Synthesis and emission characteristics of rare earth ions (Eu3+ and Tb3+) doped calcium orthogermanate phosphors

Abstract

In this study, rare earth ions (Eu3+ and Tb3+) doped calcium orthogermanate (Ca2GeO4) phosphors were synthesized through the high temperature solid-state route. PL (Photoluminescence), FTIR (Fourier transform infrared spectroscopy), SEM (Scanning electron microscopy), EDS (Energy dispersive spectroscopy) and PXRD (Powder X-ray diffraction) techniques were used to characterize all the prepared powder samples. The PXRD results of the samples give an orthorhombic phase system. The SEM-EDS measurements are used to confirm the doping of europium and terbium ions into the Ca2GeO4 lattice. The vibrational characteristics of the proposed phosphors are investigated from FTIR spectra. As per the PL studies, the Eu3+ and Tb3+ activated Ca2GeO4 phosphors are exhibited a prominent red emission at 610 nm and bright green emission at 547 nm under 244 nm and 229 nm excitation wave lengths respectively. The obtained results are ascribed to the ED (Electric Dipole) transition and MD (Magnetic Dipole) transitions 5D0 → 7F2 and 5D4 → 7F5 of europium and terbium ions respectively. The CIE diagram illustrates the emission colors of the synthesized phosphors which are given as red and green emission regions. Based on obtained results, the prepared phosphors may be suitable for solid state light and display devices.