Fabrikasi GPS antena menggunakan bahan zink aluminat berstruktur nano didopkan dengan kobalt

Kaedah sol gel digunakan untuk menghasilkan filem nipis CoxZn(1-x)Al2O4 berstruktur nano pada suhu 600°C. Corak pembelauan XRD menunjukkan pembentukan struktur tunggal spinel ZnAl2O4 dan CoAl2O4. Saiz hablur dan ketumpatan bahan berkurangan apabila kepekatan bahan dopan Co bertambah, iaitu masing-masing daripada 19.52 kepada 10.39 nm dan 4.609 kepada 4.585 g/cm3. Parameter kekisi pula meningkat daripada 8.085 kepada 8.098 Å apabila Co meningkat. Analisis FTIR menunjukkan ikatan ZnO, Co dan Al-O berlaku antara 487 hingga 550 cm-1, manakala ikatan spinel bagi ZnAl2O4 dan CoAl2O4 pula terbentuk pada 655 cm-1. Imej AFM menunjukkan kekasaran permukaan menurun apabila Co bertambah iaitu daripada 30.21 nm (×=0.00) kepada 14.83 nm (×=0.30). Nilai pemalar dielektrik (εr) menunjukkan penurunan secara linear apabila Co meningkat iaitu daripada 8.53 kepada 7.31. Seterusnya, GPS antena difabrikasi menggunakan sampel CoxZn(1-x)Al2O4. Prestasi dan frekuensi operasi GPS antena diukur menggunakan penganalisis rangkaian siri PNA pada frekuensi kenaan 1-2 GHz. Analisis mendapati antena beroperasi pada frekuensi 1.570 Ghz dengan kerungian pulangan -15.6 hingga -21.2 dB dan lebar jalurnya pula adalah 80 hingga 315 MHz. Kesemua antena yang telah difabrikasi memenuhi keperluan minimum antena untuk beroperasi pada aplikasi GPS

Effect of Zn Site for Ca Substitution on Optical and Microwave Dielectric Properties of ZnAl 2

CaxZn(1-x)Al2O4 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30) thin films were prepared by a sol gel method. The XRD patterns displayed the characteristic peaks of (Ca/Zn)Al2O4 with the standard pattern of face-centred cubic (fcc). The addition of Ca decreased the lattice constant from 14.6 nm to 23.2 nm. The optical bandgap of undoped thin film was found to be at 3.84 eV while for doped Ca was observed at 3.50 to 3.73 eV. The substitution of Zn2+ by Ca2+ in ZnAl2O4 thin films was found to increase the crystallite size, grain size, and surface morphology which evidently affect the density and dielectric constant. The CaxZn1-xAl2O4 thin films were characterized at 20 to 1 MHZ frequency to determine the dielectric constant εr and unloaded quality factor Qu using LCR spectrometer. It can be observed that specimen using Ca0.25Zn0.75Al2O4 possesses εr~10.41 and Qu~5770 which is suggested as a candidate material for millimetre-wave applications. Therefore, this ceramic is suggested as a candidate material for GPS patch antennas

Characterizations of natural dye from garcinia mangostana with graphene oxide (GO) as sensitizer in dye-sensitizer solar cells

Usage of natural product in improvement of dye-sensitized solar cell (DSSC) have been look upon in research field. There is numerous different type of nature product was used as natural dye but the performance of DSSC with natural dye are low efficiency compare to DSSC with Ruthenium (II) dye due to low anchoring strength between dye molecule with TiO2 surface. This paper is about an experiment DSSC device with sensitizer of Mangosteen with Graphene Oxide as catalyst. The highest device efficiency with graphene oxide (GO) concentration of 0.50 mg/ml obtained in this experiment is 0.40% with short-circuit current density (Jsc) = 1.00 mA/cm2, open circuit voltage (Voc) = 0.61 V and fill factor(FF) = 65.72%. It shows that GO helped to increase device performance by increase the ability of sensitizer absorbed onto TiO2 and adding more passageway for carriers movement between TiO2 surface and dye sensitizer

Effect of Mn-site for Al substitution on structural, electrical and magnetic properties in La0.67Sr0.33Mn1-xAlxO3 thin films by sol-gel method

Nanocrystalline La0.67Sr0.33Mn1-xAlxO3 (x=0.00 , 0.05, 0.10, 0.15, 0.20, and 0.25) thin films have been prepared on quartz substrates by sol-gel method. The structural and morphology studies were investigated via X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). XRD graph patterns show rhombohedral distorted perovskite structures. FESEM images show that the average grain size decreased as the concentration of x increased. Electrical property was investigated using four-point probe technique. Resistivity results show that metal-insulator transition (MIT) temperatures (Tp) decreased when the concentration of x increased. Tp shifted to lower temperature when the concentration of x increased. The data was analyzed based on theoretical models, where the ferromagnetic resistivity is followed with the equation p = p0 + p2T2, where p0 is due to the significance of grain boundary effects and a second-term ~p2T2 appears that might be applied to the electrons scattering. In the high temperature regime (T > Tp), the resistivity data can be well described by small polaron hopping (SPH) and variable range hopping (VRH) mechanisms. Magnetic property was investigated using a vibration sample magnetometer. All samples that were obtained showed hysteresis curve with the highest value of magnetization for sample x = 0.10

Characteristics of nanostructured CaxZn(1-x)Al2O4 thin films prepared by Sol-Gel method for GPS patch antennas

CaxZn(1-x)Al2O4 thin films (x = 0.00; 0.05; 0.10; 0.15 and 0.20) were prepared by sol-gel method with the substitution of Zn2+ by Ca2+ in the framework of ZnAl2O4. The effect of Ca addition on the structure and morphology of CaZnAl2O4 thin films was investigated by x-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), energy-dispersive x-ray spectroscopy (EDX), ultra-violet visible (UV-Vis) and atomic force microscope (AFM). The XRD patterns showed the characteristic peaks of face-centred cubic (fcc) ZnAl2O4 and CaZnAl2O4. The addition of Ca increased the crystallite size from 8.9 to 30.2 nm. The bandgap of CaxZn(1-x)Al2O4 thin film was found in the range of 3.40 to 3.84 eV. SEM micrograph shows the morphology of all thin films is sphere-like, with the grain size increased from 33 to 123 nm. The AFM images show the roughness of surface morphology increased. The substitution of Zn2+ by Ca2+ increased the crystallite size, grain size and surface roughness which evidently increased the density (4.59 to 4.64 g/cm3) and dielectric constant (8.48 to 9.54). The composition of CaxZn(1-x)Al2O4 is considered as suitable material for GPS patch antennas