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Magnetocaloric and electronic properties of the layered perovskite La1.34Sr1.66Mn2O7 manganese oxide have been investigated. Broadening of the magnetic entropy change peak was observed above Curie temperature (Tc=118 K), which can be associated with the existence of two-dimensional short-range magnetic order in the bilayered perovskite. There is an additional reinforcement of the magnetization in a narrow range under Tc when magnetic field is above ∼2 T, leading to a positive magnetic entropy change. It is noticeable that a wide peak of magnetoresistance (MR ∼66%) near Tc as well as two field-dependent peaks in R–T curves was found in our sample.

Temperature dependent X-ray diffraction is carried out in order to study lattice vibrational behavior in Bi1.6Pb0.4Sr2Ca2Cu3−xFexOy (x=0 and 0.08 respectively). The study focuses attention on the (002) diffraction peak. The lattice parameters and the anomalous behavior of the intensity of the (002) peak show the existence of a lattice softening effect at approximately 130 and 200 K. The samples with different values of Tc show different vibrational behavior.

Anomalous behavior of the Mossbauer factor for tin impurity atoms in Bi-system Superconductors is found by Mossbauer spectroscopy. This indicates the occurrence of lattice softening above Tc.

X-ray diffraction study was conducted over the range from 77K to room temperature about high-Tc superconducting phase Bi-system. Temperature dependent intensity of (002) peak and lattice parameter show evidence of lattice vibrations softening, which occurs at about 130K and 210K.

The occupied position of Fe in the superconducting phase of Fe-doped YBa2Cu2.8807-x was estimated by point charge model. The Mossbauer spectra were measured in the temperature range from 78 K to 273 K. Lattice softenings were found near 110 and 220 K. The observed variations of hyperfine parameters can be considered tobe related to the lattice softening near 110 K. It is suggested that the lattice softening near 110 K is related to the Peierls instability of the one-dimensional Cu(1)−0 chains.