Room temperature synthesis, Judd Ofelt analysis and photoluminescence properties of down-conversion K0·3Bi0·7F2.4:Eu3+ orange red phosphors

This work aims at studying optical properties of Eu3+ dopant in K0·3Bi0·7F2.4 host and seeking their applications. A series of orange red emitting K0·3Bi0·7F2.4:Eu3+ phosphors were synthesized via a chemical precipitation reaction method at room temperature, which is convenient, economical and less time consuming. XRD and Rietveld refinement results confirm the pure phase of as-prepared materials. The optimal doping concentrations are determined to be 40%mmol, and both of the corresponding concentration quenching mechanism have been validated to be dipole−dipole interactions. Additionally, the Judd-Ofelt theory was selected to study the local structure environment of the Eu3+ ions in the K0·3Bi0·7F2.4 host lattices and the tendency of J-O parameters (Ω2>Ω4) confirm the asymmetric environment around Eu3+ ions. The thermogravimetric analysis and activation energy results of K0·3Bi0·7F2.4:Eu3+ materials with high thermal stability exhibit promising performances for temperature sensor applications. Moreover, the temperature-dependent of samples are investigated in a large temperature range of 303–573 K to explore thermal quenching performance. Significantly, luminescent temperature sensing has been accomplished by specifically utilizing thermal quenching performance and high temperature sensitivity around 1.54 × 104 K−1 is achieved, which indicates that K0·3Bi0·7F2.4:Eu3+ fluorescent nanoparticles can be exploited for promising luminescent thermometer. Another important results are the K0·3Bi0·7F2.4:40%Eu3+ nanoparticles exhibiting orange red emission with the CIE coordinates (0.6226, 0.3747) and the luminescence photographs of K0·3Bi0·7F2.4:40%Eu3+ samples under UV lamp (365 nm) irradiation revealing obvious orange red. Besides, the color purity of orange red K0·3Bi0·7F2.4:40%Eu3+ phosphor is demonstrated to be about 98.4%, which indicate that the as-prepared K0·3Bi0·7F2.4:Eu3+ phosphors may be a candidate component applied in UV w-LEDs.