Test of channel-cut perfect crystals for neutron small angle scattering experiments

Schwahn, D.; Mikšovsky, A.; Rauch, H.; Seidl, E.; Zugarek, G.

doi:10.1016/0168-9002(85)90720-x

Cited by 79 publications

(40 citation statements)

References 13 publications

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“…Each sample scan required 16 h to complete. The slit-smeared data were corrected for background and put in absolute units by measuring the beam intensity as explained by Schwahn [28]. The data were slit desmeared by a linear method [29].…”

Section: Methodsmentioning

confidence: 99%

Hydration water and microstructure in calcium silicate and aluminate hydrates

Fratini

Chen

Baglioni

2006

J. Phys.: Condens. Matter

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Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C 3 S, C 2 S) and aluminates (C 3 A, C 4 AF) were studied by quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and nearinfrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm −1 monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the 1 H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small 3 Author to whom any correspondence should be addressed. www.csgi.unifi.it. angle neutron scattering (USANS) and wide angle x-ray scattering (WAXD) that characterize how additives affect both the hydrated microstructure development and the original grain size. In particular, SPs alter the morphology of the hydrated phases, which no longer grow with the classic fibrillar structure on the grain surface, but nucleate in solution as globular structures. All this information converges in a quantitative, and at molecular level, description of the mechanisms involved in the setting process of one of the materials most widely used by human beings.

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Section: Methodsmentioning

confidence: 99%

Hydration water and microstructure in calcium silicate and aluminate hydrates

Fratini

Chen

Baglioni

2006

J. Phys.: Condens. Matter

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“…DCDs currently operate in the US (Christen et al, 1977;Popovici, Yelon & Berliner, 1995), Austria (Mik~lovsky, Amenitch, Rauch & Seidl, 1992), Germany (Schwahn et al, 1985;Hempel & Eichhorn, 1995), Japan (Aizawa & Tomimitsu, 1995;Takahashi & Hasimoto, 1995) and Russia (Abov, Elyutin, Matveev & Eidlin, 1994). This wide geographical spread reflects the growing interest in USANS structural studies.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a Bonse–Hart Ultra-Small-Angle Neutron Scattering Facility by Elimination of the Rocking-Curve Wings

Agamalian¹,

Wígnall²,

Triolo³

1997

J Appl Crystallogr

112

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The ORNL Ultra-Small-Angle Neutron Scattering (USANS) facility at the High Flux Isotope Reactor (HIFR) has been recently upgraded, using the BonseHart technique. Si(111) triple-bounce channel-cut single crystals have been used for both the monochromator and analyzer. The total width of the rocking curve of the analyzer is about 1.6" and the wavelength of the primary neutron beam is 2.59 ,~,. It has been demonstrated that, owing to the low neutron absorption of silicon, the wings of the rocking curve are generally contaminated by neutrons propagating and diffracting inside the walls of channel-cut crystals. This parasitic intensity has been eliminated by the cutting of a groove in the long wall and the insertion of a cadmium absorber (0.6 mm thick). This modification effectively suppresses the wings of the rocking curve by over two orders of magnitude and thus dramatically improves the sensitivity of the diffractometer. The upgraded facility has been tested with several samples, including a polystyrene latex with a radius of 2.50 × 104 ,~ as determined by optical microscopy. The average radius calculated from USANS data is 2.48 × 104/~, in excellent agreement with independently determined dimensions. The minimum accessible scattering vector of the upgraded USANS facility is Qmin "~ 2 x 10 -5 ~-1, which corresponds to a maximum resolvable real-space dimension of 27t/Qmi n ~ 3 x 105 ,~ (30 ~tm).

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“…Bonse-Hart cameras for neutron scattering experiments are also available at neutron facilities. [23][24][25][26] Silicon single crystals are used as the monochromators and the analyzers in this technique as well as in the USAXS instruments. Bonse-Hart cameras used in neutron scattering experiments can cover 2 Â 10 À4 oqo4 Â 10 À3 nm À1 with an incident neutron wavelength of 0.2 nm.…”

Section: Scattering Studies Of Rubber-filler Systems M Takenakamentioning

confidence: 99%

Analysis of structures of rubber-filler systems with combined scattering methods

Takenaka

2012

Polym J

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This review presents an analysis of the hierarchical structures formed in rubber-filler systems by using combined scattering methods. The combined scattering methods utilize various scattering methods and are powerful tools for the quantitative characterization of hierarchical structures over a wide range of length scales, ranging from nanometers to micrometers. Scattering theories for the analysis of the experimental scattering functions and their applications are described. Polymer Journal (2013) 45, 10-19; doi:10.1038/pj.2012.187; published online 21 November 2012Keywords: combined scattering methods; hierarchical structure; rubber-filler systems INTRODUCTION Rubber-filler systems have been widely used in industrial applications, such as for tires and belts so on. 1-6 The use of fillers in rubber compounds reinforces the rubber material and improves the barrier properties. There are several important factors for controlling the efficiency of rubber reinforcement by fillers. The dispersion of filler particles in the rubber matrix is one of the most important factors in this process. Typically, following the use of conventional compounding processes, the fillers are not dispersed homogeneously and form hierarchical structures within the rubber matrices. For example, in rubber-carbon black (CB) systems, the CB primary particles are not distributed independently but coalesce into aggregates, which are indestructible units of CB, during conventional compounding processes. 2 The aggregates of CB, which are called aggregates or agglomerates, can also lead to the formation of hierarchical structures, which consist of higher levels of ordered structure. 2 It is believed that the hierarchical structures affect the efficiency of filler reinforcement. Other rubber-filler systems also form hierarchical structures; furthermore, the characteristic lengths and morphologies of each level of ordered structure, such as agglomerates, vary with the specific combination of rubber and filler used in the system in addition to the compounding processes. To analyze the hierarchical structure, scattering techniques are one of useful techniques. In scattering experiments, we investigated the angular dependence of the scattered intensities induced by the incident beam hitting samples. Although the interpretation of the scattering intensities is complicated, nonetheless, scattering techniques are suitable for obtaining the statistical features of rubber-filler systems. However, the length scales of the hierarchical structures can extend from nanometers to micrometers, which prevents the characterization

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Test of channel-cut perfect crystals for neutron small angle scattering experiments

Cited by 79 publications

References 13 publications

Hydration water and microstructure in calcium silicate and aluminate hydrates

Hydration water and microstructure in calcium silicate and aluminate hydrates

Optimization of a Bonse–Hart Ultra-Small-Angle Neutron Scattering Facility by Elimination of the Rocking-Curve Wings

Analysis of structures of rubber-filler systems with combined scattering methods

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