The high ionic conductivity in lithium lanthanum titanate perovskite ceramics, Li3x La(2/3)‑x TiO3 (LLTO), is well-known for the x ≈ 0.11 lithium concentration. The grain conductivity is approximately 10–3 S·cm–1 at room temperature, which makes this compound one of the best candidates for the development of solid-state electrolytes. However, lower grain boundary conductivity (10–6 to 10–4 S·cm–1) blocks lithium diffusion. In order to increase the total conductivity of LLTO ceramics, single crystal fibers of lanthanum aluminate (LAO) were inserted into its green ceramic matrix. Our hypothesis is that single crystal fibers are capable of inducting LLTO abnormal grain growth, thus improving the overall electrical conductivity of the composite. The results show that LAO single crystals act like seeds, creating abnormal grain growth at the LaAlO3 fiber surface. The impedance spectroscopy shows that the new composites have a substantial relative enhancement of total ionic conductivity (more than 200%) in comparison with the monolithic ceramic samples. This result shows the possibility of developing a novel composite design as a candidate for solid electrolyte applications.

Laser-heated microstructure crystallization control of a eutectic composition Li2O–CaO–SiO2 glass system.

Perovskite La 0.557 Li 0.330 TiO 3 (LLTO) has been considered as one of the most promising solid-state electrolytes for lithium-ion batteries because of its high bulk ionic conductivity at room temperature (∼10 −3 S/cm). However, the full potential of this compound, as a ceramic electrolyte, is limited by the low ionic conductivity of the grain boundary (<10 −5 S/cm). One way to avoid the grain boundary barrier is to introduce LLTO crystals connecting the two electrodes. In this work, using LaAlO 3 (LAO) single-crystal fibers as seeds, the conditions for oriented crystal growth of the LLTO compound, inside a bulk ceramic, are presented and discussed for different crystallographic directions ([100], [110], and [111]). The relationship between the LLTO crystal region and sintering parameters was investigated in detail, and a maximum growth rate was obtained using a [111]-oriented LAO singlecrystal fiber. It is also shown that anisotropic epitaxial growth behaviors of LLTO crystals, in the LLTO/LAO composites, could be explained by morphological analysis and DFT simulations. The successful implementation of controllable LLTO crystal growth provides a feasible design for new solid-state electrolytes.

ResumoNeste trabalho mostramos que a falsificação de produtos tecnológicos atinge também as baterias recarregáveis de níquel hidreto metálico (Ni-HM). Investigamos o desempenho elétrico e a composição química dos eletrodos de baterias de Ni-HM de formato AAA, originais e falsificadas, comercializadas em Londrina, Norte do Paraná. O desempenho elétrico das baterias foi quantificado medindo-se sua capacidade de carga, sob taxa de 0,2C, e a sua potência elétrica média, nas taxas de 0,2 e 0,8 C. Para as análises da composição química as baterias foram desmontadas em vácuo, e seus eletrodos analisados por Fluorescência de Raios-X por Dispersão em Energia (EDXRF) e Difração de Raios-X (XRD). Observou-se que a capacidade de carga da bateria original foi de 920 mAh contra 155 mAh da falsificada, e as potências médias foram respectivamente 210 mW e 41 mW. A composição química dos catodos das baterias, original e falsificadas, é de hidróxido de níquel (Ni (OH) 2 ). Os anodos, no entanto, são diferentes. Na original encontrou-se o composto LaNi 5 e na falsificada o hidróxido de cádmio (Cd (OH) 2 ). As baterias originais, portanto, exibem 6 vezes mais capacidade de carga, 5 vezes mais potência a 0,2 C e 6 vezes a 0,8 C, e ainda são menos agressivas ao meio ambiente por não conterem cádmio. Palavras-chave: Baterias falsificadas. Níquel hidreto metálico. Cádmio. AbstractWe show in this paper that falsifications on technological products have hit even rechargeable nickel metal hydride batteries (Ni-MH). The electrical performance and the electrode chemical composition were investigated for authentic and falsified AAA Ni-MH batteries, purchased in the Londrina market, Paraná State. Battery charge capacities were measured at 0,2 C discharge rate and average electrical power was measured at 0.2 and 0.8 C discharge rate. To perform chemical composition analysis, the batteries were vacuum dismantled and their electrodes were characterized by Energy Dispersive X-Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD) techniques. It was observed that the charge capacities for the authentic and falsified batteries were 920 and 154 mAh, respectively. The average electrical powers were 210 mW for authentic and 41 mW for falsified batteries. The cathode chemical

Bonacin de O liveira, R. Electrical and microstructural correlation between thermistor PTCR and varistor behavior in erbium doped barium titanate eletroceramics. 2013. 125 p. D issertação (Mestrado)-Escola d e E ngenharia d e