The new PrNi6Si6 intermetallic: from crystal structure to thermal and electrical transport properties across a wide temperature range (2–900 K)

In the present study, the new ternary rare earth intermetallic compound PrNi6Si6 has been investigated. This work completes the study of the RNi6Si6 series (R = rare earth). While the RNi6Si6 compounds for R = La and Ce adopt the CeNi6Si6-type (tP52, P4/nbm, No. 125), surprisingly PrNi6Si6 crystallizes in the YNi6Si6 prototype (tP52, P - 4b2, No. 117) as do all the heavier lanthanides (but Lu). The YNi6Si6-type and its homolog CeNi6Si6 are two tetragonal ordered derivative of the cubic NaZn13-type structure. Lattice parameters for PrNi6Si6 are a = 7.7846(1) & Aring;, c = 11.2144(1) & Aring;, with a unit cell volume, Vobs = 679.585(5) & Aring;3. The temperature dependence of the inverse magnetic susceptibility chi-1(T) follows the Curie-Weiss law, with calculated values of the effective magnetic moment (mu eff) and Weiss temperature (Theta pm) of 3.55 mu B and - 4.5 K, respectively. While the observed mu eff is very close to the theoretical value of 3.58 mu B for the free Pr3+ ions, a negative value of the Weiss temperature suggests antiferromagnetic interactions in PrNi6Si6. Magnetization measurements confirm that PrNi6Si6 orders antiferromagnetically (AFM) below a N & eacute;el temperature (TN) of 9 K. The Ni atoms contribute negligibly to the magnetic properties of this phase. The specific heat of PrNi6Si6 is approximately 0.42 J K - 1 g - 1. Measurements of electric and thermal transport reveal that PrNi6Si6 exhibits metallic behavior across a wide temperature range of 2-900 K, accompanied by a relatively low thermal conductivity of around 6 W K - 1 m - 1 at room temperature. Such properties, together with its high-temperature refractory behavior, make PrNi6Si6 worthy of consideration in technological applications where fairly good electrical conductivity should be accompanied by a limited thermal conductivity.