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Several Aluminium coumarinolates doped with various amounts of quinoline were studied. Normally pure coumarin along with the chelates show weak luminescence and the emission is observed around 450 nm along with emission around 350nm. Therefore such chelates don’t find any practical applications. Adding quinoline in small amount affects the emission and excitation of Al-Coumarin significantly. In most of these coumarinolates the emission is observed in blue green region with the excitation shifted in blue region. Of the several samples, sample doped with 40% quinoline shows the most intense emission. Thus this phosphor having intense emission along with good overlap of excitation with the near UV to blue emission of GaN based LED will find application as white phosphor in PCLED applications. The results are discussed in this paper. [ABSTRACT FROM AUTHOR]

Coumarin (2H-chromen-2-one) is a perfumed organic chemical compound in the benzopyrone chemical class. It is a colorless crystalline substance in its standard state and is also a natural substance found in many plants. The survey shows, though several coumarin chelates were prepared but its luminescence was not studied. We have synthesized Mg, Ca and Sr chelates of coumarin by simple chemical synthesis method. The effect of coumarin on the photoluminescence properties was studied. The results are discussed in this paper.The alkaline earth coumarinolates shows well defined XRD peaks which suggest that all the complexes are crystalline in nature. The careful observations of the XRD pattern shows that all the patterns are more or less the same. The only change is the relative intensities of the observed lines. The alkaline earth coumarinolate shows intense luminescence compared to pure coumarin. The emission and excitation was found to be red shifted compared to pure coumarin and is observed at 500 nm and 400 nm respectively. Of all the alkaline earth coumarinolates, Sr-Coumarinolate shows the most intense emission. [ABSTRACT FROM AUTHOR]

The effects of synthesis conditions on the luminescence properties of Eu2+ doped barium borophosphate phosphors are investigated. BaBPO5-Eu is synthesized using conventional solid state synthesis method and is subjected to different heating treatments. Effect of different heat treatments on the various luminescent properties such as photoluminescence, optically stimulated luminescence and thermoluminescence were studied. It is observed that heating treatment has profound effect on the OSL_TL properties of the material. The preliminary investigations put forward this material as good TL-OSL phosphor, with good sensitivity and dose linearity in the 0.1Gy to 1 Gy dose range. The observed sensitivity is 20% compared to that of commercial Al2O3:C (Landaur Inc.). After the initial decrease of OSL signal within 24 hrs no significant decrease in signal with time is observed. The preliminary investigation shows that the Eu doped BaBPO5 will be a good high Z OSL material and may find applications particularly in X-ray imaging techniques. [ABSTRACT FROM AUTHOR]

NaCl:Ca,Cu,P NaCl:Mg,Cu,P OSL phosphors are synthesized. Intense OSL is observed in these samples which is 14 times more than Al2O3:C. Same samples coated with PVA(poly vinyl actetae) polymer also show similar OSL properties and these coated samples are found to be less susceptible to the moisture due to protected layer of hydrophobic polymer. These coated samples may be useful as OSL dosimetersdue to high sensitivity and less or no susceptibility to moisture. [ABSTRACT FROM AUTHOR]

In this work enhancement of SrF2:Ce nanophosphor which was synthesized by co-precipitation method is presented. Synthesized phosphor was characterized by SEM and PL measurements. Average particle size is found to be in the range 150nm-200 nm and PL studies showed emission peaks at 330nm,360nm,380nm when samples were excited by 254nm. The observed double humped emission is characteristic emission of Ce3+ similar to that observed in bulk SrF2. However under identical condition it is observed that intensity of emission get enhanced and is about nearly 1.75 times in Ce3+ doped SrF2 nanocrystals than the bulk. [ABSTRACT FROM AUTHOR]

Now a days red emitting Mn4+ activated dialkali fluorosilicate phosphors have found applications in solid state lighting and displays. In this paper we describe development of K2SiF6 phosphor doped with Mn synthesized by simple method using Si metal powder with addition of oxidizing agent KMnO4. The photoluminescence spectra of K2SiF6:Mn show that emission is in the red region. In addition to this we studied LED spectra by coating the LED with phosphor mixed in different proportions with epoxy. [ABSTRACT FROM AUTHOR]