11 research outputs found
Approach combining the Rietveld method and pairs distribution function analysis to study crystalline materials under high-pressure and/or temperature: Application to rhombohedral Bi2Te3 phase
An approach combining the Rietveld method and pairs distribution function
analysis to study crystalline materials under high pressure or temperature was
early proposed by us, and in this study, it was applied to investigate de
effect of high pressure on the rhombohedral Bi2Te3 phase. The refined
structural parameters obtained from the Rietveld refinement of the XRD patterns
measured for pressures up to 9.1 GPa were used as input data to simulate the
partial and total structure factors SBiBi, SBiTe, STeTe, and SBi2Te3. Fourier
transformation of the Sij factors permitted to obtain the partial and total
pairs distribution functions GBiBi, GBiTe, GTeTe, and GBi2Te3. The first
coordination shells of these Gij functions are formed by subshells and, with
increasing pressure in the 1.1 to 6.3 GPa range, occur a partial separation of
subshells. Also, the increase of pressure in this range promotes a drastic
reduction in the values of the intralayer angles TeBiTe, and consequently, in
the intralayer distance TeTe. A drastic reduction in the interlayers distance
Te-Te was also observed. Several studies are reported in the literature,
including one carried out by us, show the presence of an ETT in this pressure
range. The obtained results suggest that the ETT is related with the decrease
of the intralayer angles TeBiTe, and intra- and interlayer distance TeTe.
Experimental results describing the pressure dependence the thermoelectric
power, electrical resistivity, and power fator for rhombohedral Bi2Te3 are
reported, and an enhancement of the power factor in the 1.1 to 6.3 GPa range is
observed. The results obtained in this study give evidence that this
enhancement in the power factor is related with the decrease of the intralayer
angles TeBiTe, and with the decrease of intralayer- and interlayers homopolar
TeTe bonds
Jogos Paralímpicos Rio/2016 no Twitter
caracterizar conteúdos de narrativas transmidiáticas que foram produzidos e circularam
acerca do esporte e dos atletas paralímpicos durante a abertura e encerramento dos JP Rio/2016
no Twitter. Mapeamos tweets das hashtags propostas pelas emissoras de tv oficiais do evento, TV
Brasil (#VemPraPara) e SporTV (#JogosParalímpicosNoSporTV), e organizamos em três categorias:
1) prática e valores midiáticos-esportivos; 2) nacionalismo no esporte paralímpico; e 3) o senti mento
paralímpic
Conflito ambiental em águas costeiras: relação porto - cidade no canal de São Sebastião
O artigo descreve os conflitos ambientais associados aos usos das águas do Canal de São Sebastião, litoral norte de São Paulo, onde ocorrem atividades portuárias de um porto de cargas gerais e do maior terminal de petróleo da América Latina. Recuperando referências da literatura sobre cidades com frentes de água e da discussão de conflitos ambientais, o trabalho explora a dinâmica porto - cidade e as possibilidades de novas combinações entre as atividades em ambos os compartimentos territoriais, na perspectiva da sustentabilidade