Structural and Electrical Properties of K(Ta, Nb)O3 Thin Films with the Variation of Sintering Temperature

In this study, KTa0.55Nb0.45O3 (KTN) thin films were manufactured by using Chemical Solution Deposition (CSD) method with variations in the sintering temperature and were investigated in order to apply their applicability in memory devices. The KTN thin films were made after coating the PZT bufferlayer on Pt/Ti/SiO2/Si substrate. Each layer was dried at 200°C for 5 min to remove any organic materials and pyrolyzed at 400°C for 10 min. Finally, the layers were sintered for 30 min under an oxygen atmosphere, respectively. The pattern of KTN thin films showed a preference to the (100) and (200) orientations. Also, an increase in the sintering temperature caused the KTN crystalline peak intensities to also increase. When looking at the results from the Scanning Electron Microscope and Atomic Force Microscope data, the average grain size and root mean square roughness (Rrms) of KTN thin films were 109~157 nm and about 4 nm, respectively. Typical dielectric dispersion characteristics were observed in which the dielectric constant decreases with an increase of the applied frequency. The specimen sintered at 750°C showed the highest dielectric constant of 769 at 1 kHz.

Effect of Sr on the Bioactivity of Sol-Gel Derived New Silicate Bioglass S55P4

Strontium (Sr) stimulates osteoblast and inhibits osteoclast activities in-vitro and is used clinically as a treatment for osteoporosis. In this research, the effect of Sr substitution on the apatite formation of sol-gel derived bioactive glass (BG) (55.90SiO2-1.72P2O5 -21.67Na2O - (20.69-x) CaO -x SrO) (x=0, 5 and 8 mol. %) were investigated. The synthesized Sr doped BG samples were treated in Hank's Balanced Salt Solution (HBSS) for 14 days to study the bioactivity. The achieved samples were evaluated by X-ray powder diffraction (XRD) and Scanning electron microscope (SEM). In XRD, the hydroxyapatite (HA) crystalline peak for 8% Sr-BG is less compared with others. When Sr amount is increased to 8%, the low crystalline peaks of HA were detected although the same soaking duration. FTIR spectra supported the delay precipitation of calcium phosphate (CaP), especially for the specimen containing 8% Sr. After 14 days soaking, SEM images confirmed the bioactivity of the synthesized samples by the formation of apatite on the glass surface.

Synthesis of biomass-supported CuNi zero-valent nanoparticles through wetness co-impregnation method for the removal of carcinogenic dyes and nitroarene

Stabilization of zero-valent CuNi nanoparticles (NPs) supported on Cicer arietenum (CP) is reported here for the reduction and removal of persistent organic pollutants. The functional groups and interactions of NPs with the CP were determined by ATR-FTIR. The crystallinity, morphology, and the elemental composition of the samples were determined through powder XRD, FESEM, and EDS techniques, respectively. The XRD spectrum displayed a sharp crystalline peak at 43.9 for CuNi. The Cu and Ni zero-valent NPs displayed a peak at almost the same region, and thus, both the peaks are merged and appeared as a single peak. The chemical reduction/degradation of eight model pollutants, viz., 2-nitrophenol (ONP), 3-nitrophenol (MNP), 4-nitrophenol (PNP), 2,4-dinitrophenol (DNP), methyl orange (MO), congo red (CR), methylene blue (MB), and rhodamine B (RB) were carried out in the presence of NaBH4. The kapp value of 0.1 mM 4NP was highest which was 1.8 × 10−1 min−1 while the slowest rate was observed for CR and RB with kapp 5.5 × 10−3 and 5.4 × 10−3 min−1 respectively. This article helps in the removal of toxic organic pollutants through green supported NPs.

A new method to exfoliate Graphite oxide and application for synthesis Graphene by chemical method

A new method to separate graphite oxide (GO) modified by polyethylene oxide (PEO) by the aid of ultrasonic radiation was developed. Modified GO (graphene oxide or single layer of graphite oxide) did not show not appear crystalline peak (d002) on the X-Ray and took the form of a single layer graphene oxide on the image AFM and TEM. The exfoliated graphene oxide was reduced (RGO) to graphene by the reducing agent system HI – Acetic acid (HI-AcOH). The sheet resistance of RGOHI-AcOH is about 120 Ω/sq in the form graphene paper. In addition, FTIR, UV-Vis and Raman spectra showed more clearly about characteristics of graphite oxide, graphene oxide and RGOHI-AcOH.

Improvement of Crystallization Rate in Post-Annealed Ge2Sb2Te5 Films

Crystallization behaviors of dc sputtered Ge2Sb2Te5 films were studied by X-ray diffraction and transient optical transmittance. Crystalline peak at 29.0° in diffraction patterns appeared after thermal annealing at 180 and 210 °C. Crystallization rate increased after thermal annealing below crystallization temperature. These observations indicate that heat-induced structural change enhances crystallization rate of Ge2Sb2Te5films.

Shape Memory Behavior of Ti-Rich Ti-Ni-Cu Melt-Spun Ribbons

Crystal structures and shape memory properties of Ti-rich Ti52Ni23Cu25 (at.%) ribbon annealed at 450°C for 10 min and 1 h were investigated by X-ray diffraction and dynamic mechanical analyzer. As-spun ribbon was full amorphous and its crystalline peak temperature is 455.4°C. The annealed ribbon is crystallized with strong preferential (110)-B2 orientation. It shows a well-defined shape memory effect and the transformation hysteresis for the annealed ribbon under an external load in the range of 3-9 N is about 38.5°C. With annealing time increasing from 10 min to 1 h, the maximum of transformation strain under the external stress decreases from 1.93% to 1.7%. The temperature dependence of the external stress increases from 0.3 N/°C to 0.43 N/°C. The residual plastic strain is up to about 0.4% at a load of 9 N.

The Influence of the Hot Wire Temperature on the Crystallization of μc-Si:H Films Prepared by Hot Wire-Assisted-ECR-CVD

We have constructed a hot wire assisted ECR-CVD system to prepare a-Si:H and μc-Si:H films. The effect of hot wire temperature on crystallization of a-Si:H films is studied in the films prepared by these system. The crystalline fraction and crystalline grain size are analyzed by Raman scattering. The hydrogen content and the bonding scheme of hydrogen were measured by Fourier transform infrared (FTIR) spectroscopy. At low hot wire temperature, about 20 at.% hydrogen is included in the film. With increasing the hot wire temperature, the total content of the hydrogen, SiH2 and SiH decrease and the microcrystalline phase appears. It is found from the ratio of the crystalline TO peak to the total area of the TO peak of the Raman scattering spectra that the volume fraction of the crystalline phase increases with increasing the hot wire temperature. The crystalline peak has a tendency to shift toward the higher wavenumber with increasing the hot wire temperature, suggesting that the grain size increases with increasing the hot wire temperature.