A. V. Klochkov

Spin Kinetics of 3He in Contact with Synthesized PrF3 Nanoparticles

Two nanosized PrF3 samples were synthesized using two different procedures. The X-ray and HRTEM experiments showed high crystallinity of synthesized sample. Comparison of enhanced 141Pr NMR spectra of microsized (45

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

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Size Effect in the (PrF 3 Nanoparticles- 3 He) System

m) and nanosized PrF3 powder is presented. Experimental data on spin kinetics of 3He in contact with PrF3 nanoparticles at T = 1.5 K are reported.

Experimental proof of the existence of water clusters in fullerene-like PrF3 nanoparticles

Results of experiments in which the Bose-Einstein condensate of magnons is created in the CsMnF3 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.

Nuclear pseudoquadrupole resonance of 141Pr in Van Vleck paramagnet PrF3

Spin kinetics of adsorbed and liquid 3He in contact with crystalline nanopowders of the Van Vleck paramagnet PrF3 at a temperature of 1.5 K has been studied by nuclear magnetic resonance. The correlation between the parameters of the nuclear magnetic relaxation of 3He and the sizes of the sample particles has been found. A qualitative model of the magnetic relaxation of 3He describing the experimental results has been proposed.

Observation of magnetic coupling between the nuclei of liquid 3He and the 141Pr nuclei of PrF3 crystalline powder

Synthesized fullerene-like nanoparticles of the Van Vleck paramagnet PrF3 have been studied by nuclear magnetic resonance cryoporometry. Water clusters have been discovered in the internal cavities of the nanoparticles. The analysis of the experimental data indicates that the cluster radius is 1–2.3 nm. The obtained data agree well with the high-resolution transmission electron microscopy data.

Anomalous nuclear spin–lattice relaxation of 3Не in contact with ordered Al2O3 aerogel

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.

Microwave-Assisted Hydrothermal Synthesis and Annealing of DyF3 Nanoparticles

The resonance magnetic coupling between the nuclei of liquid 3He and the 141Pr nuclei of a fine-dispersed powder of PrF3 Van Vleck paramagnet with the grain size below 45 μm has been discovered at a temperature of 1.5 K with the use of a pulsed NMR technique. The magnetic specific heat of the corresponding spin systems is estimated theoretically.

Annealing of PrF3 nanoparticles by microwave irradiation

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.

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

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.