91 citations · 259 across the 11 of their papers we have counts for
11 papers
Low-temperature Raman spectra of L-histidine crystal
G. P. De Sousa, P. T. C. Freire, J. Mendes Filho +2
We present a Raman spectroscopy investigation of the vibrational properties of L-histidine crystals at low temperatures. The temperature dependence of the spectra show discontinuit…
Fossilization in Geopark Araripe studied through X-ray diffraction, scanning microscopy and thermogravimetric analysis
Ricardo J. C. Lima, Paulo T. C. Freire, Zélia S. Macedo +2
The Geopark Araripe, located in Northeastern Brazil, is the first UNESCO Natural Park in the South hemisphere and a world-famous fossil deposit of the Early Cretaceous period (appr…
Raman spectra of L-leucine crystals
P. F. Facanha Filho, P. T. C. Freire, K. C. V. Lima +3
Single crystal samples of L-leucine, C6H13NO2, a fundamental aliphatic amino acid of the human body, have been studied by Raman spectroscopy at temperatures from 300 to 430 K over…
Raman studies of polycrystalline CaCuTiO under high-pressure
D. Valim, A. G. Souza Filho, P. T. C. Freire +5
We report a Raman scattering study of polycrystalline CaCuTiO (CCTO) under pressure up to 5.32 GPa. The pressure dependence of several Raman modes was investigated.…
Low Temperature Phase Transition in Sr(0.66)Ba(0.34)Nb2O6 single Crystal Fibers
J. L. B. Faria, C. W. A. Paschoal, P. T. C. Freire +5
The structural changes in Sr(0.66)Ba(0.34)Nb2O6 single crystal fibers when the temperature decreases from 295 to 10 K is investigated by dielectric constant measurements and Raman…
A Raman Study of Morphotropic Phase Boundary in PbZr1-xTixO3 at low temperatures
K. C. V. Lima, A. G. Souza, A. P. Ayala +5
Raman spectra of PbZr1-xTixO3 ceramics with titanium concentration varying between 0.40 and 0.60 were measured at 7 K. By observing the concentration-frequency dependence of vibrat…