The key for gel-casting is the preparation of ceramic aqueous slurries with excellent rheological properties. The effect of ammonium polyacrylate and pre-oxidation on rheological properties of Si3N4 slurries was investigated. The Si3N4 isoelectric point (IEP) is between 3 and 4 in premix solution and particle surface potential is maximum at pH between 9.5 and 10.5. PAA-NH4 of dispersant can obviously decrease the viscosity of Si3N4 slurries, and the optimal dosage is about 1.6wt% of Si3N4 powders. Meanwhile, the Si3N4 slurries exhibit pseudoplastic fluid with the characteristic of shear-thinning behavior. Due to the improvement of powder surface characteristic, the pre-oxidation significantly improve the rheological properties of the Si3N4 slurries.
New 1-D zigzag chain coordination polymer {[HgBr2(pbbm)].DMF}n (1) has been successfully constructed with the aim of exploiting new and potent ion-exchange materials. Remarkably, the coordinated Br- anions in the title polymer can be replaced completely by F-, Cl- and I- anions when the crystals are immersed in the aqueous solutions of the corresponding potassium salts, respectively. This exchange is quantified by FT-IR spectra, the PXRD pattern as well as EDS analyses.
The precursor Ni (OH)2 was synthesized by a simple hydrothermal method with NiSO4•6H2O and (CH2)6N4 as reactants. Both concentrations of reactants are 0.02 M, 0.04 M, 0.06 M, 0.08 M for experiment contrast, and then NiO was gained after calcination at 400°C. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The electrochemical capacitive characterization was performed using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrical impedance spectroscopy (EIS) measurements in a 6mol/L KOH aqueous solution electrolyte. The result shows that with the increase of concentrations of reactants, nanosheets stack together and turn into thick slices. CV curves have obvious redox peak, the GCD curves are nonlinear and EIS curves of high frequency area are semicircle. From electrochemical analysis, the capacitance type is pseudocapacitance. And a maximal specific capacitance value when two reactants concentration both are 0.08 M which the specific capacitance decreases from 97 F/g (at a current density of 0.3A/g) to 56 F/g (at a current density of 1 A/g).
The precursor nickel and manganese carbonates were synthesized by co-precipitation with sodium carbonate as precipitant, and then nickel and manganese oxides were gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical characterization was performed using cyclic voltammetry (CV), galvanostatic charge–discharge tests (GCD) and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result showed that the products were the mixture of nickel and manganese oxides and solid solution. nanoparticles and spherical particles were gained by controlling the molar ratio of nickel and manganese. All of the samples exhibited typical Faradic redox capacitance. The specific capacitance was different with the change of nickel and manganese molar ratio. The specific capacitance (Cs) reached 130F/g at 1A/g when the ratio was 2:1.
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