P. Pasierb

Transport properties of (Sn,Ti)O2 polycrystalline ceramics and thin films

Polycrystalline ceramics and thin films of (Sn,Ti)O 2 were prepared with the aim of investigating the mass and electronic charge transport as well as the electronic structure. The re-equilibration kinetics were monitored by measuring the dc electrical conductivity as a function of temperature, 850 K < T < 1050 K, and oxygen partial pressure, 10 - 15 Pa <p(O 2 )< 10 5 Pa. The chemical diffusion coefficient was found to be independent of p(O 2 ). The energy of the forbidden band gap, evaluated on the basis of optical measurements, is presented as a function of tin dioxide mole fraction. The influence of the chemical and phase composition on the microstructure, electronic and optical properties of polycrystalline ceramics and thin films of (Sn,Ti)O 2 is discussed.

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.