Zalita Zainuddin

Morphology and Optical Studies of (1-x)ZnAl2O4 – xSiO2 Thin Films Prepared by Sol-Gel Method

The effect of morphological structures and optical band gap of (1-x)ZnAl2O4xSiO2 samples with compositions of x = 0.00, 0.05, 0.10 and 0.15 were prepared by sol-gel method. Spin coating technique was used to deposited the (1-x)ZnAl2O4xSiO2 as a thin film and to investigate the structural and optical band gap. The produced thin film samples were annealed at 450 °C for 1h. Field emission scanning electron microscope (FESEM) was used to investigate the surface morphology of the samples. The average particle size for (1-x)ZnAl2O4xSiO2 is about 331.23 nm. The particle size are tend to increase as the composition of SiO2 increased. XRD analysis shows the formation of cubic structure phase and dominant peak has been observed with Miller Indices (311) plane. The average crystallite size, D was calculated with average size about 8 13 nm. The optical band gap was calculated for (1-x)ZnAl2O4xSiO2 samples and it was found within range of 3.34 to 3.94 eV.

Structure, humidity sensitivity and magnetic properties of Ce substituted magnesium ferrite

The effect of Ce ions substitution at Fe ions site on the microstructure, humidity sensing and magnetic properties of magnesium ferrite was investigated. MgCexFe2-xO4 ceramics with x = 0.00, 0.02 and 0.04 were prepared using sol-gel auto combustion technique. X-ray diffraction analysis confirms the formation of cubic spinel structure of magnesium ferrite for all samples. However a second phase of CeO was also present in samples with Ce substitution. Scanning electron images show porous structures with irregularly shaped grain. Sample with composition x = 0.04 has the highest percentage of porosity and smallest grain size. This sample also has the highest sensitivity towards humidity. Magnetic hysteresis loops show a soft magnetic material behavior with low coercive force for all samples. The magnetization decreases while the coercive field increases with Ce substitution.

Influence Different Compositions of (1-x)ZnFe2O4 – xSiO2 Nanostructures Thin Film Synthesized by Sol-Gel Method

SiO2 compound was introduced into zinc ferrite using formula (1-x)ZnFe2O4 – xSiO2 synthesized by sol-gel method where distilled water and citric acid was used as a solvent and binder agent. The produced samples were annealed at 450 °C for 1h. The AFM result analysis show that the average surface roughness and particle size decreased as the compositions of x was increased. XRD results analysis confirmed the formation of spinel structures with crystallite size within range 11.27 – 4.72 nm. UV-Vis analysis to determine the energy band gap of the (1-x)ZnFe2O4 – xSiO2 samples. It shows that the energy band gap increased as the composition of SiO2 was increased due to the dielectric properties of silicon dioxide. FTIR results analysis exhibit common band in the range of 400 – 4000 cm-1. The observed band near 2350 cm-1 shows the presence of oxygen-oxygen bond in the face centered cubic (fcc) crystal lattice of oxygen atoms. The addition of SiO2 into ZnFe2O4 will help to enhance the morphological structures and optical properties. This new proposed dielectric material can be used as dielectric substrate microstrip patch antenna.

Effect of Sintering Temperature on Properties of Multiferroic BaFe12O19/MgFe2O4/BaTiO3 Composites

In this paper, the structural, magnetic and electrical properties of multiferroic BaFe12O19/MgFe2O4/BaTiO3 composites have been studied. BaFe12O19/MgFe2O4/BaTiO3 composites were synthesized by using the conventional solid state reaction technique and sintered at different temperatures. XRD analysis confirmed the existence of hexagonal BaFe12O19, cubic spinel MgFe2O4 and tetragonal BaTiO3 for ferrites and ferroelectric phases, respectively. The suitable sintering temperature for preparing BaFe12O19/MgFe2O4/BaTiO3 composites is between 1000 °C and 1050 °C. SEM analysis showed that as a whole the grain size increases and the pores is reduced with sintering temperature; thus the sample became denser. The coercive field and saturation magnetization decreases when sintering temperature is increased. Resistance of the samples decrease from 103 kW to 19 kW while the capacitance increases from 0.8 nF to 4.0 nF with sintering temperature.

Microstructural studies of nanocrystalline barium zirconium titanate (BZT) for piezoelectric applications

Lead-free piezoelectric ceramics based on barium titanate (BaTiO3) with substitution of Zr4+ were prepared using sol-gel method. The Ba(ZrxTi1-x)O3, (BZT) powders with x = 0.0, 0.1, 0.2 and 0.3 were pressed into pellets and sintered at 1250 °C for 2 h. Focusing on the effect of Zr4+ substitutions into BaTiO3 perovskite system, the phase transition and microstructural properties of BZT ceramics were studied using XRD, SEM and EDX spectroscopy. All X-ray diffractograms were fitted using Pawley refinement model. The XRD diffractograms revealed the progressive phase transition from tetragonal to cubic phase as Zr content increased. The crystallite exhibited decreasing trend and was supported by shrinkage in grain size. The EDX analysis confirmed the successful substitution of Ti4+ with Zr4+ in BaTiO3 crystal.

Structural and electrical evaluation of KNN ceramic

The aim of this study is to determine the effect of temperatures on structures and piezoelectric properties of Ka0.5Na0.5NbO3 (KNN) ceramic. The KNN sol was prepared using sol-gel method. The xerogels was annealed at 800 °C for 1.5h to form KNN powders. 10wt% of silicate glass was added to assist densification of KNN pellets. The pellets were sintered at different temperatures ranging from 800 °C to 1000 °C for 6h. XRD analysis confirmed the formation of KNN ceramics in all samples with monoclinic structure. However, minor impurities of KNbO3 were detected for samples sintered at 900oC and 1000oC signifying that different sintering temperatures affect the microstructure of the samples. SEM image indicates that the KNN have agglomerated granules and sintering temperature affect the densification properties. Impedance analysis showed the resistances, RT increased with the increments of sintering temperature while the piezoelectric constant, d33 of the prepared samples were in the range of 22–31 pC/N.The aim of this study is to determine the effect of temperatures on structures and piezoelectric properties of Ka0.5Na0.5NbO3 (KNN) ceramic. The KNN sol was prepared using sol-gel method. The xerogels was annealed at 800 °C for 1.5h to form KNN powders. 10wt% of silicate glass was added to assist densification of KNN pellets. The pellets were sintered at different temperatures ranging from 800 °C to 1000 °C for 6h. XRD analysis confirmed the formation of KNN ceramics in all samples with monoclinic structure. However, minor impurities of KNbO3 were detected for samples sintered at 900oC and 1000oC signifying that different sintering temperatures affect the microstructure of the samples. SEM image indicates that the KNN have agglomerated granules and sintering temperature affect the densification properties. Impedance analysis showed the resistances, RT increased with the increments of sintering temperature while the piezoelectric constant, d33 of the prepared samples were in the range of 22–31 pC/N.

Performance Effect of ZnAl2O4 - SiO2 Thin Film for Wireless Patch Antenna Application

Polycrystalline of (1-x)ZnAl2O4 – xSiO2 compound with compositions of x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25 have been prepared using sol-gel method. Structural properties was investigated by atomic force microscopy (AFM) and x-ray diffractometer (XRD). The AFM images analysis showed that the surface roughness of the highest composition had rougher surface compared with other samples. XRD measurement indicated that the crystallite size also increased with average crystallite size around 18 nm with cubic phase had been found. The dielectric permittivity value were measured with frequency range of 1 Hz to 1 MHz. It is showed that the dielectric value decreased as the freqeuncy was applied to the samples. The performance of the patch antenna showed that the antenna resonated at 3.30 GHz and give-13.87 dB with frequency range about 2 – 4 GHz.

Structural and Electrical Transport Properties of La 0.67 Ba 0.33 Mn 1-y Ti y O 3 Ceramics

The structural and electrical transport properties of La0.67Ba0.33Mn1-yTiyO3 manganite, with y = 0.00, 0.05, 0.10, 0.15, 0.20, 0.40 and 0.60, prepared using the solid state reaction technique have been investigated. The X-ray diffraction spectra of the Ti substituted samples showed the formation of single phase compound with Pm3m cubic structure except for the y = 0.60 sample, which showed La2Ti2O7 phase formation. Lattice parameter increased with Ti content and then decreased at y = 0.60. Resistivity versus temperature study showed that only samples with y = 0.05 and 0.10 exhibited both metallic and semiconductor-like behaviour with the metal-insulator transition temperature, Tp of 167 K and 43 K, respectively. At higher Ti concentration the samples only showed the semiconducting behaviour. At T Tp, the curves can be fitted with the nearest neighbour hopping (NNH), variable range hopping (VRH) or/and the small polaron hopping (SPH) models.