dc and ac magnetic measurements combined with Mossbauer spectroscopy have been used to study the evolution of magnetic order below the critical temperature T, in polycrystalline powders of the intermetallic compounds YFe&OMo& and LuFe&0Mo&. Irreversibility of the dc thermomagnetic curves after zero-field-cooling (ZFC) and field-cooling (FC) processes has been observed. A hysteresis loop has been detected for both compounds at 4.5 K and a shifting of the loop after FC has been observed in LuFe&OMo2. Strong spin-relaxation eff'ects were recorded in ' Fe Mossbauer absorption spectra in temperatures well below the T, =360 and 260 K for R = Y and Lu alloys, respectively. Furthermore, a number of magnetic properties common to conventional spin glasses and true ferromagnets has been revealed, which suggest the existence of a spin-glass-like magnetic phase below T, .

Thin films of the three members of the superconducting series Bi 2 Sr 2 Ca n−1 Cu n O 2n+4 , n = 1, 2, 3, were prepared by diode sputtering. X-ray characterization shows that all the films are single phase and c-axis oriented and in addition they are epitaxially grown. The latter is found by x-ray pole-figure measurements taken with a four-circle diffractometer. These are emphasized in this work. AC susceptibility measurements show that, while the 2201 films are not superconducting until 4 K, the transition temperatures of the 2212 films are 82 K-90 K and of the 2223 films 84 K-89 K.

A simple sputtering technique is presented for the fabrication of (YBCO) films over large areas. The magnetron sputtering source combines operation in an unbalanced magnetic field configuration and use of large YBCO targets. YBCO films were deposited on substrates with sizes up to . The films are characterized by x-ray diffraction, pole figures, ac susceptibility, transport properties and thickness uniformity. The results show that these films are of good quality with perfect c-axis orientation, epitaxial growth, critical temperature of , critical current density of at 77 K and thickness uniformity better than 5% over an substrate. A two-pole bandpass filter with centre frequency of 13 GHz and 3 dB fractional bandwith of about 15% was designed to test the microwave performance of these films. A YBCO filter exhibits at 77 K an insertion loss of more than 5 dB lower than an equivalent Au filter on substrate at the same temperature.