The magnetic properties of the rare earth molecular compounds with hydrazone ligands containing Nd3+ Gd3+ and Yb3+ have been investigated by electron paramagnetic resonance (EPR) and magnetization measurements. For the Gd-compound, partially resolved fine structure due to Gd and exchange narrowing effects at low temperatures are observed in the EPR spectra, suggesting, consistent with the EPR and dc magnetic susceptibility, weak antiferromagnetic exchange interactions. Paramagnetic behavior sustained down to low temperatures is derived for Yb3+ ions, whereas substantial ferromagnetic exchange coupling is inferred for the lighter Nd3+ ions, indicating significant variations of the exchange integrals along the lanthanide series.

Scanning force microscopy in the dynamic contact mode with resonance enhanced domain contrast is applied to study in situ pattern formation and relaxation kinetics of ferroelectric domains on the cleavage surface of triglycine sulfate subjected to successive annealing-cooling cycles. Substantial differences in the domain morphology and kinetics are disclosed upon cooling at temperatures close to Tc. Convolution of stripe domains with residual domain nuclei and random pinning forces due to intrinsic defects are suggested to account for variations in the domain structure and slowing down of domain kinetics.

A comparative study of powder and bulk specimens of MgB2 by electron spin resonance (ESR) verifies the presence of intense conduction electron spin resonance (CESR) in the normal state. A low concentration paramagnetic center stemmimg from the initial amoprhous boron powder along with traces of Fe3+ impurities are identified in the ESR spectra. Intense microwave absorption, that distorts CESR below Tc, is observed in fine powders implying enhanced microwave dissipation due to the viscous flux motion.

Micro-Raman measurements under hydrostatic pressures up to 6GPa have been carried out on high-quality La2-xSrxCuO4 polycrystalline compounds with Sr concentration up to x=0.45. The zz scattering polarization has been investigated, where two strong modes due to La/Sr and the apex oxygen, and (in the low Sr concentrations) the soft mode at ≃100cm-1 are observed. The frequency of the strong modes increases almost linearly with pressure for the Sr concentrations studied. Modifications in the increment rate dω/dp and the phonon width have been detected depending on the amount of doping. For x=0.45 a considerable increase in the width of both strong phonons with pressure was found, which must reflect a separation into phases, since this concentration is close to the solubility limit. The relative intensity of the strong phonons was investigated in connection with its correlation to the transition temperature.

A comparative study of powder and bulk specimens of (formula presented) by electron spin resonance (ESR) verifies the presence of intense conduction electron spin resonance (CESR) in the normal state. A low concentration paramagnetic center stemmimg from the initial amoprhous boron powder along with traces of (formula presented) impurities are identified in the ESR spectra. Intense microwave absorption, that distorts CESR below (formula presented) is observed in fine powders implying enhanced microwave dissipation due to the viscous flux motion. © 2002 The American Physical Society.

Three iron oxide pigments: Hematite, goethite and magnetite, have been synthesized from the copperas by-product produced as a waste material in large quantities in the titanium dioxide plant in Chemical Works "Police," Poland. These pigments have been characterized by X-ray diffractometry and X-ray fluorescence spectroscopy and it has been found that they are mono-phase systems with only a small addition of other spurious phases. The electrical resistivity measurements reveals that the ion oxide samples are semiconductor materials. Conductivity of magnetite at room temperature is over six orders of magnitude greater than that of the other two materials. Photoacoustic (PA) spectra of hematite and goethite in the visual region of the electromagnetic radiation shows a single intense absorption peak centred at 558 and 480nm, respectively, while for the magnetite a continuous spectrum of increasing amplitude with increasing wavelength of the measurement is obtained. EPR spectra for the iron(III) complexes have been registered at room temperature which indicate hematite and goethite have only one similar EPR line centred at g ∼ 2 with different linewidths, while magnetite has two very intense overlapping and broad EPR lines centred at low and high magnetic resonance fields. Additional EPR line of Mn2+ ions has been also recorded for the hematite sample. Application of these pigments is discussed in terms of economic and environmental advantages. © 2002 Elsevier Science Ltd. All rights reserved.