L.N. Komissarova

Reaction of hafnium hydroxide with the hydroxides of yttrium, lanthanum, neodymium, and ytterbium

1. The interaction of hafnium hydroxide with the hydroxides of yttrium, lanthanum, neodymium, and ytterbium was studied by the methods of thermographic and x-ray diffraction analyses within the temperature range 100–1000°. 2. In the coprecipitated state, the corresponding hydroxides react at temperatures below 600°, forming chemical compounds-pyrohafnates of lanthanum and neodymium or solid solutions in the case of the oxides of yttrium and ytterbium. In a mechanical mixture of the hydroxides, the reactions take place at high temperatures (> 1000°). 3. The reactivity of the oxides of the rare earth elements in their interaction with HfO2 decreases in the series La2O3-Nd2O3-Y2O3-Yb2O3. 4. The temperature at which crystallization begins, just like the value of the lattice parameter of the new phases formed, decreases with decreasing dimensions of the rare earth ions.

Complex lanthanide chromate(VI)-phosphates K2R(CrO4)(PO4) (R = Dy-Lu, Y)

The conditions of formation of complex lanthanide chromate(VI)-phosphates K2R(CrO4)(PO4) were found and these compounds were synthesized by solid-state synthesis with variation of the starting compounds, the temperature of synthesis (500–800 °C), and the annealing time (6–200 h). These salts are typical of late lanthanides, R = Dy-Lu, Y. Using lutetium derivatives as examples, it was shown that no similar compounds with lithium or sodium are formed. All the complex chromate(VI)-phosphates obtained decompose under static conditions at temperatures above 550 °C. They are isostructural and crystallize in the monoclinic system. The unit cell parameters for thulium, ytterbium, and lutetium compounds were calculated. It is shown by IR spectroscopy that PO4 tetrahedra in the crystal lattice of potassium lanthanide chromate(VI)-phosphates are substantially distorted, whereas the CrO4 tetrahedra retain the regular tetrahedron symmetry (Td).

Study of the process of extraction of 1,10-phenanthroline- and collidine-thiocyanate complexes of scandium

1. The mechanism of the extraction of scandium thiocyanate with 1,10-phenanthroline and collidine against a background of NaCl and NaNO3 was studied by the method of mathematical planning of experiments (the method of two-dimensional cross sections). 2. In the case of the 1,10-phenanthroline-thiocyanate complex, the background electrolyte NO3− is inserted into the complex; in the case of the collidine-thiocyanate complex, the background electrolytes NO3− and Cl− are not inserted into the complexes.

Planning of an experiment in the study of the extraction of scandium thiocyanate with chloroform solutions of 1,10-phenanthroline and collidine

1. Second-order regression equations, characterizing the extraction of scandium thiocyanate by chloroform solutions of 1,10-phenanthroline and collidine, were obtained by the method of mathematical planning of experiments. 2. The optimum conditions of extraction of scandium were found.