Pleomorphic structural imperfections caused by pulsed Bi-implantation in the bulk and thin-film morphologies of TiO2

TL;DR

This study combines experimental and theoretical methods to investigate how pulsed Bi-implantation causes structural imperfections and different Bi incorporation behaviors in bulk and thin-film TiO2, revealing substitutional and clustering effects.

Contribution

It provides new insights into Bi-doping mechanisms in TiO2, highlighting the pleomorphic origin of chemical bonding and contrasting behaviors in bulk versus thin-film morphologies.

Findings

Bi substitutes Ti in bulk TiO2,

Bi forms metal-like clusters in thin films,

Different embedding mechanisms in bulk and thin-film TiO2.

Abstract

The results of combined experimental and theoretical study of substitutional and clustering effects in Bi-doped TiO2 hosts (bulk and thin-film morphologies) are presented. Bi-doping of the bulk and thin-film titanium dioxide was made with help of pulsed ion-implantation (E(Bi+) = 30 keV, D = 1 * 1017 cm-2) without posterior tempering. The X-ray photoelectron spectroscopy (XPS) qualification (core-levels and valence bands) and Density-Functional Theory (DFT) calculations were employed in order to study the electronic structure of Bi-ion implanted TiO2 samples. According to XPS data obtained and DFT calculations, the Bi -> Ti cation substitution occurs in Bi-implanted bulk TiO2, whereas in the thin-film morphology of TiO2:Bi the Bi-atoms have metal-like clusters segregation tendency. Based on the combined XPS and DFT considerations the possible reasons and mechanism for the observed effects are discussed. It is believed that established peculiarities of bismuth embedding into employed TiO2 hosts are mostly the sequence of pleomorphic origin for the formed "bismuth-oxygen" chemical bonding.