S. Komornicki

Structural and optical properties of Sr1−xBaxTiO3 thin films prepared by rf sputtering

Abstract Sr1−xBaxTiO3 thin films (0≤x≤1) were deposited at T=723 K by the rf sputtering method from targets comprised of ceramic, SrTiO3–BaTiO3 mosaic. The influence of barium content and the post-deposition annealing at T=1173 K on the structural and optical properties were studied. It has been found that the crystallinity of the as-sputtered (at T=723 K) thin films decrease with the increase of Ba content (x). The perovskite structure with preferred orientation (changing from (1 1 0) for x=0 to (h 0 0) for x=1) was detected for the post-deposition annealed (at T=1173 K) Sr1−xBaxTiO3 thin films. The annealing of Sr1−xBaxTiO3 thin films affects the optical transmission spectra and absorption edge position. The observed changes are the strongest in case of BaTiO3 films and those of related compositions. The refractive index derived for the well-developed perovskite structure was found to be independent on the chemical composition (x) and was n=2.1, for λ=1.55 μm.

Structural Properties and Thermal Behavior of Li2CO3–BaCO3 System by DTA, TG and XRD Measurements

The binary system Li2CO3–BaCO3 was studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and X-ray phase analysis. The composition of carbonate and CO2 partial pressure influence on the thermal behavior of carbonate were examined. It was shown that lithium carbonate does not form the substitutional solid solution with barium carbonate, however the possible formation of diluted interstitial solid solutions is discussed. Above the melting temperature the mass loss is observed on TG curves. This loss is the result of both decomposition of lithium carbonate and evaporation of lithium in Li2CO3–BaCO3 system. Increase of CO2 concentration in surrounding gas atmosphere leads to slower decomposition of lithium carbonate and to increase the melting point.

Application of proton-conducting SrCeO3 for construction of potentiometric hydrogen gas sensor

The purpose of this work was to investigate the performance and working mechanism of potentiometric hydrogen sensors, based on proton-conducting oxide solid electrolytes. The SrCe1-xYxO3-y compounds (0≤×≤0.2) were prepared by solid-state reaction method; different concentrations of yttrium dopant (x) were used. The measurements of Open Cell Voltage (OCV) of constructed cells-sensors as a function of gas concentration and temperature were performed. Studied sensors exhibited short response and recovery times and satisfactory repeatability of the sensor signal. The discussion of the working mechanism within the frame of defect structure and transport properties of proton-conducting solid electrolyte was also presented in this work.