Bi1−xEuxFeO3 (BEFO) powders 0≤x≤0.20 were synthesized by sol-gel method. Europium substituted BFO (RE-BFO) materials lead to a change in BiFeO3 crystal structure from rhombohedral to pseudo-cubic symmetry at x=0.20. Transmission electron microscopy investigation was performed to estimate the particle size. Magnetic measurements indicate that BEFO are antiferromagnetic with a small remanant magnetization and show a typical weak ferromagnetic ordering when x=0.20. Photoinduced optical second harmonic generation has shown a high sensitivity to the different phases.

Multiferroic materials have attracted great attention due to their potential applications in multifunctional devices. In this work, powders of Bi1−xNdxFeO3 (BNFO) with x = 0.00, 0.05, 0.15 and 0.20 were successfully synthesized by a sol–gel method using bismuth nitrate, iron nitrate and neodymium nitrate as sources. The BNFO powders were annealed at 500 °C. X-ray diffraction patterns revealed the formation of single phases BiFeO3 and BNFO. We observed that the neodymium substitution leads to the change of the BiFeO3 crystal structure from rhombohedral with space group R3c (α-phase) to pseudo-cubic symmetry Pm3 m. A high temperature variety (γ-phase) of multiferroic BiFeO3 compound has been stabilized for 15 % of neodymium content. The morphology of the particles seemed to be approximately spherical, the particle size of the BNFO is between 23 and 67 nm. Those powders show both magnetic transition at Neel temperature (TN) and ferroelectric transition around Curie temperature (TC). In addition a clear ferromagnetic component is observed for all powders. The variations of dielectric constant and dielectric loss, proves a possible coupling between the electric and magnetic dipole in these systems.

A possibility of changes the non-linear optical response was shown for the first time in the BiFeO3 doped by the Eu and Nd materials synthesized by the sol–gel method. Grain size here plays a substantial role. At the same time the latter is responsible for the non-linear optical response. The photoinduced optics was performed by the Nd:YAG lasers of different powers for samples of different nanosizes.

The photoinduced grating for polymer embedded micropowders of Bi1−x Eu x FeO3 (BEFO) with \( {\text{x}} = 0, \, 0.05, \, 0.10{\text{ and }}0.20 \) synthesized by sol–gel method were studied. The illumination by the laser has lead to occurrence of micro-grating with period varying from 50 up to several hundred micrometers. The maximal grating frequency was observed for the treatment by lasers at wavelength 1540 nm formed by Er:glass 12 ns lasers. The incident polarized laser light was split on two and was incident on the samples under the angle up to 40°. Optimal parameters were obtained for the samples with x = 0.15. The possible mechanisms of the observed micro-gratings are discussed.

Cu2ZnSnS4 (CZTS) thin films were successfully prepared using a single-step electrodeposition process in aqueous ionic solution, followed by the sulfurization in elemental sulfur vapor ambient at different annealing temperatures and under Argon atmosphere. The structural, morphological, compositional and optical properties of the samples have been investigated. Raman spectroscopy and X-ray diffraction (XRD) have confirmed the Kesterite structure of CZTS films sulfurized at 500 °C. The chemical composition was determined by Rutherford Back Scattering (RBS) and energy dispersive X-ray spectroscopy (EDS) that show the formation of near stoichiometric CZTS thin films. The surface morphology of the samples was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties of the CZTS thin film were studied by photoluminescence spectroscopy (PL).