Propriedades estruturais e de transporte dos compostos de grafite intercalados com FeCL3 e ZnCL2
AUTOR(ES)
Mario Pereira
DATA DE PUBLICAÇÃO
1990
RESUMO
Samples of Intercalation Graphite Compounds (GIC) were prepared using Highly Oriented Pyrolytic Graphite (HOPG) as a host material. X-ray diffractograms reveal important structural information, such as the repeated distance between the intercalated layers and the stage n. X-ray diffraction, together with the Ic values for the reflection with maximum intensity were used as a method for stage identification of the acceptors GIC-FeCl3, n = 1,2,3,4,5,6 and 11, and also GIC-ZnCl2, n = 4 and 5. C-axis Electrical resistivity measurements for GIC-FeCl3, stages 1-6 and 11, and for GIC-ZnCl2, 4-stagged, as the temperature changes in the 4.2 and 300K range, show the following the resistivity of the compounds is larger than that of HOPG. An entirely metallic temperature dependence is observed for stages 1-4 GIC-FeCl3. GIC-FeCl3 higher stages and GIC-ZnCl2, show this behavior only at high temperature as the temperature decreases one observes a crossover to an activated dependence of the resistivity. The model for the fonon-assisted and impurity-assisted hopping conduction to account for the c-axis conduction. An order-disorder like transition is observed for both compounds. The GIC-FeCl3 transition is followed by a histeresis that characterizes an irreversible process for 120 £ T £ 160K. Transverse magnetoresistance measurements show that in the low field range, the magnetic field dependence is significantly different from a band-like dependence. Magnetoresistance values for GIC-FeCl3 show a minimum for n = 5. A magnetoresistance with an oscillatory behavior was observed for these compounds. An explanation of this complex behavior is based on the influence of magnetic field and temperature on the fluctuations of magnetization produced by impurities and dislocations, the spin-polarization of carriers, and the carrier concentration in the compound
ASSUNTO(S)
fibras de carbono grafite raios x - difração
ACESSO AO ARTIGO
http://libdigi.unicamp.br/document/?code=vtls000045419Documentos Relacionados
- Theoretical study of solid C60 and FeCl3 intercalated with CrO3
- Preparação de carvão ativado em baixas temperaturas de carbonização a partir de rejeitos de café: utilização de FeCl3 como agente ativante
- Propriedades estruturais e magneticas de compostos TR2Fe17Nx
- Pretreatment and Enzymatic Saccharification of Water Hyacinth, Sugarcane Bagasse, Maize Straw, and Green Coconut Shell Using an Organosolv Method with Glycerol and FeCl3
- Estudo do comportamento anódico do aço inoxidável ABNT 304 com filme de interferência, em NaCl 3,5% e FeCl3.6H2O 6% p/v.