /M 2 : Fe, Zn, Mn, Cd) solid solutions are prepared (60 new compositions) to investigate the effects of systematically changing the relative sizes of [Ln 2O2] 2+ and [MSe2] 2layers on transition metal ordering by powder X-ray and neutron diffraction. Transition metal ordering is determined by the relative sizes of the [Ln 2O2] 2+ and [MSe2] 2layers and can be exquisitely tuned by substitution in either layer. The two extremes of transition metal ordering contain MSe 4/2 tetrahedra that are exclusively edge-sharing (stripe-like) or exclusively corner-sharing (checkerboard-like). Ce 2O2Fe3/4Zn1/4Se2 and Ce 2O2Zn1/6Mn5/6Se2 crystallize in the orthorhombic space group Bmab with Z = 16 and Z = 24, respectively. Ce 2O2Fe1/8Zn7/8Se2 and La2O2Zn1/10Mn9/10Se2 crystallize in the orthorhombic space group Imcb with Z = 20. Ce 2O2CdSe2 crystallizes in the tetragonal space group P4 2/nmc with Z = 2. -(AINSWORTH, C. M.; WANG, C.-H.; JOHNSTON, H. E.; MCCABE, E. E.; TUCKER, M. G.; BRAND, H. E. A.; EVANS*, J. S. O.; Inorg. Chem. 54 (2015) 15, 7230-7238, http://dx.doi.org/10.1021/acs.inorgchem.5b00599 ; Dep. Chem., Univ. Durham, Durham DH1 3LE, UK; Eng.) -W. Pewestorf 41-002 M 1 1-x M 2 x

Publisher's copyright statement:Reprinted with permission from the American Physical Society: Wang, Chun-Hai, Ainsworth, C. M., Champion, S. D., Stewart, G. A., Worsdale, M. C., Lancaster, T., Blundell, S. J., Brand, Helen E. A. Evans, John S. O. (2017). Crystal structure and magnetic modulation in Ce2O2FeSe2. Physical Review Materials 1(3): 034403 c 2017 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modi ed, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.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-pro t 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. We report a combination of x-ray and neutron diffraction studies, Mössbauer spectroscopy, and muon spin relaxation (μ + SR) measurements to probe the structure and magnetic properties of the semiconducting β-Ce 2 O 2 FeSe 2 oxychalcogenide. We report a structural description in space group P na2 1 which is consistent with diffraction data and second harmonic generation measurements and reveal an order-disorder transition on one Fe site at T OD ≈ 330 K. Susceptibility measurements, Mössbauer, and μ + SR reveal antiferromagnetic ordering below T N = 86 K and more complex short range order above this temperature. 12 K neutron diffraction data reveal a modulated magnetic structure with q = 0.444b N * .

The title compound is prepared from powder mixtures of CeO2, Zn, and Se in a 1:2:1 ratio in an alumina crucible using Al placed in a different crucible as oxygen getter (1100—1225 °C, 1—24 h).