The MRO-accompanied modes of Re-implantation into SiO2-host matrix: XPS and DFT based scenarios

TL;DR

This study explores various Re-implantation scenarios into SiO2 using XPS and DFT, revealing different impurity configurations, defect formations, and structural distortions depending on Re concentration levels.

Contribution

It introduces detailed Re-implantation modes into SiO2, combining experimental XPS data with DFT modeling to elucidate atomic and electronic structures at different impurity concentrations.

Findings

Low Re concentration leads to substitutional and interstitial impurities with Re2O7-like structures.

High Re concentration results in Re-metal clusters and ReO2-like structures.

Intermediate modes show growth of Re-impurity clusters and increased Re-metal contribution.

Abstract

The following scenarios of Re-embedding into SiO2-host by pulsed Re-implantation were derived and discussed after XPS-and-DFT electronic structure qualification: (i) low Re-impurity concentration mode -> the formation of combined substitutional and interstitial impurities with Re2O7-like atomic and electronic structures in the vicinity of oxygen vacancies; (ii) high Re-impurity concentration mode -> the fabrication of interstitial Re-metal clusters with the accompanied formation of ReO2-like atomic structures and (iii) an intermediate transient mode with Re-impurity concentration increase, when the precursors of interstitial defect clusters are appeared and growing in the host-matrix structure occur. An amplification regime of Re-metal contribution majority to the final Valence Band structure was found as one of the sequences of intermediate transient mode. It was shown that most of the qualified and discussed modes were accompanied by the MRO (middle range ordering) distortions in the initial oxygen subnetwork of the a-SiO2 host-matrix because of the appeared mixed defect configurations.