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In this work, the synthesis of the Li 2 TiSiO 5 photoluminescent compound, obtained from a stoichiometric mixture of Li 2 CO 3 , SiO 2 and TiO 2 nanoparticles, was investigated by two different routes named route I (melting and quenching) and route II (solid-state reaction). In the route I, the raw materials were melted (1550°C/2 h) and cooled into water. Subsequently, the solidified product was milled (30 min) in a high-energy mill. In the route II, the raw materials were directly milled (10 min). The obtained powders, from both routes, were heat treated at different temperatures (900-1000°C/60 min) and then subjected to crystallographic (XRD) and thermal (DSC) analyses in order to investigate the resulting structure and the associated physical-chemical reactions. The results showed that it is possible to obtain the Li 2 TiSiO 5 compound from both synthesis routes but, apparently, the route I seems to be more appropriated to obtain the Li 2 TiSiO 5 compound and to demonstrate the photoluminescence phenomena with and even without thermal treatment.

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Ion specimens can be incorporated in glasses or natural clays by ionic exchange process with different concentrations dependent of matrix´s type and of the ionic exchange parameters. In particular, the incorporation of silver ions presents high interest by its biocidal properties. A compound contending ion silver specimens presents bactericidal and fungicidal properties with effect proportional to ion concentration. This work presents results about application of the atomic absorption technical to determine the silver ion concentration incorporated in a glass matrix by ionic exchange process. The ionic exchange experiments were realized with different AgNO3 concentration and constant temperature. After ionic exchange process, the glass samples were submitted to characterization by Energy Dispersive X-Ray Spectroscopy and Atomic Absorption Techniques. The comparative results between different techniques showed that atomic absorption technical is adequate to determine ion silver concentration incorporated in the glass matrix after ionic exchange process.

Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que o trabalho original seja corretamente citado. a ResumoO objetivo deste trabalho foi caracterizar e avaliar o reaproveitamento de varistores de óxido de zinco. Os resíduos foram moídos e prensados uniaxialmente. A queima dos corpos verdes foi realizada na temperatura de 1400 ºC por 60 minutos em atmosfera oxidante, com ciclo de aquecimento de 10 ºC/min. A porosidade final apresentou-se homogeneamente distribuída por toda a sua microestrutura e resistência à flexão de 12 MPa. O comportamento elétrico do material obtido sob tensão x corrente elétrica apresentou comportamento de curto-circuito aos 600 V. Assim, as cerâmicas novas e usadas não apresentaram diferenças que possam ser associadas à degradação após utilização, indicando que os materiais descartados e novos se apresentam similares, favorecendo a reutilização e reciclagem dos mesmos. Palavras-chave: Varistores de ZnO; Reaproveitamento; Sinterização. Chemical, mechanical, electrical and microstructural characterizationof lightning rod waste from the Blumenau region