Magnetic properties of nanosized γ-Fe2O3 and α-(Fe2/3Cr1/3)2O3, prepared by thermal decomposition of heterometallic single-molecular precursor

Thermal decomposition of the trinuclear complex [Fe₂CrO(CH₃COO)₆(H₂O)₃]NO₃ at 300, 400 and 500 °C gave γ-Fe₂O₃ nanoparticles along with amorphous chromium oxide, while decomposition of the same starting compound at 600 and 700 °C led to the formation of α-(Fe_2/3Cr_1/3)₂O₃ nanoparticles. Size of γ-Fe₂O₃ nanoparticles, determined by X-ray diffraction, was in the range from 9 to 11 nm and increased with formation temperature growth. Average size of α-(Fe_2/3Cr_1/3)₂O₃ nanoparticles was about 40 nm and almost did not depend on the temperature of its formation. γ-Fe₂O₃ nanoparticles possessed superparamagnetic behavior with blocking temperature 180-250 K, saturation magnetization 29-35 emu/g at 5 K, 44-49 emu/g at 300 K and coercivity 400-600 Oe at 5 K. α-(Fe_2/3Cr_1/3)₂O₃ nanoparticles were characterized by low magnetization values (2.7 emu/g at 70 kOe). Such magnetic properties can be caused by non-compensated spins and defects present on the surface of these nanoparticles. The increase of α-(Fe_2/3Cr_1/3)₂O₃ formation temperature led to decrease of magnetization (being compared for the same fields), which may be caused by decrease of the quantity of defects or non-compensated spins (due to decrease of particles' surface).     

Impact of a spherical rigid body on the surface of a cavity in a compressible liquid: An axisymmetric problem

The shock interaction of a spherical rigid body with a spherical cavity is studied. This nonstationary mixed boundary-value problem with an unknown boundary is reduced to an infinite system of linear Volterra equations of the second kind and the differential equation of motion of the body. The hydrodynamic and kinematic characteristics of the process are obtained __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 1, pp. 11–19, January 2008.     

Origin of Structure Inversion Asymmetry in Double HgTe Quantum Wells

JETP Letters - The density dependences of the splitting values of the dominant magneto-absorption lines in undoped p-type double HgTe/CdHgTe quantum wells are studied. An analysis of the splitting...     

On Reaction of Sulfur Dioxide with Aqueous Solutions of Carbamide

A mechanism of SO₂ chemisorption by aqueous solutions of carbamide was suggested. The effective rate constants of accumulation of hydrogen ions in the reaction of sulfur dioxide with aqueous solutions of carbamide in the range 278-313 K were determined.     

Axisymmetric problem of the penetration of a compressible fluid by thin elastic spherical shells

Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev, Kiev Highway Institute. Translated from Prikladnaya Mekhanika, Vol. 24, No. 4, pp. 63–74, April, 1988.     

Preconcentration of phenols on a polymethacrylate sorbent for their gas-chromatographic determination in water

The preconcentration of phenol and its homologues by sorption on a polymethacrylate sorbent followed by capillary gas-chromatographic determination is studied. The optimal sorption conditions are the following: the sorbent mass, 400 mg; the volume of aqueous solution with pH 3, 150 mL; the flow rate of solution, 3–4 mL/min; and the volume of ethylacetate for elution, 3 mL. The detection limit is 0.7–1.0 μg/mL.