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X-ray photoelectron spectroscopy (XPS), magnetic and dielectric studies were performed for flux grown PbFe1/2Nb1/2O3 (PFN) single crystals. The core level XPS spectra show that the Pb, Nb and O ions exist in one valence state while Fe ions in two Fe2+ and Fe3+ states. Temperature dependences of magnetic susceptibility reveals maximum at 10 K (ZFC) and anomaly at TN = 156 K related to AFM-PM transition. Dielectric and pyroelectric studies point to two ferroelectric phase transitions at 356 K and 376 K. The influence of appearance of the Fe2+ state on magnetic and semiconductor properties of PFN is discussed. [ABSTRACT FROM AUTHOR]

Abstract: The XPS examination of GdCa4O(BO3)3 revealed that the chemical composition of the crystals grown by the Czochralski method using of the sol–gel GdCOB nanopowder as a starting material have the stoichiometric composition and the smallest carbon contamination in comparison with crystals grown from oxides. [Copyright &y& Elsevier]

Abstract: The praseodymium-aluminium perovskite–praseodymium oxide, PrAlO3–Pr2O3, and praseodymium-aluminium perovskite–praseodymium hexaluminate, PrAlO3–PrAl11O18, eutectics have been recently obtained by the micro-pulling down method. The aim of this work was determination of the chemical composition and electronic structure examination of the above-mentioned eutectics. [Copyright &y& Elsevier]

XPS examinations of NdGaO3 single crystals were performed. A change of the chemical composition was found in wafers cut from the beginning, middle and end part of a crystal grown along the [0 1 1] direction. The existence of core level satellites at low binding energy related to defects was revealed. Unpolished, polished and substrates etched with H3PO4 show a decrease of gallium concentration in relation to a broken surface and to the nominal composition. Annealing of the substrates at different temperatures causes a decomposition due to escape of gallium not only from the surface but from inner parts as well. A comparison of the wafers from the crystals grown along different crystallographic direction reveals changes of the chemical composition and a variable level of defects. This was confirmed by etch pitch density measurements. The above measurements demonstrate the high sensitivity of gallium on processing. [Copyright &y& Elsevier]

The electronic structure measurements of three LSAT single crystals, annealed in hydrogen atmosphere at 900–1400 °C for 1 or 4 h, slowly or rapidly cooled were performed. The existence of core level peak satellites at the lower binding energy site were found. These satellites may be related to the defect states. The crystal annealed at 1400 °C and slowly cooled has the smallest low binding energy satellites. For La 3d, besides the satellites at lower binding energy (SII), the satellites (SI) at higher binding energy to the main peak (M) were detected. It was found that the area peak ratio IM/ISI of the La 3d states is not sensitive to the annealing, polishing or treatment with HCl and HNO3:HF of the wafer surfaces. Contrary to that, the area peak ratio IM/ISII depends on such treatment. The XPS results show that the treatment of the surface with HNO3:HF increases the roughness of the surface which confirmed the AFM results and showed that the surface chemical composition changes with processing. [Copyright &y& Elsevier]

Abstract: X-ray photoelectron spectroscopy was used to study the chemical composition and electronic structure of the YVO4:Tm,Yb crystals. The measurements revealed reduction of V5+ to the lower oxidation state due to high melting temperature and the growing of crystal at the nitrogen atmosphere which caused formation of oxygen vacancies. The inhomogenous distribution of dopants was found from the XPS studies and confirmed by scanning electron microscopy (SEM) measurements. [Copyright &y& Elsevier]

Abstract: The Pb(Mn1/3Nb2/3)O3 ceramics has been obtained from oxides by sintering in air, using a two-stage process with precursor columbite-like (Mn0.5Nb)O3 phase. The PbO oxide was added in the second stage. Analysis of the X-ray diffraction pattern shows that the ceramics consist of 91% of major perovskite phase. A monoclinic distortion of the perovskite structure was found. The cell parameters are a =12.193(3)Å, b =11.966(6)Å, c =12.144(2)Å, β =90°10.7′. The microanalysis made with SEM exhibited fluctuation in chemical composition of the perovskite phase. Precipitation of MnO2, PbO and the Pb–Mn–Nb–O phase different from perovskite was found. The X-ray photoelectron spectroscopy was used to study the electronic structure of the Pb(Mn1/3Nb2/3)O3 ceramics. The core levels of lead, manganese, niobium and oxygen were measured. The shape of valence band ridge is influenced by Mn 3d states. The real average chemical composition obtained from the XPS measurement is Pb0.99(Mn0.42Nb0.67)O2.92. Broadband dielectric measurement was carried out in 10−2 to 106 Hz and within 80–700K ranges. The dominant relaxation process exhibits characteristic times typical for ionic processes τ 0,H =1×10−11 s for the higher temperature range and, τ 0,L =1×10−9 s for lower temperatures. The activation energy of relaxation process, E M,H =0.43eV and E M,L =0.34eV corresponds to activation energy of electric conductivity. The dielectric relaxation is ascribed to dipoles created by oxygen vacancies and/or Mn–V O complexes. [Copyright &y& Elsevier]