Atom species energy dependence on magnetic configurations in the perovskite yttrium orthoferrite

The article represents the results of studying of the influence of atom species in the perovskite multiferroic yttrium orthoferrite YFeO3 on magnetic configurations by ab-initio methods. Four magnetic configurations possible in magnetic sublattice that were formed by iron atoms were analyzed. It is shown that different magnetic orderings change the lattice parameters and the ions occupied positions while preserving symmetry of the unit cell, the lowest state responds G-AFM type magnetic ordering. The lattice parameters are in good relevant published experimental data. The atom species energy dependence shows that the main role in magnetic properties goes to iron and oxygen. In the ground state, magnetic properties relate with Dzyaloshinskii – Moriya interaction, while in other configurations, these relate with superexchange through Fe- O-Fe chains. Obtained results are useful for analyzing and designing straintronics devices. Also, the results can be interesting for interpretation and predicting magnetic properties of partially or fully substituted orthoferrites including substitution on rare-earth elements.

Studies on Structural, Morphological, Local Electrical, Optical and Magnetic Properties of Iron Site Manganese Substituted Yttrium Orthoferrite

Yttrium orthoferrite (YFeO3) is of considerable interest for its potential application in magnetic field sensors and magneto optical data storage devices. Doping is one of the effective approaches to tune the compound properties. And it is important to determine the doping sites of the dopants to better understanding the related mechanism. In this work, Manganese (Mn) doped YFeO3, i.e., YFMxO powders with 0 ≤ x ≤ 0.1 were synthesized by hydrothermal method to study the influences of doping on their structural, morphological, local electrical, optical and magnetic properties. The experimental results show that Mn dopants occupy Iron (Fe) sites and that all these samples exhibit an orthorhombic structure with space group Pnma. Refined structure parameters are presented. Morphology images show the shape evolution from layered to multilayered with increasing Mn content. The Fe and Y K-edge local structure studies indicate that the valency of Fe and Y is mainly found in trivalent state, which also indicate that substitution of Mn ions not only affects the nearest neighbor atomic shell of Fe but also affects the nearest neighbor’s local structure of Y atoms. IR spectra reveal the characteristic vibrations of the obtained YFMxO samples. From the magnetic study, it is observed that the substitution of Y ions by Mn ions changes the magnetic property of YFeO3 from ferromagnetic to paramagnetic. Our results show that the addition of Mn exhibits an evident influent on the local structural and magnetic properties.

Computer Simulation of Oxygen Vacancy Formation in YFeO3 Perovskite

The pseudopotential method and density functional theory with Hubbard correction were used to study changes in the atomic and electronic structure of yttrium orthoferrite (YFeO3) during vacancy formation. Depending on the value of non-stoichiometry in YFeO3−δ (δ = 0.0625 and 0.25), the energy gain of one of the two types of vacancy decreases from 0.3 to 0.1 eV. So it have been shown that high concentrations of oxygen vacancies make more insignificant the difference in the type of formed vacancies.

Enhanced Multiferroic Properties of YFeO3 by Doping with Bi3+

Tthe present work studied the cationic substitution of Y3+ by Bi3+ on the crystal structure of orthorhombic YFeO3 and its effect over magnetic, dielectric and electric properties of multiferroic yttrium orthoferrite. Stoichiometric mixtures of Y2O3, Fe2O3 and Bi2O3 were mixed and milled for 5 h using a ball to powder weight ratio of 10:1 by high-energy ball milling. The obtained powders were pressed at 1500 MPa and sintered at 700 °C for 2 h. The test samples were characterized at room temperature by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and impedance spectroscopy (IS). The X-ray diffraction patterns disclosed a maximum solubility of 30 % mol. of Bi3+ into the orthorhombic YFeO3. For higher concentrations, a transformation from orthorhombic to garnet structure was produced, obtaining partially Y3Fe5O12 phase. The substitution of Bi3+ in Y3+ sites promoted a distortion into the orthorhombic structure and modified Fe-O-Fe angles and octahedral tilt. In addition, it promoted a ferromagnetic (FM) order, which was attributed to both the crystal distortion and Dzyaloshinskii-Moriya interaction. For doped samples, an increase in real permittivity values was observed, and reduced with the increase of frequency. This in good agreement with the Maxwell-Wagner effect.

Микроволновый синтез ортоферрита иттрия и допирование его никелем

Установлено активирующее действие микроволнового излучения в процессе синтеза нанопорошков ортоферрита иттрия, допированного никелем, заключающеесяв значительном увеличении скорости процесса, снижении температуры отжига, высокой химической гомогенности синтезированных образцов. Реальная степень допирования согласно результатам локального рентгеноспектрального микроанализа оказалась несколько ниже номинальной, максимальная реальная степень допирования составляет 0.12. Средний размер частиц YFeO3 и NiхY1-хFeO3 находится в диапазоне 200–300 нм. REFERENCES Popkov V. I., Almjasheva O. V. Yttrium orthoferrite YFeO3 nanopowders formation under glycine-nitrate combustion conditions. Russian Journal of Applied Chemistry, 2014, v. 87(2), pp. 167-171. https://doi.org/10.1134/S1070427214020074 Letyuk L. M., Kostishin V. G., Gonchar A. V. Tekhnologiya ferritovykh materialov magnitoelektroniki [Technology of ferrite materials of magnetoelectronics]. Moscow, MISiS Publ., 2005, 352 p. (in Russ.) Petrova E., Kotsikau D., Pankov V. Structural characterization and magnetic properties of sol–gel derived ZnxFe3-xO4 Journal of Magnetism and Magnetic Materials, 2015, v. 378, pp, 429–435. https://doi.org/10.1016/j.jmmm.2014.11.076 Mittova I. Ya., Tomina E. V., Lavrushina S. S. Nanomaterialy: sintez nanokristallicheskikh poroshkov i poluchenie kompaktnykh nanokristallicheskikh materialov: uchebnoe posobie dlya vuzov [Nanomaterials: the synthesis of nanocrystalline powders and the production of compact nanocrystalline materials: a textbook for universities]. Voronezh, LOP VGU Publ., 2007, 35 p. (in Russ.) Brandon D., Kaplan W. Microstructural Characterization of Materials. Chichester: John Wiley & Sons Ltd, 1999, 424 p. Tretyakov Yu. D. Development of inorganic chemistry as a fundamental for the design of new generations of functional materials. Russian Chemical Reviews, 2004, v. 73(9), pp. 831–846. https://doi.org/10.1070/RC2004v073n09ABEH000914 Tomina E. V., Mittova I. Ya., Burtseva N. A., Patent RF, N 2548089, 2015. Kuznetsova V. A., Almjasheva O. V., Gusarov V. V. Infl uence of microwave and ultrasonic treatment on the formation of CoFe2O4 under hydrothermal conditions. Glass Physics and Chemistry, 2009, v. 35(2), pp. 205–209. International Center for Diffraction Data. Shpanchenko R. V., Rozova M. G. Metodicheskaya razrabotka dlya spetspraktikuma k kursu lektsii «Prakticheskie aspekty rentgenovskoi difraktometrii» [Methodical development for the special practical course for lectures “Practical aspects of X-ray diffractometry”]. Moscow, Izd-vo Mosk. un-ta Publ., 1998, 25 p. (in Russ.) Tret’yakov Yu. D. Neorganicheskaya khimiya. Khimiya elementov: uchebnik dlya stud. vuzov, obuch. po napravleniyu 510500 “Khimiya” i spetsial’nosti 011000 “Khimiya” : v 2 t [Inorganic chemistry. Chemistry of elements: a textbook for students. universities enrolled in the direction 510500 “Chemistry” and specialization 011000 “Chemistry”: in 2 volumes]. Moscow, Izd-vo Mosk. un-ta: Akademkniga Publ., 2007, v. 1, 538 p.; v. 2, 670 p. (in Russ.) Tomina E. V., Darinskii B. M., Mittova I. Ya., Churkin V. D., Boikov N. I., Ivanova O. V. Sintez nanokristallov YСоxFe1-xO3 pod vozdeistviem mikrovolnovogo izlucheniya [Synthesis of YСоxFe1-xO3 Nanocrystals Under the Microwave Radiation], Inorganic Materials, v. 55(4), 2019, pp. 421–425. https://doi.org/10.1134/S0002337X19040158 (in Russ.)

Lamb Wave Analysis for Plate of Weak Ferromagnetic YFeO3

The present work presents the analysis of Lamb waves in weak easy-axis ferromagnetic yttrium orthoferrite YFeO3, where the frequency and velocities spectrums were calculated based on dispersion equations. The specialties in calculated Lamb wave spectrum show the possibility of wave generation by an external source. The influence of the sample thickness on the characteristics of wave propagation in a plate is investigated.