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http://hdl.handle.net/1843/57129| Type: | Artigo de Periódico |
| Title: | Optical phonon modes and infrared dielectric properties of monoclinic CoWO4 microcrystals |
| Authors: | Roberto Luiz Moreira Rafael Mendonça Almeida Kisla Prislen Felix Siqueira Cíntia Grossi de Abreu Anderson Dias |
| Abstract: | The phonon characteristics of CoWO4 microcrystals with monoclinic Wolframite structure were investigated by far-infrared (IR) and Raman spectroscopies. Near-normal spectra were taken for IR light polarization along the principal b-axis (Au modes) and along several angles within the ac-plane (Bu modes). The IR spectra were analyzed with a generalized Drude–Lorentz model, and all predicted polar phonon modes were fully determined, including their symmetries, the dielectric Lorentz parameters and the non-orthogonal phonon polarizations for the Bu modes. Anomalous dispersion and negative values for the real and imaginary parts of the off-diagonal components of the dielectric tensor functions were identified and discussed under the light of the varying phonon polarization directions (spread out in the ac-plane). The obtained static and background dielectric tensors gave an average permittivity of 16.1 (at microwave region), refractive indices along the principal dielectric axes of 2.22, 2.33 and 2.44 (at 1 μm), the optical axes, and an estimated value for the biaxial angle of the crystal. Polarized Raman spectra on appropriate scattering configurations revealed the 18 non-polar gerade phonons of CoWO4 crystals, with their correct symmetries attributed. |
| Subject: | Fonons Dispositivos dielétricos Espectroscopia de infravermelho Cristais Raman, Efeito de |
| 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://dx.doi.org/10.1088/0022-3727/49/4/045305 |
| URI: | http://hdl.handle.net/1843/57129 |
| Issue Date: | 2016 |
| metadata.dc.url.externa: | https://iopscience.iop.org/article/10.1088/0022-3727/49/4/045305 |
| metadata.dc.relation.ispartof: | Journal of Physics D: Applied Physics |
| Appears in Collections: | Artigo de Periódico |
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