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Abstracl-The timetemperature dependent Perminvar effect in amorphous( x = 17-30 at% ) alloys was investigated io the temperature region of 150 to 450 K for stabilization times of up to 12 hours. After stabilization of the demagnetized domain structure the AC susceptibility (permeability) dependent on the driving magnetic field H shows a constant value up to the Perminvar critical field HCw The fact that HCR in COB alloys can be higher than coercive field H, is rather curious. In the Co7,B2, aUoy HcR reaches values of 1.5 to 56 A/m dependent on the time and temperature of the stabilization. From the relative difference between two values of H, R measured at two times t, and t2 a magnetic relaxation spectrum similar to that obtained from reluctivity have been constructed. The kinetics of the HCR increase measured at different temperatures indicates that relaxation parameters are equal to those obtained from the magnetic reluctivity aftereffect and that both effects have the same inherent nature.-1

The infrared reflectivity of the bismuth-based high-T c superconductors Bi 2.07 Sr 1.8 CuO 6+δ (2201) with T c = 7 K, Bi 2.1 Sr 1.9 CaCu 2 O 8+δ (2212) with T c = 85 K, and Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3 O 10+δ (2223) with T c = 108 K have been measured between 25 and 8000 cm −1 at temperatures between 5 and 300 K. The temperature-and frequency-dependent far-infrared part of the spectrum is analysed. The Kramers-Kronig analysis was used to determine the optical conductivity and a tentative mode assignment was investigated for all three phases. The softening of phonon modes in Cu-O and Bi-O layers was also observed.