Local structure and dynamics of tungsten oxide-based glasses: insights from concurrent neutron diffraction and Compton scattering

Abstract

In this work, following our previous work on molybdate glasses, we employ a combination of neutron diffraction and neutron Compton scattering, augmented by ab initio harmonic lattice dynamics and Reverse Monte Carlo modelling to characterise the force-constant disorder in the tungsten oxide-based glasses. Specifically, we discuss the correlations between the average interatomic force constant magnitudes inferred from neutron Compton scattering and the glass formation ability, measured in terms of the value of the glass transition temperature, as well as the average bond-lengths and interatomic distances obtained from diffraction data analysis. Moreover, we provide a comparative analysis of the widths of force-constant distributions of individual atomic species in glasses and their precursor metal oxides based on the distributions of the widths of nuclear momentum distributions. Furthermore, we assess the degree of softening of atom-projected vibrational densities of states induced by the force-constant disorder in the glasses.

Force constant disorder in the Ni44Nb56 bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

“…Similar values of the effective force constants correlate with similar average first-neighbour interatomic distances, or even similar atomic coordination, as revealed by the recent joint DINS and neutron diffraction study of the positional, isotopic mass and force constant disorder in molybdate and tungsten-oxide based glasses [54,55]. These recent DINS and neutron diffraction results are in accordance with the results of the modelling of dynamical properties of disordered alloys [19,[112][113][114][115][116].…”

“…The standard deviations (widths) of NMDs are proportional to the Boltzmann population-weighted first moments of the atom-projected vibrational densities of states (apVDOSs), and the variances of NMDs can be used to obtain the values of vibrational zero-point energies (ZPEs) [49][50][51][52]. Moreover, as recently shown [53], the NMD widths can be related to effective interatomic force constants, and thus DINS can be employed to study force constant disorder [54,55].…”

Hydrogen Spillover in Tungsten Oxide Bronzes as Observed by Broadband Neutron Spectroscopy

“…Despite the limitation of the Trotter approximation in the limit of zero K [29], Formula (3) has been successfully applied to the description of the mean force in polycrystalline and amorphous ice at 100 K [29] and in the investigation of the local dynamics of tungsten oxide-based glasses at RT [115].…”