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Samples of RuSr2([Gd.sub.(1.5)][Ce.sub.(0.5)])Cu2[O.sub.(10-delta)] were prepared and annealed in pure oxygen at 30, 62 and 78 atm. A low-temperature Schottky-type anomaly was found in their heat capacity below 20 Kelvin, which can be attributed to splitting of the ground [[.sup.8.S].sub.7/2] of paramagnetic [Gd.sup.3+] ions.

Resistivity, thermoelectric power, heat capacity, and magnetization for samples of RuSr2(Gd1.5Ce0.5)Cu2O10-δ were investigated in the temperature range 1.8–300 K with a magnetic field up to 8 T. The resistive transitions to the superconducting state are found to be determined by the inhomogeneous (granular) structure, characterized by the intragranular, Tc0, and intergranular, Tcg, transition temperatures. Heat capacity, C(T), shows a jump at the superconducting transition temperature Tc0≈37.5 K. A Schottky-type anomaly is found in C(T) below 20 K. This low-temperature anomaly can be attributed to splitting of the ground term 8S7/2 of paramagnetic Gd3+ ions by internal and external magnetic fields. [ABSTRACT FROM AUTHOR]