Matthew Rowles - Profile on Academia.edu (original) (raw)

Papers by Matthew Rowles

Journal of Applied Crystallography

A description is given of the program pdCIFplotter. This program is used for visualizing powder d... more A description is given of the program pdCIFplotter. This program is used for visualizing powder diffraction data and models published in powder CIF format (pdCIF). In particular, support for the visualization of multi-pattern data sets, such as in situ diffraction experiments, is provided by means of stack and surface plots. pdCIFplotter is written in Python 3 and can run wherever a compatible runtime is available. TOPAS macros for the production of pdCIF files are also presented.

Journal of Applied Crystallography, 2021

The quality of X-ray powder diffraction data and the number and type of refinable parameters have... more The quality of X-ray powder diffraction data and the number and type of refinable parameters have been examined with respect to their effect on quantitative phase analysis (QPA) by the Rietveld method using data collected from two samples from the QPA round robin [Madsen, Scarlett, Cranswick & Lwin (2001). J. Appl. Cryst. 34, 409–426]. From the analyses of these best-case-scenario specimens, a series of recommendations for minimum standards of data collection and analysis are proposed. It is hoped that these will aid new QPA-by-Rietveld users in their analyses.

CCDC 1902529: Experimental Crystal Structure Determination

Novel analysis methods for reactions in molten salts

The role of the 2D-to-3D transition in x-ray diffraction analysis of crystallite size

Journal of Physics: Condensed Matter, 2021

The diffraction behaviour of stacked layers of graphene and hexagonal boron nitride are studied c... more The diffraction behaviour of stacked layers of graphene and hexagonal boron nitride are studied computationally by direct calculation of the diffraction pattern using the Debye scattering equation. Analysis of the position and profile of the diffraction peaks show that while single-layer graphene is unambiguously a 2D material, ordered stacks of three or more layers diffract as bulk material. Following the Scherrer equation, we correlate the known crystallite size with the diffraction peak parameters and observe strong affine relationships which exist separately for single-layer, bi-layer and three or more layer (bulk) structures. We determine a series of expressions to calculate the crystallite size which do not suffer the well-known size-dependence or rely on assumptions about the shape. We present a detailed workflow showing how these expressions can be applied to experimental data.

arXiv: Materials Science, 2020

The quality of X-ray powder diffraction data and the number and type of refinable parameters has ... more The quality of X-ray powder diffraction data and the number and type of refinable parameters has been examined with respect to their effect on quantitative phase analysis (QPA) by the Rietveld method using data collected from two samples from the QPA round robin [Madsen et al. J. Appl. Cryst. (2001), 34, 409--26]. For specimens where the diffracted intensity is split between all phases approximately equally accurate results could be obtained with a maximum observed intensity in the range of 1000--200000 counts. The best refinement model was one that did not refine atomic displacement parameters, but did allow other parameters to refine. For specimens where there existed minor or trace phases, this intensity range changed to 5000--1000000 counts. The refinement model with the most accurate results was one that refined a minimum of parameters, especially for the minor/trace phases. Given that all phases were quite crystalline, step sizes for both types of specimen could range between ...

Acta Crystallographica Section A Foundations and Advances, 2017

Quantitative phase analysis (QPA) by powder diffraction is a key staple of almost all diffraction... more Quantitative phase analysis (QPA) by powder diffraction is a key staple of almost all diffraction laboratories around the world. There have been several Round Robins [1-3] which have probed specimen preparation, data collection, and analysis techniques, mainly in Bragg-Brentano geometry, which have shown that although the mathematics behind the technique is sound, its implementation leaves room for improvement. With the growth in synchrotron experimentation, the use of in situ techniques, and the availability of multiple optical configurations for laboratory instruments, more measurements are being conducted in geometries that deviate from the de facto Bragg-Brentano standard. As the experimental geometry changes, so too do the peak intensities, line profiles, and how influences such as specimen displacement and absorption manifest themselves in the diffraction pattern, further complicating analysis. One focus of our current research is generating realistic instrument models to correctly incorporate instrumental effects into our models. An understanding of the data collection geometry allows for an understanding of how peak intensities, line profiles, and other factors differ, and how to correct their effects in Rietveld modelling, potentially removing a source of error in a Rietveld refinement.

Scientific Reports, 2021

Kafirin, the hydrophobic prolamin storage protein in sorghum grain is enriched when the grain is ... more Kafirin, the hydrophobic prolamin storage protein in sorghum grain is enriched when the grain is used for bioethanol production to give dried distillers grain with solubles (DGGS) as a by-product. There is great interest in DDGS kafirin as a new source for biomaterials. There is however a lack of fundamental understanding of how the physicochemical properties of DDGS kafirin having been exposed to the high temperature conditions during ethanol production, compare to kafirin made directly from the grain. An understanding of these properties is required to catalyse the utilisation of DDGS kafirin for biomaterial applications. The aim of this study was to extract kafirin directly from sorghum grain and from DDGS derived from the same grain and, then perform a comparative investigation of the physicochemical properties of these kafirins in terms of: polypeptide profile by sodium-dodecyl sulphate polyacrylamide gel electrophoresis; secondary structure by Fourier transform infra-red spect...

Inhibiting in situ phase transition in Ruddlesden-Popper perovskite via tailoring bond hybridization and its application in oxygen permeation

Matter, 2021

Summary Ruddlesden-Popper perovskite oxide (An+1BnO3n+1) mixed ionic-electronic conducting membra... more Summary Ruddlesden-Popper perovskite oxide (An+1BnO3n+1) mixed ionic-electronic conducting membranes are proposed as a new method for oxygen separation from air. Element doping was used to improve the ionic conductivity and to stabilize the crystal structure. The doping of orthorhombic Pr2NiO4 with Mo resulted in the ex situ collapse of the crystal together with the generation of impurities by the rearrangement of Pr atoms. Mo doping also inhibited the in situ phase transition from low-order Pr2NiO4 to high-order Pr4Ni3O10 by weakening the covalent interaction between Pr and O. Membranes made from Pr2Ni0.95Mo0.05O4+δ showed an oxygen flux of 3.35 mL min−1 cm−2 at 1,000°C, high permeation stability in air and helium, and high CO2 tolerance with no decline of oxygen flux during 500 h at 900°C. This work advances a comprehensive understanding of phase transitions on Pr2Ni1−xMoxO4 and provides an effective way to improve the oxygen permeability via in situ stabilization of the phase structure.

Journal of Materials Research and Technology, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Scientific Reports, 2021

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion... more Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated. We have investigated corrosion resistance of iron manufactured according to traditional metallurgical processes by the Indian tribes called ‘Agaria’. Iron samples were recovered from central India (Aamadandh, Korba district, Chhattisgarh). Iron artefacts are investigated using a range of correlative microscopic, spectroscopic, diffraction and tomographic techniques to postulate the hidden mechanisms of superlative corrosion resistance. The importance of manufacturing steps, ingredients involved in Agaria’s iron making process, and post-metal treatment using metal-working operation called hot hammering (forging) is highlighted. This study also hypothesizes the probable protective mechanisms of corrosion resistance of iron. Findings are expected to have a broad impact across multiple disciplines such as a...

Universal Scherrer equation for graphene fragments

Carbon, 2020

Abstract Graphene fragments spanning a wide range of size and shape were studied computationally ... more Abstract Graphene fragments spanning a wide range of size and shape were studied computationally using the Debye scattering equation. The calculated diffraction patterns were analysed using the Scherrer equation to infer the fragment size, L a . Comparison with the known fragment sizes reveals a strong affine relationship between L a and the Scherrer quantity λ / ( B cos θ ) . To preserve this relationship, we propose modifying the Scherrer equation to include an empirical additive constant. Our approach solves the well-known problem of size-dependence in the shape factor and yields a universal expression by defining L a as the square-root of the fragment area. The relationship between observed diffraction peak positions and unit cell parameters is also discussed.

Destabilized Calcium Hydride as a Promising High-Temperature Thermal Battery

Calcium hydride (CaH2) is considered an ideal candidate for thermochemical energy storage (therma... more Calcium hydride (CaH2) is considered an ideal candidate for thermochemical energy storage (thermal battery) due to its high energy density and low cost. Its very high operating temperature and poor...

Journal of Applied Crystallography, 2020

A simple modification to an existing powder diffraction specimen holder is given to allow for the... more A simple modification to an existing powder diffraction specimen holder is given to allow for the presentation of filter papers for analysis. A mild steel annulus holds the filter paper in place using magnets added to the rear of the specimen holder.

Geostandards and Geoanalytical Research, 2020

Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analyt... more Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation precludes the analysis of both micrometre-scale discrete monazite grains and fine textures within monazite crystals that are commonly found. Here, we analyse reference materials by atom probe tomography and develop a protocol for 208 Pb/ 232 Th dating of nanoscale domains of monazite (0.0007 μm 3 analytical volume). The results indicates that the 208 Pb ++ / 232 ThO ++ are higher than the true values. Such fractionation can be corrected using a linear regression between 208 Pb ++ / 232 ThO ++ and the M/ΔM10 peak shape parameter, where M is the position of the O2 + peak and ΔM10 the full-width-tenth-maximum for the same peak. This correction results in 15 to 20 % analytical uncertainty on the corrected 208 Pb/ 232 Th age. Nonetheless, this approach opens the possibility of obtaining 208 Pb/ 232 Th ages with sufficient precision to address geological questions on an unprecedented small scale. To illustrate the approach, atom probe geochronology of a small monazite grain from the contact aureole of the Fanad pluton (Ireland) yielded a 208 Pb/ 232 Th atom probe age of 420 ± 60 Ma (2σ) and is consistent with the known metamorphism in the region.

Table S1a. Quantitative Rietveld analysis of SR-XRD data for Mg(HxF1−x)2 solid solutions. Errors ... more Table S1a. Quantitative Rietveld analysis of SR-XRD data for Mg(HxF1−x)2 solid solutions. Errors are in parentheses. The phases in shaded grey were used in the weight averaged calculations. Lattice Parameter (Å) Axial Mg-H(F) bond distance (Å) Equatorial Mg-H(F) bond distance Refined H occupancy factor MgF2 wt% a c Wt. av. a Wt. av. c Wt. av. Wt. av.

The Journal of Physical Chemistry C, 2020

Ion conductivity; batteries; crystal structure; thermal properties; boranes; borates

The Journal of Physical Chemistry C, 2020

Fluorine-substituted sodium hydride is investigated for application as a thermal energy storage m... more Fluorine-substituted sodium hydride is investigated for application as a thermal energy storage material inside thermal batteries. A range of compositions of NaHxF1−x (x = 0, 0.5, 0.7, 0.85, 0.95, 1) have been studied using synchrotron radiation powder X-ray diffraction (SR-XRD), near edge X-ray absorption fine structure spectroscopy (NEXAFS), and nuclear magnetic resonance spectroscopy (NMR), with the thermal conductivity and melting points also being determined. SR-XRD and NMR spectroscopy studies identified that the solid solutions formed during synthesis contain multiple phases rather than a single stoichiometric compound, despite the materials exhibiting a single melting point. As the fluorine content of the materials increases, the Na−H(F) bond length decreases, increasing the stability of the compound. This trend is also observed during the melting point analysis where increasing the fluorine content increases the melting point of the material, i.e. x < 0.3 (i.e. F − > 0.7) enables melting at temperatures above 750 °C.

Activation-free supercapacitor electrode based on surface-modified Sr2CoMo1-xNixO6-δ perovskite

Chemical Engineering Journal, 2020

Abstract Oxygen anion intercalation-type supercapacitors are promising charge storage devices. In... more Abstract Oxygen anion intercalation-type supercapacitors are promising charge storage devices. In this study, by taking advantage of the capability of selective exsolution of elements from perovskite lattice, a nanoparticles-modified perovskite composite is developed as new perovskite-based electrode for supercapacitor with further improved performance that allow the energy storage via two different mechanisms, i.e., Faradaic surface redox pseudocapacitance and oxygen anion-intercalation pseudocapacitance. The derived supercapacitor shows high power density and energy density, and no surface activation process, and stable performance. Specifically, perovskite oxides with the nominal composition of Sr2CoMo1-xNixO6-δ are designed and the strategy of controlled in-situ exsolution and re-oxidation of B-sites Ni and Co element to create Co3O4 and NiO nanoparticles on the perovskite surface and extra oxygen vacancies in perovskite bulk is applied. The Co3O4 and NiO nanoparticles on surface of electrode are found to effectively improve the surface redox pseudocapacitance, while the creation of additional oxygen vacancies enhances the oxygen anion intercalation pseudocapacitance. Consequently, the electrode displays excellent charge storage capability with a stable capacity as high as ~930 F g−1 and superior rate performance. As a universal strategy, it may also be applicable for the design and synthesis of alternative high-performance electrodes with mixed energy storage mechanisms.

The role of ferrite-cementite interface in formation of hierarchical film on carbon steel in CO2-saturated brine

Applied Surface Science, 2019

Abstract Carbon steels with ferrite-pearlite structures are commonly used materials in many indus... more Abstract Carbon steels with ferrite-pearlite structures are commonly used materials in many industrial operations, and their protection against corrosion often relies on preventative inhibition measures. Film-forming corrosion inhibitors are known to provide protection to carbon steels in oil and gas productions lines for decades. However, the mechanisms of how these protect against corrosion are not known. Corrosion inhibitor films with hierarchical structures can be protective to the steel surface due to their large surface area and interconnected hierarchical porosity. The compounds that contribute to the formation of hierarchical morphology can be components of corrosion inhibitor formulations. This study demonstrates solution deposition of a hierarchically structured film derived from sodium thiosulphate. The film forms on an AISI 1030 carbon steel (UNS G10300) substrate in CO2-saturated sodium chloride containing solution under ambient conditions. We identified that the hierarchical film derived from sodium thiosulphate occurs originally at the interface of ferrite-cementite phase in pearlite and elucidate the role of oxygen in the formation of the hierarchical structures. These findings are expected to facilitate developments of novel corrosion inhibition strategies, through a controlled growth of surface films at metallic substrates for specific applications, including corrosion protection in oil and gas industry, catalysis and energy-storage applications.

Journal of Applied Crystallography

A description is given of the program pdCIFplotter. This program is used for visualizing powder d... more A description is given of the program pdCIFplotter. This program is used for visualizing powder diffraction data and models published in powder CIF format (pdCIF). In particular, support for the visualization of multi-pattern data sets, such as in situ diffraction experiments, is provided by means of stack and surface plots. pdCIFplotter is written in Python 3 and can run wherever a compatible runtime is available. TOPAS macros for the production of pdCIF files are also presented.

Journal of Applied Crystallography, 2021

The quality of X-ray powder diffraction data and the number and type of refinable parameters have... more The quality of X-ray powder diffraction data and the number and type of refinable parameters have been examined with respect to their effect on quantitative phase analysis (QPA) by the Rietveld method using data collected from two samples from the QPA round robin [Madsen, Scarlett, Cranswick & Lwin (2001). J. Appl. Cryst. 34, 409–426]. From the analyses of these best-case-scenario specimens, a series of recommendations for minimum standards of data collection and analysis are proposed. It is hoped that these will aid new QPA-by-Rietveld users in their analyses.

CCDC 1902529: Experimental Crystal Structure Determination

Novel analysis methods for reactions in molten salts

The role of the 2D-to-3D transition in x-ray diffraction analysis of crystallite size

Journal of Physics: Condensed Matter, 2021

The diffraction behaviour of stacked layers of graphene and hexagonal boron nitride are studied c... more The diffraction behaviour of stacked layers of graphene and hexagonal boron nitride are studied computationally by direct calculation of the diffraction pattern using the Debye scattering equation. Analysis of the position and profile of the diffraction peaks show that while single-layer graphene is unambiguously a 2D material, ordered stacks of three or more layers diffract as bulk material. Following the Scherrer equation, we correlate the known crystallite size with the diffraction peak parameters and observe strong affine relationships which exist separately for single-layer, bi-layer and three or more layer (bulk) structures. We determine a series of expressions to calculate the crystallite size which do not suffer the well-known size-dependence or rely on assumptions about the shape. We present a detailed workflow showing how these expressions can be applied to experimental data.

arXiv: Materials Science, 2020

The quality of X-ray powder diffraction data and the number and type of refinable parameters has ... more The quality of X-ray powder diffraction data and the number and type of refinable parameters has been examined with respect to their effect on quantitative phase analysis (QPA) by the Rietveld method using data collected from two samples from the QPA round robin [Madsen et al. J. Appl. Cryst. (2001), 34, 409--26]. For specimens where the diffracted intensity is split between all phases approximately equally accurate results could be obtained with a maximum observed intensity in the range of 1000--200000 counts. The best refinement model was one that did not refine atomic displacement parameters, but did allow other parameters to refine. For specimens where there existed minor or trace phases, this intensity range changed to 5000--1000000 counts. The refinement model with the most accurate results was one that refined a minimum of parameters, especially for the minor/trace phases. Given that all phases were quite crystalline, step sizes for both types of specimen could range between ...

Acta Crystallographica Section A Foundations and Advances, 2017

Quantitative phase analysis (QPA) by powder diffraction is a key staple of almost all diffraction... more Quantitative phase analysis (QPA) by powder diffraction is a key staple of almost all diffraction laboratories around the world. There have been several Round Robins [1-3] which have probed specimen preparation, data collection, and analysis techniques, mainly in Bragg-Brentano geometry, which have shown that although the mathematics behind the technique is sound, its implementation leaves room for improvement. With the growth in synchrotron experimentation, the use of in situ techniques, and the availability of multiple optical configurations for laboratory instruments, more measurements are being conducted in geometries that deviate from the de facto Bragg-Brentano standard. As the experimental geometry changes, so too do the peak intensities, line profiles, and how influences such as specimen displacement and absorption manifest themselves in the diffraction pattern, further complicating analysis. One focus of our current research is generating realistic instrument models to correctly incorporate instrumental effects into our models. An understanding of the data collection geometry allows for an understanding of how peak intensities, line profiles, and other factors differ, and how to correct their effects in Rietveld modelling, potentially removing a source of error in a Rietveld refinement.

Scientific Reports, 2021

Kafirin, the hydrophobic prolamin storage protein in sorghum grain is enriched when the grain is ... more Kafirin, the hydrophobic prolamin storage protein in sorghum grain is enriched when the grain is used for bioethanol production to give dried distillers grain with solubles (DGGS) as a by-product. There is great interest in DDGS kafirin as a new source for biomaterials. There is however a lack of fundamental understanding of how the physicochemical properties of DDGS kafirin having been exposed to the high temperature conditions during ethanol production, compare to kafirin made directly from the grain. An understanding of these properties is required to catalyse the utilisation of DDGS kafirin for biomaterial applications. The aim of this study was to extract kafirin directly from sorghum grain and from DDGS derived from the same grain and, then perform a comparative investigation of the physicochemical properties of these kafirins in terms of: polypeptide profile by sodium-dodecyl sulphate polyacrylamide gel electrophoresis; secondary structure by Fourier transform infra-red spect...

Inhibiting in situ phase transition in Ruddlesden-Popper perovskite via tailoring bond hybridization and its application in oxygen permeation

Matter, 2021

Summary Ruddlesden-Popper perovskite oxide (An+1BnO3n+1) mixed ionic-electronic conducting membra... more Summary Ruddlesden-Popper perovskite oxide (An+1BnO3n+1) mixed ionic-electronic conducting membranes are proposed as a new method for oxygen separation from air. Element doping was used to improve the ionic conductivity and to stabilize the crystal structure. The doping of orthorhombic Pr2NiO4 with Mo resulted in the ex situ collapse of the crystal together with the generation of impurities by the rearrangement of Pr atoms. Mo doping also inhibited the in situ phase transition from low-order Pr2NiO4 to high-order Pr4Ni3O10 by weakening the covalent interaction between Pr and O. Membranes made from Pr2Ni0.95Mo0.05O4+δ showed an oxygen flux of 3.35 mL min−1 cm−2 at 1,000°C, high permeation stability in air and helium, and high CO2 tolerance with no decline of oxygen flux during 500 h at 900°C. This work advances a comprehensive understanding of phase transitions on Pr2Ni1−xMoxO4 and provides an effective way to improve the oxygen permeability via in situ stabilization of the phase structure.

Journal of Materials Research and Technology, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Scientific Reports, 2021

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion... more Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated. We have investigated corrosion resistance of iron manufactured according to traditional metallurgical processes by the Indian tribes called ‘Agaria’. Iron samples were recovered from central India (Aamadandh, Korba district, Chhattisgarh). Iron artefacts are investigated using a range of correlative microscopic, spectroscopic, diffraction and tomographic techniques to postulate the hidden mechanisms of superlative corrosion resistance. The importance of manufacturing steps, ingredients involved in Agaria’s iron making process, and post-metal treatment using metal-working operation called hot hammering (forging) is highlighted. This study also hypothesizes the probable protective mechanisms of corrosion resistance of iron. Findings are expected to have a broad impact across multiple disciplines such as a...

Universal Scherrer equation for graphene fragments

Carbon, 2020

Abstract Graphene fragments spanning a wide range of size and shape were studied computationally ... more Abstract Graphene fragments spanning a wide range of size and shape were studied computationally using the Debye scattering equation. The calculated diffraction patterns were analysed using the Scherrer equation to infer the fragment size, L a . Comparison with the known fragment sizes reveals a strong affine relationship between L a and the Scherrer quantity λ / ( B cos θ ) . To preserve this relationship, we propose modifying the Scherrer equation to include an empirical additive constant. Our approach solves the well-known problem of size-dependence in the shape factor and yields a universal expression by defining L a as the square-root of the fragment area. The relationship between observed diffraction peak positions and unit cell parameters is also discussed.

Destabilized Calcium Hydride as a Promising High-Temperature Thermal Battery

Calcium hydride (CaH2) is considered an ideal candidate for thermochemical energy storage (therma... more Calcium hydride (CaH2) is considered an ideal candidate for thermochemical energy storage (thermal battery) due to its high energy density and low cost. Its very high operating temperature and poor...

Journal of Applied Crystallography, 2020

A simple modification to an existing powder diffraction specimen holder is given to allow for the... more A simple modification to an existing powder diffraction specimen holder is given to allow for the presentation of filter papers for analysis. A mild steel annulus holds the filter paper in place using magnets added to the rear of the specimen holder.

Geostandards and Geoanalytical Research, 2020

Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analyt... more Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation precludes the analysis of both micrometre-scale discrete monazite grains and fine textures within monazite crystals that are commonly found. Here, we analyse reference materials by atom probe tomography and develop a protocol for 208 Pb/ 232 Th dating of nanoscale domains of monazite (0.0007 μm 3 analytical volume). The results indicates that the 208 Pb ++ / 232 ThO ++ are higher than the true values. Such fractionation can be corrected using a linear regression between 208 Pb ++ / 232 ThO ++ and the M/ΔM10 peak shape parameter, where M is the position of the O2 + peak and ΔM10 the full-width-tenth-maximum for the same peak. This correction results in 15 to 20 % analytical uncertainty on the corrected 208 Pb/ 232 Th age. Nonetheless, this approach opens the possibility of obtaining 208 Pb/ 232 Th ages with sufficient precision to address geological questions on an unprecedented small scale. To illustrate the approach, atom probe geochronology of a small monazite grain from the contact aureole of the Fanad pluton (Ireland) yielded a 208 Pb/ 232 Th atom probe age of 420 ± 60 Ma (2σ) and is consistent with the known metamorphism in the region.

Table S1a. Quantitative Rietveld analysis of SR-XRD data for Mg(HxF1−x)2 solid solutions. Errors ... more Table S1a. Quantitative Rietveld analysis of SR-XRD data for Mg(HxF1−x)2 solid solutions. Errors are in parentheses. The phases in shaded grey were used in the weight averaged calculations. Lattice Parameter (Å) Axial Mg-H(F) bond distance (Å) Equatorial Mg-H(F) bond distance Refined H occupancy factor MgF2 wt% a c Wt. av. a Wt. av. c Wt. av. Wt. av.

The Journal of Physical Chemistry C, 2020

Ion conductivity; batteries; crystal structure; thermal properties; boranes; borates

The Journal of Physical Chemistry C, 2020

Fluorine-substituted sodium hydride is investigated for application as a thermal energy storage m... more Fluorine-substituted sodium hydride is investigated for application as a thermal energy storage material inside thermal batteries. A range of compositions of NaHxF1−x (x = 0, 0.5, 0.7, 0.85, 0.95, 1) have been studied using synchrotron radiation powder X-ray diffraction (SR-XRD), near edge X-ray absorption fine structure spectroscopy (NEXAFS), and nuclear magnetic resonance spectroscopy (NMR), with the thermal conductivity and melting points also being determined. SR-XRD and NMR spectroscopy studies identified that the solid solutions formed during synthesis contain multiple phases rather than a single stoichiometric compound, despite the materials exhibiting a single melting point. As the fluorine content of the materials increases, the Na−H(F) bond length decreases, increasing the stability of the compound. This trend is also observed during the melting point analysis where increasing the fluorine content increases the melting point of the material, i.e. x < 0.3 (i.e. F − > 0.7) enables melting at temperatures above 750 °C.

Activation-free supercapacitor electrode based on surface-modified Sr2CoMo1-xNixO6-δ perovskite

Chemical Engineering Journal, 2020

Abstract Oxygen anion intercalation-type supercapacitors are promising charge storage devices. In... more Abstract Oxygen anion intercalation-type supercapacitors are promising charge storage devices. In this study, by taking advantage of the capability of selective exsolution of elements from perovskite lattice, a nanoparticles-modified perovskite composite is developed as new perovskite-based electrode for supercapacitor with further improved performance that allow the energy storage via two different mechanisms, i.e., Faradaic surface redox pseudocapacitance and oxygen anion-intercalation pseudocapacitance. The derived supercapacitor shows high power density and energy density, and no surface activation process, and stable performance. Specifically, perovskite oxides with the nominal composition of Sr2CoMo1-xNixO6-δ are designed and the strategy of controlled in-situ exsolution and re-oxidation of B-sites Ni and Co element to create Co3O4 and NiO nanoparticles on the perovskite surface and extra oxygen vacancies in perovskite bulk is applied. The Co3O4 and NiO nanoparticles on surface of electrode are found to effectively improve the surface redox pseudocapacitance, while the creation of additional oxygen vacancies enhances the oxygen anion intercalation pseudocapacitance. Consequently, the electrode displays excellent charge storage capability with a stable capacity as high as ~930 F g−1 and superior rate performance. As a universal strategy, it may also be applicable for the design and synthesis of alternative high-performance electrodes with mixed energy storage mechanisms.

The role of ferrite-cementite interface in formation of hierarchical film on carbon steel in CO2-saturated brine

Applied Surface Science, 2019

Abstract Carbon steels with ferrite-pearlite structures are commonly used materials in many indus... more Abstract Carbon steels with ferrite-pearlite structures are commonly used materials in many industrial operations, and their protection against corrosion often relies on preventative inhibition measures. Film-forming corrosion inhibitors are known to provide protection to carbon steels in oil and gas productions lines for decades. However, the mechanisms of how these protect against corrosion are not known. Corrosion inhibitor films with hierarchical structures can be protective to the steel surface due to their large surface area and interconnected hierarchical porosity. The compounds that contribute to the formation of hierarchical morphology can be components of corrosion inhibitor formulations. This study demonstrates solution deposition of a hierarchically structured film derived from sodium thiosulphate. The film forms on an AISI 1030 carbon steel (UNS G10300) substrate in CO2-saturated sodium chloride containing solution under ambient conditions. We identified that the hierarchical film derived from sodium thiosulphate occurs originally at the interface of ferrite-cementite phase in pearlite and elucidate the role of oxygen in the formation of the hierarchical structures. These findings are expected to facilitate developments of novel corrosion inhibition strategies, through a controlled growth of surface films at metallic substrates for specific applications, including corrosion protection in oil and gas industry, catalysis and energy-storage applications.