Fuels: a key factor to influence the luminescence properties of CaAl2O4: Dy phosphors

Abstract

Most commercially available phosphors are made from appropriately doped polycrystalline materials while the activation methods have often been examined, the impact of fuels on the host preparation and its effect on the final performance of the products has received less focus. This paper explores the use of various fuels in the synthesis of Dy-doped CaAl₂O₄ phosphors. Dysprosium-doped monoclinic CaAl₂O₄ phosphors were obtained at low temperatures (500 °C) by the process of combustion of the corresponding metal nitrate–fuel mixtures, over a period of 5 min. In this paper, attention has been paid to the influence of fuels on the luminescence properties of the phosphor sample which is prepared by solution combustion method. Dy-activated CaAl₂O₄ phosphor was synthesized by combustion technique using hydrazine, carbohydrazide, and urea as fuels. XRD analysis reveals that introducing a small quantity of rare earth ions into the raw materials did not alter the crystal structure of CaAl₂O₄. XRD result confirms the formation of the sample. Photoluminescence (PL) emission spectrum showed characteristic emission of Dy doped in the CaAl₂O₄ samples. The highest photoluminescence intensity was observed at a 0.02 mol% concentration of Dy. The PL spectrum exhibits wide peaks near 488 and 573 nm when excited at 347 nm. Mechanoluminescence (ML) and Thermoluminescence (TL) properties of the material have been emphasized. Various ML and TL curves have been recorded to assess which of the fuels yields the most efficient CaAl₂O₄: Dy compound. The prepared sample may be useful in TL dosimetry. In the present investigation it is found that urea is a better fuel for preparing CaAl₂O₄: Dy phosphors and enhances the ML and TL intensity of the sample.

Graphical abstract

PL emission spectra of CaAl2O4: Dy phosphors synthesized by urea, carbohydrazide and hydrazine, where urea provides the highest PL intensity, making it an optimal choice for enhancing optical performance.