4 research outputs found
Temperatures of Primary Crystallization and Density of the KF + AlF<sub>3</sub> + LiF + Al<sub>2</sub>O<sub>3</sub> Molten System
This
work deals with the investigation of the temperatures of primary
crystallization and density of the KF + AlF<sub>3</sub> + LiF + Al<sub>2</sub>O<sub>3</sub> molten system for three cryolite ratios (CR
= 1.3, 1.5 and 1.7). Thermal analysis and the Archimedean method of
hydrostatic weighing were used for the determination of studied properties.
The dependence of liquidus temperature on composition shows different
trends for different CRs, whereas the density increased with increasing
content of LiF for all CRs
Physicochemical Properties of the (LiF + CaF<sub>2</sub>)<sub>eut</sub> + LaF<sub>3</sub> System: Phase Equilibria, Volume Properties, Electrical Conductivity, and Surface Tension
The
physicochemical behavior of the molten system (LiF (1) + CaF<sub>2</sub> (2))<sub>eut</sub> + LaF<sub>3</sub> (3) has been studied
and the phase equilibria, density and volume properties, electrical
conductivity, and surface tension have been selected for investigation.
Well-established methods for determination of these physicochemical
properties of molten salts have been used, such as thermal analysis,
the Archimedean method of hydrostatic weighing, and the phase shift
and maximum bubble pressure methods. A significant change in all investigated
properties was detected in the region of <i>x</i><sub>3</sub> = 0.04–0.06. In regard to phase equilibria, this region is
close to and may contain the eutectic point; in volumetric properties,
the initial volume contraction (on increasing mol %) starts to reverse.
A sharp change of electrical conductivity reflects the changes in
ionic composition, and surface tension also shows different behavior
below and above this region
Physicochemical Properties of the (LiF + CaF<sub>2</sub>)<sub>eut</sub> + LaF<sub>3</sub> System: Phase Equilibria, Volume Properties, Electrical Conductivity, and Surface Tension
The
physicochemical behavior of the molten system (LiF (1) + CaF<sub>2</sub> (2))<sub>eut</sub> + LaF<sub>3</sub> (3) has been studied
and the phase equilibria, density and volume properties, electrical
conductivity, and surface tension have been selected for investigation.
Well-established methods for determination of these physicochemical
properties of molten salts have been used, such as thermal analysis,
the Archimedean method of hydrostatic weighing, and the phase shift
and maximum bubble pressure methods. A significant change in all investigated
properties was detected in the region of <i>x</i><sub>3</sub> = 0.04–0.06. In regard to phase equilibria, this region is
close to and may contain the eutectic point; in volumetric properties,
the initial volume contraction (on increasing mol %) starts to reverse.
A sharp change of electrical conductivity reflects the changes in
ionic composition, and surface tension also shows different behavior
below and above this region
Combined Approach for the Structural Characterization of Alkali Fluoroscandates: Solid-State NMR, Powder X‑ray Diffraction, and Density Functional Theory Calculations
The
structures of several fluoroscandate compounds are presented here
using a characterization approach combining powder X-ray diffraction
and solid-state NMR. The structure of K<sub>5</sub>Sc<sub>3</sub>F<sub>14</sub> was fully determined from Rietveld refinement performed
on powder X-ray diffraction data. Moreover, the local structures of
NaScF<sub>4</sub>, Li<sub>3</sub>ScF<sub>6</sub>, KSc<sub>2</sub>F<sub>7</sub>, and Na<sub>3</sub>ScF<sub>6</sub> compounds were studied
in detail from solid-state <sup>19</sup>F and <sup>45</sup>Sc NMR
experiments. The <sup>45</sup>Sc chemical shift ranges for six- and
seven-coordinated scandium environments were defined. The <sup>19</sup>F chemical shift ranges for bridging and terminal fluorine atoms
were also determined. First-principles calculations of the <sup>19</sup>F and <sup>45</sup>Sc NMR parameters were carried out using plane-wave
basis sets and periodic boundary conditions (<i>CASTEP</i>), and the results were compared with the experimental data. A good
agreement between the calculated shielding constants and experimental
chemical shifts was obtained. This demonstrates the good potential
of computational methods in spectroscopic assignments of solid-state <sup>45</sup>Sc NMR spectroscopy