Azman Kasim

THE EFFECT OF PHOSPHORUS AND COPPER OXIDE ON THE PHOTOLUMINESCENCE CHARACTERISTICS OF Li2CO3-K2CO3-H3BO3 GLASS

In this paper, glass sample was prepared by the conventional wet chemical method. A series of borate glass consists of lithium and potassium carbonate doped with 0.1mol% of NH4 H2PO4 and copper oxides have been well prepared. The structural and the optical properties of the glass have been measured by means of their XRD, FTIR, PL and UV-VIS spectra. From the results, the current sample shows a nonlinear optical property by emitting two prominent peaks at 504 and 540 nm (green light emission) under the excitation of 630 nm. A significant enhancement on the PL spectra due to increment of phosphorus impurities dopant has also been observed. Some other physical parameters were also been measured and identified. The results of structural as well as the optical were then being estimated and discussed.

Absorption and upconversion of (Nd 3+ /Er 3+ ) doped tellurite glass

A serie of tellurite glass of the system 78TeO₂-10PbO-10Li₂O-(2-x)Nd₂O₃-xEr₂O₃, where x = 0, 0.5, 1.0, 1.5 and 2.0 was successfully been fabricated. A study of absorption and upconversion luminescence of the (Nd³⁺/Er³⁺) co-doped tellurite glass has been carried out. From the absorption spectra, the excitation spectrum is found dominant at 585 nm. Two absorption peaks of Nd³⁺ are found to overlap to Er³⁺ centered at 525 nm and 805 nm which correspond to the (Nd³⁺: ⁴I_9/2→⁴G_7/2, Er³⁺: ⁴I_15/2→²H_11/2) and (Nd³⁺: ⁴I_9/2→²H_9/2, Er³⁺: ⁴I_15/2→⁴I_9/2) respectively. Meanwhile, there are eight significant upconverted luminescence spectra correspond to Nd³⁺ ions centered at 485nm, 560nm, 605nm, 880nm, 1062nm and 1340nm with two more spectra that contributed from Er³⁺ ions centered at 493 nm (⁴F_7/2→⁴I_15/2) and 524 nm (⁴S_3/2→⁴I_15/2) respectively have been observed The upconversion mechanism of the co-doped tellurite glass has been shown in the schematic energy diagrams In this works, it is found that the excited state-absorption (ESA) is still dominant in the upconversion excitation process as the upconversion excitation mechanism of the Nd³⁺ excited-state levels is accomplished through a stepwise multiphonon process An efficient excitation energy transfer (ET) has been observed between Nd³⁺ as a donor and Er³⁺ as the acceptor. As a result, respective emission spectra had been observed. From Judd-Ofelt analysis the results of experimental lifetimes τ_exp and the emission cross section, σ Tare found to vary with respect to compositions.

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.

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.

Optical Properties of Nd Doped Lead Borotellurite Glass

Many trivalent rare earth ions such as Er3+, Tm3+, Ho3+, Pr3+ and Nd3+ were doped as absorption and emission centers in glass hosts. In this work, lead borotellurite (PBT) glass doped with neodymium ion (Nd3+) has been prepared and characterized by mean of their optical properties. The UV-Vis measurement has been carried out in order to determine the optical band gap energy, reflective indices and the polarizability. Optical absorption spectra of the glass samples are recorded in the range 400–900 nm at room temperature From the result, there are six significant absorption peaks that corresponds to 525 nm, 584 nm, 683 nm, 747 nm, 805 nm and 878 nm wavelength have been observed with the most predominant peak to be used as excitation wavelength is found centered at 584 nm. The energy band gaps as well as the refractive indices were found to vary from 2.50eV to 2.59eV and from 1.89 to 1.96 with mol% of Nd content respectively. Meanwhile, the polarizability shows a similar trend of results to refractive indices as it varies from 5.56 x 10-24 cm3 to 5.63 x 10-24 cm3. These results will be discussed further in details.

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.

The Preparation and Characterization of Nd{sub 2}O{sub 3} Doped Borate Glass

The Nd3+ doped borate glass of Nd2O3‐MgO‐ZnO‐B2O3 glass system is successfully been prepared by melt‐quenched technique. Batches of 15g were prepared from certified reagent grades of B2O3 (99.95% purity), MgO (97%), ZnO (98% purity), and Nd2O3 (99.99%). The measured glass densities are found varies from 5683.2 kgm−3 to 5724.0 kgm−3. The increment in density implies that an addition of Nd2O3 with higher atomic masses than B2O3 tend to increase the packing density of the glass structures since the atomic masses of B2O3 and Nd2O3 are 69.62 and 336.42 respectively. From the density values obtained, the molar volume of glasses was calculated. From the results, it is found that the molar volume of these glasses decreases slightly from 22.50 cm3 to 27.54 cm3 with respect to Nd2O3 content.

The Preparation and Characterization of Nd2O3Doped Borate Glass

The Nd3+ doped borate glass of Nd2O3‐MgO‐ZnO‐B2O3 glass system is successfully been prepared by melt‐quenched technique. Batches of 15g were prepared from certified reagent grades of B2O3 (99.95% purity), MgO (97%), ZnO (98% purity), and Nd2O3 (99.99%). The measured glass densities are found varies from 5683.2 kgm−3 to 5724.0 kgm−3. The increment in density implies that an addition of Nd2O3 with higher atomic masses than B2O3 tend to increase the packing density of the glass structures since the atomic masses of B2O3 and Nd2O3 are 69.62 and 336.42 respectively. From the density values obtained, the molar volume of glasses was calculated. From the results, it is found that the molar volume of these glasses decreases slightly from 22.50 cm3 to 27.54 cm3 with respect to Nd2O3 content.

The Preparation and Characterization of Nd2O3 Doped Borate Glass

The Nd3+ doped borate glass of Nd2O3‐MgO‐ZnO‐B2O3 glass system is successfully been prepared by melt‐quenched technique. Batches of 15g were prepared from certified reagent grades of B2O3 (99.95% purity), MgO (97%), ZnO (98% purity), and Nd2O3 (99.99%). The measured glass densities are found varies from 5683.2 kgm−3 to 5724.0 kgm−3. The increment in density implies that an addition of Nd2O3 with higher atomic masses than B2O3 tend to increase the packing density of the glass structures since the atomic masses of B2O3 and Nd2O3 are 69.62 and 336.42 respectively. From the density values obtained, the molar volume of glasses was calculated. From the results, it is found that the molar volume of these glasses decreases slightly from 22.50 cm3 to 27.54 cm3 with respect to Nd2O3 content.