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Here we report a simple and effective method in tailoring the optoelectronic properties of semi-conducting metal oxide for suitable device application. Sol-gel synthesis was used to synthesize manganese doped TiO2 nanopowder and commercially available TiO2 nanopowder was used as reference material. Thick films of these powder were screen printed on FTO coated glass and annealed at 450 degrees C in ambient air. Separately, 60 µL of neodymium chloride prepared from neodymium oxide, 60 µL of ruthenium based commercial dye (N719) and 60 µL of extracts of calendula orange and dog flower were used as sensitizer to improve the photoconductance properties. Elemental analysis confirmed synthesis of composite material of Mn and TiO2. Morphological observation showed a uniform particles of 25 to 50 nm diameter. Optoelectronic properties were studied by using thick films of these powders as working electrode as a function of wavelength from 430 to 750 nm and the cyclic voltammogram were obtained by scanning potential from -1.5 V to +1.5 V at the illumination intensity of 1000 Wm(-2). Sensitization resulted in additional absorption and functional bands. Oxidation peak current was found decreasing with increasing wavelength. Sensitization with flower extract resulted in increased oxidation current at higher wavelength indicating the improved photoconduction in comparison with N719 and neodymium.
RESUMO
BACKGROUND: High Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications. METHOD: In our previous work (BioMedical Engineering OnLine 2013), different ratios of HDPE/HA nanocomposites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The accelerated aging effects on the tensile properties and torsional viscoelastic behavior (storage modulus (G') and Loss modulus (G")) at 80°C of irradiated and non-irradiated HDPE/HA was investigated. Also the thermal behavior of HDPE/HA were studied. In this study, the effects of gamma irradiation on the tensile viscoelastic behavior (storage modulus (E') and Loss modulus (E")) at 25°C examined for HDPE/HA nanocomposites at different frequencies using Dynamic Mechanical Analysis (DMA). The DMA was also used to analyze creep-recovery and relaxation properties of the nanocomposites. To analyze the thermal behavior of the HDPE/HA nanocomposite, Differential Scanning Calorimetry (DSC) was used. RESULTS: The microscopic examination of the cryogenically fractured surface revealed a reasonable distribution of HA nanoparticles in the HDPE matrix. The DMA showed that the tensile storage and loss modulus increases with increasing the HA nanoparticles ratio and the test frequency. The creep-recovery behavior improves with increasing the HA nanoparticle content. Finally, the results indicated that the crystallinity, viscoelastic, creep recovery and relaxation behavior of HDPE nanocomposite improved due to gamma irradiation. CONCLUSION: Based on the experimental results, it is found that prepared HDPE nanocomposite properties improved due to the addition of HA nanoparticles and irradiation. So, the prepared HDPE/HA nanocomposite appears to have fairly good comprehensive properties that make it a good candidate as bone substitute.