RNi8Si3 (R = Gd, Tb): Novel ternary ordered derivatives of the BaCd11 typeстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 6 апреля 2016 г.
Аннотация:The title compounds have been synthesized and characterized
both from the structural and magnetic point of view. Both crystallize in
a new monoclinic structure strictly related to the tetragonal BaCd11
type. The structure was solved by means of X-ray single-crystal
techniques for GdNi8Si3 and confirmed for TbNi8Si3 on powder data: the
corresponding lattice parameters are a=6.3259(2), b=13.7245(5),
c=7.4949(3) Å, β=113.522(3)°, Vcell=596.64(3) Å3 and a=6.3200(2),
b=13.6987(4), c=7.4923(2) Å, β=113.494(2)°, Vcell=594.88(2) Å3. The
symmetry relationship between the tI48-I41/amd BaCd11 aristotype and the
new ordered mS48-C2/c GdNi8Si3 derivative is described via the
Bärnighausen formalism within the group theory.
The large Gd-Gd (Tb-Tb) distances mediated via Ni-Si network likely
lead to weak magnetic interactions. The low-field magnetization vs
temperature measurements indicate weak and field-sensitive
antiferromagnetic ground state, with ordering temperatures of 3 K in
GdNi8Si3 and about 2-3 K in TbNi8Si3. On the other hand, the isothermal
field-dependent magnetization data show the presence of competing
interactions in both compounds, with a field-induced ferromagnetic
behavior for GdNi8Si3 and a ferrimagnetic-like behavior in TbNi8Si3 at
the ordering temperature TC/N of about (or slightly higher than) 3K. The
magnetocaloric effect, quantified in terms of isothermal magnetic entropy
change Sm, has the maximum values of -19.8 J(kg.K)-1 (at 4K for 140 kOe
field change) and -12.1 J(kg.K)-1 (at 12K for 140 kOe field change) in
GdNi8Si3 and TbNi8Si3, respectively.