Dellafossite CuAlO2 film growth and conversion to Cu–Al2O3 metal ceramic composite via control of annealing atmospheres

Abstract

In this work we demonstrate simple techniques to form well crystallised CuAlO 2 powders and thick films from CuO and boehmite or alumina, using a novel molten salt painting process. We examine the formation mechanism using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray 15 spectroscopy and in situ high temperature X-ray diffraction and find that the annealing atmosphere plays a critical role. From this we develop a method to create Cu-Al 2 O 3 conductive metal-ceramic composite materials with novel morphologies via the thermal decomposition of CuAlO 2 precursor films.

Copper‐alumina nanocomposites derived from CuAlO2: Phase transformation and microstructural coarsening

“…CuAlO 2 is a p‐type electrical semiconductor, and thin films have been shown to be optically transparent in the visible range, suggesting applications to optical electronics. Byrne et al have studied the synthesis of CuAlO 2 powder by solid‐state reaction between CuO and boehmite, and the subsequent reduction of delafossite thin films to copper and alumina. Another technological area in which Cu‐Al‐O materials have received increased attention is that of chemical looping combustion (CLC) reactions …”

The luminescent properties of CuAlO2

“…The origins of the spinel impurity are discussed in more detail elsewhere. 11,20 In both lm type samples the strongest peak intensity of the phase impurities corresponded to the strongest peak intensity of their corresponding PDF database entry. Given the texture of the CuAlO 2 was along an axis which has approximately halve the maximum peak intensity, the relative peak ratios may overestimate the phase impurities present.…”

“…11 In brief, aluminium isopropoxide was added in small portions to DI-H 2 O preheated to 80 C under vigorous stirring. CuO powder was then added to the resultant Boehmite gel.…”

“…[2][3][4][5][6][7][8] Thin lms have also been prepared by sputtering, using pulsed laser deposition from CuAlO 2 targets made by high temperature methods, and by interfacial reactions. [7][8][9][10][11] Additionally, more exotic methods such as polymer assisted deposition and fungus assisted synthesis have also been demonstrated. 12,13 Despite this rapid advance, many questions remain, particularly with respect to the intrinsic band gap and optical properties of this material.…”

Microstructure evolution of a Cu and θ-AI2O3 composite observed by aberration corrected HAADF-STEM

“…Delafossite-structured CuAlO2 is a p-type transparent semiconductor that is of interest for optoelectronic applications [1]. The stability of thick film [2] and bulk [3] CuAlO2 has been examined in varying atmospheres where novel metal-ceramic composite microstructures were observed to form during reduction. These composite microstructures, consisting of nano-scale metallic copper and θalumina are expected to provide interesting combinations of mechanical and electrical properties.…”