Up-conversion and IR Luminescence of Ytterbium–Erbium Oxyfluoride Silicate Glassceramics

The paper studied the luminescent properties of lead fluoride silicate nanostructured glassceramics doped with ytterbium and erbium ions. We have measured luminescence spectra of glassceramics in the visible and near-IR ranges at temperatures of 300 and 77 K and under their pumping at a wavelength of 975 nm. We have examined changes in the luminescence spectra of glassceramics depending on the time of their secondary thermal treatment, concentration of dopant ions, specimen temperature, and power of exci-tation radiation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3551

Distribution peculiarities of stray fields and magnetization near magnet singularities

Distributions of both magnetization and stray fields near singularities of a permanent magnet with high uniaxial anisotropy have been studied. On the basis of calculations it is shown that in magnets with high magnetic anisotropy, strong stray fields H > 4πMs occurring near the edge of a magnet do not practically result in deviation of magnetization from easy axis if the quality factor of the magnetic material g = K/(2πMS²) is g > 10. In such magnet systems, the distribution of magnetization is close to homogeneous, and it is possible to use the method of "magnetic charges" for calculations of stray fields. It is shown that the stray field near an edge of a magnet takes finite values, and the presence of a singularity at the dependence of the tangent component of the stray field Hτ ~ Ms-ln(a/r) at r → 0 is related to macroscopic characteristics generally accepted in magnetism, namely the surface density of "magnetic charges" σ

Hard-magnetic melt-spun R–Fe–B alloys on the base of light rare-earth metals (R=La, Nd)

Effects of La addition on microstructure and magnetic properties of LaxNd₃₃₋xFe₆₅.₉B₁.₁ (wt. %) melt-spun ribbons and isotropic bonded magnets were systematically studied. X-ray diffraction and DSC data revealed that addition of La led to the formation of highly refined and inhomogeneous La-rich phase. It was shown that the average grain size and volume fraction of the main magnetic (La,Nd)₂Fe₁₄B phase depend on La concentration. For better LaxNd₃₃₋xFe₆₅.₉B₁.₁x = 2.5 and 5 wt. % bonded samples, the room-temperature magnetic properties of Hci = 1343 kA/m and 1300 kA/m, and Br= 0.61 T and 0.614 T were obtained. Magnetic flux aging loss for alloys with appropriate La content (x = 5–10 wt. %) did not exceed 5 % in the range of 100–125°C, which is typical for conventional ternary Nd–Fe–B melt-spun magnets