The study of thermodynamic properties of PrNi 5

Abstract

We have studied the influence of interaction of magnetic ions with conduction electrons on the thermodynamic properties of PrNi5 rare earth intermetallic compound. Starting in the zero approximation from ttm model of the crystal field and using equations of the thermodynamic perturbation theory, we have derived the formalism for evaluation of the partition function in the n-th order. The computations of higher order terms were performed by symbolic programming. The derived formalism was applied for explanation of temperature dependence of paramagnetic susceptibility, specific heat and electrical resistivity of PrNi5 compound. PACS: 70.00 Key words: rare earth intermetallic compounds 1 Theory In the thermodynamic perturbation theory [1] operator a, determining the partition funtion Z of the system is expressed by the infinite operational sum: oo cr(/~) = 1 + ~ an(/?) , (1) n=l where the n-th order contribution ff.,f.:-, an(/~) = (-1) n Jo Jo ""Jo V(T1)...V(r~) dr,,...drl (2) mid V(r) = eH"*Ve -Jt~ (3)Here H = H0 + V, H0 is the Hmniltonian of the unperturbed system, V is the perturbation and/~ = 1/kT. We have studied the properties of 4f-electron systems. In our approach we have taken tim advantage of the fact that tim Hilbert space of the lowest crystalfield multiplet has the finite dimension 2J+l and therefore in resulting expressions we can perform summations over eigenvalues and eigenstates of the crystal-field Hamiltonian.The thermal average <an (/3)> used for the calculation of macroscopic properties can be then written as [2]: *) Presented at ll