E. B. Merkulov

Ionic mobility and electrical transport in 45ZrF4 · 35BiF3 · 20MF (M - Li, Na, K) glasses studied by NMR and impedance spectroscopy

The ionic mobility and electrical transport in 45ZrF4 · 35BiF3 · 20MF (M - Li, Na, K) glasses have been studied by 7Li, 19F, and 23Na NMR and impedance spectroscopy at temperatures from 200 to 500 K. In the range 400–440 K, the main kinds of ionic mobility in these glasses are local motions of fluorine-containing groups and lithium ion diffusion. The temperature range where the dominant kind of ion motion in the glasses is fluoride ion diffusion depends on the nature of the M+ cation. Above 470 K, the glasses offer rather high ionic conductivity: σ ≥ 10−5 S/cm.

Glass formation in the ZrF4-BiF3-MeF (Me = Li, Na, K) fluoride systems

The glass formation in the ZrF4-BiF3-MeF (Me = Li, Na, K) systems is investigated. Bismuth fluorozirconate glasses are synthesized in this system, and their thermal and optical properties are described.

Ionic Mobility, Phase Transitions, and Electric Conductivity in Ammonium Tetrafluoroantimonate and Heptafluorodiantimonate(III)

The dynamics of the fluoride and proton sublattices and the electrophysical properties of NH4SbF4 (I) and NH4Sb2F7 (II) in the temperature range 210-435 K were studied by 19F and 1H NMR and impedance spectroscopy. Types of ionic motion were determined and their activation energies were estimated. The structural phase transitions in I and II form the high-temperature modifications β-NH4SbF4 and β-NH4Sb2F7, having high ionic (superionic) conductivity in the range 425-435 K (σ∼1.9-1.5×10-3 S/cm).

Formation of supramolecular complexes in reactions of adduct formation of zinc diethyldithiocarbamate with morpholine. Molecular structures and thermal properties

A supramolecular compound of the general formula [Zn{NH(CH2)4O} {S2CN(C2H5)2}2]4 · NH(CH2)4O · C2H4{N(CH2)4O}2 (I) was obtained and examined by X-ray diffraction analysis and thermography. According to X-ray diffraction data, the crystal lattice of compound I shows an unusual alternation of two independent centrosymmetric supramolecular complexes [Zn{NH(CH2)4O} {S2CN(C2H5)2}2]2 · C2H4{N(CH2)4O}2 (Ia) and [Zn{NH(CH2)4O} {S2CN(C2H5)2}2]2 · NH(CH2)4O (Ib). Either complex includes two molecules of an adduct of bis(diethyldithiocarbamato)zinc with morpholine and outer-sphere molecules of 1,2-dimorpholinoethane or morpholine. Adduct molecules are structurally nonequivalent in pairs and linked with solvate molecules by hydrogen bonds. The calculated geometries of the zinc polyhedra are intermediate between trigonal bipyramid and tetragonal pyramid. Thermal decomposition of supramolecular compound I proceeds through desorption of the outer-sphere and coordinated organic molecules; in the final step, defragmentation of the dithiocarbamate part gives zinc sulfide.

Synthesis and characterization of bismuth-containing oxyfluoroniobate glasses

New glasses are prepared in the MnNbOF5-BaF2-BiF3 system. The thermal parameters of these glasses are analyzed as influenced by bismuth trifluoride. IR and Raman spectroscopy shows that the glass structures are built of Nb(O, F)6 polyhedra, which are linked by oxygen bridges to form glass nets via. A medium-order order region in the glass includes fluoroniobate polyhedra not linked directly to bismuth trifluoride polyhedra. A Ba0.55Bi0.45F2.45 crystalline phase is discovered at 320°C in a glass of composition 20MnNbOF5-40BaF2-40BiF3.

Effect of bismuth trifluoride on the characteristics of fluoroindate glasses : The InF3-BiF3-BaF2 system

Glass formation in the InF3-BiF3-BaF2 system is studied. Partial substitutions of BiF3 for InF3 in the InF3-BaF2 system reduce the glass-transition and glass-crystallization temperatures and increase the thermal stability range and refractive index. The glass structure is studied using IR and Raman spectroscopy. InF6 and BiFn polyhedra are identified in the system. Doping the glass with bismuth trifluoride changes the degree and linkage character of the InF6 polyhedra in the glass network. The medium-range order length is not affected by the bismuth trifluoride concentration in the glass. The modifier cation (Ba2+) substantially determines the correlation length in the glasses.

Mobility of Fluorine Ions and Electrical Conductivity in InF3–BaF2–BiF3Glasses

The dynamics of the fluorine subsystem in InF3–BaF2–BiF3glasses was characterized by 19F NMR spectroscopy, impedance spectroscopy, and electrical conductivity measurements. The results demonstrate that increasing the BiF3content improves the dynamic characteristics of the fluorine subsystem and increases the conductivity of the glasses.

Synthesis, Molecular Structure, and Thermal Properties of the Supramolecular Complex [Zn{NH(CH2)4O}{S2CN(C2H5)2}2]2 · CH2N(CH2)4O}2

The supramolecular complex [Zn{NH(CH2)4O}{S2CN(C2H5)2}2]2 · CH2N(CH2)4O}2 (I) has been synthesized and studied by X-ray crystallography and thermal analysis. The noncentrosymmetric complex is composed of two structurally nonequivalent molecules of the adduct of bis(diethyldithiocarbamato)zinc with morpholine, which are linked with the outer-sphere N,N’-dimorpholinomethane molecule through two hydrogen bonds N-H⋯O. The major differences between the adduct molecules are related to the strength of Zn-N bonds, spatial orientation of the coordinated morpholine heterocyclic rings, and the proportion between the contributions of the trigonal bipyramidal (TBP) and tetragonal pyramidal (TP) components to the geometry of zinc polyhedra. Calculations show that the geometry of the zinc polyhedra is almost halfway between TBP and TP. The thermal destruction of supramolecular compound I is accompanied by desorption of the outer-sphere and coordinated organic molecules. At the final stage, defragmentation of the “dithiocarbamate part” of the complex leads to the formation of ZnS.

Ionic Mobility in Glasses in the ZrF4-BiF3-MF Systems (M = Li, Na, K) as Probed by 7Li, 19F, and 23Na NMR

The ion mobility in new fluoride glasses (mol %) 45ZrF4 · 25BiF3 · 30MF (I) (M = Li, Na, K), (70 - x)ZrF4 · xBiF3 · 30LiF (II) (15 ≤ x ≤ 35), and 45ZrF4 · (55-x)BiF3 · xMF (III) (M = Li, Na; 10 ≤ x ≤ 30) has been studied by 7Li, 19F, and 23Na NMR in the temperature range 250–500 K. The character of ion motion in bismuth fluorozirconate glasses I and III is determined by temperature and the nature and concentration of an alkali-metal cation. Major type of ion mobility in glasses I–III at temperature 400–440 K are local motions of fluorine-containing moieties and diffusion of lithium ions (except for the glass with x = 10). The factors responsible for diffusion in the fluoride sublattice of glasses I have been determined. Sodium ions in glasses I and III are not involved in ion transport.

Structure and properties of oxofluoroniobate glasses based on MnNbOF5

The MnNbOF5-BaF2 and MnNbOF5-PbF2 systems have a wider glass region than the binary system NbO2F-BaF2. According to thermogravimetric analysis data, the glasses in these systems are characterized by lower glass transition temperatures than the similar binary glass 50NbO2F·50BaF2. The thermal stability range and the degree of thermal stability of the glasses depend on the modifying cation. As demonstrated by IR and Raman spectroscopy, the glass structure is built from Nb(O,F)6 polyhedra linked into a glass network by oxygen and fluoride bridges. This is explained by the fact that the starting component MnNbOF5·4H2O decomposes to NbO2F upon melting. The manganese cations form their own polyhedra, which are incorporated into the glass network. The modifying cations exert a considerable effect on the glass network structure and on short-and medium-range order domains.