Production of Zinc-Doped Yttrium Ferrite Nanopowders by the Sol–Gel Method

Zinc-doped yttrium orthoferrite nanocrystals having the perovskite structure were prepared by coprecipitation of yttrium, zinc, and iron hydroxides. The limiting zinc doping level of the yttrium ferrite to yield a ZnFe₂O₄ spinel second phase was determined. The yttrium orthoferrite particle size was found to be a nonmonotone function of dopant concentration. The specific magnetization of yttrium ferrite nanocrystals increases with increasing zinc doping level from 0.242 A m²/kg (in undoped YFeO₃) to 1.327 A m²/kg (the ratio (1–x)YFeO₃: xZn (x = 0.4)) at Т = 300 K in 1250-kA/m field. A zinc ferrite impurity in samples enhances the ferromagnetism of the material.     

Formation of nanosized oxide films via thermal oxidation of Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/InP heterostructures

Modification of InP film with magnetron-deposited 30 nm nanolayer of Co₃O₄ has resulted in the transit mechanism of thermal oxidation of the semiconductor and formation of nanosized oxide-phosphate films. Efficient transit interactions of Co₃O₄ with the semiconductor due to fast chemical binding of indium has led to the suppression of its diffusion inside the films. Secondary interactions of the oxides result in the formation of phosphate scaffold in the inner film regions, whereas the surface layer contains cobalt and indium oxides.     

Erratum to: “Sol-Gel Synthesis and Properties of Y1–xBaxFeO3 Nanocrystals”

Russian Journal of General Chemistry - The fourth author of the article should read A. T. Nguyen. Affilation of A.T. Nguyen should read Ho Chi Minh City University of Education, Ho Chi Minh City,...     

Sol-Gel Synthesis and Properties of Y<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ba<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>FeO<Subscript>3</Subscript> Nanocrystals

The sol-gel method was used to prepare Y_1–xBa_xFeO₃ (x = 0, 0.05, 0.1, 0.15, 0.2) nanocrystals. The influence of the dopant content on the particle size and magnetic properties of yttrium ferrite was examined.     

Effect of the degree of doping on the size and magnetic properties of nanocrystals La<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>FeO<Subscript>3</Subscript> synthesized by the sol–gel method

Nanopowders La_1–x Zn _x FeO₃ (nominal degree of doping x _nom = 0, 0.05, 0.075, 0.1, 0.15, 0.2, 0.3, and 0.4) were synthesized by the sol–gel method using aqueous ammonia as a precipitator and were then annealed at 950°C for 60 min. From the data of X-ray powder diffraction analysis and local electron probe microanalysis, the maximum actual limit of doping of lanthanum ferrite with zinc was determined: x = 0.072. The dependence of the particle size on the Zn²⁺ content was found to be nonmonotonic. The magnetic characteristics (specific magnetization J, coercivity H _c, and magnetic susceptibility χ) of samples at temperatures of 300 and 100 K in fields of up to 1300 kA/m. It was shown that, with increasing degree of doping, J increases from 0.188 A m²/kg (at x = 0) to 0.245 A m²/kg (at x = 0.072), and χ varies nonmonotonically from 11.5 × 10^–6 (at x = 0) to 15.3 × 10^–6 (at x = 0.072) (at 300 K). With decreasing measurement temperature to 100 K, the magnetization and susceptibility monotonically increase.     

Influence of the synthesis conditions on the particle size and morphology of yttrium orthoferrite obtained from aqueous solutions

The size and morphology of yttrium orthoferrite nanoparticles were examined in relation to the synthesis conditions. The chemical composition of the crystalline phases resulted from heat treatment of the samples at 650°C varies with the procedure of coprecipitation of yttrium and iron(III) hydroxides. At the same time, heat treatment at 750°C leads to formation of yttrium orthoferrite solely. The size of the YFeO₃ crystals is weakly dependent on the initial composition preparation procedure, and the size and shape of their agglomerates are sensitive to the conditions of coprecipitation of the hydroxides.     

Role of tungstic acid in thermal film growth on indium phosphide

The influence of tungstic acid on oxide film growth during indium phosphide thermal oxidation is studied. When H₂WO₄ is added to the reaction zone, tungsten is captured by growing layers and heteropoly compounds are formed.     

Sol-gel preparation and magnetic properties of nanocrystalline lanthanum ferrite

LaFeO₃ nanoparticles (30–40 nm) have been prepared via the sol-gel method using polyvinyl alcohol as a stabilizer. Addition of polyvinyl alcohol results in the formation of smaller LaFeO₃ particles and decreases the temperature of transition into the single-phase product as compared with the samples prepared via precipitation with aqueous ammonia. Residual magnetization, magnetization at saturation, and coercive force of LaFeO₃ nanoparticles are monotonous decreasing functions of the nanopowder annealing temperature.