THE EFFECT OF CHEMICAL PRESSURE UPON THE MAGNETISM OF (BA1-XSRX)2PRNBCU2O8

We present specific-heat and susceptibility measurements and a structu ral analysis of (Ba1-xSrx)2PrNbCu2O8 in order to explore the effect of the chemical pressure on the magnetic properties of the Pr sublattice . These systems are similar to PrBa2Cu3O7-delta for which the Cu-0 cha in layers have been fully replaced by layers of Nb-O octahedra. The ov erall volume compression of - 5.5% across the series is found to be ra ther inhomogeneous yielding an anomalous expansion of the average Pr-O bond length of 3.8% which is accompanied by a reduction of T(N) from 11.6 K to 2.3 K. The variation of the magnetic properties across the s olid solution is discussed in terms of hybridization of the Pr 4f stat es with the Cu-O valence bands.