Shining light on Pr-doped Bi(SiO) phosphors for wide-range high-temperature luminescent thermometers.

Non-contact optical thermometer has been propelled to the frontiers of research due to its non-invasive operation, high thermal sensitivity, and fast response. Herein, a novel, to our knowledge, class of Pr-doped Bi(SiO) (BSO) phosphors was developed to achieve advancing fluorescent ratiometric thermometry: having a maximum relative sensitivity () of ~3.54% K at 298 K, and sustaining an entire value beyond 1.59% K over the range of 298-468 K. The intriguing peak overlaps among Pr intra-4f emissions and BSO host emission (i.e., BiP → S), as well as the involved energy transfer (ET) mechanisms, were clearly distinguished for the BSO:Pr system. A temperature-stimulated ET from the BSO host to Pr ions was proved with greatly enhancing the entire emission intensities of Pr to 318.19% at 428 K relative to the initial value at 298 K, and in reverse reducing that of the BSO host to 10.54% versus the case at 298 K. Such a rapid changing mode of fluorescent intensity ratio of intra-4f emissions over host emission will strategically develop the desired wide-range high-temperature luminescent thermometers.