Polarized Raman scattering and infrared spectroscopy of a naturalmanganocolumbite single crystal.

Moreira, Roberto Luiz; Rubinger, Carla Patricia Lacerda; Krambrock, Klaus Wilhelm Heinrich; Dias, Anderson

Polarized Raman scattering and infrared spectroscopy of a naturalmanganocolumbite single crystal.

Date

2010

Authors

Moreira, Roberto Luiz

Rubinger, Carla Patricia Lacerda

Krambrock, Klaus Wilhelm Heinrich

Dias, Anderson

Abstract

A well-ordered natural manganocolumbite single crystal of high quality was used as a prototype for the first determination of the polarized optical phonon modes of materials with the columbite structure. Electron microprobe and X-ray diffraction characterizations determined the chemical formula asMn0.60Fe0.40(Nb0.80Ta0.20)2O6, a cationic ordering of 81%, and the crystal structure as belonging to the Pbcn group. Polarized Raman and infrared-reflectivity spectroscopies on oriented samples allowed us to discern 50 of the 54 predicted gerade (Raman) modes and 31 of the 38 predicted ungerade (infrared) modes for the columbite structure. The selection rules were verified, and polarization leaks only due to slight sample misorientation, confirming the high purity, ordering and quality of the material. From the polar phonon spectra, intrinsic dielectric merit factors <εr> = 29.2 and <Qu × f> of 64 THz were determined, showing adequate values for designing applications in microwave circuitry.

Keywords

Columbite, Niobates, Tantalite, Raman scattering

Citation

MOREIRA, R. L. et al. Polarized Raman scattering and infrared spectroscopy of a naturalmanganocolumbite single crystal. Journal of Raman Spectroscopy, v. 41, p. 1044-1049, 2010. Disponível em: <http://onlinelibrary.wiley.com/doi/10.1002/jrs.2541/abstract>. Acesso em: 20 abr. 2017.