Mössbauer investigation of the europium state in fluoride glasses

The structure of glasses based on fluorides of alkaline-earth metals, aluminum, and europium, in which aluminum fluoride is partially replaced by aluminum nitride, is investigated by ¹⁵¹Eu Mössbauer spectroscopy. It is found that these glasses contain europium atoms in two oxidation states (+2 and +3). The isomer shifts of the Mössbauer spectra of Eu³⁺ and Eu²⁺ ions entering into the composition of the fluoride glasses are somewhat different from the isomer shifts of the Mössbauer spectra of EuF₃ and EuF₂ compounds. This difference is explained by the effect of the alkaline-earth metal and aluminum atoms (not bound directly to the europium atoms) on the electron density at the ¹⁵¹Eu nuclei. The broadening of the Mössbauer spectra of the Eu²⁺ ions in the fluoride glasses is explained by the nonuniform isomer shift.     

Yb<Superscript>3+</Superscript>-Activated inorganic aprotic liquids for diode-pumped lasers

This paper presents experimental data on the solubility of Yb(III) compounds in POCl₃–MCl _x , SOCl₂–MCl _x , and SO₂Cl₂–GaCl₃ binary aprotic solvents (where MClx is a Lewis acid). We have measured the absorption and luminescence spectra of Yb³⁺ in the solutions thus prepared. Liquid POCl₃–MCl₄–Yb³⁺ (M = Zr or Sn), SOCl₂–GaCl₃–Yb³⁺, and SO₂Cl₂–GaCl₃–Yb³⁺ gain media with [Yb³⁺] > 0.2 mol/L and an Yb³⁺ luminescence quantum yield η > 0.5 for diode-pumped lasers have been prepared for the first time.     

Two-electron exchange between neutral and ionized negative-<Emphasis Type="Italic">U</Emphasis> tin centers in lead chalcogenides

Two-electron exchange between neutral and doubly ionized negative-U tin centers in PbS and PbSe has been studied by Mössbauer emission spectroscopy. The activation energy for this process in PbS is 0.11(2) eV, which is comparable to the depth of tin levels in the band gap of PbS, whereas the activation energy for this process in PbSe, 0.05(1) eV, is comparable to the correlation energy of negative-U donor tin centers in PbSe. The exchange occurs through simultaneous transfer of two electrons and involves valence band states.     

Parameters of luminescence and the local structure of Eu<Superscript>3+</Superscript> centers in fluorogermanate glasses

The influence of the chemical nature of the local environment of Eu³⁺ ions on the parameters of luminescence of these centers in glasses of the (BaGeO₃)_{1 ? x ? y} (Al₂O₃) _x (0.45CaF₂ · 0.55MgF₂) _y (x = 0.25, y = 0; x = 0.17, y = 0.17; x = 0.15, y = 0.22; x = 0.07, y = 37.00; x = 0, y = 0.45) system is investigated. The oxidation state of europium atoms and the degree of homogeneity of their local environment in the glasses are determined using ¹⁵¹Eu Mössbauer spectroscopy.     

Hubbard energy of two-electron tin centers in PbS1−zTez solid solutions

It is shown by Mössbauer spectroscopy of the isotope ¹¹⁹Sn that an isovalent tin impurity in PbS_1?z Te_z solid solutions is a two-electron donor with a negative correlation energy, where the energy levels associated with tin centers are situated against the background of the valence band continuum. The Hubbard energy U is estimated for impurity tin atoms in PbS_1?z Te_z (|U|>0.2 eV), which is found to be substantially higher than for analogous tin centers in PbS_1?z Se_z solid solutions (|U|=0.058 eV).     

Role of precursors in the formation of lead zirconate titanate thin films

Thin ferroelectric Pb(Zr_0.48Ti_0.52)O₃ lead zirconate titanate films have been prepared on platinized silicon substrates via chemical solution deposition. The starting film-forming solutions were prepared by reacting lead acetate with Ti and Zr alkoxides in 2-methoxyethanol. The electrical properties of the films were shown to depend on the Ti and Zr alkoxide precursors used in synthesis. The nature of the zirconium alkoxide had the strongest effect on the properties of the films. The best properties were obtained with zirconium n-propoxide.     

Antistructural Defects in Ge–Te,As–Te,and Ge–As–Te Vitreous Alloys

Glass Physics and Chemistry - Emission Mössbauer spectroscopy on 119mmSn(119mSn), 119Sb(119mSn), 119mTe(119mSn), 125mTe(125Te), 125Sb(125Te), 125Sn(125Te), and 129mTe(129I) isotopes is used as...     

Energy parameters of two-electron tin centers in PbSe

Relations that make it possible to use an experimentally measured temperature dependence of carrier concentration to determine the Hubbard energy U and temperature dependence of the Fermi level F for two-electron tin centers in lead selenide are derived. A study of Pb_1?x?ySn_xNa_ySe solid solutions shows that their Fermi level in the temperature region 100–600 K lies below the valence band top E _v and that their F(T) dependences are linear, with extrapolation to T = 0 yielding E _V ?F = 210±10 meV. The Hubbard energy of the two-electron tin centers in PbSe is found to be U = ?80±20 meV.     

A study of tin impurities in crystalline and amorphous silicon by means of Mössbauer spectroscopy

Using the Mössbauer spectroscopy method for the ¹¹⁹Sn isotope the state of tin impurity atoms in crystalline c-Si and amorphous a-Si silicon is studied. If tin concentration in c-Si does not exceed 2 × 10¹⁹ atoms/cm³ then tin enters the lattice as substitutional impurity forming sp ³ hybrid system of chemical bonds. There is discussed a model that describes tin impurity atom as an isotopic impurity. If tin concentration in c-Si exceeds the value, associates of tin impurity atoms are formed in the structure of the doped semiconductor. There are studied the electrical and optical properties of tin doped films of thermally spray-coated amorphous silicon. It is shown that in contrast to the crystalline silicon where tin is an electrically inactive substitution impurity, in vacuum deposited amorphous silicon it produces an acceptor band near the valence band and a fraction of the tin atoms becomes charged.