Cao Minghe

Preparation and properties of pillared montmorillonite by polyhydroxyl-aluminum-manganese cations

Al−Mn-pillared montmorillonite (AMPM) was prepared by using the artificial Na-montmorillonite from the Qingfengshan bentonite mine as starting materials mixed with Al−Mn pillaring solutions at different Al/Mn molar ratios (R). The basal spacing and specific surface area of the materials were increased significantly compared with untreated clays. When R=0.5, the d(001) value and specific surface area of pillared montmorillonite were 1.8987 nm and 146.01 m2 g−1, respectively. The thermal stability was determined using calcined tests, X-ray diffraction (XRD) analysis, thermal gravimetry and differential thermal analysis(TG-DTA). The materials formed at initial R=0.5 exhibited a high stability, the basal interlayer spacing was stabilized at 1.7859 nm after calcined for 2 h at 300°C. The adsorption behavior of the materials was studied by adsorption experiments. The results show the AMPM and calcined Al−Mn-pillared montmorillonite(CAMPM) exhibit a strong capacity of adsorbing the Zn(II) in aqueous solution at pH 10.0.

Relationship between Liquid Phase Content and the Orientation of PMNT Ceramics by TGG Method

The effects of glass frit on the sintering and electric properties of PMN-PT textured ceramics were investigated. The glass frits, including PbO, Bi2O3 and ZnO, were selected since liquid phase sintering lowered the PMN-PT sintering temperature. The piezoelectric properties of PMN-PT ceramics with glass frit addition are strongly dependent on the densification. The addition of glass frits into PMN-PT matrix reduced the sintering temperature to 1 100 °C instead of 1 150 °C for samples without glass. The piezoelectric coefficients (d33) of PMN-PT textured ceramics achieved 568 pc/N with 1 wt% excess PbO.

Synthesis and structure of NaNbO3 ceramic powders in ultrahigh pressure field

The NaNbO3 powders were synthesized and their crystal structure changes were analyzed by ultrahigh pressure up to 6 GPa. The results indicate that the pure NaNbO3 powders can be synthesized at 300°C under a pressure of 4 GPa, to significantly restrain the Na element volatilization compared with the traditional synthesis method. It is found that the crystal structure of synthesized NaNbO3 changes from low symmetry to high symmetry with the increase of the pressure.