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Nascimento JFDL, Nobre FX, Batista FMC, Cabot A, Vendrell X, Mestres L, da Cunha Mendes O, Ferreira RD, Leyet Ruiz Y, Quaresma JNN. Synthesis of CaNb 2O 6 with a Rynersonite-like Structure: Morphology, Rietveld Refinement, Optical, and Vibrational Properties. Inorg Chem 2023; 62:16323-16328. [PMID: 37755155 DOI: 10.1021/acs.inorgchem.3c01311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
In this study, we report the easy and low-cost synthesis of calcium niobate (CaNb2O6) with the isomorphic structure of the Rynersonite mineral for CaTa2O6. The samples were prepared by the ball milling method at room temperature at a synthesis time of 0.5, 1, 2, 3, and 4 h. The structural analysis by XRD, Rietveld refinement, and vibrational Raman spectroscopy confirms all diffraction peaks and active mode characteristics of the pure phase of CaNb2O6 for the 3-h and 4-h samples, with a crystallite size of 22.5 and 23.2 nm, respectively. The optical band gap obtained was 3.18(2) eV (3-h sample), lower than the optical band gap for niobium oxide, characteristic of materials with strong photon absorption in the UVA region of the spectrum. The surface analysis by scanning electron microscopy reveals the obtention of several agglomerates of irregular particles ranging in the submicro and micro scales. Therefore, the present approach successfully obtained calcium niobate with the formula CaNb2O6 at a short synthesis time and room temperature.
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Affiliation(s)
- José Fábio de Lima Nascimento
- Graduate Program in Natural Resources Engineering in the Amazon, PRODERNA/ITEC/UFPA, Federal University of Pará, Campus Universitário do Guamá, Rua Augusto Corrêa, 01, Belém, Pará 66075-110, Brazil
| | - Francisco Xavier Nobre
- Federal Institute of Education, Science and Technology of Amazonas, Campus Manaus Centro, Rua Sete de Setembro, 1975, Centro, Manaus, Amazonas 69020-120, Brazil
- Programa de Pós-Graduação em Química, Universidade Federal do Piauí, Campus Ministro Petrônio Portella, Centro de Ciências da Natureza, Ininga, Piauí 64049-550, Brazil
- Programa Multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Universidade do Estado do Amazonas, Escola Superior de Saúde, Av. Carvalho Leal, 1777, Cachoeirinha, Manaus, Amazonas 69065-001, Brazil
| | - Francisco Marcos Costa Batista
- Catalonia Institute for Energy Research - IREC, Sant Adrià de Besòs, Barcelona 08930, Spain
- Department of Inorganic & Organic Chemistry, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Andreu Cabot
- Catalonia Institute for Energy Research - IREC, Sant Adrià de Besòs, Barcelona 08930, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona 08010, Spain
| | - Xavier Vendrell
- Department of Inorganic & Organic Chemistry, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Lourdes Mestres
- Department of Inorganic & Organic Chemistry, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Otoniel da Cunha Mendes
- FENTOMLAB, Universidade do Estado do Amazonas, Escola Superior de Tecnologia, Av. Darcy Vagas, 1200, Parque Dez de Novembro, Manaus, Amazonas 69050-020, Brazil
| | - Robson Dantas Ferreira
- Laboratório de Microscopia e Nanotecnologia, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Aleixo 69060-001, Brazil
| | - Yurimiler Leyet Ruiz
- Departamento de Engenharia de Materiais, Laboratório de Processamento de Materiais Tecnológicos (LPMaT), Universidade Federal do Amazonas, Instituto de Ciências Exatas, Rua Av. General Rodrigo Otávio Jordão Ramos, 1200, Coroado I, Manaus 69067-005, Brazil
| | - João Nazareno Nonato Quaresma
- Graduate Program in Natural Resources Engineering in the Amazon, PRODERNA/ITEC/UFPA, Federal University of Pará, Campus Universitário do Guamá, Rua Augusto Corrêa, 01, Belém, Pará 66075-110, Brazil
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Gribchenkova NA, Smirnov AS, Smorchkov KG, Belova EV, Alikhanyan AS. Thermodynamic Characteristics of Zinc Niobates Zn3Nb2O8, ZnNb2O6, and Zn2Nb34O87. p–x Diagram of the ZnO–Nb2O5 System. RUSS J INORG CHEM+ 2021. [DOI: 10.1134/s0036023621120044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Sayagués MJ, Krumeich F, Hutchison JL. Solid-gas reactions of complex oxides inside an environmental high-resolution transmission electron microscope. Micron 2001; 32:457-71. [PMID: 11163720 DOI: 10.1016/s0968-4328(00)00055-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In a gas reaction cell (GRC), installed in a high-resolution transmission electron microscope (HRTEM) (JEOL 4000EX), samples can be manipulated in an ambient atmosphere (p<50mbar). This experimental setup permits not only the observation of solid-gas reactions in situ at close to the atomic level but also the induction of structural modifications under the influence of a plasma, generated by the ionization of gas particles by an intense electron beam. Solid state reactions of non-stoichiometric niobium oxides and niobium tungsten oxides with different gases (O2, H2 and He) have been carried out inside this controlled environment transmission electron microscope (CETEM), and this has led to reaction products with novel structures which are not accessible by conventional solid state synthesis methods. Monoclinic and orthorhombic Nb(12)O(29) crystallize in block structures comprising [3x4] blocks. The oxidation of the monoclinic phase occurs via a three step mechanism: firstly, a lamellar defect of composition Nb(11)O(27) is formed. Empty rectangular channels in this defect provide the diffusion paths in the subsequent oxidation. In the second step, microdomains of the Nb(22)O(54) phase are generated as an intermediate state of the oxidation process. The structure of the final product Nb(10)O(25), which consists of [3x3] blocks and tetrahedral coordinated sites, is isostructural to PNb(9)O(25). Microdomains of this apparently metastable phase appear as a product of the Nb(22)O(54) oxidation. The oxidation reaction of Nb(12)O(29) was found to be a reversible process: the reduction of the oxidation product with H(2) results in the formation of the starting Nb(12)O(29) structure. On the other hand, the block structure of Nb(12)O(29) has been destroyed by a direct treatment of the sample with H(2) while NbO in a cubic rock salt structure is produced. This in situ technique has also been applied to niobium tungsten oxides which constitute the solid solution series Nb(8-n)W9(+n)O47 with 0< or =n< or =4. All of these phases crystallize in the threefold tetragonal tungsten bronze (TTB) superstructure of Nb(8)W(9)O(47) (n=0). In the main reaction, these phases decompose in a gas plasma (O2, H2 or He, p=20mbar) into WO(3-x), which evaporates and solidifies again near the irradiated crystallite, and (Nb,W)(24)O(64), which crystallizes in a 2a superstructure of the TTB type observed here for the first time in the system Nb-W-O. Nb(8)W(9)O(47), Nb(7)W(10)O(47) and Nb(6)W(11)O(47) always react in this way, independent of the applied gas. On the other hand, the treatment of Nb(5)W(12)O(47) (n=3) and Nb(4)W(13)O(47) (n=4) in an oxygen atmosphere often caused a different reaction: these phases have been oxidized and a heavily disordered bronze-type structure has been formed. The oxygen excess in these products is largely accommodated in segregated domains of WO(3).
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Affiliation(s)
- M J Sayagués
- Instituto de Ciencia de Materiales de Sevilla, C.S.I.C. c/ Américo Vespucio, s/n Isla de la Cartuja, 41092, Sevilla, Spain
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