Application of Calcium Aluminate Doped with Mn and Cr in Optical Thermometry

Optical thermometers are advantageous for temperature measurement in electromagnetic fields and aggressive environments; however, their composition mostly relies on materials doped with expensive and resource-limited rare earth ions.

In this article, we describe the application of calcium aluminate doped with transition metal ions (Mn²⁺ and Cr3+) in optical thermometry, employing optical fibres for signal transmission. Upon excitation with 450 nm laser diode radiation, changes in the luminescence of Mn²⁺ ions in the 500–550 nm band are followed along with changes in the Cr³⁺ band at 750–800 nm.

The application has been tested in the temperature range from 20 °C to 800 °C. The temperature dependence of Cr³⁺ luminescence encompasses the high-temperature range, whereas the luminescence band of Mn²⁺ ions gives an increase in the total intensity and provides a more consistent change in the range from 400 °C to 550 °C.