Thermochromic luminescent nanomaterials based on Mn4+/Tb3+ codoping for temperature imaging with digital cameras

A new thermographic nanocrystalline Sr4Al14O25 :Mn4+, Tb3+ phosphor was developed including the optimization of the concentrations of both dopants and of the synthesis conditions. The combination of the thermally quenched luminescence from the Mn4+ ions to the almost temperature independent emission from Tb3+ provides a sensitive luminescent thermometer (SR=2.8%/oC at 150oC) with strong emission colour variability. In addition, a figure of merit for this luminescence thermochromism was proposed, as the relative sensitivities of the x and y CIE coordinates, which for this phosphor reaches at 150°C SR(x)=0.6%/oC and SR(y)=0.4%/oC, respectively. Non-contact thermal imaging was demonstrated with this phosphor using a single consumer digital camera and exploiting the ratio of red (R) and green (G) channels of the RGB images thereby confirming the high applicative potential of Sr4Al14O25 :Mn4+, Tb3+ nanocrystals for thermal sensing and mapping.