N. V. Proskurnina

Phase equilibria and crystal structures of phases in the La-Fe-Ni-O system at 1370 K in air

The phase equilibria in the La-Fe-Ni-O system have been studied at 1370 K in air, and the La-Fe-Ni-O phase diagram at constant temperature and pressure has been constructed. Based on x-ray diffraction results for samples prepared by standard solid-state reactions and via citrate and nitrate routes, the following solid solutions have been shown to exist at 1370 K in air: LaFe1 − xNixO3 − δ (0 < x ≤ 0.4, sp. gr. Pbnm; 0.6 ≤ x ≤ 0.8, sp. gr. R-3 c), La4(Ni1 − yFey)3O10 − δ (0 < y ≤ 0.3), La3(Ni1 − zFez)2O7 − δ (0 < z ≤ 0.05), La2Ni1 − vFevO4 + δ (0 < v ≤ 0.05), NikFe3 − kO4 (0.81 ≤ k ≤ 1.05), Ni1 − mFemO (0 < m ≤ 0.05), and Fe2 − pNipO3 (0 < p ≤ 0.04). The lattice constants and structural parameters of single-phase samples have been refined by the Rietveld profile analysis method.

Crystal structure of the low-temperature form of K3PO4

The crystal structure of the low-temperature form of K3PO4 has been determined for the first time using neutron diffraction (Rietveld method) and Raman spectroscopy: orthorhombic cell (sp. gr. Pnma, Z = 4), lattice parameters a = 1.12377(2) nm, b = 0.81046(1) nm, c = 0.59227(1) nm. The structure is made up of isolated [PO4] tetrahedra, with the potassium ions in between.

Crystal structure of the low-temperature forms of cesium and rubidium orthophosphates

The crystal structure of the low-temperature forms of the Cs3PO4 and Rb3PO4 orthophosphates has been determined for the first time by neutron diffraction using the Rietveld method. Cs3PO4 and Rb3PO4 are shown to be isostructural with K3PO4: orthorhombic cell (sp. gr. Pnma, Z = 4); lattice parameters a = 1.23177(6) nm, b = 0.88948(4) nm, c = 0.64197(3) nm for Cs3PO4; a = 1.17362(2) nm, b = 0.81046(1) nm, c = 0.615167(9) nm for Rb3PO4.

Structural state of the claddings of fuel elements of the BN-600 reactor prepared from cold-deformed 16Cr–15Ni–2Mo–2Mn–Ti–V–B steel: Study using the method of high-resolution neutron diffraction

The applicability of the method of high-resolution neutron diffraction for determining defects (dislocations) in the bulk of a material is shown based on the example of a standard sample of deformed copper. The structural state of several samples of fuel-element claddings made of cold-worked steel 16Cr–15Ni–2Mo–2Mn–Ti–V–B (grade ChS68-ID) used in the BN-600 reactor, which were prepared by two producers, i.e., at the PJSC Mashinostroitel’nyi Zavod (MSZ) and at the PJSC Pervoural’sk Novotrubnyi Zavod (PNTZ), have been investigated. The conclusion has been drawn that the claddings have a texture in which the crystallographic planes of grains are oriented along the axis of the shells. It has been shown that the main defects in these claddings are edge dislocations; their density has been determined.

Defects in a lattice of pure nickel subjected to fast-neutron irradiation followed by annealings: Neutron-diffraction examination

Nickel specimens subjected to fast-neutron irradiation followed by annealings have been examined using neutron and X-ray diffraction. The type of structural defects, which result from the fast-neutron irradiation of nickel crystals, has been first identified using neutron diffraction and the experimental dependence of the lattice parameter on the concentration of interstitial defects has been determined. It is shown that the changes in the lattice parameters due to both irradiation and annealings are primary related to the variations in the concentration of interstitial atoms in the lattice.

Correlation of the properties of ionic conductivity–structure for the RbGaO2 solid electrolyte

The crystal structure of rubidium gallate RbGaO2 in the temperature range of 300–853 K has been investigated using high-temperature neutron diffraction. The channels available for the motion of rubidium cations in the low-temperature and high-temperature modifications of RbGaO2 have been determined using the computer simulation with the TOPOS program. A correlation between the radius of the migration channel cross section and the rubidium cation conductivity has been established.

Phase equilibria and crystal structures of solid solutions in the Sr-Fe-Ni-O system at 1100°C in air

The phase equilibria in the Sr-Fe-Ni-O system at 1100°C in air have been studied by x-ray diffraction, and the corresponding phase diagram at constant temperature and pressure has been constructed. The system has been shown to contain two solid-solution series at 1100°C in air: SrFe1 − xNixO3 − δ (0 < x ≤ 0.075, sp. gr. Cmmm) and Sr3(Fe1 − yNiy)2O7 − δ (0 < y ≤ 0.15, sp. gr. I4/mmm). Neither Sr4(Fe1 − zNiz)6O13 nor Sr(Fe1 − zNiz)12O19 solid solutions have been identified. The lattice constants and structural parameters of single-phase samples have been refined by the full profile Rietveld analysis method.