Lanthanum doped barium titanate (BaTiO3) were studied for high-K dielectric and exhibit a relaxor ferroelectric properties and it can be prepared by using various method. Relaxor ferroelectric offers a wide temperature and frequency range of application for materials with high dielectric constant for microelectronic application. This paper reviews the preparation methods, the important features, advantages and limitation for the lanthanum doped barium titanate. Thus, the phase purity and mixture selected also been review on the second part of the article. The article concludes with a brief discussion of the methods with good dielectric behavior. The objectives of this paper are to determine the selection of suitable preparation methods and the properties of the high-K dielectric based on pure barium titanate and lanthanum doped barium titanate.
This research was conducted to analyze the Mg doping concentration effect on the structure, morphology, and optical properties of ZnO thin film prepared using the sol gel spin coating method. The Mg concentration was varied in the mole fraction of 1%, 3%, and 5%. Firstly, ZnO: Mg solution was dropped on a substrate and grown with a rotating speed of 3000 rpm and then annealed at 500 °C for 2 hours. The characterization of thin films' structure, morphology, and optical properties was done using XRD, FESEM, EDX, and UV-VIS spectrophotometer. XRD result showed a polycrystalline structure with three dominant peaks of (100), (002), and (101) plane, hexagonal wurtzite structures. Furthermore, the crystallite size was increased with the increase of Mg doping. FESEM results showed that the 5% ZnO: Mg thin film was the densest and least void from other films. In addition, the results of UV-Vis-NIR analysis showed the highest absorption value at a wavelength of 360-370 nm. The bandgap energy increased at 1% and 3% Mg doping samples but decreased by 5% Mg doping comes from the excess of oxygen in thin film with 5% Mg doping.
ZnO:Cu thin films were deposited on corning glass substrate using sol gel method with different concentration of Cu (0, 1, 3, and 5%) has been done. The effect of the different Cu concentration on the structural properties of these films was studied in detail. Based on the XRD result, the ZnO thin films undoped and doped Cu are polycrystalline with hexagonal wurtzite structure and has preferred orientation is c-axis. All peaks of ZnO thin films undoped and doped Cu shows that reflection peaks associated with (100),(002) and (110) planes. The film quality was improved with the increasing of the Cu concentration. The value of the lattice constant a and c was found to be increased with increases of the Cu concentration. Changes in the lattice constant affect the bond length of ZnO (L) and the volume of one hexagonal system unit (V). The lattice parameter also affects to the crystallite size. The crystallite size was increased with Increasing of the Cu concentration and the lattice parameter. Furthermore, the strain value of the film decreases with increases of the Cu concentration. Lattice strain that has decreased is due to the cavity around of the formed film. Cavities between atoms also affect the density of the dislocation. The larger cavity between atoms on the films that makes the dislocation density becomes smaller.
This paper presents a simulation study of the outdoor and indoor propagation losses utilizing 5G small cells at suggested millimeter-wave frequencies of 26 GHz, 28 GHz, and 38 GHz. The environment of this study is conducted with penetration loss of new and old
building characteristics. The simulation is performed with help of 3D ray tracing model NVIDIA OptiX engine and MATLAB. The targeted frequencies are 26 GHz, 28 GHz, and 38 GHz that specified by International Telecommunication Union ITU-R organization. The
simulation routes are investigated in term of signal strength at multiple receiving points. The strength angular spectrum are represented for fixed points and the power receiving delay is presented by their attributes. The simulated responses showed an efficient and sufficient outdoor and indoor service might be provisioned at 26 GHz and 28 GHz. The received signals at 28 GHz and 38 GHz are found around 4.5 dB and 11 dB with comparison with signal received level at 26 GHz. However, at 38 GHz the indoor signal strength and power receiving delays demonstrate a weak signal reception which offers a poor solution to indoor user by outside fixed base station.
The current fifth generation (5G) and millimeterwave technologies are urgently needed to provide huge bandwidth, dual-bands, multi bands, high gain and high directivity radiation pattern beams antennas. However, antennas at millimeterwave suffer from radiation loss and component loss with narrow bandwidth, especially when it is implemented using microstrip structures. Different transmission lines such as waveguide and substrate integrated waveguide (SIW) are studied and introduced for realizing antennas at millimeterwave bands. SIW structures are good candidate for implementation of antenna due to its property of low loss transmission line comprises the properties of microstrip and waveguide technology. However, SIW antennas and structures at millimeterwave have unwanted radiation losses comes from the vias holes. In addition, the vias separation distance is depended on waveguide size, which leads to a bigger size for massive antenna array network at proposed 26 GHz and 28 GHz. Hence, this paper proposed a dual band, compact size, and optimal SIW antenna structure to reduce the vias losses and provides higher bandwidth and gain at 26 GHz and 28 GHz. The proposed design is implemented using three slots to achieve the dual band property and increases the return loss. The proposed design is simulated and studied using CST software. The outcomes of dual-band response at 26 GHz and 28 GHz with a return loss more than 10 dB and a fractional bandwidth of 15% are achieved. A good gain around 8 dB is achieved. These results give a promising solution for realizing a full antenna array based on SIW technology at millimeterwave and 5G technology.
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