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http://hdl.handle.net/1843/57609| Type: | Artigo de Periódico |
| Title: | Investigation of polymorphism and vibrational properties of MnMoO4 microcrystals prepared by hydrothermal process |
| Authors: | Guilherme Mendes Martins Pâmela de Oliveira Coelho Kisla Prislen Félix Siqueira Roberto Luiz Moreira Anderson Dias |
| Abstract: | MnMoO4 microcrystals were synthesized by hydrothermal methods, and their structural, morphological, and vibrational properties were investigated. Conventional reactors and microwave-heated hydrothermal vessels were used to synthesize micrometer-sized MnMoO4 polymorphs at different temperature and time conditions. MnMoO4·H2O crystals were obtained in both reactors at temperatures below 200 °C, for times up to 24 h. These microcrystals belong to the triclinic P1̅ space group, and their 26 characteristic Raman bands were identified. A monoclinic MnMoO4 polymorph belonging to the P2/c structure was synthesized at temperatures higher than 200 °C only into conventional hydrothermal reactors. Polarized micro-Raman analyses have evidenced and allowed the assignment of 18 phonon modes predicted by group-theory calculations for this polymorph. Another MnMoO4 polymorph, within the monoclinic C2/m space group, was obtained by two processing routes: (i) heating the P2/c microcrystals at 600 °C; or (ii) heating the MnMoO4·H2O phase at 250 °C. For this monoclinic phase, 33 Raman-active bands were identified and assigned, in very good agreement with group-theoretical calculations, which predict 36 modes for the C2/m polymorph. Well-faceted, highly crystalline microcrystals were clearly observed by scanning and transmission electron microscopies, in perfect agreement with X-ray diffraction and Raman spectroscopic analysis. Finally, the appearance of characteristic phonon modes related to molybdenum in octahedral coordination suggests an incipient crystallization of a new, unreported α-MnMoO4 polymorph, at least in a short-range degree. |
| Subject: | Cristais Processos químicos Metais de transição Microscopia eletrônica |
| language: | eng |
| metadata.dc.publisher.country: | Brasil |
| Publisher: | Universidade Federal de Minas Gerais |
| Publisher Initials: | UFMG |
| metadata.dc.publisher.department: | ICX - DEPARTAMENTO DE FÍSICA ICX - DEPARTAMENTO DE QUÍMICA |
| Rights: | Acesso Restrito |
| metadata.dc.identifier.doi: | https://doi.org/10.1021/acs.cgd.8b00102 |
| URI: | http://hdl.handle.net/1843/57609 |
| Issue Date: | 2018 |
| metadata.dc.url.externa: | https://pubs.acs.org/doi/10.1021/acs.cgd.8b00102 |
| metadata.dc.relation.ispartof: | Crystal Growth & Design |
| Appears in Collections: | Artigo de Periódico |
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