Katarzyna Kołodziejak

Here, we describe a method for testing photoelectrochemical stability developed using photoanodes from an SrTiO ₃ –TiO ₂ eutectic composite. The initial value of the photocurrent density was 1.95 mA cm ⁻² at 1.5 V vs. Ag/AgCl and increased to 7.22 mA cm ⁻² after 88.5 h of stability cycles.

Hydrogen as a potential fuel of the future can be produced in a photoelectrochemial water splitting process. Herein, we demonstrate the fabrication of photoelectrochemical electrodes based on SrTiO₃-TiO₂ with a eutectic composition on titanium and conductive glass FTO (fluorine doped tin oxide) substrates by magnetron sputtering. The XRD and SEM/EDS reveal the amorphous nature and homogeneity of the sputtered material. The influence of the layer thickness on the photoactivity was investigated. There were three-layer thicknesses (50, 350, and 750 nm) selected by sputtering for 12, 80 and 220 min for the preparation of photoelectrodes. The photoelectrochemical analysis confirms the photoactivity of the obtained layers under illumination with a xenon lamp (600 mW/cm²). The highest photocurrent density of 11.8 × 10⁻³ mAcm⁻² at 1.2 V vs. SCE was recorded for a layer thickness of 50 nm on titanium as better matching between the Ti work function and the conduction band.

Tb₃Sc₂Al₃O₁₂-TbScO₃ eutectic crystallizes in a rodlike microstructure, and its potential to exhibit photonic bandgap has been presented tentatively. In order to model its optical properties there is a need for precise determination of the optical properties of its component materials in a wide spectral range. Spectroscopic data in the range from 0.6 to 6.5 eV (190-2100 nm) were obtained using spectroscopic ellipsometer UVISEL, Horiba Jobin-Yvon. The measurement was completed with mid infrared reflection data using Bruker FTIR spectrometer in the spectral range from 7500 to 550 cm^-1. Optical functions were obtained using fitting of the data with model dielectric function fulfilling the Kramers-Kronig dispersion relations. Obtained optical functions enable to model the optical properties of self-organized eutectic micro- and nanostructures.

Eutectics are the materials with foreseen application in the field of photonic crystals and metamaterials. In this paper, the dependence on chemical composition of the microstructures of terbium-scandium-aluminium gamet and terbium-scandium perovskite (Tb₃Sc₂Al₃O₁₂-TbScO₃) eutectics has been studied. The growth of the eutectic rods by the micro-pulling down method is presented, using compositions with several different volume fractions of the garnet and the perovskite phases, V_TSAG:V_TSP = 4, 3, 2, 1, 1/2. The phases have been characterized by powder X-ray diffraction and energy dispersive spectrometry. The relationship between the lattice constant of individual phases and the chemical composition is presented. The unidirectional growth of microrods has been also investigated by electron backscattering diffraction.