Halimah Mohamed Kamari

Structural and Optical Properties of Lead-Boro-Tellurrite Glasses Induced by Gamma-Ray

Spectrophotometric studies of lead borotellurite glasses were carried out before and after gamma irradiation exposure. The increasing peak on the TeO4 bi-pyramidal arrangement and TeO3+1 (or distorted TeO4) is due to augmentation of irradiation dose which is attributed to an increase in degree of disorder of the amorphous phase. The structures of lead tellurate contain Pb3TeO6 consisting of TeO3 trigonal pyramid connected by PbO4 tetragonal forming a three-dimensional network. The decrease of glass rigidity is due to irradiation process which is supported by the XRD diffractograms results. The decreasing values of absorption edge indicate that red shift effect occur after irradiation processes. A shift in the optical absorption edge attributed to an increase of the conjugation length. The values of optical band gap, Eopt were calculated and found to be dependent on the glass composition and radiation exposure. Generally, an increase and decrease in Urbach’s energy can be considered as being due to an increase in defects within glass network.

Effect of erbium nanoparticles on optical properties of zinc borotellurite glass system

Erbium nanoparticles (NPs) doped zinc borotellurite glasses have been prepared by conventional melt-quenching technique with the chemical composition {[(TeO2)0.70(B2O3)0.30]1-x(ZnO)x}1-y(Er3O2)y (where y = 0.005, 0.01, 0.02, 0.03, 0.04, 0.05). The structural properties of the prepared glasses were determined via X-ray diffraction (XRD) analysis and FTIR analysis. It was confirmed that the prepared glasses are amorphous. Thebonding parameters of the glasseswere analyzed by using FTIR analysis and were confirmed to be ionic in nature. The refractive index increases as the content of erbium NPs increases. The optical absorption spectra revealed that fundamental absorption edge shifts to longer wavelength as the content of erbium NPs increases. The value of band gap had been calculated and shown to be decreased with an increase content of erbium NPs. The Urbach energy was shown to be linearly increased with an increase content of erbium NPs oxides.

Fabrication and Crystallization of ZnO-SLS Glass Derived Willemite Glass-Ceramics as a Potential Material for Optics Applications

Willemite glass-ceramics were successfully derived from conventional melt-quench ZnO-SLS precursor glass by an isothermal heat treatment process. The effect of heat treatment temperatures on the physical properties was investigated by Archimedes principle and linear shrinkage. The generation of willemite crystal phase and morphology with increase in heat treatment temperature was examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and field emission scanning electron microscopy (FESEM) techniques. X-ray diffraction revealed that the metastable -Zn2SiO4 and thermodynamically stable zinc orthosilicate α-Zn2SiO4 phases can be observed at temperatures above 700°C. The experimental results indicated that the density and shrinkage of the glass-ceramic vary with increasing the sintering temperature. FTIR studies showed that the structure of glass-ceramic consists of SiO2 and ZnO4 units and exhibits the structural evolution of willemite glass-ceramics. The characteristic of strong vibrational bands can be related to the tetrahedron corresponding to reference spectra of willemite.

Effects of milling atmosphere and increasing sintering temperature on the magnetic properties of nanocrystalline Ni 0.36 Zn 0.64 Fe 2 O 4

Nanocrystalline Ni0.36Zn0.64Fe2O4 was synthesized by milling a powder mixture of Zn, NiO, and Fe2O3 in a high-energy ball mill for 30 h under three different atmospheres of air, argon, and oxygen. After sintering the 30 h milled samples at 500°C, the XRD patterns suggested the formation of a single phase of Ni-Zn ferrite. The XRD results indicated the average crystallite sizes to be 15, 14, and 16 nm, respectively, for the 30 h milled samples in air, argon, and oxygen atmospheres sintered at 500°C. From the FeSEM micrographs, the average grain sizes of the mentioned samples were 83, 75, and 105 nm, respectively, which grew to 284, 243, and 302 nm after sintering to 900°C. A density of all the samples increased while a porosity decreased by elevating sintering temperature. The parallel evolution of changes in magnetic properties, due to microstructural variations with changes in the milling atmosphere and sintering temperature in the rage of 500-900°C with 100°C increments, is also studied in this work.

Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82.

Green emission of tellurite based glass containing erbium oxide nanoparticles

Investigation on green emission and spectral intensity of tellurite based glass containing erbium oxide NPs is one of the crucial issues. Tellurite based glass containing erbium oxide NPs with the composition of {[(TeO2)0.70(B2O3)0.30]0.7(ZnO)0.3}0.95(Er2O3)0.05 has been prepared by using conventional melt-quenching method. The structural and optical properties of the glass sample were characterized by using XRD, FTIR, UV-Vis absorption, and PL spectroscopy. The amorphous structural arrangement was proved through XRD method. The formation of TeO3 and BO3 units was revealed by FTIR analysis. Five transition states of excitation were shown in UV-Vis spectra which arise from the ground state 4I15/2 to the excited states 4G11/2 + 2H9/2 + 4F5/2 + 4F7/2 + 2H11/2 + 4S3/2 + 4F9/2 + 4I9/2 + 4I11/2. The intensity parameters Ωt (t = 2, 4, 6) are calculated and follow the trend of Ω2 > Ω4 > Ω6. Broad green emission at 559 nm under 385 nm excitation was obtained.

Effects of additives and sintering time on the microstructure of Ni-Zn ferrite and its electrical and magnetic properties

This work aims to investigate the relationship between the microstructure of Ni-Zn ferrite and its electrical and magnetic properties in the presence and absence of as small amounts as 0.12% of 0.4CaO

Optical Properties of Erbium Zinc Tellurite Glass System

Er3+-doped tellurite glasses with molar compositions of xEr2O3-20ZnO-( )TeO2 ( , 1, 2, 3, and 4 mole%) (EZT) have been successfully synthesized by the melt-quenching method. Density and molar volume have been measured. UV-VIS absorption spectra in the wavelength range of 400–800 nm at room temperature has been measured. The band gap for every composition has been calculated. Photoluminescence spectroscopy in the wavelength range of 400–650 nm and at room temperature has been evaluated.

Linear Optical Properties of Zinc Borotellurite Glass Doped with Lanthanum Oxide Nanoparticles for Optoelectronic and Photonic Application

Enhancing the optical properties of glasses for the sake of optical application in various fields is an ongoing challenge in materials science and technology. Thus, the optical properties of zinc borotellurite glass doped with lanthanum oxide nanoparticles (La2O3 NPs) with the chemical composition of {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1−x (La2O3 NPs)x, where = 0.01, 0.02, 0.03, 0.04, and 0.05 molar fraction, have been investigated. Characterization techniques such as x-ray diffraction, Fourier Transform Infrared Spectroscopy, and Ultraviolet-Visible Spectroscopy are employed to yield the structural properties and optical parameter of the glass. The amorphous nature of the fabricated glasses is confirmed with the presence of a broad hump via XRD diffraction pattern. The decreasing amount of high polarizable nonbridging oxygen as the concentration of La2O3 NPs increases has contributed to the increasing trend of energy band gap in the range of 2.70 to 3.52 eV and decreasing value of refractive index between 2.34 and 2.48. The fabricated glasses that have a higher refractive index than the widely used fiber material, pure silica glass, indicate that zinc borotellurite glass doped with lanthanum nanoparticles is a promising material to be applied as optical fibers.

Distribution of Trace Elements in Core Marine Sediments of Coastal East Malaysia by Instrumental Neutron Activation Analysis

A study was carried out on the distribution and enrichment of trace elements in the core marine sediments of East Malaysia from three stations at South China Sea and one station each at Sulu Sea and Sulawesi Sea. Five stations of sediment cores were recovered and the vertical concentration profiles of six elements namely Br, Cs, Hf, Rb, Ta, and V were determined using the instrumental neutron activation analysis. The enrichment factor, geoaccumulation index and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. Except for Cs and Hf, which by the enrichment factor are categorized from minimum enrichment to moderate enrichment in all stations and for V and Rb in Sulu Sea and Sulawesi Sea, which are categorized minimum enrichment, other elements are found to be no enrichment at all stations. The geoaccumulation index of Hf in one station shows moderately polluted and for other elements are unpolluted. However, the modified degree values of all samples are less than 1, suggesting very low contamination of elements found in all the stations.