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Ilett M, Freeman HM, Aslam Z, Galloway JM, Klebl DP, Muench SP, McPherson IJ, Cespedes O, Kim Y, Meldrum FC, Yeandel SR, Freeman CL, Harding JH, Brydson RMD. Evaluation of correlated studies using liquid cell‐ and cryo‐transmission electron microscopy: Hydration of calcium sulfate and the phase transformation pathways of bassanite to gypsum. J Microsc 2022; 288:155-168. [PMID: 35348205 PMCID: PMC10084335 DOI: 10.1111/jmi.13102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/10/2022] [Accepted: 03/15/2022] [Indexed: 11/29/2022]
Abstract
Insight into the nucleation, growth and phase transformations of calcium sulphate could improve the performance of construction materials, reduce scaling in industrial processes and aid understanding of its formation in the natural environment. Recent studies have suggested that the calcium sulphate pseudo polymorph, gypsum (CaSO4 ·2H2 O) can form in aqueous solution via a bassanite (CaSO4 ·0.5H2 O) intermediate. Some in situ experimental work has also suggested that the transformation of bassanite to gypsum can occur through an oriented assembly mechanism. In this work, we have exploited liquid cell transmission electron microscopy (LCTEM) to study the transformation of bassanite to gypsum in an undersaturated aqueous solution of calcium sulphate. This was benchmarked against cryogenic TEM (cryo-TEM) studies to validate internally the data obtained from the two microscopy techniques. When coupled with Raman spectroscopy, the real-time data generated by LCTEM, and structural data obtained from cryo-TEM show that bassanite can transform to gypsum via more than one pathway, the predominant one being dissolution/reprecipitation. Comparisons between LCTEM and cryo-TEM also show that the transformation is slower within the confined region of the liquid cell as compared to a bulk solution. This work highlights the important role of a correlated microscopy approach for the study of dynamic processes such as crystallisation from solution if we are to extract true mechanistic understanding.
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Affiliation(s)
- M. Ilett
- The Bragg Centre for Materials Research, School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
| | - H. M. Freeman
- The Bragg Centre for Materials Research, School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
| | - Z. Aslam
- The Bragg Centre for Materials Research, School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
| | - J. M. Galloway
- The Bragg Centre for Materials Research, School of Chemistry University of Leeds Leeds LS2 9JT UK
| | - D. P. Klebl
- The Bragg Centre for Materials Research, School of Biomedical Sciences and Astbury Centre for Structural and Molecular Biology University of Leeds Leeds LS2 9JT UK
| | - S. P. Muench
- The Bragg Centre for Materials Research, School of Biomedical Sciences and Astbury Centre for Structural and Molecular Biology University of Leeds Leeds LS2 9JT UK
| | - I. J. McPherson
- Department of Chemistry University of Warwick Gibbet Hill Coventry CV4 7AL
| | - O. Cespedes
- The Bragg Centre for Materials Research, Department of Physics University of Leeds Leeds LS2 9JT UK
| | - Y‐Y. Kim
- The Bragg Centre for Materials Research, School of Chemistry University of Leeds Leeds LS2 9JT UK
| | - F. C. Meldrum
- The Bragg Centre for Materials Research, School of Chemistry University of Leeds Leeds LS2 9JT UK
| | - S. R. Yeandel
- Department of Materials Science and Engineering University of Sheffield Sheffield S1 3JD
| | - C. L. Freeman
- Department of Materials Science and Engineering University of Sheffield Sheffield S1 3JD
| | - J. H. Harding
- Department of Materials Science and Engineering University of Sheffield Sheffield S1 3JD
| | - R. M. D. Brydson
- The Bragg Centre for Materials Research, School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
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Yeandel SR, Molinari M, Parker SC. Nanostructuring perovskite oxides: the impact of SrTiO3 nanocube 3D self-assembly on thermal conductivity. RSC Adv 2016. [DOI: 10.1039/c6ra23887d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The thermal conductivity of SrTiO3 assembled nanocubes is low and depends on the interface composition to a greater extent compared to the packing arrangement.
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Affiliation(s)
| | - M. Molinari
- Department of Chemistry
- University of Bath
- UK
- Department of Chemistry
- University of Huddersfield
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Srivastava D, Azough F, Freer R, Combe E, Funahashi R, Kepaptsoglou DM, Ramasse QM, Molinari M, Yeandel SR, Baran JD, Parker SC. Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO 3: a combined experimental and computational study. J Mater Chem C Mater 2015; 3:12245-12259. [PMID: 28496979 PMCID: PMC5361175 DOI: 10.1039/c5tc02318a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/30/2015] [Indexed: 06/07/2023]
Abstract
A combination of experimental and computational techniques has been employed to study doping effects in perovskite CaMnO3. High quality Sr-Mo co-substituted CaMnO3 ceramics were prepared by the conventional mixed oxide route. Crystallographic data from X-ray and electron diffraction showed an orthorhombic to tetragonal symmetry change on increasing the Sr content, suggesting that Sr widens the transition temperature in CaMnO3 preventing phase transformation-cracking on cooling after sintering, enabling the fabrication of high density ceramics. Atomically resolved imaging and analysis showed a random distribution of Sr in the A-site of the perovskite structure and revealed a boundary structure of 90° rotational twin boundaries across {101}orthorhombic; the latter are predominant phonon scattering sources to lower the thermal conductivity as suggested by molecular dynamics calculations. The effect of doping on the thermoelectric properties was evaluated. Increasing Sr substitution reduces the Seebeck coefficient but the power factor remains high due to improved densification by Sr substitution. Mo doping generates additional charge carriers due to the presence of Mn3+ in the Mn4+ matrix, reducing electrical resistivity. The major impact of Sr on thermoelectric behaviour is the reduction of the thermal conductivity as shown experimentally and by modelling. Strontium containing ceramics showed thermoelectric figure of merit (ZT) values higher than 0.1 at temperatures above 850 K. Ca0.7Sr0.3Mn0.96Mo0.04O3 ceramics exhibit enhanced properties with S1000K = -180 μV K-1, ρ1000K = 5 × 10-5 Ωm, k1000K = 1.8 W m-1 K-1 and ZT ≈ 0.11 at 1000 K.
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Affiliation(s)
- D Srivastava
- School of Materials , University of Manchester , Manchester , M13 9PL , UK .
| | - F Azough
- School of Materials , University of Manchester , Manchester , M13 9PL , UK .
| | - R Freer
- School of Materials , University of Manchester , Manchester , M13 9PL , UK .
| | - E Combe
- National Institute of Advanced Industrial Science and Technology , Midorigaoka , Ikeda , Osaka 563-8577 , Japan
| | - R Funahashi
- National Institute of Advanced Industrial Science and Technology , Midorigaoka , Ikeda , Osaka 563-8577 , Japan
| | - D M Kepaptsoglou
- SuperSTEM Laboratory , SciTech Daresbury Campus , Daresbury WA4 4AD , UK
| | - Q M Ramasse
- SuperSTEM Laboratory , SciTech Daresbury Campus , Daresbury WA4 4AD , UK
| | - M Molinari
- Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , UK .
| | - S R Yeandel
- Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , UK .
| | - J D Baran
- Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , UK .
| | - S C Parker
- Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , UK .
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