The Calcium Carbonate Geological Samples Study by ³He NMR

© 2017 Springer-Verlag WienGeological samples of calcium carbonates (CaCO3) were investigated by 3He NMR, nitrogen porosimetry, X-ray diffraction and electron microscopy methods. The integral porosity of the samples was obtained by 3He nuclear magnetic resonance method and compared with nitrogen adsorption isotherms data. The advantages of 3He porometry method are discussed

Nuclear pseudoquadrupole resonance of 141Pr in Van Vleck paramagnet PrF3

Nuclear pseudoquadrupole resonance of 141Pr in Van Vleck paramagnet PrF3 has been observed in singlecrystal and micro- and nanopowder samples at a temperature of 4.2 K. The spectra of nuclear pseudoquadrupole resonance of 141Pr, as well as the spin-spin and spin-lattice relaxation parameters, have been obtained. The parameters of the nuclear spin Hamiltonian have been determined. It has been found that the parameters of the crystal electric field in nanocrystals differ strongly from those in microcrystals. © 2011 Pleiades Publishing, Ltd

Electron paramagnetic resonance of Gd3+ ions in powders of LaF3+:Gd3+ nanocrystals

The observation of electron paramagnetic resonance of Gd3+ ions in nanosized powders of rare-earth fluorides LaF3:Gd3+ has been reported. The measurements have been performed on a single crystal and microand nanosized powders at room temperature. Electron paramagnetic resonance spectra and spin-Hamiltonian parameters of Gd3+ ions have been obtained. A qualitative difference of spectra in nano-and micropowders due to the increase in the spread of the crystal field parameters with the decrease in the particle size has been found. The relationship between the single-crystal domain size and the hydrothermal treatment time has been established. © Pleiades Publishing, Ltd., 2014

Application of cryogenic technologies for NMR logging tool

The development of heavy oil and bitumen deposits is becoming an actual problem in last years. In this paper the authors propose to use cryogenic technologies for improving the sensitivity of nuclear magnetic resonance logging tool. Particularly, it is proposed to use a magnetic system made of a high temperature superconductor. The low temperature of the magnetic system is provided by the thermal contact with cryocapacitor, which is made of a material with a high specific heat at low temperatures. Experimental data are presented

Anomalous nuclear spin–lattice relaxation of ³Не in contact with ordered Al<inf>2</inf>O<inf>3</inf> aerogel

© 2016, Pleiades Publishing, Inc.Spin–lattice relaxation of 3Не in contact with the ordered Al2O3 fiber aerogel has been studied at the temperature of 1.6 K in fields of 0.1–0.5 T by the pulsed nuclear magnetic resonance (NMR) method. An additional mechanism of the relaxation of 3Не in aerogels is found and it is shown that this relaxation mechanism is not associated with the adsorbed layer. A hypothesis about the influence of intrinsic paramagnetic centers on the relaxation of gaseous 3Не is proposed

Microwave-Assisted Hydrothermal Synthesis and Annealing of DyF 3

The series of DyF3 nanosized samples was synthesized by the colloidal chemistry method. The microwave-assisted hydrothermal treatment was used for the first time for the modification of DyF3 nanoparticles. Transmission electron microscopy images show that the DyF3 nanoparticles have average particle size of about 16–18 nm and the size distribution becomes narrower during the microwave irradiation. The X-ray diffraction analysis shows the narrowing of the diffraction peaks versus microwave treatment time. The experimental data demonstrates restructuring of the nanoparticles and their crystal structure becomes closer to the ideal DyF3 regular structure during the microwave irradiation of colloidal solution. The defect-annealing model of the microwave-assisted hydrothermal modification process is suggested

High-T c spin superfluidity in antiferromagnets

We report the observation of the unusual behavior of induction decay signals in antiferromagnetic monocrystals with Suhl-Nakamura interactions. The signals show the formation of the Bose-Einstein condensation (BEC) of magnons and the existence of spin supercurrent, in complete analogy with the spin superfluidity in the superfluid He3 and the atomic BEC of quantum gases. In the experiments described here, the temperature of the magnon BEC is a thousand times larger than in the superfluid He3. It opens a possibility to apply the spin supercurrent for various magnetic spintronics applications. © 2012 American Physical Society

Discovery of the classical Bose-Einstein condensation of magnons in solid antiferromagnets

Results of experiments in which the Bose-Einstein condensate of magnons is created in the CsMnF 3 easy-plane antiferromagnet in a system with coupled nuclear-electron precession with dynamical frequency shift are presented. This condensate is similar to the Bose-Einstein condensate of magnons in superfluid 3He-A in aerogel. © 2011 Pleiades Publishing, Ltd