abstract
In order to study the crystal structure, phase relationships, and magnetic properties of the systemTb5−xLaxSi2Ge2, a series of polycrystalline samples with compositions ranging from x = 0 to x = 5 have beensynthesized and characterized in detail. At room temperature, two structures have been detected: Compounds inthe concentration range 0 x < 1 present a monoclinic Gd5Si2Ge2-type structure, while for x > 1 a tetragonalZr5Si4-type structure is observed. The unit cell volume increases linearly with La concentration but with twodifferent slopes: ∼18 A˚ 3/x and ∼33 A˚ 3/x for 0 x < 1 (monoclinic) and x > 1 (tetragonal), respectively. In themonoclinic region, an increase of TC was observed, reaching a maximum value of TC ∼ 154 K, at the x = 0.75composition. This feature is explained based on specific La occupancy at the R2 site which was supported bydensity functional calculations for low La concentration. The samples that crystallized in the tetragonal structureexhibit a linear decrease of TC(x) with a slope of ∂TC/∂x ∼ −38 K/x, reaching 0 K for the x = 5 composition.A magnetic and structural x-T phase diagram of the Tb5−xLaxSi2Ge2 system in the temperature range 4–300 Kis proposed.
authors
J. H. Belo, A. M. Pereira, J. P. Araújo, C. de la Cruz, A. M. dos Santos, J. N. Gonçalves, V. S. Amaral, L. Morellon, M. R. Ibarra, P. A. Algarabel, and C. Magen
our authors
João Silva
Post-Doc FellowshipGroups