Lattice constants of CeCu5 under pressure

The p-T phase diagram of the AFM Kondo lattice CeCu5 is rather complex as c ompared to the model of Doniach. Moreover, a description of the pseudobinar y system CeCu5-xMx (M = Al, Ga) in terms of chemical pressure completely fa ils. The distinct anisotropies of the crystal structure (CaCu5) must be all owed for in such a way that the magnetic properties depend on the individua l lattice parameters a and c. We present results on the pressure dependence of these lattice parameters from X-ray diffraction measurements up to 12 G Pa in a diamond anvil cell. A bulk modulus B-0 = 104 GPa and a slight incre ase in the c/a ratio is found. These data support the anisotropic model for the exchange interaction. (C) 1999 Elsevier Science B.V. All rights reserv ed.