Growth of Zr/ZrO2 core-shell structures by Fast Thermal Oxidation

TL;DR

This study demonstrates a resistive heating method to synthesize ZrO₂ core-shell structures on zirconium wires, thoroughly characterizing their morphology, composition, crystallinity, and luminescent defect properties.

Contribution

It introduces resistive heating as an effective synthesis technique for zirconium oxide core-shell structures and provides detailed characterization of their structural and luminescent properties.

Findings

Successful formation of Zr/ZrO₂ core-shell structures via resistive heating.

Identification of defect-related luminescent emissions in the oxide shell.

Confirmation of uniformity and defect distribution using PL and CL measurements.

Abstract

This research has been conducted to characterize and validate the resistive heating as a synthesis method for zirconium oxides (ZrO$_2$). A wire of Zr has been oxidized to form a core shell structure, in which the core is the metal wire, and the shell is an oxide layer around 10${\mu}$m thick. The characterization This research has been conducted to characterize and validate the resistive heating as a synthesis method for zirconium oxides (ZrO$_2$). A wire of Zr has been oxidized to form a core shell structure, in which the core is the metal wire, and the shell is an oxide layer around 10${\mu}$m thick. The characterization of the samples has been performed by means of Scanning Electron Microscopy (SEM). The chemical composition was analysed by X-ray spectroscopy (EDX). X-ray diffraction (XRD) and Raman spectroscopy have been used to assess crystallinity and crystal structure. Photoluminescence (PL) and cathodoluminescence (CL) measurements have allowed us to study the distribution of defects along the shell, and to confirm the degree of uniformity. The oxygen vacancies, either as isolated defects or forming complexes with impurities, play a determinant role in the luminescent processes. Colour centres, mainly electron centres as F, F$_A$ and F$_{AA}$, give rise to several visible emissions extending from blue to green, with main components around 2eV, 2.4-2.5eV and 2.7eV. The differences between PL and CL are also discussed.