The preparation of cadmium selenide nanoparticles in the interlayer space of magadiite, a layered sodium silicate, modified with the cetyltrimethylammonium cation was studied. The preparation was based on the formation of cadmium selenide by the reaction between the cetyltrimethylammonium modified magadiite and an aqueous mixture of cadmium sulfate and sodium selenosulfite at room temperature. The resulting hybrids were characterized by XRD, FT-IR, HRTEM, TG-DTA, as well as UV-visible and photoluminescence spectroscopy. The expansion of the interlayer spaces as well as TG-DTA results indicated the presence of the cetyltrimethylammonium cation and cadmium selenide in the hybrids. The HRTEM images showed the presence of cadmium selenide in the diameter range of 2-3 nm in the interlayer space of magadiite. The luminescence intensity of the cadmium selenide varied depending on the particle size, which was controlled by the loading amount of cadmium selenide precursor.

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Based on a typical ZnO varistor composition (97?0 mol.-% ZnO, 1?0 mol.-% Bi 2 O 3 , 1?0 mol.-% Sb 2 O 3 , 0?5 mol.-% MnO and 0?5 mol.-% Co 3 O 4 ), phase development of the ZnO varistor during sintering has been investigated using in situ high temperature X-ray diffraction up to 900uC, and conventional ambient X-ray diffraction for samples sintered at 900uC to 1250uC. The results indicate that a-Bi 2 O 3 can be detected until 700uC; the pyrochlore phase can be detected in the samples heat treated at 700uC and up to 1250uC; the spinel phase is present at and .900uC. However, the main phases in the varistor are established by 950uC. By this temperature, the essential microstructure features are formed, and the varistors exhibit non-linear electrical properties, with a non-linear coefficient a of 35 and breakdown field of 8000 V cm 21 . With increasing sintering temperature, both the a value and breakdown field decrease.

The incorporation of metal sulfide mixture, manganese sulfide and zinc sulfide (MnS–ZnS) or manganese sulfide and cadmium sulfide (MnS–CdS), in two types of montmorillonites (sodium montmorillonite and cetyltrimethylammonium modified montmorillonite) was investigated. The hybrids were characterized by powder X-ray diffraction, thermogravimetric-differential thermal analysis, transmission electron microscopy (TEM), and Raman, UV-visible and photoluminescence spectroscopies. The experimental evidences such as the expansion of the interlayer spaces and the presence of the absorption and photoluminescence due to MnS, ZnS and/or CdS revealed that the mixed metal sulfides formed in the interlayer space of montmorillonites. TEM images of the hybrids showed diskor plate-shaped nanoparticles with a mean diameter of ca. 2 nm. The increase of the luminescence intensities of the hybrids was assumed to be caused by quantum confinement effect in the interlayer space of montmorillonite.

The doping effects of Cu on the microstructure and non-ohmic electrical properties of ZnO varistors were studied. Addition of Cu2O can enhance the ZnO grain growth during sintering. The SEM and EDS results revealed that the added Cu mainly distributed in the grain boundary and spinel phases of ZnO varistors. The Cu2O addition increased the both of grain and grain boundary resistances. However it decreased the non-ohmic electrical characteristics of ZnO varistors, which is a good agreement with similar findings on Ag2O additions, but contrasts to the reports of good non-ohmic electrical property which found on binary Cu doped ZnO varistors.