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Determination and refinement of crystal structure of pyrochlore group minerals

Grant number: 08/04984-7
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): September 01, 2008
Effective date (End): December 31, 2010
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal researcher:Javier Alcides Ellena
Grantee:Marcelo Barbosa de Andrade
Home Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The pyrochlore-group of minerals comprises cubic Nb-, Ta- and Ti-bearing oxides, with general formula A2B2X6Y and space group Fd3m. They are important source of niobium and tantalum and display technological importance in a diverse range of applications, including fast ion conductors, electrocatalysts, resistors, sensors and nuclear waste disposals. Several minerals and synthetic compounds have the pyrochlore structure. New microprobe analyses for Brazilian occurrences of pyrochlore-group minerals were obtained during the doctorship grade thesis developed by the proponent of this project, six from pegmatites [Morro Redondo, Coronel Murta, Minas Gerais; Jonas (today Fiote), Conselheiro Pena, Minas Gerais; Volta Grande, Nazareno, Minas Gerais; Ipê, Marilac, Minas Gerais; Ponte da Raiz, Santa Maria de Itabira, Minas Gerais; and Quixabá, Frei Martinho, Paraíba] and one from carbonatite [Jacupiranga mine, Cajati, São Paulo]. These data were used for discussion of ideas about new nomenclature schemes for the pyrochlore-group minerals. In this project we will obtain single-crystal structure data for the studied minerals in a 4-cicle goniometer. The structures will be determined by the heavy atom method or direct methods and the structure will be refined by the least-square method. (AU)

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Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ANDRADE, MARCELO B.; ATENCIO, DANIEL; MENEZES FILHO, LUIZ A. D.; ELLENA, JAVIER. THE CRYSTAL STRUCTURE OF A MICROLITE-GROUP MINERAL WITH A FORMULA NEAR NaCaTa2O6F FROM THE MORRO REDONDO MINE, CORONEL MURTA, MINAS GERAIS, BRAZIL. CANADIAN MINERALOGIST, v. 49, n. 2, p. 615-621, . (09/09125-5, 08/04984-7)
ANDRADE, MARCELO B.; ATENCIO, DANIEL; CHUKANOV, NIKITA V.; ELLENA, JAVIER. Hydrokenomicrolite, (square,H2O)(2)Ta-2(O,OH)(6)(H2O), a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. AMERICAN MINERALOGIST, v. 98, n. 2-3, p. 292-296, . (09/09125-5, 11/22407-0, 08/04984-7)
ATENCIO, DANIEL; ANDRADE, MARCELO B.; CHRISTY, ANDREW G.; GIERE, RETO; KARTASHOV, PAVEL M.. THE PYROCHLORE SUPERGROUP OF MINERALS: NOMENCLATURE. CANADIAN MINERALOGIST, v. 48, n. 3, p. 673-698, . (09/09125-5, 08/04984-7)
ATENCIO, DANIEL; CONTREIRA FILHO, REYNALDO R.; MILLS, STUART J.; COUTINHO, JOSE M. V.; HONORATO, SARA B.; AYALA, ALEJANDRO P.; ELLENA, JAVIER; DE ANDRADE, MARCELO B.. Rankamaite from the Urubu pegmatite, Itinga, Minas Gerais, Brazil: Crystal chemistry and Rietveld refinement. AMERICAN MINERALOGIST, v. 96, n. 10, p. 1455-1460, . (09/09125-5, 08/04984-7)
ANDRADE, M. B.; ATENCIO, D.; PERSIANO, A. I. C.; ELLENA, J.. Fluorcalciomicrolite, (Ca,Na,square)(2)Ta2O6F, a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. MINERALOGICAL MAGAZINE, v. 77, n. 7, p. 2989-2996, . (11/22407-0, 08/04984-7)

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