Structure factor determination of amorphous materials by neutron diffraction

Melt quenched silicate glasses containing calcium, phosphorus and alkali metals have the ability to promote bone regeneration and to fuse to living bone. Of these glasses 45S5 Bioglass s is the most widely used being sold in over 35 countries as a bone graft product for medical and dental applications; particulate 45S5 is also incorporated into toothpastes to help remineralize the surface of teeth. Recently it has been suggested that adding titanium dioxide can increase the bioactivity of these materials. This work investigates the structural consequences of incorporating 4 mol% TiO 2 into Bioglass s using isotopic substitution (of the Ti) applied to neutron diffraction and X-ray Absorption Near Edge Structure (XANES). We present the first isotopic substitution data applied to melt quench derived Bioglass or its derivatives. Results show that titanium is on average surrounded by 5.2(1) nearest neighbor oxygen atoms. This implies an upper limit of 40% four-fold coordinated titanium and shows that the network connectivity is reduced from 2.11 to 1.97 for small quantities of titanium. Titanium XANES micro-fluorescence confirms the titanium environment is homogenous on the micron length scale within these glasses. Solid state magic angle spinning (MAS) NMR confirms the network connectivity model proposed. Furthermore, the results show the intermediate range order containing Na-O, Ca-O, O-P-O and O-Si-O correlations are unaffected by the addition of small quantities of TiO 2 into these systems.

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“…[60][61][62] The program Correct was used to perform the data reduction and corrections. 63,64 The total structure factor is given by 65 iðQÞ¼…”

Section: Neutron Diffraction Methods and Analysismentioning

confidence: 99%

Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction

Martin

Moss

Lakhkar

et al. 2012

Phys. Chem. Chem. Phys.

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“…In order to correct and normalize the data, the empty cryostat, an empty sample holder, a boron powder sample, and a vanadium rod were also measured, as in previous works. 37,38 Absorption and multiple-scattering corrections and normalization of the data were performed using the program CORRECT. 39 Additionally, inelastic corrections were also carried out by subtracting a polynomial expansion in powers of q 2 .…”

Section: B Neutron Diffraction Experimentsmentioning

confidence: 99%

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

et al. 2011

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We report on the interplay between the short-range order of molecules in the liquid phase of 1,1,2,2-tetrachloro-1,2-difluoroethane and the possible molecular conformations, trans and gauche. Two complementary approaches have been used to get a comprehensive picture: analysis of neutron-diffraction data by a Bayesian fit algorithm and a molecular dynamics simulation. The results of both show that the population of trans and gauche conformers in the liquid state can only correspond to the gauche conformer being more stable than the trans conformer. Distinct conformer geometries induce distinct molecular short-range orders around them, suggesting that a deep intra-and intermolecular interaction coupling is energetically favoring one of the conformers by reducing the total molecular free energy.

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“…These materials have no intrinsic structural length scale despite the interatomic distance, as can be probed by measuring its static structure factor 1 or, equivalently, pair correlation function. It includes amorphous semiconductors like silicon, 2,3 oxide glasses like silica and silicate glasses, 4 metallic glasses, 5 and other disordered assemblies like colloidal glasses.…”

Section: Introductionmentioning

confidence: 99%

Vibration Modes and Characteristic Length Scales in Amorphous Materials

Tanguy

2015

JOM

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The numerical study of the mechanical responses of amorphous materials at the nanometer scale shows characteristic length scales that are larger than the intrinsic length of the microstructure. In this article, we review the different scales appearing upon athermal elastoplastic mechanical load and we relate it to a detailed study of the vibrational response. We compare different materials with different microstructures and different bond directionality (from Lennard-Jones model materials to amorphous silicon and silicate glasses). This work suggests experimental measurements that could help to understand and, if possible, to predict plastic deformation in glasses.

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Structure factor determination of amorphous materials by neutron diffraction

Cited by 33 publications

References 33 publications

Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction

Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction

Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

Vibration Modes and Characteristic Length Scales in Amorphous Materials

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