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Effects of cores types on non-solvent displacement nonaqueous precipitation synthesis of core-shell structured materials were investigated via taking case study on effects of carbon sources on C@ZrSiO 4 preparation. The influencing mechanism of carbon sources was investigated via XRD, FE-SEM, TEM and the CIELAB colorimeter. The results show that the optimized carbon source for non-solvent displacement nonaqueous precipitation synthesis of C@ZrSiO 4 is amorphous and isolated spheroid-like carbon source. Neither layer-structured particle nor sheet-like particle can be effectively encapsulated through non-solvent displacement nonaqueous precipitation method. The shell layer is difficult to be effectively encapsulated on the edges of the around of corresponding particle. In comparison with the higher crystallinity core, the amorphous core is more favorable for encapsulation. The core materials selection principles discovered in this work are expected to be widely referred in the preparation of other core-shell structural materials. [ABSTRACT FROM AUTHOR]

A novel non-solvent displacement-nonaqueous precipitation method was developed for the preparation of core-shell materials by considering C@ZrSiO 4 black pigments synthesis as the case. The effects of the impregnation time, precursor concentration, and carbon content on the synthesis and coloration of the C@ZrSiO 4 pigment and the mechanism of this method were investigated via X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and CIELAB colorimetry. The results showed that the optimal impregnation time, precursor concentration, and carbon content were 24 h, 1.5 mol/L, and 9 wt%, respectively. C@ZrSiO 4 -encapsulated pigments prepared by a non-solvent displacement-nonaqueous precipitation method have a uniform and dense shell-encapsulated zircon layer with a thickness of 10–20 nm. The size of C@ZrSiO 4 encapsulated pigments was 50–210 nm, without particle agglomeration. This uniform and dense encapsulation facilitated an excellent color-rendering effect in the high-temperature glaze, and the chromaticity values of the glaze were L* = 35.05, a* = 0.34, and b* = 1.08. The alkyl halide elimination non-hydrolytic heterocondensation reaction ensured the formation of a uniform precipitate along the surface of the carbon particles with Si–O–Zr bonds as the skeleton. The introduction of the non-solvent kerosene ensured the complete, uniform, and dense progress of the precipitation process to form a C@ZrSiO 4 pigment with a high-quality core-shell structure. The non-solvent displacement-nonaqueous precipitation method might be an extremely promising method for preparing core-shell structural materials. [ABSTRACT FROM AUTHOR]

Abstract Monodispersed alumina powders were prepared via nonaqueous precipitation process using aluminum powders as aluminum source, acetic acid as precipitant. Effect of oxygen donor and solvent alcohol such as methanol, ethanol, isopropanol on the preparation of ultrafine alumina powders and the precursor reaction mechanism have been investigated by XRD, FT-IR, TEM, FE-SEM and performance tests of sintered bodies. The intermolecular condensation of methanol with the catalysis of Lewis acid aluminum methoxide leads to hydrolysis of aluminum methoxide, forming amorphous precipitates, dehydration polycondensation of aluminum hydroxide and resulting in serious agglomeration of precipitates and alumina powders, the worst morphology and properties of sintered body. The pulling electron effect and steric hindrance of isopropyl group make the structure of aluminum isopropoxide overwhelmingly stable and relatively arduous to be replaced by precipitant acetic acid, which results in underdeveloped crystallinity and agglomeration of both precipitates and alumina powders, poor morphology and properties of sintered body. The optimized oxygen donor and solvent alcohol is ethanol. Monodispersed, high crystallinity C 4 H 7 AlO 7 precipitates and alumina powders can be obtained when ethanol is used as oxygen donor and solvent, and the highest relative density, mechanical properties and the most homogeneous microstructure was obtained. The density, flexural strength, volume resistivity, breakdown voltage and thermal expansion coefficient are 99.1% of TD, 128.0 ± 2.2 MPa, 9.8 × 1016 Ω∙cm, 45.2 kV/mm and 7.6 × 10−6 °C−1, respectively. Precursor reaction mechanism is deduced that aluminum powders react with oxygen donor alcohol to form aluminum alkoxide with the catalyst iodine, and then react with acetic acid to form crystal C 4 H 7 AlO 7 precipitates. Nonaqueous precipitation method is expected to become a promising candidate for mass production of alumina powders. [ABSTRACT FROM AUTHOR]

A monodispersed Al 2 O 3 @YAG: Ce core-shell phosphor has been synthesized by coating Y 2 O 3 : Ce film on Al 2 O 3 particle. The phosphor has particles size of 60–120 nm and shows high dispersity due to the high dispersed Al 2 O 3 particles prepared by nonaqueous precipitation method. The core-shell structured phosphor consists of a corundum core and a YAG shell. The Al 2 O 3 @YAG: Ce core-shell yellow phosphor presents high yellow emission. The light-emitting diode (WLED) based on this yellow phosphor and InGaN blue chip displays high white purity. This Al 2 O 3 @YAG: Ce core–shell phosphor can be viewed as a promising candidate yellow phosphor for white LEDs. [ABSTRACT FROM AUTHOR]