Luminescência e absorção fotoacústica do fósforo SrGa2O4 codopado por íons de Nd3+ e Cr3+

• Autor(a) principal: Lima, Ludiane Silva
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12871
• topic: Photoluminescence; Photoacoustic spectroscopy; Transition metals; Rare earth - metals; Energy transfer; Fotoluminescência; Espectroscopia fotoacústica; Metais de transição; Metais - terras raras; Transferência de energia; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA

Polycrystalline samples of SrGa2O4 codoped with Cr3+ and Nd3+ ions were stoichiometrically prepared by mixing powder materials SrCO3, Ga2O3, Cr2O3 and Nd2O3. The concentrations of Cr3+ and Nd3+ ions in the codoped system Sr(Ga1-x-yCrxNdy)2O4 followed two distinct situations: (i) The concentration of Nd3+ ion was fixed at 1%, which means, y = 0.01, and the concentrations of Cr3+ ion were 0%; 0.1%, 0.5%, 1% and 2%, thus, x = 0; 0.001; 0.005; 0.01 and 0.02; (ii) Subsequently, reversed the situation for a codoped system with 1% of Cr3+ ions (x = 0.01) and the concentrations of Nd3+ ion with the same values used for the first situation (y = 0; 0.001; 0.005; 0.01 and 0.02). The crystalline structure of the codoped sample was analyzed by X-ray diffraction measurements (XRD) and through of the measurements obtained in scanning electron microscopy (SEM). The diffraction patterns showed a single phase for doping only with Cr3+ ions related to the β-SrGa2O4 phase. For doped only with Nd3+ ions and codoped samples with Cr3+ and Nd3+ ions the diffraction patterns revealed the presence of two phases, β-SrGa2O4 and γ- SrGa2O4. The data were fitted by using the Rietveld Method for structural refinements and the lattice parameters were determined. The micrographs obtained in SEM confirmed the presence of the two phases, β-SrGa2O4 and γ-SrGa2O4. The luminescence of Cr3+ and Nd3+ ions in SrGa2O4 lattice was investigated by emission spectroscopy at room temperature through which we verified the energy transfer mechanism between the Cr3+ and Nd3+ ions. Moreover, photoacoustic spectroscopy measurements was performed and they confirmed the transitions identified in the emission spectra and supported in understanding of the formation of Cr4+ ions in the samples containing Cr3+ ions.