P. Kúš

Hydrogen gas sensors based on nanocrystalline TiO2 thin films

Titanium dioxide thin films are extensively studied for applications in solid state gas sensor devices. Their gas sensing properties are strongly dependent on deposition technique, annealing temperature, film thickness and consequent properties like crystalline structure, grain size or amount of defects and impurities. In this work we report the gas sensing properties of TiO2 thin films prepared by reactive magnetron sputtering technique and subsequently annealed at temperatures 600°C and 900°C. The films were exposed to different concentrations of H2 gas up to 10 000 ppm. Their sensitivity to gas at various operating temperatures, ranging from 250°C to 450°C, was obtained by measuring their resistance.

MgB2 superconducting thin films on Si and Al2O3 substrates

Thin films of MgB2 superconductor were prepared by three different procedures on sapphire and silicon substrates. Boron thin films, ex-situ annealed in magnesium vapour, resulted in textured polycrystalline films with crystal dimensions below about 1000 nm, onset critical temperature Tcon near 39 K and width of phase transition about 1 K. Both, ex-situ and in-situ annealed co-deposited boron and magnesium thin films on sapphire and silicon substrates give smooth nanocrystalline films. DC properties of nanocrystalline MgB2 films co-deposited on silicon substrate reached Tcon = 33 K and zero resistance Tco = 27 K, the highest values received until now on Si substrates. In addition, microwave analyses prove the existence of superconducting parts of the film below 39 K. This result confirms the possibility to synthesise nanocrystalline superconducting MgB2 thin films on silicon substrate with critical temperature near 39 K, prepared by vacuum co-deposition of boron and magnesium films.Abstract Thin films of the superconductor MgB 2 were prepared by three different procedures on sapphire and silicon substrates. Boron thin films, ex situ annealed in magnesium vapour, resulted in textured polycrystalline films with crystal dimensions below about 1 μm, onset critical temperature T c on near 39 K and width of phase transition ΔT ⩽1 K. Both, ex situ and in situ annealed co-deposited boron and magnesium thin films on sapphire and silicon substrates give smooth nanocrystalline films. DC properties of nanocrystalline MgB 2 films co-deposited on silicon substrate reached T c on =33 K and zero resistance T c0 =27 K, the highest values received until now on Si substrates. In addition, microwave analyses prove the existence of unconnected superconducting parts of the film below 39 K. This result confirms the possibility to synthesize nanocrystalline superconducting MgB 2 thin films on silicon substrate with critical temperature near 39 K, prepared by vacuum co-deposition of boron and magnesium films.

Phonons in MgB 2 by polarized Raman scattering on single crystals

This paper presents a detailed Raman scattering study of the unusually broad

Time-resolved photoexcitation of the superconducting two-gap state in MgB2 thin films.

{E}_{2g}

In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts

phonon mode in

Superconducting properties of MgB2 thin films prepared on flexible plastic substrates

{\mathrm{MgB}}_{2}

Studies of resistance switching effects in metal/YBa2Cu3O7−x interface junctions

crystal. It is shown by polarized Raman scattering on a few-micron-size crystallites with natural faces that the observed broad Raman feature really does obey the selection rules of an

Superconducting gap parameters of MgB2 obtained on MgB2/Ag and MgB2/In junctions

{E}_{2g}

Effect of crystallographic anisotropy on the resistance switching phenomenon in perovskites

mode. Raman spectra on high quality polycrystalline superconducting

Effect of Post-Deposition Annealing Treatment on the Structural, Optical and Gas Sensing Properties of TiO2 Thin Films

{\mathrm{MgB}}_{2}