Preparation, Microstructure And Properties Of Ultrafine Barium Carbonate Nanowires And Ferrous Selenide Nanomaterials

1.In recent years, the rapid development of the microwave absorbing materials in military and mobile communications equipment industry result in a new trend: the research of dielectric materials. BaTiO3could be a good microwave absorbing candidate as its dielectric loss. As "the pillar of electronic ceramics", ferroelectric barium titanate (BaTiO3) is widely used in the electronic ceramics industry as its unique properties, such as high dielectric constant, low dielectric loss, excellent ferroelectric and piezoelectric properties, and good insulating properties. As, It can reduce and absorb microwave through electronic polarization, ion polarization or interfacial polarization.The first part of this paper mainly focouses on the preparation and characterization of the one-dimensional ultra thin BaTiO3nano-wires.We also compare the microwave absorption property of the ultra thin BaTiO3nanowires and the hollow BaTiO3nanop nano-torus.Ultra thin BaTiO3nanowires with high aspect ratio are synthesized by an one step hydrothermal method. Experimental observations indicate that the ultra thin BaTiO3nanowires with an average diameter about6nm is of tetragonal phases at room temperature. Each nanowire owns a length up to several tens of micrometers. Hence, nanowires with an ultra high aspect ratio. The synergistic effects including both Ostwald ripening and cation exchange reaction are responsible for the growth of the ultra thin BaTiO3nanowires. Our group compared the microwave absorption properties of BaTiO3nano-torus and the BaTiO3solid nanoparticles and found that there is nearly120%enhancement of the reflection loss with BaTiO3nano-torus. So we compared the microwave absorption properties of the ultra thin BaTiO3nanowires and BaTiO3nano-torus. The ultra thin BaTiO3nanowires/EP composites with the film thickness of3.0mm shows a maximum reflection loss of-24.56dB while that of the BaTiO3nano-torus/EP composite shows-20.68dB with the same thickness. The excellent microwave absorption properties of the ultra thin BaTiO3nanowires might caused by the relaxation channel with enough length inside ultra thin nanowires and spontaneous polarization coupling among the entanglement/assemble of ultra thin nanowires. Our method has some unique advantages:simple, facile, low cost and high synthesis yield, which might be developed to large scale synthesis.2. After the reports of the electrochemical behavior of transition metal oxide materials since2000, transition metals oxide based on such as iron, cobalt and nickel, is regarded as a kind of extremely potential new lithium storage material. The research team and scientists of all over the world have conducted extensive research on the metal oxide materials. Among these materials, the iron is abundant, cheap, environmental friendly and owns other many other advantages. So iron compounds has more advantages as transition metal compound relative to other transition metals compounds. On the other hand, because of their special structures and effects, nano-materials has received the widespread attention in the field of lithium ion batteries. Related studies have shown that iron selenide thin film has good electrochemical stability, which makes it can be used as a good lithium battery cathode material. It’s necessary to look for the hydrothermal methods of iron selenide nanometer materials with a simple process and low cost. Herin, we use a simple hydrothermal method to synthetize the layered iron selenide nano-material. That may provide more possibility for its use in the applied energy.