The family of Cr（Ⅲ） and Fe（Ⅲ）-doped rutile pigments of nominal composition （M^ⅢM^V）xTi1-2xO2, with M^Ⅲ = Cr（Ⅲ） or Fe（Ⅲ） and M＇（V） = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as cera...The family of Cr（Ⅲ） and Fe（Ⅲ）-doped rutile pigments of nominal composition （M^ⅢM^V）xTi1-2xO2, with M^Ⅲ = Cr（Ⅲ） or Fe（Ⅲ） and M＇（V） = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as ceramic pigments covering the yellow-ochre-brown palette. The formulations containing Fe（Ⅲ） are novel compositions not included in the commercial rutile pigments. The materials were characterized by XRD （X-ray diffraction） analysis and FTIR （Fourier transformed infrared spectroscopy）. The transition temperature from anatase-to-rutile was estimated by the evolution of the spectral patterns. This crystal phase transition is responsible of the color formation. A higher distortion of TiO6 octahedra is observed in the case of （FeSb） containing cells which contribute to the enhancement of the light absorption. The coloring performance of all the formulations were evaluated by enameling the mixtures containing 5% pigments and commercial frits representative of single and double firing industrial processes. The chromatic values obtained are in the yellow to brown domain of the chromatic plot, depending on the composition of the pigment-frit batch. In the case of the Fe-glazes, and particularly the combination （FeNb）, the chromatic values are close to the best yellow tinting. This new FeNb-rutile pigment could be a more benign substitute of Cr-yellow pigments. The homogeneity of the enamels was confirmed by SEM （scanning electron microscopy）-EDAX （energy dispersive X-ray analysis） microscopy.展开更多
Structural changes due to coalification and oxidation influence the coal quality, geochemically and petrologically. Understanding of the coal structures helps to predict the behaviour of coal at various processes. The...Structural changes due to coalification and oxidation influence the coal quality, geochemically and petrologically. Understanding of the coal structures helps to predict the behaviour of coal at various processes. The objective of this paper is to study the changes in organic structure and mineral phase transformation during combustion. Different density fractions were generated and then heated at different temperatures from 200 to 1000 ℃. Petrography, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction （XRD） were carried out on all the density fractions aimed to accomplish this objective. Here, through petrography, it was observed that the vitrinite and liptinite macerals disappear at higher temperature while porous inertinite is seen. The inertinite structure is exposed which is assumed by the presence of -OH and C-O-C stretches with the aromatic nucleus （CH） and three to four adjacent H from FTIR spectra. Moreover, it can be concluded that aliphatic groups get collapsed at high temperature. In case of inorganic matter, through XRD and FTIR, it is also revealed that with increasing temperature, clay minerals converted into elemental oxides. Hence, this study is suggesting that the structures of coal are altered by the degree of contact metamorphism.展开更多
文摘The family of Cr（Ⅲ） and Fe（Ⅲ）-doped rutile pigments of nominal composition （M^ⅢM^V）xTi1-2xO2, with M^Ⅲ = Cr（Ⅲ） or Fe（Ⅲ） and M＇（V） = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as ceramic pigments covering the yellow-ochre-brown palette. The formulations containing Fe（Ⅲ） are novel compositions not included in the commercial rutile pigments. The materials were characterized by XRD （X-ray diffraction） analysis and FTIR （Fourier transformed infrared spectroscopy）. The transition temperature from anatase-to-rutile was estimated by the evolution of the spectral patterns. This crystal phase transition is responsible of the color formation. A higher distortion of TiO6 octahedra is observed in the case of （FeSb） containing cells which contribute to the enhancement of the light absorption. The coloring performance of all the formulations were evaluated by enameling the mixtures containing 5% pigments and commercial frits representative of single and double firing industrial processes. The chromatic values obtained are in the yellow to brown domain of the chromatic plot, depending on the composition of the pigment-frit batch. In the case of the Fe-glazes, and particularly the combination （FeNb）, the chromatic values are close to the best yellow tinting. This new FeNb-rutile pigment could be a more benign substitute of Cr-yellow pigments. The homogeneity of the enamels was confirmed by SEM （scanning electron microscopy）-EDAX （energy dispersive X-ray analysis） microscopy.
文摘Structural changes due to coalification and oxidation influence the coal quality, geochemically and petrologically. Understanding of the coal structures helps to predict the behaviour of coal at various processes. The objective of this paper is to study the changes in organic structure and mineral phase transformation during combustion. Different density fractions were generated and then heated at different temperatures from 200 to 1000 ℃. Petrography, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction （XRD） were carried out on all the density fractions aimed to accomplish this objective. Here, through petrography, it was observed that the vitrinite and liptinite macerals disappear at higher temperature while porous inertinite is seen. The inertinite structure is exposed which is assumed by the presence of -OH and C-O-C stretches with the aromatic nucleus （CH） and three to four adjacent H from FTIR spectra. Moreover, it can be concluded that aliphatic groups get collapsed at high temperature. In case of inorganic matter, through XRD and FTIR, it is also revealed that with increasing temperature, clay minerals converted into elemental oxides. Hence, this study is suggesting that the structures of coal are altered by the degree of contact metamorphism.
