Laves Phase C15 Research Articles

Enhanced itinerant paramagnetism in C14-type laves Ti(Cu 1− xAl x) 2 (0.45 ⩽ x ⩽ 0.70) alloys

Ti(Cu 1- x Al x ) 2 in the range of 0.45 ⩽ x ⩽ 0.70 is found to crystallize into the C14-Laves phase and to exhibit magnetic properties characteristic of an enhanced itinerant paramagnet. A detailed study has been made particularly on the equiatomic alloy TiCuAl through the measurements of the magnetic susceptibility (4.2–1000 K) and the low-temperature specific heat (1.5–6 K). The results are discussed in comparison with those in similar systems like Pd and TiBe 2.

Ordering of atoms in 3d sublattice of the intermetallic quasibinary system Dy(Fe1?xMnx)2

Methods of x-ray analysis and nuclear γ-resonance (Mossbauer effect) have been used to study the distribution of iron and manganese atoms in the intermetallic quasibinary system Dy(Fe1−xMnx)2, which is isostructural to the Laves phase C15. Ordering of atoms of transition metals has been found in 3d sublattice of intermetallic compounds Dy(Fe1−xMnx)2 with the formation of a triple superstructure having the stoichiometric composition Dy(Fe0·.25Mn0·.75)2.

Hydrogen capacity and crystallography of ErFe 2-based and ErCo 2-based ternary systems

The hydrogen capacity of the C15 Laves-phase alloys ErFe 2− x Al x ( x = 0 − 0.6), ErFe 2− x Mn x ( x = 0 −1.4), ErFe 2− x Co x ( x = 0 − 2.0) and ErCo 2− x Ni x ( x = 0 − 2.0) was measured at 25 °C and 525 Ib in −2. Lattice parameters of the alloys and their hydrides were also measured. Al substitution for Fe decreases the hydrogen capacity of ErFe 2. Mn substitution for Fe in ErFe 2 increases the hydrogen capacity considerably, with a maximum hydride composition ErFe 0.8Mn 1.2H 4.6. Hydrogen concentration in this alloy exceeds 7 × 10 22 atoms cm −3. Co substitution for Fe in ErFe 2 first increases and then decreases hydrogen capacity, the maximum hydride composition being ErFe 1.2Co 0.8H 4.2. Ni substitution for Co in ErCo 2 has little effect on the hydrogen capacity of the alloy, although a large Ni concentration results in an increase in the equilibrium pressure. Lattice expansion is observed to correlate with hydrogen concentration for the group of systems ErFe 2-H, ErFe 2− x Al x - H and ErFe 2− x Mn x - H. The maximum hydrogen capacity in the ErFe 2− x Co x system occurs at the same Co:Fe ratio which gives the maximum Fe moment in these ternaries.

Calculation of the electrostatic energy of the laves phases C14, C15, and C36

AbstractThe electrostatic energies of point ions in a uniform compensating background are evaluated for a number of crystal structures using a modified form of the Ewald‐Fuchs method. These are the first calculations for the Laves phases C15 and C36.

Moment variation in rare earth-transition metal C15 compounds of type AFe2-ACo2, ACo2-ANi2

The magnetic and structural parameters of a number of pseudobinary rare earth and transition metal compounds are reported. These all belong to the cubic Laves phase C15 structure and have the general formula R(Fe, Co)2 and R(Co, Ni)2 where R includes Nd, Gd, Dy, Ho and Er.

Neutron Diffraction Study of the Pseudobinary System ErCo2–ErAl2

Results obtained by neutron diffraction indicate that the magnetic moment of the ferromagnetic sublattice in the Laves phase structures, C15 (ErCo2, ErAl2) and C14 (ErCoAl), varies with composition while the ordering temperatures stay approximately constant. Low values of the aligned moment, however, are accompanied by high values of the disorder scattering at low temperatures. Co carries no moment from 30 mole % ErAl2 on. Results are discussed in terms of tendencies toward antiferromagnetism at certain values for the valence electron concentration.