Microwave-assisted hydrothermal synthesis followed by heat treatment: A new route to obtain CaZrO3

Autor(es)

Macedo, Jr., Wagner D. ^[1] ; Souza, Agda E. ^[1] ; Santos, Gleyson T. A. ^[1] ; Teixeira, Silvio R. ^[1] ; Longo, Elson ^[2]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Dept Phys, BR-19060900 Sao Paulo - Brazil

^[2] Fed Univ Sao Carlos UFSCar, CDMF CEPID, BR-13565905 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: CERAMICS INTERNATIONAL; v. 44, n. 1, p. 953-958, JAN 2018.
• Citações Web of Science: 4

Resumo

CaZrO3 nanoparticles were obtained by a new synthesis route: nucleation using the microwave-assisted hydrothermal method (MAH) and crystallization by heat treatment. Structural characterization by X-ray diffraction (XRD) was performed for the synthesized material and after heat treatment at 700, 800, 900, 1000 and 1200 degrees C. At 800 degrees C, the lakargite phase crystallization (CaZrO3) starts and portions of the non-stoichiometric calcium zirconium oxide phase were observed by XRD and Raman spectroscopy. A residual CaCO3 phase was present in the untreated samples. At 1200 degrees C, the well-crystallized stoichiometric and non-stoichiometric mixed oxide phases of CaZrO3 (crystallites of about 75 nm) were observed, along with particle agglomerates often in the micrometer range. The synthesized material was subjected to differential thermal analysis, which revealed carbonate degradation at approximately 695 degrees C, resulting in a small loss of mass of 6%. An endothermic reaction at 85 degrees C was observed for water loss, where there was a considerable amount of energy involved. This result showed the sensitivity to moisture absorption and adsorption processes of the CaZrO3 sample, obtained by the MAH route. UV-Vis spectroscopy showed the characteristic gap energies for the two phases, which were 2.9 (non-stoichiometric) and 4.9 eV (stoichiometric), values smaller than those obtained by usual synthesis routes. (AU)

• Processo FAPESP: 13/07296-2 - CDMF - Centro de Desenvolvimento de Materiais Funcionais
• Beneficiário: Elson Longo da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs