Thermally stimulated luminescence of oxygen-deficient zirconia nanotubes

TL;DR

This study investigates the thermally stimulated luminescence of oxygen-deficient zirconia nanotubes, revealing specific emission bands and trap states related to oxygen vacancies, which are relevant for energy detection and storage applications.

Contribution

It provides the first spectrally resolved TSL analysis of oxygen-deficient ZrO₂ nanotubes, identifying emission bands and trap energies associated with intrinsic defects.

Findings

Identified two emission bands at 2.5 and 2.8 eV linked to T and F+ centers.

Discovered four TSL peaks with activation energies of 0.7-0.8 eV.

Proposed a band diagram explaining the role of oxygen vacancies and interstitials in TSL processes.

Abstract

ZrO$_2$ nanotubular arrays with intrinsic defects are a promising solid-state basis for the development of devices for detecting, storing, and converting energy. Layers of the self-ordered zirconia nanotubes of 5 $\mu$m length and 30 nm diameter, containing oxygen vacancies and their complexes, have been synthesized by anodic oxidation. The spectrally resolved TSL (thermally stimulated luminescence) above room temperature for the samples exposed by UV-irradiation with an energy of 4.1 eV have been studied. Two emission bands with maxima near 2.5 and 2.8 eV, associated with radiative relaxation of T and F+ centers, respectively, have been found. An analysis of the measured glow curves within the framework of general order kinetics established the presence of four TSL peaks caused by charge carriers traps with activation energies of 0.7 - 0.8 eV. A band diagram is proposed to explain the role of optically active centers based on electron (vacancies in positions of three- and four-coordinated oxygen) and hole (interstitial oxygen ions) traps in observed TSL processes during the irradiation and the followed heating of anion-deficient ZrO$_2$ nanotubes.