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Abstract: The crystal field (CF) interaction was calculated from first principles for the NdNi2B2C borocarbide. The parameters of the CF Hamiltonian were used to obtain the CF splitting of the ground state multiplet of the Nd3+ ion. This allows a comparison of the calculated specific heat and magnetic susceptibility of NdNi2B2C with the experiment yielding qualitatively good agreement. [Copyright &y& Elsevier]

Abstract: We have studied influence of the Pt–Ni substitution on the crystal structure and magnetic behavior of the PrNi x Pt1−x compounds. Polycrystalline samples with x =1, 0.9, 0.75, 0 were prepared and characterized by X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The analysis of XRPD data confirmed that the orthorhombic CrB-type structure owned by the parent binary compounds remains conserved through the entire series. The samples were subsequently investigated by specific heat (C p ), magnetization (M) and ac susceptibility measurements in the temperature range 2–350K and in magnetic fields up to 9T. All compounds were found to order ferromagnetically. The T C values monotonously increase with increasing Ni content. To inspect the crystal-field (CEF) effects and magnetocaloric properties specific-heat data were analyzed in detail and the magnetic contribution to the specific heat together with the magnetic entropy have been determined. The results of first principles electronic structure calculations of the PrNi and PrPt confirmed that besides the stable Pr magnetic moments due to localized 4f-electrons only a very small magnetic moments of at most 0.2μ B is induced at the Ni (Pt) site due to the polarized 3d-electron states (5d-electron states) hybridizing with the Pr 5d-electron states, i.e. the Ni (Pt) moment plays only minor role in the total balance of the magnetic moments in these compounds. [Copyright &y& Elsevier]

Abstract: We have confirmed polymorphism of PrIr2Si2 and performed the in situ high-temperature X-ray powder diffraction (XRPD) experiments focused on the dynamics of the crystallographic phase transition from the high-temperature CaBe2Ge2-type phase to the low-temperature ThCr2Si2 phase above 250°C. A double-exponential time evolution of this phase transformation has been observed at 325°C. We have also performed density functional calculations to analyze why the low-temperature crystallographic modification becomes the ground state crystal structure. The important role of the c/a ratio in this process can be argued from results of calculations. [Copyright &y& Elsevier]

Abstract: REIr2Si2 (RE = La, Ce, Pr and Nd) were found to be polymorphic compounds which can crystallize in two different tetragonal types of crystallographic structures (β-phase: CaBe2Ge2-type; α-phase: ThCr2Si2-type). Here we study the structural phase transitions (α- to β- and β- to α-) using thermal expansion, differential thermal analysis and neutron diffraction. Both phase transitions occur at temperatures lower than 1300 °C, have a hysteresis up to 300 °C, do not show any intermediate steps and are accompanied with the absorption/release of the latent heat. We conclude that these structural phase transitions are of the first order. [Copyright &y& Elsevier]

A single crystal of UFeSi has been grown and studied with respect to crystal structure, magnetic and electrical resistivity behavior. UFeSi crystallizes in the orthorhombic TiNiSi-type crystal structure and shows no signs of magnetic ordering. The temperature dependence of magnetic susceptibility measured in all three principal crystallographic directions is weakly temperature-dependent, nevertheless it exhibits easy-plane magnetocrystalline anisotropy. The broad χ(T) maximum around 80 K observed in the a–c plane is reminiscent of spin-fluctuation behavior. The temperature dependence of electrical resistivity measured for a current along the b-axis obeys quadratic dependence for temperatures below 33 K and shows a tendency to saturation at high temperatures typical for most U intermetallics. [Copyright &y& Elsevier]