XANES Study of Si and Zr in Composite Hollow Spheres

LEANDRO ANDRINI; PABLO M. ARNAL; FÉLIX G. REQUEJO

LNLS, Campinas, SP, Brasil

Otro; Reunião Anual de Usuários (19º RAU); 2009

Laboratorio Nacional de Luz Sincrotron, LNLS

Zirconia is an extremely important material with wide-ranging applications including as a high-performance transformation-toughened structural engineering ceramic and as a solid electrolyte1, and has also found application as a catalyst and catalyst support, especially when durability to chemical attack is required (A. V. Chadwick et al., Chem. Mater. 13, 1219 (2001).). The Zr L2-L3 and Si K-edges XANES measurements were carried out at D04A-SXS beamline at LNLS. The preparation of nanocrystalline zirconia and hollows spheres (@ZrO2) were already reported elsewhere (Arnal, P. M. et al., Chemistry of Materials, 18 (2006)) In this work we report a XANES study of Zr and Si present in @ZrO2 to obtain information about the electronic and local morphological structure of Zr and Si. These hollow spheres are made of nanometer-sized zirconia domains surrounded at least partially by a Si-containing material. A pore structure extends from the inner surface, which defines the inner macropore, to the external surface of the spheres, allowing mater diffusion across the shell. (Arnal, P. M. et al., Angewandte Chemie Internation Edition, 45 (2006)) According to white line (WL) intensity and the feature of the Si K-edge absorption spectra, the Si atoms in @ZrO2 samples have similar neighborhood that Si in SiO2 and they are not forming ZrSiO4. The evaluation of the splitting at the WL of the Zr L2,3 XANES spectra of the samples indicates that, for low treatments temperatures (293 K), the local environment of Zr is similar to ZrO2, and for temperatures higher than 973 K, the phase of Zr in @ZrO2 samples is similar to BaZrO3, where Zr is octahedrally coordinated. 19ª Reunião Anual de Usuários do LNLS - RAU   9/2/2009 a 10/2/2009   LNLS, Campinas, SP     Prezado(a) Senhor(a) Leandro Rubén Andrini,   Temos o prazer de informar que seu trabalho "XANES Study of Si and Zr in Composite Hollow Spheres" submetido para a 19ª RAU foi aceito para apresentação na forma de pôster.   Os trabalhos deverão ser afixados no primeiro dia da reunião (09/02/2009) e ficarão expostos até o dia 10/02/2009. A numeração dos painéis seguirá de acordo com o nº da página onde se encontra o trabalho publicado no livro de resumos.   As dimensões máximas para o pôster são 130 cm de Altura x 90 cm de Largura.    A programação completa está disponível no site do LNLS (www.lnls.br).     Comissão Organizadora da 19ª RAU