Refinement of the crystal structure of (RS)-carnitine hydrochloride

A single crystal of (RS)-carnitine hydrochloride has been obtained, and its crystal structure has been refined by an x-ray structural experiment.Tashkent Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 842–844, November–December, 1991.     

Magnetization studies on ErCo3-hydride and TmCo3-hydride

The compounds ErCo₃ and TmCo₃ are ferrimagnetic with Curie temperatures of 401 K and 370 K, respectively. These absorb hydrogen to form ErCo₃H_4.3 and TmCo₃H_3.3. From magnetization studies on these as well as other RCo₃ hydrides in the temperature interval 4.2 to 300 K, it is inferred that hydrogen absorption leads to a reduction in magnetic moment on cobalt and a weakening of the R-Co interaction (R = rare earth). Except in the case of the GdCo₃-hydride, saturation in magnetization is not achieved at 4.2 K in applied fields up to 21 kOe. This suggests the possibility of fanning of rare earth moments. The RCo₃-hydrides investigated earlier with R = Gd, Dy and Ho and the ErCo₃-hydride and TmCo₃-hydride all appear to be magnetically ordered at room temperature.     

Refinement of the crystal structure of (RS)-carnitine hydrochloride

A single crystal of (RS)-carnitine hydrochloride has been obtained, and its crystal structure has been refined by an x-ray structural experiment.     

Magnetic and structural properties of Y6−xErxFe23 alloys and their hydrides

The magnetic characteristics and structural features of the Y_6?xEr_xFe₂₃ alloys and their hydrides are reported. The parent alloys all formed in a face-centered cubic structure. A pronounced minimum in the lattice parameter was observed for Er₄Y₂Fe₂₃. A similar minimum was also observed in the 1 atm hydrogen capacity of the alloys. The hydrides of the Y-rich compounds were found to retain the cubic structure of the parent compounds, whereas the hydrides of Er₅YFe₂₃ and Er₆Fe₂₃ adopt tetragonally distorted structures. Both the intermetallics and their hydrides were observed to be ferrimagnetic, exchange-dominated systems. In all cases, absorption of hydrogen resulted in an increase in both the saturation magnetization and the Curie temperature.     

Effect of hydrogen absorption-desorption cycle on the magnetic susceptibility of CeNi4Al

The effect of hydrogen on the magnetic susceptibility of CeNi₄Al has been investigated. It is observed that following a hydrogen absorption-desorption cycle, without exposing the sample to air, the magnetic susceptibility of CeNi₄AlH₀(I) increases over that of CeNi₄Al. If, after hydrogenation, the sample is kept in the air and then hydrogen removed, the increase in susceptibility of CeNi₄AlH₀(II) is even larger. Magnetic precipitation of Ni due to the presence of O₂ and H₂O is thought to be responsible for this behavior. An increase in susceptibility of CeNi₄AlH_3.7 over that of CeNi₄Al is also observed and attributed partly to the tendency of valence change of cerium from 4+ toward 3+.     

Magnetic characteristics of R2(Fe, Co)14B systems (R = Y, Nd and Gd)

R₂(Fe, Co)₁₄B compounds (R = Y, Nd and Gd) were prepared in high purity. The magnetic behavior of R₂(Fe, Co)₁₄B compounds is reported over the temperature range 4 to 300 K. The effects of Fe substitution by Co on the saturation magnetization, Curie temperature and anisotropy are presented. The spin-reorientation temperature is lowered as Co replaces Fe. This also results in a reduced cone angle.

The R₂Fe_14−xCo_xB alloys crystallize in the tetragonal structure over the entire concentration range of 0 x 14. When Fe is substituted by Co, the Curie temperature increases significantly, the saturation magnetization increases to a maximum value around x = 2, and the anisotropy becomes planar for R = Y and Gd. The Nd₂(Fe, Co)₁₄B systems all exhibit uniaxial anisotropy at room temperature and Nd₂Co₁₄B is strongly uniaxial at 77 K. The Nd₂(Fe, Co)₁₄B systems are conical at 77 K.     

Effect of absorbed hydrogen on magnetic behavior of Th7Co3 and Th7Ni3

The Pauli paramagnets Th₇Fe₃, Th₇Co₃ and Th₇Ni₃ become superconducting below 1.86 K, 1.83 K and 1.98 K, respectively. These compounds absorb large amounts of hydrogen to form the very hydrogen-rich phases Th₇Fe₃H₃₀, Th₇Co₃H₂₂ and Th₇Ni₃H₂₄. From magnetization studies it is found that hydrogenation results in an increase in the susceptibility of Th₇Co₃, and in a decrease in the susceptibility of Th₇Ni₃, but magnetic ordering is not observed in these two. This is in contrast to the behavior of Th₇Fe₃H₃₀ which is magnetically ordered with a Curie temperature above 350 K.     

Magnetic and crystallographic characteristics of Th6–xYxMn23 alloys

Crystallographic studies of Th_6–xY_xMn₂₃ ternaries show that Y₆Mn₂₃ and Th₆Mn₂₃ are miscible in all proportions with lattice parameters that are essentially independent of composition. Magnetic properties of the ternaries have been examined over the temperature range 4 to 500 K. The Curie temperatures and the saturation magnetizations decrease monotonically with decreasing Y content; magnetic ordering is observed for all compositions within the range 1.50 < x ? 6. Since the Mn-Mn spacing is nearly invariant with composition, it follows that electron concentration variation is responsible for the compositional variation of magnetic properties.