This study demonstrates bulk crystallization of CaO-AlO-SiO (CAS) glass with suppression of surface crystallization via hydrothermal treatment under acidic conditions. It focuses on CAS glass-ceramics (GCs) with precipitated metastable CaAlSiO, a layered calcium aluminosilicate, because it features a single bulk crystallization phase with a relatively lower volume fraction. After hydrothermal treatment under nitric acid, the resultant glasses possessed silica-rich surface layers.
View Article and Find Full Text PDFNanoscroll-supported platy particles were prepared by incomplete rolling-up of kaolinite layers; when the rolling-up of the kaolinite layer followed by its exfoliation incompletely proceeds, kaolinite nanoscrolls were found at the edge of kaolinite platy particles. To assess the support property of these nanoscroll-supported platy particles, when the deposition of Ag nanoparticles was conducted, these nanoparticles were present on the surface of platy particles and in the tubular interior of nanoscrolls at the edge of platy particles but absent on the surface of ordinal kaolinites, as revealed by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. These results indicated the successful formation and support property of nanoscroll-supported platy particles.
View Article and Find Full Text PDFThis study investigated the effect of vanadium oxide on the crystallization of CaO-AlO-SiO (CAS) glass. Specifically, this study subjected CAS glass-ceramics (GCs) with precipitated hexagonal platy particles of metastable CaAlSiO (CAS GC-H), a layered crystal, that was prepared using metallic molybdenum (Mo) particles as nucleation agents. When the parent glass of CAS GC-H was crystallized with the addition of vanadium oxide in the 0.
View Article and Find Full Text PDFThis study demonstrated simple redox control in glasses by improving the method used to added glass raw materials. Specifically, the effect of carbon on the co-presence of metallic tungsten (W) particles as nucleation agents and Eu ions in CaO-AlO-SiO (CAS) glass was investigated their crystallization to form CAS glass-ceramics (GCs). In this study, the glass specimens were prepared by mixing glass cullet containing metallic W particles and Eu ions, respectively, with a glass batch containing carbon.
View Article and Find Full Text PDFMicrostructural control of CaO-AlO-SiO (CAS) glass ceramics (GCs) was achieved by oxidation and mixing with nucleation agents. CAS GCs were precipitated with hexagonal platy particles of metastable CaAlSiO layered crystals (CAS GC-H), which are typically prepared under a reductive atmosphere that forms metallic Mo or W particles as nucleation agents. The average particle size of crystals decreased significantly from 50 to 11 μm when the CAS GC-H containing metallic W particles was prepared under an oxidative atmosphere.
View Article and Find Full Text PDFPhotoreduction of Cu ions to Cu metal by titanium(IV) oxide (TiO) was conducted in the presence of a silica-surfactant hybrid under sulfuric acid conditions. After irradiation, a dark-red color, reflections due to Cu metal in the X-ray diffraction pattern, and peaks due to Cu 2 and 2 in the X-ray photoelectron spectrum indicated the precipitation of Cu metal in the product. In addition, an increase in the Brunauer-Emmett-Teller specific surface area from 36 and 45 m/g for the silica-surfactant and TiO, respectively, to 591 m/g for the product, and a decrease in the intensity of the C-H stretching band in the Fourier-transform infra-red spectra implied the removal of surfactant during the reaction.
View Article and Find Full Text PDFThe ratio of the intensity of Tb fluorescence at 543 nm because of an electric dipole transition (D-F) relative to that at 437 nm due to a magnetic dipole transition (D-F) was determined to be proportional to the amount of metastable CaAlSiO crystals precipitated in CaO-AlO-SiO glass. The present results indicate that Tb luminescence can be used as a probe to evaluate the crystallization of glass.
View Article and Find Full Text PDFThis study assessed the effect of kaolinite edge surfaces on solid-state reactions. Specifically, Tb-doped metastable CaAlSiO showing green phosphorescence was prepared a solid-state reaction between expanded kaolinite, a methoxy-modified kaolinite, having Tb ions adsorbed on its edge surfaces and CaCO. This material cannot be obtained by the conventional grinding of kaolinite, CaCO and TbO, indicating that the use of kaolinite edge surfaces is advantageous as a means of achieving certain solid-state reactions.
View Article and Find Full Text PDFExpanded kaolinite without impurities was found to serve as a suitable raw material for the rapid formation of metastable CaAlSiO with the suppression of byproduct formation. This was accomplished based on the solid-state reaction of the kaolinite with calcium carbonate promoted by mechanical grinding.
View Article and Find Full Text PDFThe expansion of metakaolinite layers with stacking order and the order destruction were examined by the heat treatment of a kaolinite-tetraphenylphosphonium chloride intercalation compound (Kaol-TPhPCl) at 540 °C under a nitrogen atmosphere followed by the manual grinding of the product using a mortar and a pestle. Fourier-transform infrared spectroscopy and solid-state Al nuclear magnetic resonance spectroscopy with magic angle spinning revealed the kaolinite dehydroxylation. Moreover, the absence of kaolinite diffraction lines and the appearance of the 1.
View Article and Find Full Text PDFIn this paper, the regioselective reactions of kaolinite and methoxy-modified kaolinite (MeO-Kaol), methanol-expanded kaolinite, with octadecyltrimethylammonium salts are compared. This study mainly concerns the reactions of kaolinite or MeO-Kaol with octadecyltrimethylammonium chloride (C18TAC) in methanol and the subsequent exhaustive washing of the resultant products with ethanol. X-ray diffraction patterns of the products reveal no intercalation of C18TAC between pristine kaolinite layers.
View Article and Find Full Text PDFAn original route for the intercalation of a 1,1'-diethyl-2,2'-cyanine iodide (PIC) cationic dye, through the use of anionic surfactants as vector/carrier phases, within Mg-Al layered double hydroxide (LDH) was investigated. From the data acquired from complementary techniques (X-ray diffraction, infrared and UV-visible spectroscopies, thermogravimetry, and fluorimetry), it appears that both the intercalation and aggregation states of the cationic dye within the internal structure of LDH mainly depend on both the surfactant state (monomer form or spherical micelle) and its amount. The intercalation of PIC at a low molar ratio to the anionic surfactant leads to the formation of -aggregates with singular fluorescence properties that mainly depend on the nature of the anionic surfactant used for the co-intercalation process.
View Article and Find Full Text PDFCharacteristics of a kaolinite-acetone intercalation compound prepared using a kaolinite N-methylformamide intercalation compound (Kaol-NMF) as an intermediate were obtained by a set of techniques with attention to suppressing evaporation and deintercalation of acetone. X-ray diffraction (XRD) with spectroscopic analyses, Fourier-transform infrared spectroscopy (FTIR) accompanied by solid-state C and Si nuclear magnetic resonance (NMR) spectroscopy with cross polarization (CP) and magic angle spinning (MAS) enable us to demonstrate full replacement of a pre-intercalated NMF monolayer with an acetone monolayer between the layers of kaolinite with an increase in the basal spacing from 1.08 nm (Kaol-NMF) to 1.
View Article and Find Full Text PDFA kaolinite-tetrabutylphosphonium bromide (TBPBr) intercalation compound (Kaol-TBPBr) was prepared from kaolinite providing inorganic aluminosilicate layers and TBPBr as intercalated salts between the layers through the use of an intermediate, a kaolinite-dimethylsulfoxide (DMSO) intercalation compound (Kaol-DMSO). The experimental data through complementary techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, solid-state C and Si nuclear magnetic resonance (NMR) spectroscopy with cross polarization and magic angle spinning, inductively coupled plasma emission spectrometry, and ion chromatography, indicate complete removal of DMSO and intercalation of TBPBr with an increase in the basal spacing from 1.12 nm (Kaol-DMSO) to 1.
View Article and Find Full Text PDFInterlayer grafting of kaolinite using trimethylphosphate (TMP), a phosphoric acid triester, was achieved using a methoxy-modified kaolinite (MeO-Kaol) as an intermediate. First, TMP was intercalated between the layers of MeO-Kaol upon dispersing MeO-Kaol to TMP at room temperature (TMP/MeO-Kaol_RT). The X-ray diffraction (XRD) pattern of TMP/MeO-Kaol_RT revealed that the basal spacing of MeO-Kaol was increased from 0.
View Article and Find Full Text PDFThe solid acidity of the interlayer aluminol surfaces of kaolinite was explored by solid-state P nuclear magnetic resonance with magic angle spinning (MAS) using triethylphosphine oxide (TEPO), which formed a monolayer with a uniform orientation between the layers of kaolinite as a probe molecule. Intercalation of TEPO between the layers of kaolinite was achieved using methoxy-modified kaolinite as an intermediate. The presence of TEPO in the reaction products was revealed by the two signals at 21 and 7 ppm, which were assignable to ethyl groups in TEPO, in the solid-state C nuclear magnetic resonance with cross polarization and magic angle spinning techniques (C CP/MAS NMR).
View Article and Find Full Text PDFJ Colloid Interface Sci
April 2014
Well-defined plate and hollow disk of silica-dioctadecyldimethylammonium hybrid particles were obtained by the sol-gel reaction of tetraethoxysilane in the presence of dioctadecyldimethylammonium chloride, where synthetic condition was determined based on the Stöber synthesis for micron size silica sphere. The particle size was several hundreds of nm in the radius and several tens of nm in the thickness. X-ray powder diffraction patterns indicated that the products possess layered mesostructures, which were thought to be directed by the lamellar aggregates of dioctadecyldimethylammonium.
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