Photoluminescence behavior of the 'Sm POT. 3+' and 'Tb POT. 3+' ions doped into the 'Gd IND. 2''('WO IND. 4')IND. 3' matrix prepared by the Pechini and ceramic methods - Kodaira, Cláudia Akemi; Brito, Hermi Felinto de; Teotonio, Ercules Epaminondas de Sousa; Felinto, Maria Claudia França da Cunha; Malta, Oscar Loureiro; Brito, Giancarlo Espósito de Souza (Journal of the Brazilian Chemical Society, 2004)