Fônons nos sistemas RVO4 e La1-xCexPO4

• Ano de defesa: 2006
• Autor(a) principal: Santos, Clenilton Costa dos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: RVO4; Vanadato de terras raras; RPO4; Fosfato de terras raras; Duplo fosfato; Espalhamento Raman
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/9653

In this work we present a Raman investigation of RVO4 (where R = Sm, Ho, Yb and Lu) and La1-xCexPO4 (where x = 0,00, 0,04, 0,16, 0,22, 0,32 and 1,00) compounds. Polarized Raman scattering measurements were carried out in the RVO4 compounds to obtain a better description of the room temperature phonons than those previously reported in literature. We observe that the frequencies of most of phonons increase with increasing atomic number (Z) of R. This behavior results from the lattice contraction when R goes from La to Lu. On the other hand, due to their dimensions and shape, unpolarized Raman scattering was used to investigate the room temperature phonon spectra of La1-xCexPO4 compounds. No appreciable changes were observed, indicating that the LaPO4 lattice is not substantially modified by Ce doping. However, some extra or additional phonons were observed. The origin of these modes comes probably from the activation of infrared modes due to the breakdown of symmetry rules.