Effect of Molten Salt Synthesis Processing Duration on the Photo- and Radioluminescence of UV-, Visible-, and X-ray-Excitable La2Hf2O7:Eu3+ Nanoparticles

Jose P Zuniga; Santosh K Gupta; Maya Abdou; Yuanbing Mao

doi:10.1021/acsomega.8b00987

Effect of Molten Salt Synthesis Processing Duration on the Photo- and Radioluminescence of UV-, Visible-, and X-ray-Excitable La₂Hf₂O₇:Eu³⁺ Nanoparticles

ACS Omega. 2018 Jul 12;3(7):7757-7770. doi: 10.1021/acsomega.8b00987. eCollection 2018 Jul 31.

Authors

Jose P Zuniga¹, Santosh K Gupta^{1

2}, Maya Abdou¹, Yuanbing Mao^{1

1}

Affiliations

¹ Department of Chemistry and School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, 1201 West University Drive, Edinburg, Texas 78539, United States.
² Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.

Abstract

Ln³⁺-ion-doped nanomaterials possess excellent properties because of their high color purity, longer excited state lifetime, narrow emission, and large Stokes shifts. In this work, we studied the correlation between the luminescence properties of La₂Hf₂O₇:Eu³⁺ pyrochlore nanoparticles (NPs) synthesized by a molten salt synthesis (MSS) method at a relatively low temperature and several MSS processing durations (from 1 to 12 h). We synthesized these NPs with different sizes just by changing the MSS processing time without subjecting to high temperature. Raman spectroscopy confirmed the stabilization of the ideal pyrochlore structure of the La₂Hf₂O₇:Eu³⁺ NPs at various MSS processing durations. The synthesized NPs exhibited bright red emission under UV, visible, and X-ray excitations, highlighting their potential applications as a red phosphor and scintillator. As the MSS processing time was increased from 1 to 12 h, a spectral change in the position of the charge transfer state in the La₂Hf₂O₇:Eu³⁺ NPs was observed. The sample processed by the MSS with a duration of 3 h exhibited the highest luminescence intensity, which was attributed to its optimum crystals with least surface defects and less agglomeration. The obtained results strongly and unambiguously indicate the brighter side of this new type of pyrochlore-based NPs in the fast growing field of solid-state lighting and scintillator materials.