Papers by Keyword: Soft Chemistry

Abstract: We report a novel soft chemical synthesis method, water assisted solid state reaction (WASSR) method. This method is very simple and can synthesize many ceramic materials just by storing or mixing raw materials added a small amount of water in a reactor at low temperature below 373 K. For example, well-crystalline SrMoO₄ was obtained using the WASSR method.

Abstract: We report novel soft chemical synthesis method, solid hydratethermal reaction (SHR) method as a new soft chemistry. This method is very simple and can synthesize the ceramic materials just by storing the mixture of raw materials added a small amount of water in a reactor at low temperature below 373 K. For example, nanosize YVO₄ (under 100 nm in diameter) was obtained using the SHR method.

Abstract: Neodymium zirconate nanocrystals doped aluminium ion Nd_xAl_2-xZr₂O₇ with pyrochlore structure were prepared by a salt-assistant glycine combustion method. Zirconium nitrate, aluminium nitrate and neodymium nitrate were used as chemicals, and glycine was used as burning agent. The as-prepared Nd_xAl_2-xZr₂O₇ nano-crystals were characterized by XRD, FT-IR, TEM and HRTEM. The results showed the Nd ions can be partially replaced by Al ions. For crystalline Nd_1.9Al_0.1Zr₂O₇, there are four strong diffraction peaks at 2θ = 29.02°, 33.70°, 48.37° and 57.37° corresponding crystal faces are 0.308nm, 0.266nm, 0.188nm and 0.161 nm, respectively, which indicates that the interstices of corresponding crystal faces are smaller than that of Nd₂Zr₂O₇. Furthermore, the fluorescent properties of Nd_1.9Al_0.1Zr₂O₇ nano-crystals evaluated by the fluorescence spectra indicate that the prepared nano-crystals are a kind of potential fluorescent-emitted material.

Abstract: Cubic pyrochlore type Nd_xCo_2-xZr₂O₇ nano-crystals were prepared by salt-assistant glycine solution combustion method (SGCM), with neodymium nitrate, cobalt nitrate and zirconium nitrate as raw materials, glycine as the incendiary agent, and KCl as a reaction inert salt. The Nd_xCo_2-xZr₂O₇ nano-crystals were characterized by means of XRD (X-ray powder diffraction), FT-IR (Fourier trans- form-infrared spectroscopy), Raman spectroscopy, TEM (Transmission electron microscope) and HRTEM (High resolution transmission electron microscopy). The results showed that neodymium ions were partially substituted by cobalt ions, while maintaining the original pyrochlore structure. The nano particles obtained had a perfect crystal structure, good dispersion, and the size was about 31nm. For Nd_1.9Co_0.1Zr₂O₇ nanocrystals, the four strong diffraction peaks were at 2θ=29.18°, 33.80°, 48.49° and 57.53°. The corresponding crystal plane distances calculated by Bragg equation λ=2dSinθ were 0.306, 0.265, 0.188 and 0.160 nm. Study the catalyst effect of Nd_xCo_2-xZr₂O₇ on the thermal decomposition of ammonium perchlorate (AP) using DSC (Differential scanning calorimetry). The results showed that nano Nd_xCo_2-xZr₂O₇ had high catalytic activity during on the thermal decomposition of ammonium perchlorate. With 2% more nano Nd_xCo_2-xZr₂O₇, the peak temperature of AP thermal decomposition reaction dropped by nearly 88°C. The apparent decomposition reaction heat increased from 655J•g^-1 to 1073J•g^-1. The results showed that the catalytic effect of thermal decomposition of AP with nano cobalt-doped zirconium acid neodymium is better than the single component of nano-metal oxides and undoped zirconate neodymium nanocrystals.

Abstract: Cubic pyrochlore type Nd_xCo_2-xZr₂O₇ nano-crystals were prepared by salt-assistant glycine solution combustion method (SGCM), with neodymium nitrate, cobalt nitrate and zirconium nitrate as raw materials, glycine as the incendiary agent, and KCl as a reaction inert salt. The Nd_xCo_2-xZr₂O₇ nano-crystals were characterized by means of XRD (X-ray powder diffraction), FT-IR (Fourier trans-form-infrared spectroscopy), Raman spectroscopy, TEM (Transmission electron microscope) and HRTEM (High resolution transmission electron microscopy). The results showed that neodymium ions were partially substituted by cobalt ions, while maintaining the original pyrochlore structure. The nano particles obtained had a perfect crystal structure, good dispersion, and the size was about 31nm. For Nd_1.9Co_0.1Zr₂O₇ nanocrystals, the four strong diffraction peaks were at 2θ=29.18°, 33.80°, 48.49° and 57.53°. The corresponding crystal plane distances calculated by Bragg equation λ = 2dSinθ were 0.306, 0.265, 0.188 and 0.160 nm. With the study of the photocatalytic activity of the product, it is found that compared with the undoped crystals, photocatalytic activity of dopped products had been significantly improved and different doping amount led to different levels of catalytic activity. When n_Nd:n_Co = 9:1, the 2 hours net degradation amount was as high as 83%.

Abstract: In the present work protonic forms of layered n=1 Ruddlesden-Popper oxides HLnTiO₄ (Ln=La, Nd) were used as starting point for synthesis of three series of the perovskite-like compounds. Characterization by SEM, powder XRD and TGA has been performed for the determination of the structure and composition of synthesized oxides.

Abstract: Nanocrystalline Fe³⁺-doped La₂Zr₂O₇ series solid solutions were prepared by a convenient salt-assisted combustion process using glycine as fuel. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The results showed the La ion can be partially replaced by Fe ion. The partial substituted products were still single-phase solid solutions and the crystal form remained unchanged. TEM images reveal that the products are composed of well-dispersed square-shaped nanocrystals. The method provides a convenient and low-cost route for the synthesis of nanostructures of oxide materials. The fluorescence of La_1.8Fe_0.2Zr₂O₇ nanocrystals was evaluated by the UV-visible absorption spectra and the fluorescence spectra. The results indicate that (La_xFe_1-x)₂Zr₂O₇ nanocrystals prepared by this method are a kind of potential fluorescent-emitted material.

Abstract: It is shown that metastable 1T-Nb2S2C can act as a host lattice for intercalation by soft chemical methods similar to isotypic Ta2S2C. The hydrated intercalation compounds Mx(H2O) y[Nb2S2C] (M…Na, K) are prepared by ion exchange in Cux[Nb2S2C] using NaCN or KCN or by reductive intercalation into the host lattices T2S2C at pH~10 using dithionite as reducing agent. The intercalation phases are characterized by TGA and X-ray powder diffraction. Nax(H2O)y[Nb2S2C] and Nax(H2O)y[Ta2S2C] have an expanded 1T-type with two layers of co-intercalated water while in Kx(H2O)y[Nb2S2C] only one layer of water is held by the less hydrated potassium ions. Kx(H2O)y[Nb2S2C] has a 3R(Ib)-type stacking. The intercalation phases are not very stable, especially Nax(H2O)y[Nb2S2C] and Nax(H2O)y[Ta2S2C] are very quickly deintercalated by oxidation. After deintercalation colloidal suspensions are formed. Ethylene diamine is spontaneously intercalated into Nb2S2C and Ta2S2C. Nb2S2C.enx has a 3R(Ib)-type stacking similar to that of Kx(H2O)y[Nb2S2C]. Ta2Se2C is isotypic to 1T- Ta2S2C (P m1, a = 3.313(1) Å, c = 8.968(2)Å, Z = 1). Ta2Se2C does not form intercalation phases under soft chemical conditions.

Abstract: Fine TiO2 particles were synthesized from titanate precursor, Na16Ti10O28, dissolved in aqueous HNO3 solution. Crystalline rutile TiO2 powders were prepared by reflux of dissolved powders in the aqueous HNO3 solution under 100 °C. Prepared TiO2 powders were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy and BET specific surface area analysis.

Abstract: Reduced niobates, MLixCa2Nb3O10 (M = Rb, K and Na) and KNaxCa2Nb3O10 were synthesized by intercalation reaction with n-butyllithium or sodium azide. Ruddlesden-Popper type structure of sodium intercalation compound, KNaCa2Nb3O10, differ from that of the parent compound and lithium intercalation compound, KLiCa2Nb3O10. The magnetic susceptibility measurements showed that the sodium intercalation compound became superconductor with transition temperatures below 3.5 K. New lithium intercalation compound Na0.1Li0.8Ca2.45Nb3O10, for an ion exchange compound, Na0.1Ca2.45Nb3O10, with KCa2Nb3O10 type structure show the diamagnetic signals below 5 K.