Research on polyaniline doped with K3[Fe(CN)6] has revealed an effect which is manifested in an unusual temperature-induced change in the ESR spectrum of the Fe3+ ion. At low temperature (T=4.2 K) one observes the first resonance line (g1=4.22±0.03), and at high temperature (T=295 K) the second line (g2=2.13±0.05). The transition from the low-to the high-temperature spectrum occurs gradually and is accompanied by a redistribution of the absorption intensity. The observed properties of the temperature dependence of the ESR spectrum are typical of systems with a multiple-minimum potential.

We have studied acoustoelectric (AE) effect produced by surface acoustic waves (SAW) in a monolithic layered structure, composed of piezodielectric We show that the anomalous effect is caused by strong modulation of the film conductivity produced by the SAW elastic deformations.

Results of structural, magnetic and specific heat investigations of the potassium erbium double tungstate, KEr(WO 4 ) 2 , are presented. Potassium erbium doubletungstate KEr(WO 4 ) 2 single crystals have been grown by the top-seeded solution growth method (TSSG) and modified Czochralski techniques. It crystallizes in the monoclinic crystal structure (C2/c space group). The unit cell contains four formula units and is described by parameters a = 10.615(2) Å, b = 10.316(2) Å, c = 7.534(2) Å, β = 130.73(3) • . From the x-ray diffraction measurements the fractional atomic coordinates, displacement parameters and interatomic distances have been determined.The specific heat C(T ) of the KEr(WO 4 ) 2 crystal has been measured over a temperature range of 0.6-300 K. The susceptibility has been studied at T = 0.25-4.0 K. The magnetic phase transition was observed at a temperature of 0.48 K. The magnetization has been measured in the temperature region from 4.2 to 60 K and in magnetic field up to 1.6 T. A strong anisotropy of magnetic properties was found. The temperature and field dependences of susceptibility and magnetization data were used for both elucidation of character of the magnetic ordering and calculation of the exchange and dipole-dipole interaction energies as well as for determination of the possible magnetic structure of KEr(WO 4 ) 2 .