Sensitive temperature reading from intensity ratio of Cr3+ and defects' emissions in MgTiO3:Cr3+

The luminescence thermometry based on the intensity ratio of Cr3+ and host emissions in the Cr3+ activated MgTiO3 phosphor powder is demonstrated over the 100-350 K temperature range. Phosphor was prepared by a two-step procedure based on the sol-gel and molten salt methods. Rhombohedral crystal structure of the material is confirmed by X-ray diffraction analysis, and the mean crystallite size of the powder was calculated to be similar to 32 nm. Morphology was investigated using scanning electron microscopy showing ellipsoidal, densely packed grains with 100 nm-150 nm average size. Photoluminescence emission spectra recorded under 385 nm excitation showed the broad host emission centered at similar to 485 nm and the Cr3+ emission around similar to 700 nm. The temperature-dependent emission spectra showed that host-emission intensity is almost temperature invariant, while the intensity of the Cr3+ emission rapidly decreases from 200 K to 350 K. Such behavior theoretically modelled and further applied for the ratiometric luminescence temperature sensing showed the maximal relative sensitivity of similar to 2.6% K-1, temperature resolution of 0.3 K, and excellent repeatability.

Automated summary

The luminescence thermometry based on the intensity ratio of Cr3+ and host emissions in the Cr3+ activated MgTiO3 phosphor powder shows good temperature sensing properties over the 100-350 K range. The powder prepared using sol-gel and molten salt methods has a small crystallite size and exhibits strong temperature-dependent emission spectra. This method demonstrates high sensitivity, temperature resolution, and repeatability for luminescence temperature sensing applications.