The motivation of this work was to improve the dielectric properties of nano-structure BaTiO 3 prepared in powder form, using a modified sol-gel method and calcinated in the air at different calcination temperatures between 350 and 1050 °C. For that, we choose to measure the dielectric properties over the high frequency range (10 6 -10 8 Hz) at room temperature (RT), which makes it the candidate for high-frequency ultrasonic and energy storage applications. The dielectric properties give remarkable results obtained maybe for the first time for this compound at the mentioned frequency range. Both the dielectric permittivity and AC conductivity were found to increase with the calcination temperature due to an increase in the crystallite size. Particularly, it has been reported that sample calcinated at 1050 °C shows high permittivity values. The effect of calcination temperature on the morphology, structure, and dielectric properties of the prepared BaTiO 3 nano-powdered was investigated. Transmission electron microscope (TEM) confirmed the nano-crystalline form of prepared samples. X-ray powder diffraction (XRD) results revealed a pure tetragonal phase between 1000 °C and 1050 °C. However, more than one phase was detected at lower temperatures. Furthermore, Raman spectra showed that the tetragonal peaks at 306 and 715 cm −1 , increase with the increase of the calcination temperature. Fourier transformation infrared spectroscopy (FTIR) showed that the crystallinity improved, accompanied with a gradual disappearance of carbonates by increasing calcination temperature.

Structural and fluorescence properties were investigated for different concentrations of Ho3+ ions doped silica titania nano-composite thin films. These films were deposited on glass substrates at two different annealing temperatures 300 and 500 °C for 3 h.The obtained films were transparent, smooth and adhesive to the substrate glass surface. The crystallite sizes were in the nano-scale phase with values ranged from 15 to 20 nm. The average thin film thickness was found to be equal to about 1.7 μm. Blue, red and green up-conversion emissions are detected using 808 nm laser diode. The highest emission bands were observed in the doped film with 0.4 mol% of Ho3+ ions. The prepared thin films could be considered promising candidates for higher efficiency up-down shifting solar cell, photonic, photo-catalytic and optical sensor applications.

Nano-structure BaTi 0.9 Sn 0.1 O 3 (BTSO) doped with Nd 3+ (BTSO: 5N) and co-doped with Nd 3+ /Yb 3+ ions (BTSO: 5NY), were prepared using the modified sol-gel method in powder form and annealed at 1050 o C in air for 4h. Their structural, morphological, photoluminescence and dielectric properties studies were investigated. The crystallite sizes from XRD and TEM found to be decreased upon doping with Nd 3+ and Nd 3+ /Yb 3+ ions, respectively. FTIR results showed enhancement of crystallinity and absence of carbonates upon increasing Yb 3+ ions. TEM micrographs show that particles have spherical shape with small size within the nano-structure phase. FESEM microphotographs showed a density increase due to replacement of Nd 3+ and Yb 3+ ions at the B-site (Ti 4+ ). From photoluminescence it was obtained that emissivity quenched by increasing Yb 3+ ions concentration as the Nd 3+ act as sensitizer for Yb 3+ . Cuire temperature (T c ) of doped and codoped samples shifted to lower values. Besides, their permittivity and AC conductivity increased in comparison with BTSO.

Heavy elements represent a source of toxicity when accumulate in the soil and be transmitted to plants, animals and humans through food chains that may affect the human and the animal health. In this study, environmental samples, vegetable samples (Cabbage, Mallow, Turnip) and soil, were collected from Qaha in Qaliubia in Egypt then subjected to investigate the availability of toxic metals such as copper, manganese and cadmium using flame atomic absorption spectroscopy (FAAS) technique. We have found Cu, Mn and Cd in cabbage with concentrations around 25.28 ±1.263 ppm, 103.83 ±5.19 ppm and 0.792 ±0.0396 ppm, respectively. The Cu, Mn and Cd concentrations in Mallow were found to be 35.26 ±1.76 ppm, 142.72 ±7.14 ppm and 1.3 ±0.0649 ppm respectively. Also, the concentrations of Cu, Mn and Cd in Turnip have achieved 29.29 ±1.45 ppm, 79.33 ±3.97 ppm and 1.99 ±0.099 ppm respectively. For soil, the concentrations of Cu, Mn and Cd were 2.4 ±0.12 ppm, 4.8 ±0.24 ppm and 1.75 ±0.088 ppm respectively. It was concluded that the pollution index values for Cu, Mn and Cd in soil were 0.024 ±1.2 ×10−3, 0.01 ±5.49 ×10−4and 0.58 ±0.029 respectively. The pollution index values in cabbage for Cu, Mn and Cd were 0.346 ±0.017, 15.708 ±0.785 and 3.96 ±0.198 respectively. The pollution index values for Cu, Mn and Cd in Mallow were 0.073 ±0.024, 21.59 ±1.08 and 6.5 ±0.32 respectively. The pollution index values for Cu, Mn and Cd in Turnip were 0.401 ±0.019, 12 ±0.6 and 9.95 ±0.5 respectively. The observed new results are important to monitor the environmental pollution in the studied samples which have an impact on human health.

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