Azhan Hashim

The Effect of PbO on the Physical and Structural Properties of Borate Glass System

Borate is one of the most popular oxide glass being used in glass research world wide. Due to good reputation, therefore lead sodium borate glasses with compositions (90 - x) B2O3 + 10ZnO + xPbO (where = 15, 20, 25, 30 and 35 mol %) have been prepared by using melt-quenching method. In this work, their physical and structural properties with respect to PbO content has been investigated. The densities of these glass samples were increased from 3946.2 kg/m3 to 5107.2 kg/m3 with an increase in PbO concentration. The molar volume are found to vary from 23.78 × 10-6 m3mol-1 to 24.39 × 10-6 m3mol-1 with respect to PbO content as well. The density and molar volume show inversed result respectively. The FTIR spectral analysis indicates that with the addition of PbO contents in the glass network, structural units of BO3 are transformed in BO4. There are no sharp peaks were observed in XRD patterns of the glass samples which confirmed the amorphous nature of the glass. Meanwhile, the micro hardness of these glass samples were also increased from 189 Pa to 355 Pa with increases on PbO content. The results will be discussed and presented in details.

Eddy Current Thermography Testing on Lack of Fusion (LOF) Defect of Carbon Steel Welded Sample

Eddy current thermography (ECT) employs the combination of conventional and advanced nondestructive testing (NDT) technique. This technology is capable to detect defect in subsurface of carbon steel welded sample of dimension 200 × 150 × 20 mm. The optimum joule heating process via eddy current distribution is 300A with the heat diffusion around 50–500 kHz (which is relatively high-frequency electromagnetic wave). Along with the emerging development of eddy current thermography, the infrared camera permits its radiation range to visualize the real-time image of the defect via the application of the thermoimager TIM software. The quantitative information about the defect will be acquired by the camera which is sensitive to the transient signal of heat through material under inspection. The analysis due to the geometrical shape, position, and length of lack of fusion (LOF) defect can be made through maximum amplitude temperature analysis. The investigation performs the temperature linescan graph of temperature amplitude via Matlab. The result obtained from ECT is compared to the error bar analysis in line with radiography technique. The studies demonstrate the effectiveness and reliability of the technique for the quantification analysis of lack of fusion (LOF) defect of welded sample.

Electrical and Structural Properties of Ca Substitution in High and Low Density Y(Ba1-xCax)2Cu3O7-δ Superconductor

The effect of Ca substitution on the electrical and structural properties in high and low density Y(Ba1-xCax)2Cu3Oδ where x = 0.00, 0.10, 0.20 and 0.30 via solid state reaction method has been investigated. The electrical properties, elemental analysis, and structural identification were measured by the four-point probe technique, energy dispersive x-ray (EDX) and X-ray diffraction (XRD) respectively. The electrical properties such as critical temperature (Tc) and critical current density (Jc) were found to be strongly dependent in both high and low densities Y(Ba1-xCax)2Cu3O7-δ. These parameters were decreased monotonously with the increasing of Ca substitution. An obvious results of the Ca-doped samples can be seen in x = 0.20 where Tc zero of high density sample is 77 K, which is higher than that of the low density sample that occurred at 73 K. Meanwhile, Jc at 60 K for high density is 1.842 A/cm2 compared to 1.410 A/cm2 in low density sample. EDX analysis confirmed the existence of Ca in all doped samples. The crystallographic structure remained orthorhombic and the volume of unit cell increased towards further increased of Ca concentration.

Strong Down-Conversion Emission of Sm3+ Doped Borotellurite Glass under 480 nm Excitation Wavelength

Tellurite glasses were generally applied in rare earth optical materials due to their excellent in physical and chemical properties. In this study, tellurite glasses composed of (70-x)TeO2-20B2O3-10ZnO-xSm2O3 (x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %) were prepared by conventional melt-quenching technique. Some basic physical parameters such as density, molar volume and oxygen packing density as well as the optical analysis by mean of their absorption and emission spectra have been carried out at room temperature using UV/Vis and photoluminescence spectrophotometer. The result of physical properties are found to vary with respect to concentration of Sm3+ ions content. Meanwhile, three strong absorption peaks are observed and are well resolved in the ultra violet and visible regions due to transitions between the ground state and various excited state of Sm3+ ions. Under 480nm laser excitation, luminescence spectra exhibit four emission bands at 562 nm, 599 nm, 645 nm and 706 nm which corresponding to the transition 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 were observed. Some other results were also been analysed and presented.

Effect of Heat Treatment on Ca Substitution in a Porous Y(Ba1-xCax)2Cu3O7-δ Superconductor

The effect of heat treatment on the superconducting properties of porous Y(Ba1-xCax)2Cu3Oδ with Ca substitution x = 0.00, 0.10, 0.20, and 0.30 via a solid-state reaction method have been investigated. The superconducting parameters, zero critical temperature, Tc zero and critical current density, Jcwere measured by the standard four point probe method in the temperature range from 20 K to 300 K, while the morphology of the samples was investigated by field emission scanning electron microscopy (FESEM). In addition structural identification was also investigated. All the samples received a heat treatment at 900 °C for 5 hours, and the Jc improved from 1.410 A/cm2 to 7.013 A/cm2 for x = 0.30 at 60 K. The heat treatment process did not change the morphology, while the crystallographic structure remained orthorhombic structure. The lattice parameter cdecreased, and the volume of the unit-cell with increasing Ca substitution.The heat treatment also led to an improvement in oxygen content to nearly 7.