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Hollow cadmium molybdate microspheres have been successfully prepared via a template-free aqueous solution method with the assistance of NaCl at room temperature. The structure and morphology of the CdMoO(4) hollow microspheres were characterized by X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The microspheres have diameters of 3-6 microm and hollow interiors of 2-3 microm. The shell is composed of numerous single-crystalline nanorods with diameters of 30-120 nm and lengths of 1-2 microm which are radially oriented to the center. A certain concentration of NaCl plays a key important role in the formation process of hollow microspheres, which might provide a suitable chemical environment to favor the formation of hollow CdMoO(4) microspheres. A possible NaCl-induced Ostwald ripening process is proposed for the formation of hollow CdMoO(4) microspheres on the basis of scanning electron microscopy observation of intermediate products at different precipitation stages.

Nearly monodispersed FeNi3 submicrometre spheres with an average diameter of 220 nm were synthesized by a simple low temperature reduction method. SiO2@FeNi3 core–shell structured submicrometre spheres with 25 nm thick SiO2 shell were then fabricated by a sol–gel process. A significant enhancement of electromagnetic absorption (EMA) performance was achieved by the silica coating over the 2–18 GHz. The reflection loss (RL) exceeding −20 dB of the composite was obtained over 6.7–15.1 GHz by choosing an appropriate sample thickness between 2.1 and 3.3 mm, and an optimal RL of −61.3 dB was obtained at 8.7 GHz with a thin absorber thickness of 2.9 mm. The coating of the dielectric silica shell significantly enhanced the EMA performance due to the enhancement of interface polarization at the alloys and dielectric interfaces.

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The effect of stretching conditions, such as stretching ratios, temperatures and rates of extension, on the relative fraction of b-phase and electron structure as well as dielectric properties of poly(vinylidene fluoride) (PVDF) films was investigated. The fraction of b-phase in PVDF film increases greatly and reaches the peak of 93% after uniaxial stretching. Meanwhile, stretched spherulites and micro-strips paralleling with the stretching direction were observed in the matrix by atomic force microscopy (AFM).The results of fine structure of fluorine and carbon elements in PVDF, identified by X-ray absorption near edge structure (XANES), indicate that the coordination between F and H atoms of the adjacent chains is produced and thus enhances the dielectric response of the stretched film. As a result, the dielectric constant of the stretched film increases by 50% and achieves up to 12.1, as well as the dielectric loss being as low as 0.02.

The transformation of a to b-phase in poly(vinylidene fluoride) (PVDF) induced by the addition of tetradecylphosphonic acid (TDPA)-BaTiO 3 nanoparticles and subsequently the isothermal crystallization kinetics of pristine PVDF and its nanocomposites have been investigated. The result of infrared spectra showed that the relative crystalline fraction of b-phase was enhanced greatly after the introduction of TDPA-BaTiO 3 nanoparticles, and reached the peak of 93% when the concentration of nanofillers was 20%. The interaction between TDPA-BaTiO 3 nanoparticles and PVDF macromolecular chains induced the change of conformation from trans-gauche to all-trans crystal structure in PVDF segment. The isothermal crystallization of TDPA-BaTiO 3 /PVDF nanocomposites was carried out by the differential scanning calorimetry (DSC). The influence of TDPA-BaTiO 3 nanoparticles concentration on crystallization rate, activate energy, melting enthalpy, and peak temperature were studied. The nanocomposite film loaded 20% TDPA-BaTiO 3 nanoparticles exhibited the highest crystallization rate and activate energy, which decreased after loading more nanofillers in the host because of high volume fraction of nanoparticles leading to steric hindrance and further weakening the mobility of PVDF chains during the crystallization.

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In this work we demonstrate that Cd(OH) 2 hollow microspheres could be prepared in high yield by a facile aqueous solution route from the mixture of aqueous solutions of CdCl 2 , Na 2 MoO 4 , and NaOH at room temperature. The synthesized products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, and the nitrogen adsorption-desorption isotherm technique. The Cd(OH) 2 hollow microspheres have an average diameter of 3 µm and hollow interior of about 1.5 µm. The shell consists of numerous single-crystalline nanoplates with thickness of about 100 nm and sizes of 400-700 nm. The controlled synthetic experiments indicate that the growth process of Cd(OH) 2 hollow microspheres involves first the formation of CdMoO 4 solid microspheres and then the formation of Cd(OH) 2 solid microspheres through the reaction between CdMoO 4 and OHions controlled by the difference of solubility product for CdMoO 4 and Cd(OH) 2 . The Ostwald ripening mechanism is proposed to account for the formation of Cd(OH) 2 hollow microspheres on the basis of scanning electron microscopy observations of intermediate products at different precipitation stages. Furthermore, the Cd(OH) 2 hollow microspheres can be easily converted to CdO semiconductors with similar morphology by calcining Cd(OH) 2 in air at 350 °C for 4 h.