A Potential Candidate for Lamp Phosphor: Eu3+ Activated K2Y2B2O7

The novel phosphor K2Y2B2O7 doped with europium is studied for its photoluminescence properties. The studies show that the phosphor gives strong red emission (PL) at 613？nm related to 5D0-7F2 transition of Eu3+ under the 260？nm excitation (PLE) related to the charge transfer (CT) from the 2p orbital of the O2？ ions to the 4f orbital of Eu3+ ions with CIE coordinates ( ; ). The results of PL and PLE spectra indicate the applicability of K2Y2B2O7:Eu as a red component in lamp phosphor. The phosphor is characterized through XRD pattern analysis, and morphology is explained on the basis of SEM image. Optimum concentration of Eu3+ required for the highest intensity of emission is also studied. 1. Introduction Borates as host for light emitting materials under UV excitation have attracted much attention. The reason behind their being in a focus of research is their variety of structure types, transparency to a wide range of wavelengths, and high optical quality [1–4]. Also borates possess excellent properties as host due to the inherent attributes of the large band gap and covalent bond energy. A variety of borate host materials doped with rare earth and other ions have been studied and reported [5]. Moreover, B–O bond generally has no absorption in near UV region and has absorption in deep UV region because of its large covalent bond energy. Some previous works show that Eu3+ doped borates exhibit relatively strong absorption in the UV region and intense red emission with good color purity [6, 7]. Recently the alkali earth metal (M) yttrium borates (M2Y2B2O7) have been well known hosts for luminescent material with better crystallinity, lower synthesis temperature, and higher radiation efficiency, as compared to the corresponding simple alkali earth metal borates [8]. The Na2Y2B2O7 is an excellent host for luminescent materials which supports all the possible trivalent rare earth dopants and shows intense emission from violet region to red region [9]. In the present work, we investigate, for the first time, the photoluminescence characteristics of Eu3+ doped K2Y2B2O7. The purpose of replacing the mostly studied Na+ by K+ is to find the ion type dependence of Eu3+ luminescence in M2Y2B2O7 host. The photoluminescence properties of the synthesized materials were studied using a fluorescence spectrometer (Hitachi F-7000). 2. Experimental 2.1. Sample Preparation The powder samples of the phosphor K2Y2B2O7 with different concentrations of Eu3+ (0.001, 0.002, 0.005, 0.01, and 0.02) have been prepared by solution combustion technique. The method is based on the