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Professor John Evans' Outputs (104)

Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor (2019)
Journal Article
Metcalfe, I. S., Ray, B., Dejoie, C., Hu, W., de Leeuwe, C., Dueso, C., García-García, F. R., Mak, C.-M., Papaioannou, E. I., Thompson, C. R., & Evans, J. S. (2019). Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor. Nature Chemistry, 11, 638-643. https://doi.org/10.1038/s41557-019-0273-2

All real processes, be they chemical, mechanical or electrical, are thermodynamically irreversible and therefore suffer from thermodynamic losses. Here, we report the design and operation of a chemical reactor capable of approaching thermodynamically... Read More about Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor.

Origin of skyrmion lattice phase splitting in Zn-substituted Cu2OSeO3 (2018)
Journal Article
Štefančič, A., Moody, S., Hicken, T., Birch, M., Balakrishnan, G., Barnett, S., Crisanti, M., Evans, J., Holt, S., Franke, K., Hatton, P., Huddart, B., Lees, M., Pratt, F., Tang, C., Wilson, M., Xiao, F., & Lancaster, T. (2018). Origin of skyrmion lattice phase splitting in Zn-substituted Cu2OSeO3. Physical Review Materials, 2(11), Article 111402(R). https://doi.org/10.1103/physrevmaterials.2.111402

We present an investigation into the structural and magnetic properties of Zn-substituted Cu2OSeO3, a system in which the skyrmion lattice (SkL) phase in the magnetic field–temperature phase diagram was previously seen to split as a function of incre... Read More about Origin of skyrmion lattice phase splitting in Zn-substituted Cu2OSeO3.

Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis (2018)
Journal Article
Liu, H., Zhang, W., Halasyamani, P. S., Stokes, H. T., Campbell, B. J., Evans, J. S. O., & Evans, I. R. (2018). Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis. Journal of the American Chemical Society, 140(41), 13441-13448. https://doi.org/10.1021/jacs.8b08591

The exploitable properties of many functional materials are intimately linked with symmetry-changing phase transitions. These include properties such as ferroelectricity, second harmonic generation, conductivity, magnetism and many others. We describ... Read More about Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis.

Phase behaviour, thermal expansion and compressibility of SnMo 2 O 8 (2017)
Journal Article
Araujo, L. R., Gallington, L. C., Wilkinson, A. P., & Evans, J. S. (2018). Phase behaviour, thermal expansion and compressibility of SnMo 2 O 8. Journal of Solid State Chemistry, 258, 885-893. https://doi.org/10.1016/j.jssc.2017.08.040

The phase behaviour and thermoelastic properties of SnMo2O8, derived from variable temperature and pressure synchrotron powder diffraction data, are reported. SnMo2O8 is a member of the AM2O8 family of negative thermal expansion (NTE) materials, but... Read More about Phase behaviour, thermal expansion and compressibility of SnMo 2 O 8.

Crystal field excitations and magnons: Their roles in oxyselenides Pr2O2M2OSe2 (M = Mn, Fe) (2017)
Journal Article
Oogarah, R., Stockdale, C., Stock, C., Evans, J., Wills, A., Taylor, J., & McCabe, E. (2017). Crystal field excitations and magnons: Their roles in oxyselenides Pr2O2M2OSe2 (M = Mn, Fe). Physical Review B, 95(17), Article 174441. https://doi.org/10.1103/physrevb.95.174441

We present the results of neutron scattering experiments to study the crystal and magnetic structures of the Mott-insulating transition metal oxyselenides Pr2O2M2OSe2 (M = Mn, Fe). The structural role of the non-Kramers Pr3+ ion was investigated, and... Read More about Crystal field excitations and magnons: Their roles in oxyselenides Pr2O2M2OSe2 (M = Mn, Fe).

Averaging the intensity of many-layered structures for accurate stacking-fault analysis using Rietveld refinement (2016)
Journal Article
Coelho, A., Evans, J., & Lewis, J. (2016). Averaging the intensity of many-layered structures for accurate stacking-fault analysis using Rietveld refinement. Journal of Applied Crystallography, 49(5), 1740-1749. https://doi.org/10.1107/s1600576716013066

Many technologically important synthetic and natural materials display stacking faults which lead to complex peak broadenings, asymmetries and shifts in their powder diffraction patterns. The patterns can be described using an enlarged unit cell (cal... Read More about Averaging the intensity of many-layered structures for accurate stacking-fault analysis using Rietveld refinement.

Microstructures of negative and positive azeotropes (2016)
Journal Article
Shephard, J., Callear, S., Imberti, S., Evans, J., & Salzmann, C. (2016). Microstructures of negative and positive azeotropes. Physical Chemistry Chemical Physics, 18(28), 19227-19235. https://doi.org/10.1039/c6cp02450e

Azeotropes famously impose fundamental restrictions on distillation processes, yet their special thermodynamic properties make them highly desirable for a diverse range of industrial and technological applications. Using neutron diffraction, we inves... Read More about Microstructures of negative and positive azeotropes.

An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7 (2016)
Journal Article
Lewis, J. W., Payne, J. L., Evans, I. R., Stokes, H. T., Campbell, B. J., & Evans, J. S. (2016). An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7. Journal of the American Chemical Society, 138(25), 8031-8042. https://doi.org/10.1021/jacs.6b04947

The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring and solving such structures which will be w... Read More about An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7.

3D Transition Metal Ordering and Rietveld Stacking Fault Quantification in the New Oxychalcogenides La2O2Cu2–4xCd2xSe2 (2016)
Journal Article
Ainsworth, C., Lewis, J., Wang, C., Coelho, A., Johnson, H., Brand, H., & Evans, J. (2016). 3D Transition Metal Ordering and Rietveld Stacking Fault Quantification in the New Oxychalcogenides La2O2Cu2–4xCd2xSe2. Chemistry of Materials, 28(9), 3184-3195. https://doi.org/10.1021/acs.chemmater.6b00924

A number of LnOCuCh (Ln = La–Nd, Bi; Ch = S, Se, Te) compounds have been reported in the literature built from alternating layers of fluorite-like [Ln2O2]2+ sheets and antifluorite-like [M2Se2]2– sheets, where M is in the +1 oxidation state leading t... Read More about 3D Transition Metal Ordering and Rietveld Stacking Fault Quantification in the New Oxychalcogenides La2O2Cu2–4xCd2xSe2.

Infinitely Adaptive Transition-Metal Ordering in Ln2O2MSe2-Type Oxychalcogenides (2015)
Journal Article
Ainsworth, C. M., Wang, C., Johnston, H. E., McCabe, E. E., Tucker, M. G., Brand, H. E., & Evans, J. S. (2015). Infinitely Adaptive Transition-Metal Ordering in Ln2O2MSe2-Type Oxychalcogenides. Inorganic Chemistry, 54(15), 7230-7238. https://doi.org/10.1021/acs.inorgchem.5b00599

The origin of transition-metal ordering in Ln2O2MSe2 oxychalcogenides has been revealed by investigating a range of solid solutions. Transition-metal ordering is determined by the relative sizes of [Ln2O2]2+ and [MSe2]2− layers and can be exquisitely... Read More about Infinitely Adaptive Transition-Metal Ordering in Ln2O2MSe2-Type Oxychalcogenides.

Infinitely Adaptive Transition Metal Oxychalcogenides: The Modulated Structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2 (2015)
Journal Article
Wang, C., Ainsworth, C. M., Gui, D., McCabe, E. E., Tucker, M. G., Evans, I. R., & Evans, J. S. (2015). Infinitely Adaptive Transition Metal Oxychalcogenides: The Modulated Structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2. Chemistry of Materials, 27(8), 3121-3134. https://doi.org/10.1021/acs.chemmater.5b00666

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... Read More about Infinitely Adaptive Transition Metal Oxychalcogenides: The Modulated Structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2.

Polar stacking of molecules in liquid chloroform (2015)
Journal Article
Shephard, J., Soper, A., Callear, S., Imberti, S., Evans, J., & Salzmann, C. (2015). Polar stacking of molecules in liquid chloroform. Chemical Communications, 51(23), 4770-4773. https://doi.org/10.1039/c4cc09235j

Using neutron diffraction and the isotopic substitution technique we have investigated the local structure of liquid chloroform. A strong tendency for polar stacking of molecules with collinear alignment of dipole moments is found. We speculate that... Read More about Polar stacking of molecules in liquid chloroform.

Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) (2015)
Journal Article
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

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

Synthesis, Structural Characterization, and Physical Properties of the New Transition Metal Oxyselenide Ce2O2ZnSe2 (2015)
Journal Article
Ainsworth, C. M., Wang, C., Tucker, M. G., & Evans, J. S. (2015). Synthesis, Structural Characterization, and Physical Properties of the New Transition Metal Oxyselenide Ce2O2ZnSe2. Inorganic Chemistry, 54(4), 1563-1571. https://doi.org/10.1021/ic502551n

We report the synthesis and characterization of the new oxyselenide Ce2O2ZnSe2, which contains fluorite-like [Ce2O2]2+ layers of Ce4O tetrahedra (red) alternating with anti-fluorite-like [ZnSe2]2− layers (blue). The Zn ordering pattern in the selenid... Read More about Synthesis, Structural Characterization, and Physical Properties of the New Transition Metal Oxyselenide Ce2O2ZnSe2.

Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure (2015)
Journal Article
Nunes, S. E., Wang, C.-H., So, K., Evans, J. S., & Evans, I. R. (2015). Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure. Journal of Solid State Chemistry, 222, 12-17. https://doi.org/10.1016/j.jssc.2014.10.036

We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn2VO6, known for its visible light photocatalytic activity. The crystal structure has been solved from laborator... Read More about Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure.

Magnetism of the Fe2+ and Ce3+ sublattices in Ce2O2FeSe2: A combined neutron powder diffraction, inelastic neutron scattering, and density functional study (2014)
Journal Article
McCabe, E., Stock, C., Bettis Jr., J., Whangbo, M., & Evans, J. (2014). Magnetism of the Fe2+ and Ce3+ sublattices in Ce2O2FeSe2: A combined neutron powder diffraction, inelastic neutron scattering, and density functional study. Physical review B, 90(23), Article 235115. https://doi.org/10.1103/physrevb.90.235115

The discovery of superconductivity in the 122 iron selenide materials above 30 K necessitates an understanding of the underlying magnetic interactions. We present a combined experimental and theoretical investigation of magnetic and semiconducting Ce... Read More about Magnetism of the Fe2+ and Ce3+ sublattices in Ce2O2FeSe2: A combined neutron powder diffraction, inelastic neutron scattering, and density functional study.

Structural and magnetic characterization of iron oxyselenides Ce2O2Fe2OSe2 and Nd2O2Fe2OSe2 (2014)
Journal Article
McCabe, E., Wills, A., Chapon, L., Manuel, P., & Evans, J. (2014). Structural and magnetic characterization of iron oxyselenides Ce2O2Fe2OSe2 and Nd2O2Fe2OSe2. Physical review B, 90(16), Article 165111. https://doi.org/10.1103/physrevb.90.165111

We present here an investigation of the magnetic ordering in the Mott insulating oxyselenide materials Ln2O2Fe2OSe2 (Ln=Ce, Nd). Neutron powder diffraction data are consistent with a noncollinear multi-k ordering on the iron sublattice structure and... Read More about Structural and magnetic characterization of iron oxyselenides Ce2O2Fe2OSe2 and Nd2O2Fe2OSe2.

Weak spin interactions in Mott insulating La2O2Fe2OSe2 (2014)
Journal Article
McCabe, E., Stock, C., Rodriguez, E., Wills, A., Taylor, J., & Evans, J. (2014). Weak spin interactions in Mott insulating La2O2Fe2OSe2. Physical review B, 89(10), Article 100402(R). https://doi.org/10.1103/physrevb.89.100402

Identifying and characterizing the parent phases of iron-based superconductors is an important step towards understanding the mechanism for their high-temperature superconductivity. We present an investigation into the magnetic interactions in the Mo... Read More about Weak spin interactions in Mott insulating La2O2Fe2OSe2.