In-Situ Hydration Studies Using Multi-Angle Energy-Dispersive Diffraction

Colston, Sally L.; Jacques, Simon D. M.; Barnes, P.; Jupe, Andrew C.

doi:10.1107/s0909049597018712

Cited by 28 publications

(18 citation statements)

References 2 publications

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“…The technique of energy-dispersive diffraction (EDD) is well suited to in situ time-resolved studies of cement hydration (Barnes et al, 1996) and this facility has been considerably enhanced by the introduction of multiangle EDD, which extends the dynamic range of usable reciprocal space Colston et al, 1998). In this study we seek to compare the hydration behaviour of the same brownmillerite samples (i.e.…”

Section: Hydration Behaviour and Multi-angle Energy-dispersive Difframentioning

confidence: 99%

The site occupancy of Mg in the brownmillerite structure and its effect on hydration properties: an X-ray/neutron diffraction and EXAFS study

Jupe¹,

Cockcroft²,

Barnes³

et al. 2001

J Appl Cryst

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Samples of pure (Ca 2 FeAlO 5 ) and lightly doped (Ca 2 Fe 0.95 Al 0.95 Mg 0.05 Si 0.05 O 5 ) brownmillerite have been synthesized. Synchrotron X-ray and neutron diffraction data have been collected so that the structures can be re®ned using, simultaneously, both diffraction data sets and known compositional information; this overcomes the problem of under-determinacy resulting from multioccupation of the tetrahedrally and octahedrally coordinated sites in the structure. For the pure form, a 2.7:1 iron/aluminium preference for octahedral/ tetrahedral (respectively) occupation is obtained. This trend is re¯ected also in the doped brownmillerite, though, because of the low level of Mg doping, the occupancy of Mg is only resolved through the additional use of Mg EXAFS (extended X-ray absorption ®ne structure) data, which shows that Mg displays a distinct octahedral site preference rather than a disordered occupation between the octahedral/tetrahedral sites. The consequences of Mg doping are then examined using time-resolved multi-angle energy-dispersive powder X-ray diffraction studies of the mineral undergoing hydration; this shows that the pure form is more active than the doped form.

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Section: Hydration Behaviour and Multi-angle Energy-dispersive Difframentioning

confidence: 99%

The site occupancy of Mg in the brownmillerite structure and its effect on hydration properties: an X-ray/neutron diffraction and EXAFS study

Jupe¹,

Cockcroft²,

Barnes³

et al. 2001

J Appl Cryst

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“…By using the technique of energy-dispersive diffraction (EDD) data can be collected on a sub-second time scale; the technique is also well suited to samples in hostile environments. Colston et al (1998) studied the transformation of cements undergoing high-temperature hydration. They used a three-element solid-state detector to partially solve the energy-dispersive data-collection problems such as limited data range, sample gauge volumes and spectral matching.…”

Section: Scienti®c Objectives Of the Beamlinementioning

confidence: 99%

The new materials processing beamline at the SRS Daresbury, MPW6.2

Cernik

Barnes

Bushnell‐Wye

et al. 2004

J Synchrotron Radiat

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A new beamline (MPW6.2) has been designed and built for the study of materials during processing where three synchrotron techniques, SAXS, WAXS and XAS, are available simultaneously. It has been demonstrated that Rietveld refinable data can be collected from silicon SRM 640b over a 60 degrees range in a time scale of 1 s. The data have been refined to a chi(2) of 2.4, the peaks fitting best to a Pearson VII function or with fundamental parameters. The peak halfwidths have been found to be approximately constant at 0.06 degrees over a 120 degrees angular range indicating that the instrumental resolution function has matched its design specification. A quantitative comparison of data sets collected on the same isotactic polypropylene system on MPW6.2 and DUBBLE at the ESRF shows a 17% improvement in angular resolution and a 1.8 improvement in peak-to-background ratio with the RAPID2 system; the ESRF data vary more smoothly across detector channels. The time-dependent wide-angle XRD was tested by comparing a hydration reaction of gypsum-bassanite-anhydrite with energy-dispersive data collected on the same system on the same time scale. Three sample data sets from the reaction were selected for analysis and gave an average chi(2) of 3.8. The Rietveld-refined lattice parameters are a good match with published values and the corresponding errors show a mean value of 3.3 x 10(-4). The data have also been analysed by the Pawley decomposition phase-modelling technique demonstrating the ability of the station to quickly and accurately identify new phases. The combined SAXS/WAXS capability of the station was tested with the crystallization and spinodal decomposition of a very dilute polymer system. Our measurements show that the crystallization of a high-density co-polymer (E76B38) as low as 0.5% by weight can be observed in solution in hexane. The WAXS and SAXS data sets were collected on the same time scale. The SAXS detector was calibrated using a collagen sample that gave 30 orders of diffraction in 1 s of data collection. The combined XRD and XAS measurement capability of the station was tested by observing the collapse and re-crystallization of zinc-exchanged zeolite A (zeolite Zn/Na-A). Previous studies of this material on station 9.3 at the SRS were compared with those from the new station. A time improvement of 38 was observed with better quality counting statistics. The improved angular resolution from the WAXS detector enabled new peaks to be identified.

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“…If we are examining the same phase, and indeed the same weight fraction w(t) of that phase in the same sample at the same time, t, then the only realistic factors that can alter the growth/decay curves, I(t), with energy are different rates of change in X-ray scattering power or of absorption with density, &. This explanation has been stated (Colston et al, 1998) in the following form,…”

Section: Re-analysing Previously Collected Datamentioning

confidence: 99%

“…Thus this ratio (or its inverse) re¯ects the relative change in density with time, &(t). Following the initial demonstration of this idea (Colston et al, 1998) the method has been applied to the case of cement hydration with addition of rheology agents to alter the mechanical behaviour (density, viscosity, shear stress) of the hydrating cement. The cement system chosen for study was synthetic (pure) tricalcium silicate (with a water:cement ration of 0.4) with and without four different rheology agents.…”

Section: Re-analysing Previously Collected Datamentioning

confidence: 99%

Time- and space-resolved dynamic studies on ceramic and cementitious materials

Barnes

Colston

Craster

et al. 2000

J Synchrotron Radiat

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A review is given of the results and lessons arising from a sustained in situ diffraction study of the structure and performance of functional ceramic/cementitious materials in which synchrotron-based energy-dispersive diffraction has been the central under-pinning technique. Five particular points of discussion emerge: the demands on time resolution; the use of penetrating radiation for the in situ mode; the need for complementary techniques; re-analysing of data; spatially resolved diffraction: a new tomography. These aspects are discussed in turn using illustrative examples taken from the ®elds of cement hydration, clay intercalation, cation-exchanged zeolites, and particulate/¯uid invasion into building and archaeological objects.

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In-Situ Hydration Studies Using Multi-Angle Energy-Dispersive Diffraction

Cited by 28 publications

References 2 publications

The site occupancy of Mg in the brownmillerite structure and its effect on hydration properties: an X-ray/neutron diffraction and EXAFS study

The site occupancy of Mg in the brownmillerite structure and its effect on hydration properties: an X-ray/neutron diffraction and EXAFS study

The new materials processing beamline at the SRS Daresbury, MPW6.2

Time- and space-resolved dynamic studies on ceramic and cementitious materials

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