Claudio Antonio Perottoni

Caracterização de matérias-primas cerâmicas do Vale do Rio Caí

da regiao nordeste do Rio Grande do Sul, limitada pelas regioes geomorfologicas da depressao periferica ao sul e pelas encostas do planalto meridional ao norte (Fig. 1). Constitui uma regiao de relevo muito peculiar chamada de rebordo do Planalto das Araucarias, que se estende da porcao sul dos patamares da bacia do Parana ate encontrar a depressao gaucha. Esta localizada entre 29° 50’ S e 29° 17’ S de latitude e 51° 41’ O e 51° 10’ O de longitude e regionalmente e denominada Encosta Inferior do Nordeste. A topografia que predomina e a de coxilhas (termo equivalente para colinas e lombas) tanto nas altitudes elevadas do planalto quanto nas baixas altitudes da depressao. A diferenciacao destas coxilhas se faz pelo processo de formacao dos solos. Enquanto no planalto sua origem e predominantemente basaltica, na depressao possui origem sedimentar e arenitica. Nestas ultimas, separando e permeando as coxilhas estao as planicies de alagamento do rio Cai e seus afluentes. A regiao e de baixa altitude (50 m) e apresenta relevo plano ou levemente ondulado ao sul, enquanto na regiao central a altitude media e de ate 200 m, com predominância de varzeas, encostas e morros. Ao norte predominam escarpas, vales profundos e elevacoes com ate 500 m de altitude. O clima da regiao e temperado subtropical umido, caracterizado por invernos frios e umidos e primaveras de temperaturas mais elevadas. O solo e predominantemente composto por argila vermelha com forte acidez natural [1].O rio Cai pertence a regiao hidrografica do Guaiba. Sua nascente esta localizada no planalto gaucho da Serra Geral, no municipio de Sao Francisco de Paula, em cotas que ultrapassam os 800 m de altitude. Seu curso de agua tem

Antimony desinsertion reaction from SbxCoSb3−x

The compound Sbxu2003CoSb3-x was produced at 7.7 GPa and 550u2003∘C in a self-insertion reaction from the binary skutterudite CoSb3. This self-insertion reaction is characterized by the collapse of some framework Sb atoms into the cages formed by the Co and Sb atoms in the skutterudite structure, as was further confirmed by Bader’s analysis of maximum-entropy charge density maps obtained from synchrotron radiation x-ray powder diffraction data. The opposite reaction (i.e., Sb desinsertion, Sbxu2003CoSb3-x→CoSb3) occurs when Sbxu2003CoSb3-x is heated above 180u2003∘C at ambient pressure. This desinsertion reaction was followed by means of differential scanning calorimetry, x-ray diffraction, and electrical resistivity measurements. Differential scanning calorimetry measurements revealed the presence of two thermal events in samples rich in the Sbxu2003CoSb3-x phase. An endothermic peak around 150u2003∘C was assigned to a small change in the position of the guest Sb atoms inside the cages of Sbxu2003CoSb3-x. This assignment was based on t...

Technological Characterization of Heavy Clay from the Caí River Valley in Brazil

This study presents the chemical, mineralogical, mechanical, physical and thermal properties of a clay widely available for use by the ceramic industry in southern Brazil. Some of the most important characteristics of the clay were studied, including its chemical and mineralogical composition, particle size distribution, thermal behaviour and green and after firing properties. The material was a kaolinitic primary clay with low organic content and high amount of finely divided quartz and goethite. This work is part of an effort to make available useful technical data on raw materials affecting ceramic business costs and to promote sustainable exploitation of mineral resources and improved practices in the local heavy clay industry.

Determination of ferrous and ferric iron from total iron content and thermogravimetric analysis

Ferrous (

Reference material for temperature calibration of differential scanning calorimeters above 1400 °C

hbox {Fe}^{2+}

Tunable linear thermal expansion coefficient of amorphous zirconium tungstate

Fe2+) and ferric (

B3LYP density functional calculations on the ground-state structure, elastic properties, and compression mechanism of α-ZrW/sub 2/O/sub 8/

hbox {Fe}^{3+}