Synergistic effect from the dual oxidation states of europium in the color-tuning of Ca3Mg3(PO4)4:Eu2+, Eu3+ thermometric phosphor

Ca3Mg3(PO4)4:Eu2+, Eu3+ phosphor was prepared by a sol-gel/Pechini method. The co-existence of Eu2+ and Eu3+ in the same matrix ensued in the color tuning of its overall luminescence emission with varying temperature. This feature was found to be suitable for non-contact temperature-sensing. The relative and absolute temperature sensitivity for this phosphor is superior to most of the previously reported optical thermometric phosphors. Ca3Mg3(PO4)4:Eu2+, Eu3+ phosphor was found to be most effective in the temperature range of 30 °C (303 K) to 250 °C (523 K). This phosphor finds potential application as temperature sensors in fire alarms and fire-safety protection devices.