Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. I...Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.展开更多
Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of sur...Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy (UV-vis), thermogravimetry and differential thermal analyses (TG/DTA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.展开更多
文摘Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.
基金supported by the Natural Sci-ence Foundation of Guangxi Province, China (No. 0640009)
文摘Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy (UV-vis), thermogravimetry and differential thermal analyses (TG/DTA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.