ECR microwave plasma modified Ti0<inf>2</inf> ceramic for biomedical application

Abstract

The biocompatibility of TiO 2 depends on many parameters: phase composition, particle size, band gap, to name only few. The use of TiO 2 -coatings for medical applications is of particular interest with respect to the UV activity, reported in literature to be a major factor affecting not only the antimicrobial activity but also the hydroxylapatite formation in simulated body fluid [1]. Within a systematic study pigment (P25 from Degussa) as well as in-house synthesised nano-TiO 2 [2] powders were utilised to sinter coatings out of them and investigate the influence of UV radiation with and without ion bombardment on the surface morphology, the wetting behaviour, the band gap and bacteria colony growth. ECR microwave plasma treatment with Ar, O 2 and mixtures of them was performed using different bias voltages to enhance ion bombardment. The temperature was kept below 200°C. OES was used to monitor the gas phase species. The different role of UV-irradiation with and without ion bombardment on the TiO 2 -surface properties was clearly shown by the wetting angle measurement as well as optical and microscopic measurements. A new effect was found: although the TiO 2 coating was sintered at high temperature prior to plasma treatment, evaporation and re-deposition of nano-titania particles on the surface occurs, which contributes significantly to the bio-as well as the photocatalytic properties of the material.

Comparing the bulk radiated power efficiency in carbon and ITER-like-wall environments in JET

“…At the moment it is being tested in a number of tokamaks [7] and is envisaged as the primary material for the divertor of ITER. However, apart from these qualities, there are some difficulties to operate machines with this type of high-Z material, in particular because it can radiate in the plasma core [8,9]. The presence of radiation in the centre of the discharge is a major concern for fusion machines and efforts are being made in present experiments to identify the radiating impurities in the core and estimate their concentration [10,11].…”

Synthesis and Properties of Graded Porous Ti-TiO₂ Multifunctional Composites Obtained by Different Processing Methods

“…The electrochemical modification of can not change dramatically the hydrophilicity of TiO 2 , because the process proceeds in an aqueous electrolyte. Therefore fundamental investigations were undertaken in high vacuum conditions in order to obtain hydrophobic surfaces, without change in chemical composition [14]. As shown in Figure 5, ion bombardment can be used to shift the surface properties of Tio2 from hydrophilic to hydrophobic and back, because of evaporation and re-deposition of nano-particles at the surface.…”

“…As shown in Figure 5, ion bombardment can be used to shift the surface properties of Tio2 from hydrophilic to hydrophobic and back, because of evaporation and re-deposition of nano-particles at the surface. Depending upon duration of treatment and power density of the ECR-plasma redeposition and etching occur, as competing processes with respect to surface nanostructuring [14]. Finally, laser treatment can be used to achieve extremely smooth surfaces with an additional mesoscale patterning, as shown in Figure 6.…”