Development of red luminescent nanocomposite based on calcium doped -Zn₂SiO₄ nanoparticles embedded in silica matrix

Nanocomposite based on alpha-Zn2SiO4:Ca nanoparticles embedded in silica matrix was synthetized by sol-gel method followed by thermal treatment at high temperature. The structural, morphological and optical properties were investigated. XRD analysis presents weak willemite peaks at 600 degrees C which has become clearer at 1200 degrees C with a grain size of about 60 nm. Optical analysis reveals a decrement in bandgap value from 5.44 eV to 5.24 eV after the incorporation of calcium ions (Ca2+). The PL spectrum presents two emission bands in red region. The most intense one appears at 735 nm and can be attributed to Non Bridging Oxygen Hole Center (NBOH) emission while the second, located at 685 nm, is attributed to silanol group Si-OH. The obtained results prove that, the incorporation of calcium in the nanocomposite enhance the creation of very active deep centers promising for many advanced technological applications.