Synthesis and PL Study of SrS : Eu Phosphor

 Abstract

The present paper reports the Synthesis and Photoluminescence study of SrS Phosphor doped with  Eu ions synthesized under reduced atmosphere at 9500C for one hour. Photoluminescence spectra were recorded at room temperature using Spectrofluorophotometer with the  Xenon lamp as excitation source at M.S.U., Baroda. The phosphor was characterized for XRD, SEM,FTIR  and particle size analysis
Keywords: XRD, SEM, Photoluminescence, FTIR and particle size analysis.

 INTRODUCTION

The work presented in this Paper consists of the experimental results of the SrS : Eu phosphors synthesized using Solid State Reaction.  The present display phosphor requirement are for energy saving lamps of LEDs which are widely used  globally.Therefore it is considered the present phosphor synthesis will help the local industry to use the indigenously developed materials. By considering the application potential, the following phosphor was   prepared and studied for photoluminescence and characterized.

The present paper reports the Synthesis and Photoluminescence study of SrS phosphor doped with  0.05 mole% of Eu ions. Strontium Carbonate and Sulphur were taken as starting compounds in a statiometry of 2:3 to prepare SrS. The starting compounds along with Europium oxide as a dopant were taken in to a agate mortar and pestle. They were mixed and grounded for one hour to make a fine powder with intermediate mixings and groundings. The obtained powder was taken into a alumina crucible and heated in a muffle furnace under reduced atmosphere at 9500C for one hour. Photoluminescence spectra were recorded at room temperature using Spectrofluorophotometer having Xenon lamp as excitation source, and characterized for SEM, XRD, FTIR and particle size analysis. 

PL Study:  fig.1 is excitation spectra of  Sr S : Eu, monitored at 600nm. The phosphor color is pale pink. It is interesting to note that there are two absorption bands from 240nm to 300nm peaking at 250nm, 280nm and another band 400nm to 580nm,  peaking around 540nm. PL of this phosphor was studied for the following excitations 254nm, 264nm, 272nm, 430nm ,450nm, 464nm, 470nm, 490nm, 543nm, 570nm.  So, what ever the excitation mentioned above the PL emission from Sr S:Eu phosphor are observed in the range from  520nm to 675nm with a peak  at 600nm. It is  interesting to note that the main PL peak at 600nm with  254 nm excitation was at 140 a.u., which increases almost 3 times for the excitation of 272nm and which was in UV  absorption. In the second band excitation i.e., blue to green 430nm to 570nm the intensity at 600nm gradually increases from 120 to 165 a.u.

XRD: It Fig.3 shws the EDS and XRD of Sr S:Eu (0.05). It is clear from XRD that the Phosphor is having crystalline nature having single phase when compared to JCPDS data.

SEM: Fig. 4 is SEM of Sr S:Eu (0.05).It is clear from the SEM, the average size of phosphor particle may be around 12-15 µm. Agglomerations of the phosphor material is seen from the SEM photograph.

Fig. 5 is FTIR of Sr S:Eu (0.05). From FTIR , the peaks at 698, 863,1437 and 1774  cm-1attributed to metal oxide stretching.

Fig. 6 is the particle size histogram of Sr S:  Eu 0.05). It is observed that various sized particles having sizes of 15 μm , 80 μm , and 300 μm  , of various percentages are present. From the data the average surface area of the phosphor particles of 1 Gram was found to be 0.672m2.

Sr S: Eu  synthesized in reducing  atmosphere having been stabilized in 2+ states of Europium (5D2→ 7F0 transition of Europium)  which  emitted a broad emission from 550nm to 650nm with a peaking at 600nm.

After careful study it is suggested, this phosphor will be a good candidate for  LED application to generate white  light from  blue  Semiconductor LED as a excitation source.

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