Sr4GaNbO8:Mn4+: a novel perovskite-structured red-emitting phosphor for a luminescence lifetime thermometer with good relative sensitivity and repeatability†

Through ion substitution, a new Sr₄GaNbO₈ perovskite structure with the same structure as Sr₄AlNbO₈ was successfully prepared, and a series of Sr₄GaNbO₈:Mn⁴⁺ phosphors were prepared using a high-temperature solid-state reaction method, after which the related concentration quenching mechanism was demonstrated to be electric dipole–dipole interaction. Furthermore, their thermal quenching characteristics were studied in detail over a temperature range from 303 K to 393 K. Based on obvious quenching of temperature-dependent decay curves, luminescence lifetime thermometers were further designed and developed. It was ultimately found that the maximum relative temperature sensitivity, absolute temperature sensitivity value and the minimum temperature uncertainty were 3.34% K⁻¹ at 393 K, 4.15 μs K⁻¹ at 303 K and 0.09 K at 393 K, respectively. Moreover, Sr₄GaNbO₈:Mn⁴⁺ maintained high stability with a maximum repeatability of 0.998 after multiple cycling tests. Multiple lifetime tests at the same temperature (333 K) revealed that the Sr₄GaNbO₈:Mn⁴⁺ phosphor exhibited strong stability. These results indicate that as-prepared Sr₄GaNbO₈:Mn⁴⁺ materials have significant potential for application in lifetime thermometers.