Investigation of the structure of beta-Tantalum

TL;DR

This study uses EXAFS measurements to determine that beta-tantalum has a disordered, low-symmetry structure best described by a beta-Uranium based model with 30 atoms per unit cell.

Contribution

The paper provides experimental evidence supporting a specific beta-Uranium based structural model for beta-tantalum, clarifying its local atomic arrangement.

Findings

Beta-tantalum is highly disordered.

The structure is consistent with a beta-Uranium based model.

The model has 30 atoms per unit cell and space group P42/mnm.

Abstract

The local structure of beta-tantalum was investigated by comparing experimental extended x-ray absorption fine structure (EXAFS) measurements with calculated spectra of proposed models. Four possible structure candidates were examined: a beta-Uranium based structure, a distorted A15 structure, a bcc-Ta based superlattice structure with N interstitials and a simple hcp structure. The local structural measurements were found to be consistent with the beta-Uranium based model containing 30 atoms per unit cell and having the space group P42/mnm. The thermal effect analysis on x-ray diffraction and EXAFS spectra, which reveals that beta-Ta is highly disordered, agrees with the low symmetry and anisotropic system of the beta-U model.