Sintered lead-free Bi[Formula: see text](Na[Formula: see text]K[Formula: see text](Ti[Formula: see text]Sn[Formula: see text]O3 ceramics (BNKTS) have been fabricated via a solid-state reaction. The effect of sintering temperature on the structural, morphological, dielectric, ferroelectric and energy storage properties of BNKTS ceramics was investigated, and it was found that the electrical properties of the synthesized ceramics increased with the increase in the sintering temperature, and the highest values were achieved at [Formula: see text]C. The ceramics sintered at the optimized temperature of [Formula: see text]C exhibited the best physical, dielectric, ferroelectric and energy storage properties, namely, high density (the relative density, [Formula: see text][Formula: see text]g.cm[Formula: see text], approximate to 96.7% of the theoretical value), high densification factor ([Formula: see text]), high dielectric constant ([Formula: see text]), low dielectric loss (tan[Formula: see text]), highest dielectric constant ([Formula: see text]), high remanent polarization ([Formula: see text]C.cm[Formula: see text], high coercive field ([Formula: see text][Formula: see text]kV/cm), high energy storage density (0.12[Formula: see text]J/cm[Formula: see text], and high energy storage efficiency (41.7% at 46.3[Formula: see text]kV/cm).
In the present study, green synthesis of silver nanoparticles (AgNPs) was conducted to prepare a preservative solution for organic bamboo straws. Spherical AgNPs were prepared with the help of ultrasound waves by inducing a reaction between silver nitrate (AgNO3) solution (0.05 M) and tea leaf extract (Camellia sinensis). Spherical AgNPs with an 11–28 nm size were formed easily in the extract at ambient temperature. The as-prepared AgNPs–chitosan solutions exhibited excellent antifungal activity against Aspergillus flavus fungi, which were isolated from bamboo straws collected from the Nam Dong district of Thua Thien Hue province in Vietnam. Therefore, the AgNPs–chitosan solution can be used as a bamboo-straw-coating material to inhibit the growth of A. flavus fungi. The optimized concentrations of AgNPs and chitosan to achieve the antifungal activity of AgNPs–chitosan solution on bamboo straws were 40 parts per million and 1.5%, respectively. Thus, coating bamboo straws with this solution can be proposed as an additional treatment to increase their postharvest quality. Moreover, AgNPs–chitosan solution can be used to protect bamboo straws from fungal infections, thereby prolonging their shelf life.
The 0.9Pb(ZrxTi1−x)O3-0.07Pb(Mn1/3Nb2/3)O3-0.03Pb(Sb1/2Nb1/2)O3(PZT-PMnN-PSN) ceramics were prepared by columbite method. The phase structure of the ceramic samples was analyzed. Results show that the pure perovskite phase is in all ceramics specimens. The effect of the Zr/Ti ratio on the region of morphotropic phase boundary for PZT-PMnN-PSN ceramics was studied. Experimental results show that the phase structure of ceramics changes from tetragonal to rhombohedral with the increase of the content of Zr/Ti ratio in the system. The composition of PZT-PMnN-PSN ceramics near the morphotropic phase boundary obtained is the ratio of Zr/Ti: 49/51. At this ratio, the ceramic has the optimal electromechanical properties: thekp=0.61, theεmax=29520, thed31=-236 pC/N, theQm=2400, high remanent polarization (Pr=49.2 μC·cm−2), and low coercive fieldEc=10.28 kV·cm−1.
This study presents a novel process to synthesize curcumin nanoparticles from fresh turmeric. An ultrasonic-assisted cajeput oil in water emulsion technique was used to synthesize nanocurcumin. The prepared nanocurcumin was spherical with an average size of 47 nm and size distribution of 5–80 nm. The synthesized nanocurcumin showed improved aqueous-phase solubility, and it was used as a reducing agent and stabilizer for biosynthesizing silver nanoparticles. Furthermore, the X-ray diffraction pattern of the silver nanoparticles showed four distinct diffraction peaks at 38.3°, 44.6°, 65.1°, and 78.1° corresponding to the lattice planes of face-centered cubic silver ((111), (200), (220), and (311)). Transmission electron microscopy analysis indicated the average size and maximum size distribution (80 %) of the silver nanoparticles were 10.9 nm and 5–15 nm, respectively. UV–visible spectroscopy measurement of samples indicated the localized surface plasmon resonance absorbance of an aqueous dispersion of silver nanoparticles at 406 nm. Zeta potential analysis revealed a negative charge with a magnitude of −27.2 mV, which indicated higher aqueous dispersion stability of the silver nanoparticles prepared from nanocurcumin. The nanoparticles showed antibacterial activity against Vibrio parahaemolyticus.
The synthesis, characterization and application of biologically synthesized nanomaterials have become an important branch of nanotechnology. In the present study, we report the synthesis of silver nanoparticles from fresh leaf extract of Centella asiatica (LEC). UV-Vis spectrum for silver colloids contains a strong plasmon band near 425[Formula: see text]nm, which confirms the formation of nanoparticles. The experimental results show that the silver nanoparticles are formed easily in the extract at ambient temperature. The resulting silver nanoparticles (AgNPs) were in the spherical form and the average size of the nanoparticles was in the range from 3[Formula: see text]nm to 30[Formula: see text]nm. From the above silver nanoparticles, we were taken up to investigate the effects of various concentrations of AgNPs on growth, development and yield of peanut plants. The results of the present experiment showed that the optimized concentration of AgNPs of the good germination, growth and pod yield of peanut plant is 5[Formula: see text]ppm.
BaTiO3 nanoparticles were synthesized by hydrothermal method using amorphous phase TiO2 precursor as the Ti-source. The microstructure and phase structure were determined using XRD, SEM and Raman spectroscopy analysis results. The results showed that BaTiO3 nanoparticles have tetragonal structure, average size of about 100 nm was obtained at Ba/Ti ratio of 1.5, synthesis temperature of 200[Formula: see text]C and reaction time of 12 h. The components of the BaTiO3 lead-free ceramic system are fabricated by conventional solid-phase reaction from the average size BaTiO3 particles about 100 nm obtained by hydrothermal process. The effects of sintering behavior on dielectric, ferroelectric and piezoelectric properties of BT high-density ceramic were studied. The BaTiO3 ceramic composition sintered at 1300[Formula: see text]C has a relative density of 97%, the value of the electromechanical coefficient [Formula: see text] = 0.40, [Formula: see text] = 0.42, the large piezoelectric coefficient [Formula: see text] = 300 pC/N, [Formula: see text]125 pC/N.
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