Relation between the fine structure of the vibrational spectrum of the crystal lattice and the cation distribution in Co1+2xFe2−3xSbxO4 ferrites

The infrared reflection spectra in the region of lattice vibrations (1500–200 cm^–1) of ferrite spinels Co_1+2xFe_2–3xSb_xO₄ with x=0.0–0.4 are investigated. The permittivity spectra are calculated using the Kramers-Kronig relations. A dispersion analysis of the ₁(v); ₂(v) spectra, carried out using the multiscintillator model, enabled the fine structure of the bands of the spectra to be determined. It was found that for CoFe₂O₄ ferrite the short-wave band (v=590 cm^–1) consists of two components, while the long-wave band (v=375 cm^–1) consists of fur components. Since cobalt ferrite is inverted spinel, in which there are only Fe³⁺ ions in the tetra positions, the doublet structure with v=590 cm^–1 must obviously belong to vibrations of the ion groups FeO₆ and CoO₆, while the second band may belong to vibrations of the ion complexes consisting of the tetra-cation (Fe³⁺), oxygen and the three closest octa-cations [3Fe], [2Fe1Co], [2Co1Fe] and [3Co]. The replacement of some of the iron ions with antimony leads to the appearance of additional lines from the short-wave edge of both bands. The intensity of these lines increases as the value of the diamagnetic substitution increases, which enables the highest-frequency component to be uniquely related to the vibrations of the complex formed by the tetra-cations Fe³⁺ or Co²⁺, the anion and the three octa-cations Sb⁵⁺.V. I. Ul'yanov-Lenin Kazan State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 105–109, July, 1995.     

Mechanism of NiZn ferrite formation

The regularities in the change of character of the ferrite formation process as a function of Ni_1?xZn_xFe₂O₄ solid solution and of the degree of zinc oxide saturation of the Ni_1?xZn_xO solid solution (x = 0.14; 0.29; 0.43) are established in the temperature range 1220–1305°C. It is shown that in the reaction zone of interacting NiO, (Ni, ZnO), or ZnO with Fe₂O₃ the ferrite phase crystallizes only on iron oxide. The distribution of the Fe, Ni, and Zn concentrations over the reaction layer thickness using electron probe and X-ray spectrum analysis is obtained. The interdiffusion coefficients over the investigated temperature range calculated in the (Ni, Zn, Fe)O and ferrite phases change from (0.8 – 7.0) × 10^?9 to (1.0 – 12.0) × 10^?10 cm²/sec, respectively. The interaction of (Ni, Zn)O with Fe₂O₃ takes place by the mechanism of interaction of interdiffusion of Fe³⁺, Fe²⁺ and Ni²⁺, Zn²⁺ along with a current of Zn²⁺ ions and electrons or oxygen ions directed to the $\text{ferrite}\text{Fe}{}_2\text{O}{}_3$ interface.     

Optical and magnetooptical properties of manganese-zinc ferrospinels

The use of optical methods for the investigation of the electronic structure of oxide ferrimagnets is complicated by the large variety of possible types of electron transitions whose energies are close to each other and lie in the near infrared, visible, and near ultraviolet regions of the spectrum. Therefore, for the correct identification of the transitions, it is desirable to apply traditional optical spectroscopy, which permits quantitative evaluation of the transition intensities (oscillator strength), in conjunction with magnetooptical (MO) methods providing information on weak intraconfigurational transitions which are not manifest in ordinary absorption or reflection spectra.     

On a reconsideration of classical nucleation theory

A correct account of the collective motion of a cluster does not require the Lothe-Pound correction; furthermore, this correction is shown to contradict the laws of thermodynamics.     

Formation of the Compound La2BaCuO5 (La4Ba2Cu2O10)

Synthesis of the compound La₂BaCuO₅ (La₄Ba₂Cu₂O_{1 0}), whose X-ray diffraction pattern is identical to that available in the literature for the solid solution La_3.6Ba_2.4Cu_1.8O_9.6, was studied.     

Linear Groups of Degree 4 Over a Quaternion Division Ring that Contain the Special Unitary Group of a Skew-Hermitian Form with Maximal Witt Index

The paper describes subgroups of the general linear group GL ₄(D) over a quaternion division ring D that contain the special unitary group of degree 4 over a non-central subfield of D. The connections between these subgroups and the spinor groups of appropriate symmetric bilinear forms are established.