Characterization ofRCo2B2C

M. El Massalami¹,

Márcio Henrique Sá Netto Costa²,

R.E. Rapp³

et al.

Rare-earth metal transition metal borocarbide and nitridoborate superconductors

“…The unit cell development with r(R 3þ ) is very similar to that of the Ni series, although with a smaller volume, a smaller c-axis and a larger a-axis, however, approaching quite similar values for the compounds with smaller rare-earth metals [147]. Again, the Ce compound shows some deviation in volume and c unit cell parameter to smaller values indicating a larger valence than þ3 [147]. The physical properties of the Co series are distinctly different from those of the Ni analogues.…”

“…The isotypes with complete substitution of Ni by Co were prepared with R ¼ Y, and La--Tm (except for the Eu and Pm compounds) [142,[146][147][148]. The unit cell development with r(R 3þ ) is very similar to that of the Ni series, although with a smaller volume, a smaller c-axis and a larger a-axis, however, approaching quite similar values for the compounds with smaller rare-earth metals [147].…”

“…The physical properties of the Co series are distinctly different from those of the Ni analogues. The differences are summarized as follows: i) absence of superconductivity, at least down to the mK temperature range, ii) a decrease in the Néel temperatures, and iii) a deviation from de Gennes scaling [34,147].…”

“…The M ¼ Co series was obtained for R ¼ Y, La--Tm (except for Eu and Pm) [24,[142][143][144][145][146][147][148]. Unfortunately, one reference only gives a diagram of the unit cell parameters as a function of the rare-earth metal radius, but no concrete values.…”

“…During this proce-XC [50,324] XP [152] À [50] a: Origin of unit cell data: XP: X-ray diffraction on powder, XC: X-ray diffraction on crystal, NP: Neutron diffraction on powder b: Removed from diagrams due to inconsistent data c: Never synthesized, unit cell parameters only predicted based on the data of the RNi 2 [B 2 C] series d: Double re-entrance: superconductivity nearly disappears at 6 K, re-emerging below 5 K e: According to [26], apparently taken from figure in [147] dure small single crystals were occasionally obtained. For some compounds rapid quenching was reported to be necessary to obtain samples of reasonable purity and annealing is thus counterproductive, e.g., for ScNi 2 [5].…”