No abstract available

No abstract available

No abstract available

[en] NMR measurements of a coefficient of He³ spin diffusion in solid H₂ at temperatures of 1.4; 1.0; 0.47 K have been carried out. Two phases, one of which is insolved He³, have been discovered for 1.6% He³ concentration. Investigations of the second phase in specimens With 0.16 and 0.10% He³ have shown that He³ diffusion has a quasi-one-dimensional character. Experimental data are explained well within the framework of fast diffusion in dislocations in solid H₂

[en] The behaviour 3 He (non-zero nuclear spin) in the 4 He (zero nuclear spin) matrix has been investigated with the pulsed NMR technique. These measurements are based upon the application of the dependence of spin echo signal in inhomogeneous magnetic field on diffusion coefficient of spins. (H.W.) 21 refs.; 6 figs

[en] Short communication. 5 refs

[en] Nuclear magnetic resonance (NMR) measurements of spin diffusion coefficient D of He³ in solid hydrogen have been carried out at 1.4; 1.0 and 0.47⁰K. Two phases have been observed for 1.6% concentration of He³, one of them being presented as undissolved He³. Studies of the other phase (0.16%; 0.10% of He³) proved diffusion of He³ to be quasi-one-dimensional. The data obtained are well explainable within the framework of the model of He³ fast diffusion along dislocations in solid H₂. (orig.)

[en] The NMR data on the phase transition kinetics of ³He-⁴He solid solutions at T=100 mK are considered. Studied are solid helium samples of a molecular volume of 20.55 cm²/mol with a ³He content of 0.54 %. An unusually long phase transition time is found which is dependent on the prehistory of sample. The spin diffusion of ³He in the transformated solution concentrated phase is found to be of a quasi-one-dimensional nature with the diffusion coefficient value typical of liquid

No abstract available

[en] Using NMR technique the diffusion coefficient D of He³ atoms in solid He⁴ in a wide range of He³ concentrations, densities and temperatures has been measured. It has been shown that in the low temperature plateau range D decreases sharply up to the values of D approx.= 3 x 10^-12 cm² sec^-1 when increasing concentrations of He³ up to 5%. The result obtained is indicative of the presence of strong localization of He³ atoms in hcp phase of He⁴ which is removed at the cost of quantum diffusion stimulated by phonons in full accordance with the theory predictions of Kagan. The critical behaviour of D in the region of strong localization has been studied. The analysis of the contributions of different mechanisms to diffusion of He³ has been made and this removes the available contradictions in the description of vacancy diffusion of He³. For the first time the constant of dipole-dipole diffusion has been measured. (author)