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Jiang B, Neu J, Olds D, Kimber SAJ, Page K, Siegrist T. The curious case of the structural phase transition in SnSe insights from neutron total scattering. Nat Commun 2023; 14:3211. [PMID: 37270591 DOI: 10.1038/s41467-023-38454-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 04/28/2023] [Indexed: 06/05/2023] Open
Abstract
At elevated temperatures SnSe is reported to undergo a structural transition from the low symmetry orthorhombic GeS-type to a higher symmetry orthorhombic TlI-type. Although increasing symmetry should likewise increase lattice thermal conductivity, many experiments on single crystals and polycrystalline materials indicate that this is not the case. Here we present temperature dependent analysis of time-of-flight (TOF) neutron total scattering data in combination with theoretical modeling to probe the local to long-range evolution of the structure. We report that while SnSe is well characterized on average within the high symmetry space group above the transition, over length scales of a few unit cells SnSe remains better characterized in the low symmetry GeS-type space group. Our finding from robust modeling provides further insight into the curious case of a dynamic order-disorder phase transition in SnSe, a model consistent with the soft-phonon picture of the high thermoelectric power above the phase transition.
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Affiliation(s)
- Bo Jiang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- Materials Science and Engineering Department, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jennifer Neu
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
- Dept. of Physics 77 Chieftain Way, Florida State University, Tallahassee, FL, 32306-4350, USA
- Dept. of Chemistry & Biochemistry 95 Chieftain Way 118 DLC, Florida State University, Tallahassee, FL, 32306-4390, USA
- Oak Ridge National Laboratory, Nuclear Nonproliferation Division, Oak Ridge, TN, 37831, USA
| | - Daniel Olds
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA
| | - Simon A J Kimber
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, F-21078, Dijon Cedex, France
| | - Katharine Page
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
- Materials Science and Engineering Department, University of Tennessee, Knoxville, TN, 37996, USA.
| | - Theo Siegrist
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL, 32310-6046, USA.
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Bird TA, Herlihy A, Senn MS. Symmetry-adapted pair distribution function analysis (SAPA): a novel approach to evaluating lattice dynamics and local distortions from total scattering data. J Appl Crystallogr 2021; 54:1514-1520. [PMID: 34667453 PMCID: PMC8493621 DOI: 10.1107/s1600576721008499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/15/2021] [Indexed: 11/22/2022] Open
Abstract
A novel symmetry-adapted pair distribution function analysis (SAPA) method for extracting information on local distortions from pair distribution function data is introduced. The implementation of SAPA is demonstrated in the TOPAS-Academic software using the freely available online software ISODISTORT, and scripts for converting the output from ISODISTORT to a SAPA input file for TOPAS are provided. Finally, two examples are provided to show how SAPA can evaluate the nature of both dynamic distortions in ScF3 and the distortions which act as an order parameter for the phase transitions in BaTiO3.
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Affiliation(s)
- Tobias A. Bird
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
| | - Anna Herlihy
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
- ISIS, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Mark S. Senn
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
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Huq A, Kirkham M, Peterson PF, Hodges JP, Whitfield PS, Page K, Hűgle T, Iverson EB, Parizzi A, Rennich G. POWGEN: rebuild of a third-generation powder diffractometer at the Spallation Neutron Source. J Appl Crystallogr 2019; 52:1189-1201. [PMID: 31636522 PMCID: PMC6782079 DOI: 10.1107/s160057671901121x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 08/11/2019] [Indexed: 11/25/2022] Open
Abstract
This work describes the design principles and upgrade of the neutron powder diffractometer POWGEN at the Spallation Neutron Source. The neutron powder diffractometer POWGEN at the Spallation Neutron Source has recently (2017–2018) undergone an upgrade which resulted in an increased detector complement along with a full overhaul of the structural design of the instrument. The current instrument has a solid angular coverage of 1.2 steradians and maintains the original third-generation concept, providing a single-histogram data set over a wide d-spacing range and high resolution to access large unit cells, detailed structural refinements and in situ/operando measurements.
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Affiliation(s)
- Ashfia Huq
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Melanie Kirkham
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Peter F Peterson
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Jason P Hodges
- Neutron Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Pamela S Whitfield
- Excelsus Structural Solutions, Park Innovaare, 5234 Villigen, Switzerland
| | - Katharine Page
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Thomas Hűgle
- Neutron Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Erik B Iverson
- Neutron Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - Andre Parizzi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
| | - George Rennich
- Neutron Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475, USA
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Peterson PF, Olds D, Savici AT, Zhou W. Advances in utilizing event based data structures for neutron scattering experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:093001. [PMID: 30278744 DOI: 10.1063/1.5034782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
This article strives to expand on existing work to demonstrate advancements in data processing made available using event mode measurements. Most spallation neutron sources in the world have data acquisition systems that provide event recording. The new science that is enabled by utilizing event mode has only begun to be explored. In the past, these studies were difficult to perform because histograms forced dealing with either large chunks of time or a large number of files. With event based data collection, data can be explored and rebinned long after the measurement has completed. This article will review some of the principles of event data and how the method opens up new possibilities for in situ measurements, highlighting techniques that can be used to explore changes in the data. We also demonstrate the statistical basis for determining data quality and address the challenge of determining how long to measure mid-measurement. Finally, we demonstrate a model independent method of grouping data via hierarchical clustering methods that can be used to improve calibration, reduction, and data exploration.
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Affiliation(s)
- Peter F Peterson
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Daniel Olds
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Andrei T Savici
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Wenduo Zhou
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Olds D, Peterson PF, Crawford MK, Neilson JR, Wang HW, Whitfield PS, Page K. Combinatorial appraisal of transition states forin situpair distribution function analysis. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717015163] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
In situtotal scattering measurements are increasingly utilized to follow atomic and nanoscale structural details of phase transitions and other transient processes in materials. This contribution presents an automated method and associated tool set to analyze series of diffraction and pair distribution function data with a linear combination of end-member states. It is demonstrated that the combinatorial appraisal of transition states (CATS) software tracks phase changes, relative phase fractions and length scales of interest in experimental data series. It is further demonstrated, using a series of local structure data simulations, that the misfit of such a model can reveal details of phase aggregation and growth related to the pair distribution function's sensitivity to interphase correlations. CATS may be applied to quantitative evaluation of many transient processes, including amorphous-to-crystalline phase transitions, the evolution of solid-solution behaviors, the precipitation and growth of aggregates, and other atomic to nanoscale details of crystallization and phase transformation phenomena.
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Senn MS, Keen DA, Lucas TCA, Hriljac JA, Goodwin AL. Emergence of Long-Range Order in BaTiO_{3} from Local Symmetry-Breaking Distortions. PHYSICAL REVIEW LETTERS 2016; 116:207602. [PMID: 27258883 DOI: 10.1103/physrevlett.116.207602] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 06/05/2023]
Abstract
By using a symmetry motivated basis to evaluate local distortions against pair distribution function data, we show without prior bias, that the off-center Ti displacements in the archetypal ferroelectric BaTiO_{3} are zone centered and rhombohedral-like across its known ferroelectric and paraelectric phases. We construct a simple Monte Carlo model that captures our main experimental findings and demonstrate how the rich crystallographic phase diagram of BaTiO_{3} emerges from correlations of local symmetry-breaking distortions alone. Our results strongly support the order-disorder picture for these phase transitions, but can also be reconciled with the soft-mode theory of BaTiO_{3} that is supported by some spectroscopic techniques.
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Affiliation(s)
- M S Senn
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - D A Keen
- ISIS, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - T C A Lucas
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - J A Hriljac
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - A L Goodwin
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
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