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Highly ordered, anodically grown TiO 2 nanotubes on titanium supports were annealed in ammonia atmosphere in order to incorporate nitrogen doping (≤2 at.%) in the titanium oxide lattice. FESEM micrographs revealed nanotubes with an average outer diameter of 101.5 ± 1.5 nm and an average wall thickness of about 13 nm. Anatase crystals were formed inside the tubes after annealing in ammonia atmosphere for 30 min. With further annealing, rutile peaks appeared due to the thermal oxidation of the foil and rise as the duration of heat treatment was increased. The concentration and chemical nature of nitrogen in the nanotube arrays can be correlated to the optical response of dry-pressed heterojunctions of doped TiO 2 /CH 3 NH 3 PbI 3 single crystals. The N-TiO 2 /perovskite heterojunction with the highest amount of interstitial nitrogen exhibited an improved photocurrent, indicating the importance of the semiconductor doping-based heterojunction optimization strategies to deliver competitive levels of halide perovskite-based optoelectronic devices to be envisioned for urban infrastructures. © 2019 Supplementary information: [http://dais.sanu.ac.rs/123456789/5969] This is the peer-reviewed version of the article: Vujančević, J., Andričević, P., Bjelajac, A., Đokić, V., Popović, M., Rakočević, Z., ... & Domanski, K. (2019). Dry-pressed anodized titania nanotube/CH3NH3PbI3 single crystal heterojunctions: The beneficial role of N doping. Ceramics International, 45(8), 10013-10020. [http://dx.doi.org/10.1016/j.ceramint.2019.02.045] Published version: [https://vinar.vin.bg.ac.rs/handle/123456789/8538]

The mass transfer coefficient (K L ) determined using an electrochemical technique was used in this work as a parameter to evaluate the hydrodynamics of hollow fiber membrane modules. A new microfiltration module configuration was investigated, taking advantage of the hydrocyclone concept aimed at reducing the concentration of the polarization layer near the membrane surface promoted by the centrifugal field. The mass transfer coefficient for the new configuration was compared with that of a conventional longitudinal module. The experimental determination of K L was obtained by monitoring the electrochemical reactions that occur at the electrode surface under mass transfer-limiting conditions. The performance of the microfiltration modules, both hybrid and longitudinal, was evaluated based on parameters such as packing density and fluid flow regimes. The results achieved for the mass transfer coefficient with the electrochemical technique allowed for performance evaluations of the proposed new module configuration and a comparison with the longitudinal module.

L'etude de l'orientation cristallographique d'un silicium polycristallin obtenu par solidification directionnelle dans un creuset de graphite est reportee dans ce travail. Les techniques usuelles de diffraction des rayons X par reflexion ont tout d'abord ete utilisees. Des variations de parametres atteignant 14 x 10-4 A ont ete mises en evidence entre les differentes zones de cristallinite du lingot. La croissance des grains, parallelement aux gradients de temperature les plus importants, produit dans le centre du lingot une structure axiale colonnaire avec des orientations privilegiees [211] et [111]. Sur les bords du creuset les orientations de croissance sont differentes. Les orientations [110] et [100] fortement defavorisees augmentent quand le taux d'impuretes (Al + B) devient superieur a 9 x 1015 atomes/cm3. Une methode d'analyse basee sur l'attaque electrochimique du silicium a ete ensuite developpee. L'analyse du depot a ete faite par diffraction des rayons X et par analyse ionique. Une correlation entre son epaisseur et la densite reticulaire du plan de surface attaque a ete etablie. La texture de solidification peut ainsi etre representee sans precision mais tres rapidement par la carte des couleurs de lame mince observee apres l'attaque electrolytique. Cette methode semble bien adaptable pour un controle rapide d'une elaboration industrielle.