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Both up and down compositionally graded Ba1−xSrxTiO3 (BST) thin films with increasing x from 0 to 0.4 were deposited on Si and Pt/Ti/SiO2/Si substrates using sol–gel technique. The microstructure of the graded BST films were characterized by X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The down graded BST film had a larger dielectric constant and lower dielectric loss than the up graded film. The tunability of the up and down graded BST films was 42.3 and 38.9%, respectively, at an applied field of 250 kV cm−1 and measurement frequency of 1 MHz at room temperature. Both of the graded films had low-leakage current density. While, the leakage current density of down graded film lower two orders than the up graded BST film at the applied electric field below 100 kV cm−1. This may be due to the BaTiO3 layer in the down graded BST film not only serves as a bottom layer but also as an excellent seeding layer to improve the electric properties of the film.

Ba 0.65 Sr 0.35 TiO 3 (BST) thin films doped with Ho 3+ were prepared on silicon substrates by a modified sol–gel technique. The microstructure of the BST films was characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The results showed that 3 mol% Ho-doped BST has the largest grain size and surface root-mean square roughness. The thickness of the film was about 1.36 μm. The Ho 3+ luminescence intensity reached a maximum value in the sample with 3 mol% Ho 3+ ions concentration sintered at 700 °C. All the results showed that the BST: Ho 3+ films may have potential use for photonic devices.

Ba 0.65 Sr 0.35 TiO 3 thin films have been prepared by radio frequency (RF) magnetron sputtering on fused quartz at different substrate temperatures. Optical constants (refractive index n , extinction coefficient k ) were determined from the optical transmittance spectra using the envelope method. The dispersion relationship of the refractive index versus substrate temperature was also investigated. The refractive index of BST thin films increased from 1.778 to 1.961 (at λ = 650 nm) as deposited temperature increases from 560 to 650 °C. The extinction coefficient of as-deposited BST thin films increased with the increase of the oxygen to argon ratio, which was due to the change of the film stoichiometry, structure and texture of BST thin films. The oxygen to argon ratio also affected the fluorescence spectra. The fluorescence peaks intensity was greatly increased, apparent frequency shift was detected and the linewidth became narrow as the ratio of oxygen to argon increased from 1:4 to 1:1. The fluorescence spectra also indicated the band transition of BST thin films was an indirect gap transition.

Ba0.65Sr0.35TiO3 (BST) thin films on p-silicon substrates were deposited by radio frequency magnetron sputtering. The effects of the deposition parameters on the crystallization and microstructure of BST thin films were investigated by X-ray diffraction and filed emission electron microscopy, respectively. The crystallization behavior of these films was apparently affected by the substrate temperature, annealing temperature and sputtering pressure. The improved crystallization can be observed for BST thin films that deposited at higher temperature. The dominant X-ray diffraction peaks became sharper and more intense as the annealing temperature increased. BST thin films deposited at high sputtering pressure of 3.9 Pa exhibited the (110) + (200) preferred orientation. Possible correlations of the crystallization with the sputtering pressure were discussed. The SEM morphology indicated the film was small grains and smooth.

(Ba1 − x Sr x )TiO3 (BST) thin films were deposited on Pt/Ti/SiO2/Si and YSZ/Pt/Ti/SiO2/Si substrates by radio frequency (RF) magnetron sputtering. The influence of YSZ interlayer on microstructures and dielectric properties of BST thin films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy and dielectric frequency spectra. It was found that the preferred orientation of BST thin films could be tailored by insertion of YSZ interlayer and adjusting the thickness of YSZ interlayer. The BST thin films deposited on YSZ interlayer exhibited a more compact and uniform grain structure than that deposited directly on Pt electrode. Dielectric measurement revealed that the BST thin films deposited on 10 nm YSZ interlayer have the largest dielectric constant and a low dielectric loss tangent. The enhanced dielectric behavior is mainly attributed to the YSZ interlayer which serves as an excellent seeding layer to enhance the crystallization of subsequent BST films layer, and a smaller thermal stress field built up at the interface between YSZ interlayer and BST film layer.

For intermittently connected mobile networks, many hybrid routing protocols combined conventional mobile ad hoc networking (MANET) routing with Delay Tolerant Networking (DTN) approach, have been proposed. These protocols transfer data quickly in networks. They transfer data by a store-carry-and-forward paradigm when network is interrupted. However, these routings do not consider the Quality of Service (QoS) requirements. In this study, we propose a QoS aware routing protocol for data communication in intermittently connected mobile networks. The protocol is developed upon the Analytic Hierarchy Process (AHP). The QoS aware routing not only deliberates QoS requirements (such as delay, bandwidth, and communication time), but also considers node performance (such as energy and buffer), and other factors. The objective of this work is to present various models based on AHP in connected/interrupted networks. The simulation results show that the QoS aware routing is a good option to meet the QoS required applications.

Ba"0"."6"5Sr"0"."3"5TiO"3 (BST) thin films doped with holmium were prepared on silicon and fused quartz substrates by a modified sol-gel technique. The microstructures of BST films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The results showed that 3mol% Ho-doped BST has the largest grain size and surface root-mean square roughness. The transmission spectra of Ho-doped BST films were measured by spectrophotometer. The refractive index and thickness of 1mol% Ho-doped BST film was calculated using envelope method from the transmission spectra. It showed that the refractive index increased from 1.94 to 2.09 as wavelength decreased from 700nm to 400nm, which was smaller than pure BST thin films we have reported. The average oscillator strength and wavelength were estimated using a Sellmeir-type dispersion equation. These results show the potential of using Ho-doped BST thin films as an electro-optical novel material.

Compositional graded Ba x Sr 1- x TiO 3 ( x =0.6, 0.7, 0.8, 0.9, 1.0) (BST) thin films (less than 400 nm) were fabricated on Si and Pt/Ti/SiO 2 Si substrates by sol-gel technique. A special heating treatment was employed to form the uniform composition gradients at 700 °C. The microstructures of the films were studied by means of X-ray diffraction, atomic force microscope and field emission scanning electron microscopy. The results show that the films have uniform and crack-free surface morphology with perovskite structure phase. The small signal dielectric constant (ɛ r ) and dielectric loss (tanδ) are found to be 335 and 0.045 at room temperature and 200 kHz. The dielectric properties change significantly with applied dc bias, and the graded thin film show high tunability of 42.3% at an applied field of 250 kV/cm. All the results indicate that the graded BST thin films prepared by sol-gel technique have a promising candidate for microelectronic device.

Ba0.65Sr0.35TiO3 thin films have been prepared by RF magnetron sputtering. The crystallization and microstructure of the films were characterized by X-ray diffraction (XRD), scan electronic microstructure (SEM) and atom force microstructure (AFM). As-deposited thin films were found to be amorphous. The more intense characteristic diffraction peaks and improved crystallization can be observed in (Ba,Sr)TiO3 (BST) thin films deposited at high temperatures and annealed at higher than 650°C. Optical constants were determined from transmittance spectra by using the envelope method. The refractive index increased from 1.778 to 1.961 as the substrate temperature increased from 560 to 650°C. Both the refractive index and extinction coefficient increased with annealing temperature. The refractive index and extinction coefficient increased when the oxygen-to-argon ratio increased from 1:4 to 1:1. The dispersion of relation of the extinction coefficient vs wavelength was also investigated. The optical band gap of BST thin films was found to be about 3.56 eV, which decreased apparently with increasing annealing temperature.