Thermal diffuse scattering analysis of Ag₂O binary system via X-ray powder diffraction.

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• Diffuse scattering in X-ray diffraction patterns contains vital information about local atomic structure and disorder in crystalline materials.
• Pair distribution function (PDF) analysis is a common method for extracting local structural information, but Fourier transforms can introduce aberrations.
• Distinguishing static and dynamic disorder components from experimental data is challenging.

Purpose of the Study:

• To develop and validate a novel method for analyzing thermal diffuse scattering directly from X-ray powder patterns.
• To investigate the local atomic structure and dynamics of silver oxide (Ag₂O) using this new approach.
• To correlate experimental findings with theoretical calculations for force constants.

Main Methods:

• Analysis of thermal diffuse scattering directly on X-ray powder patterns using the Rietveld method.
• Integration of a correlated displacement model for atomic pairs.
• Experimental data collection using synchrotron radiation and laboratory X-ray diffraction.
• Application of an Einstein model and density functional theory (DFT) for calculating force constants.
• Comparison with *ab initio* molecular dynamics simulations.

Main Results:

• The study successfully analyzed thermal diffuse scattering directly from Ag₂O powder patterns.
• Experimental force constants obtained using the Einstein model showed good agreement with DFT and *ab initio* simulations.
• The dynamic structure of Ag₂O was revealed to be complex, with anisotropic phonon dispersion and soft phonon modes.
• These dynamic features explain the observed significant atomic displacement parameters.

Conclusions:

• The proposed method offers a direct approach to analyze thermal diffuse scattering, bypassing Fourier transform limitations.
• The findings elucidate the complex dynamics and local forces within Ag₂O, linked to its structural disorder.
• This technique is applicable to various binary and complex crystalline systems for understanding local dynamics via X-ray diffraction.