INFLUENCE OF AL SUBSTITUTION IN PRBA2CU3O7-DELTA SINGLE-CRYSTALS

The role of Al substitution in single crystals of PrBa2Cu3O7-delta (PB CO) has been investigated using low temperature magnetic susceptibilit y and heat capacity measurements. The crystal composition and the amou nt of impurity have been determined using electron probe microanalysis (EPMA) and the lattice parameters have been determined using X-ray di ffraction. Heat capacity measurements on single crystals of PrBa2Cu3-y AlyO7-delta reveal a sharp peak at 16.6 K for y = 0.0 originating from an antiferromagnetic ordering of the Prion moments (T-N) and broader transitions at approximate to 10 K for y = 0.25 and approximate to 5.3 K for y = 0.4. Subtle anomalies are also found at these temperatures in the magnetic susceptibilities. The present results along with the n eutron diffraction studies demonstrate the deleterious role of Al on t he magnetic properties in this sample. (C) 1998 Elsevier Science B.V. All rights reserved.