DEPENDENCE OF THE MAGNETIC-PROPERTIES GD2-XCEXCUO4, ESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.15, ON THEIR PARTICLE-SIZE

Gd2-xCexCuO4, 0 less-than-or-equal-to x less-than-or-equal-to 0.15, ha ve been synthesized by the solid state reaction, the sol-gel technique and the water-in-oil microemulsion, in order to vary the particle siz e. The samples have been characterized by x-ray diffraction, photon co rrelation spectroscopy and transmission electron microscopy. Magnetiza tion and ac susceptibility measurements were performed between 4 and 3 00 K. The extrapolated linear part of the inverse magnetization shifts to lower temperatures as the particle size decreases. The internal fi eld associated to the WF of the Cu moments diminishes with the particl e diameter. Differences between the zero-field-cooling and the field-c ooling magnetization curves were observed for T < T(N). These differen ces depend on the particle size.