Synthesis and Characterization of Bi4Ti3O12 Nanoparticles Obtained via Pulsed Laser Ablation in Liquids.

Bismuth titanate (BTO) nanoparticles were obtained by pulsed laser ablation in liquid media (PLAL). Distilled water, ethanol, isopropanol, and acetone were used as media for laser ablation experiments, in which the colloidal solutions were obtained. Laser ablation was carried out using the second harmonic and fundamental wavelength of a pulsed Nd:YAG laser (532 nm and 1064 nm, respectively) with laser fluences of 25 and 12 mJ/cm2, respectively. Transmission electron microscopy was utilized for morphological characterization. BTO nanoparticles obtained have spherical shapes with orthorhombic structure and the average size distribution depended on the liquid media nature. In alcohols, BTO NPs were spherical with a carbon layer around them. X-ray diffraction, UV-Vis absorption spectra, and X-ray photoelectron spectroscopy were used to confirm the structural, optical, and elemental properties of the ablated products. The presented results show that PLAL is a viable technique for the synthesis of high-quality BTO nanoparticles with enhanced optical properties for possible applications in photocatalysis.

Method for fabricating self-powered cement sensors based on gold nanoparticles.

Nowadays, cement industry researchers are working hard to develop cement sensors based on nanocomposites because they can be used to develop intelligent and sustainable civil structures, self-powered, self-healing, or self-monitoring. In this light, this paper shows a methodology to obtain piezoelectric cement sensors, which produce enough energy not to require an external power source in sensing-strain applications. Mainly, two proposed experimental procedures increased the piezoelectric properties of these cement-based composites: add gold nanoparticles in the proper concentrations and apply a constant electric field during the curing stage. Firstly, the gold nanoparticles were obtained through a pulsed laser ablation system, and their particle size distribution was measured with a particle analyzer Litesizer 500 from Anton Paar, and their morphology was corroborated using a scanning electron microscope. Two concentrations (442 ppm and 658 ppm) of gold nanoparticles were obtained by changing the total ablation time. Next, we fabricated the cement sensors as described by ASTM standards C39-C39M. Hence, the cement was hand mixed with a water-to-cement ratio (w/c) of 0.47 for then poured on cylindrical molds saving the proportions recommended by the ASTM standard; in this stage, the gold nanoparticles were already part of the water ratio. Then, the cement sensors were cured under an external electric field and dried for 24 hours more in an oven to be finally ready for electromechanical characterization. Meanwhile, the electric response in altern current and the piezoelectric behavior were corroborated through electrical impedance spectroscopy and open circuit potential measurements, respectively. The piezoelectric behavior was obtained when a compressive strength was applied to the sensor, and the generated voltage was simultaneously measured. Finally, the electrical and mechanical characterization measurements were processed and analyzed using Python scripts.•The particle size and the families amount of Au NPs are affected by the ablation time.•The correct proportion of Au NPs increases the inherent piezoelectricity of cement paste.•The piezoelectric response can be addressed by coupling electric and mechanical tests.