# New Mcconnellite Ceramic Pigment as a Selective Solar Absorber: Effects of Microwave Firing and Rare Earth Doping

## TL;DR

This paper introduces a new black ceramic pigment, mcconnellite, as a selective solar absorber for solar collectors, with improvements through microwave firing and rare earth doping.

## Contribution

The first application of mcconnellite as a selective solar absorber in ceramic solar collectors is presented.

## Key findings

- Microwave firing and rare earth doping enhance mcconnellite's performance as a solar absorber.
- Quartz or anatase addition prevents pigment bluing in Zn-containing glazes.
- Lanthanide doping helps control pinhole defects and adjust IR cut-off wavelength.

## Abstract

CuCrO2 (mcconnellite) was synthesized using both the solid-state method and microwave dielectric firing. It was characterized as a novel black ceramic pigment for use in various industrial glazes. For the first time, the application of mcconnellite (CuCrO2) and its coloured glazes as selective solar absorbers (SSA) for integral ceramic solar collectors has been reported. The addition of quartz or anatase as colour modifiers was investigated to prevent the bluing of the pigment in Zn-containing glazes, a phenomenon associated with the exsolution of copper. Furthermore, doping with lanthanide oxides was explored to address two key challenges: controlling the formation of pinhole defects in porcelain glazes, which are linked to the destabilization of Cu+, and adjusting the IR cut-off wavelength to improve its performance as SSA.