Photoluminescence investigations of Eu 3+ -doped LiPbB 5 O 9 as a red emitting phosphor for warm W-LED applications

LiPbB5O9:Eu3+ phosphors were synthesized via solid-state reaction technique and studied various properties. For the prepared LiPbB5O9:Eu3+ phosphors, structural and spectroscopic characterizations were performed. Crystallinity nature of LiPbB5O9:Eu3+ phosphors was investigated from X-ray diffraction (XRD) analysis. Functional group investigations and maximum phonon energies of LiPbB5O9:Eu3+ phosphor were studied via Fourier transform infrared spectroscopy (FTIR) analysis. The thermogravimetric (TG-DSC) analysis for LiPbB5O9:0.07Eu3+ phosphor precursor was carried out in N2 atmosphere up to 800 °C. From the TG-DSC analysis, weight loss of the precursor with temperature and endothermic temperatures was studied. The optical band gaps of LiPbB5O9:xEu3+ phosphors for distinct Eu3+ ions concentrations were found using diffuse reflectance spectra (DRS) analysis. Excitation spectra of LiPbB5O9:Eu3+ phosphors were recorded at monitoring emission λemi = 614 nm wavelength, and emission spectra were recorded by monitoring excitation wavelength λexc = 393 nm. Energy transfer analysis of LiPbB5O9:Eu3+ phosphor was studied with the Blasse and Dexter theories. Fluorescence lifetime decay curves of 5D0 level of Eu3+ ions were analyzed at the above-mentioned excitation and emission wavelengths. From the emission spectral data, the CIE color coordinates and correlated color temperatures (CCT) were estimated. From the above investigations, it can be mentioned that LiPbB5O9:Eu3+ phosphors find significant applications in white light emitting diodes as a red emitting phosphor.