The ability to manipulate the structure and function of promising systems via external stimuli is emerging with the development of reconfigurable and programmable multifunctional materials. Increasing antifungal and antitumor activity requires novel, effective treatments to be diligently sought. In this work, the synthesis, characterization, andin vitrobiological screening of pure α-Ag₂WO₄, irradiated with electrons and with non-focused and focused femtosecond laser beams are reported. We demonstrate, for the first time, that Ag nanoparticles/α-Ag₂WO₄composite displays potent antifungal and antitumor activity. This composite had an extreme low inhibition concentration againstCandida albicans, cause the modulation of α-Ag₂WO₄perform the fungicidal activity more efficient. For tumor activity, it was found that the composite showed a high selectivity against the cancer cells (MB49), thus depleting the populations of cancer cells by necrosis and apoptosis, without the healthy cells (BALB/3T3) being affected.

In recent years, complex nanocomposites formed by Ag nanoparticles coupled to an α-Ag₂WO₄ semiconductor network have emerged as promising bactericides, where the semiconductor attracts bacterial agents and Ag nanoparticles neutralize them. However, the production rate of such materials has been limited to transmission electron microscope processing, making it difficult to cross the barrier from basic research to real applications. The interaction between pulsed laser radiation and α-Ag₂WO₄ has revealed a new processing alternative to scale up the production of the nanocomposite resulting in a 32-fold improvement of bactericidal performance, and at the same time obtaining a new class of spherical Ag_xW_yO_z nanoparticles.

The polymorphism of BaTi_1−xFe_xO_3−δ solid solutions: 0 < x < 0.1, prepared by a sol–gel method, has been determined and presented in the form of a temperature–composition phase diagram for T > ∼1000 °C. With increasing x, the high temperature hexagonal polymorph is stabilised to increasingly lower temperatures. The temperature of the tetragonal to cubic transition also decreases with increasing x, as shown by a combination of permittivity measurements, DSC and X-ray powder diffraction. The electrical properties of ceramics of tetragonal/cubic solid solutions, determined by impedance spectroscopy, show a ferroelectric bulk phase (for T < T_c) and a Schottky barrier associated with the grain boundaries whose resistance is sensitive to a dc bias voltage. The bulk properties are sensitive to sample heat treatment and in particular, for samples reheated in air ≤700 °C, oxidation occurs, generating Fe⁴⁺ and an increase in the level of p-type conductivity.

Nb-doped BaTiO₃ solid solutions of general formula, BaTi_1−5xNb_4xO₃ prepared by two methods, solid state reaction at 1500 °C and sol–gel synthesis from high purity alkoxide precursors with final heat treatment at 900 °C, form over the range 0 ≤ x ≤ 0.055(5). Permittivity measurements demonstrated the difficulty in obtaining high quality, electrically-homogeneous samples by solid state reaction, even though samples were nominally phase-pure by X-ray powder diffraction. A partial phase diagram has been constructed showing the transitions between tetragonal, cubic and hexagonal polymorphs as a function of composition. Pellets derived from sol–gel samples and sintered at 900 °C were highly insulating, with an activation energy of ∼1.5 eV. Under these firing conditions, there was no evidence of electronic compensation, and semiconductivity, on doping BaTiO₃ with Nb.