Abstrait

Photoluminescence Studies of Europium (III) Doped Di-Barium Magnesium Silicate Phosphors

Ishwar Prasad Sahu, Ravi Shrivastava

Di Barium Magnesium Silicate (Ba2MgSi2O7) doped with various concentrations (0.2, 0.5, 1.0, 2.0 and 2.5 mol %) of Europium (Eu3+) were prepared using solid-state reaction technique. To confirm the proper preparation and the phases available, an X-ray diffraction pattern of the sample with optimal PL concentration was recorded. The recorded sample was matched significantly with crystallographic open database card No. 96- 900-6941 reported specifically for Ca2MgSi2O7 with a Figure of Merit (FoM) of 0.8051. This FoM confirmed the proper preparation of the sample. Rietveld lattice parameter refinement process using Celref V.2 was carried out for estimating the various crystallographic information of the prepared sample. The prepared samples underwent Photoluminescence (PL) studies. The excitation spectrum, which was monitored at 620 nm, exhibited two distinct peaks centred at 294 nm and 365 nm respectively. Therefore, the emission spectra were recorded at an excitation wavelength of 294 nm. The emission spectra expressed the prominent peaks centred at 592 and 612 nm are attributed to 5D0 →7F2 of Europium (III) ions accommodated at various lattice sites having different energies, whereas peak centred at 633 nm is due to 5D0 →7F3 transition of Europium (III). Sample with a dopant concentration of 2 mol % expressed the maximum PL intensity. Overall emission was found in the red colour region which was confirmed using a CIE chromaticity diagram with coordinate (0.611, 0.387). Critical distance for energy transfer in the concentration, beyond which concentration quenching occurred in PL spectra, was calculated. In this case, the critical distance was found to be 19.34 Å, therefore the mechanism involved in concentration quenching of Ba2MgSi2O7 doped with 2.0 mol % of Europium (III) must be only multipole-multipole exchange whereas the exchange interaction is ineffective.