Rosli Hussin

A MAS NMR structural study of cadmium phosphate glasses

Abstract Cadmium phosphate glasses, of general formula xCdO(1−x)P2O5 (0.25⩽x⩽0.6), have been prepared by melting in alumina crucibles, with resulting dissolution of up to 6.4 mol% Al2O3. The local structure in these glasses has been studied using 31P, 27Al and 113Cd nuclear magnetic resonance. The distribution of [PO4]Qn species as a function of composition has been shown to follow the simple binary model. The rate of change of the chemical shift of the 31P species in the Q2 environment depends on the bond order, which in turn reflects the extent of double bonding between phosphorus and oxygen.

Structural and luminescence studies of europium ions in lithium aluminium borophosphate glasses

Abstract Eu3+ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3 (where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%) were prepared by conventional melt quenching technique. The structural and luminescence properties of the prepared Eu3+ doped borophosphate glasses were studied and compared with reported results. The XRD pattern showed the amorphous nature of the prepared glasses. Whereas, the FTIR spectra revealed the vibrational modes in the prepared glasses. The bonding parameters ( β ¯ and δ) were calculated through the excitation spectra. Judd–Ofelt (J–O) intensity parameters were calculated from the emission spectra and were used to determine transition probability (A), stimulated emission cross-section (σEP), radiative lifetime (τR) and branching ratios (βexp) for the transition 5D0→7Fj (j=1, 2, 3 and 4) of Eu3+ ions. Furthermore, the luminescence intensity ratio (R) of 5D0→7F2 to 5D0→7F1 transition was also calculated. Transition 5D0→7F2 had the highest value of stimulated emission cross-section and branching ratios and the results were comparable with the reported values. This indicated that the present glass is promising host material for Eu3+ doped fiber amplifiers.

Thermoluminescence properties of the Cu-doped lithium potassium borate glass

Characteristics of lithium potassium borate glasses with various copper concentrations are reported. The glasses were prepared by the melt quenching method and irradiated with photons to doses in the 0.5-4.0 Gy range. Glowing curves, dose response curves, reproducibility of the response, dose threshold, thermal fading and optical bleaching were studied.

Effects of Eu3+ and Dy3+ doping or co-doping on optical and structural properties of BaB2Si2O8 phosphor for white LED applications

Abstract A series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2O8 phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission from Eu3+. The f-f transitions involving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3+ to Dy3+, which enhanced the emissions of Dy3+. Combinations of the emissions from Eu3+ and Dy3+ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be adjustable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3+ to Dy3+ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si2O8 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si2O8 phosphor were also discussed in this study.

Thermoluminescence response of dysprosium doped strontium tetraborate glasses subjected to electron irradiations

The paper presents the thermoluminescence (TL) response of strontium tetraborate glass subjected to electron irradiations at various Dy2O3 concentrations ranging from 0.00 to 1.00mol%. All glass samples exhibited single broad peak with maximum peak temperature positioned at 170-215°C. The optimum TL response was found at Dy2O3 concentration 0.75mol%. This glass showed good linearity and higher sensitivity for 7MeV compared to 6MeV electrons. Analysis of kinetic parameters showed that the glasses demonstrate second order kinetic.

Structural Study of Antimony Borate Glass System Doped with Transition Metal Ions Using Infrared and Raman Spectroscopy

A series of Antimony Borate glass samples were investigated to determine the structural feature. The glass samples from the series of xSb2O3:(1-x)B2O3 with composition of 20≤x≤60 mol% and 0.6 Sb2O3:0.4B2O3:y with y is 0.01 mol% of Nb2O5, CuO, ZnO system have been prepared using melt-quenching technique. The structural properties of Sb2O3 host and the introduction of dopents onto the host sample has been investigated using Infrared and RAMAN Spectroscopy. The result of IR and Raman Spectroscopy revealed that the network structure of the studied glasses is mainly based on BO3 and BO4 units placed in different structural groups, the BO3 units being dominant. IR spectra obtained shows conversion of BO3 to BO4 units upon the introduction of Sb2O3 commonly known as boron anomaly effect. The glass network can be modified with the presence of Sb2O3 and activator ions. The significant behavior in Raman Spectra indicates the presence of boroxol groups consisting of pure BO3 groups and mixed BO3-BO4 structural units. This study shows that the vibrational spectroscopy (Infrared and Raman) provide useful method, and inter-complementary information about the structural properties of antimony modified borate glasses.

Physical and optical properties of calcium zinc borophosphate glasses doped with manganese ions

This article reports on the physical and optical properties, absorption, and luminescence spectra in the visible region, of calcium zinc borophosphate glasses doped with manganese ions. The manganese composition was varied up to 10 mol%. The aim of this work was to investigate the effect of the luminescence properties when the glasses were doped with different compositions of manganese ions. X-ray diffraction profiles confirmed their glassy nature. The optical absorption spectrum showed bands characteristic of manganese ions in octahedral symmetry. Both excitation and emission spectra were recorded for these glasses to understand their optical performances. The emission spectrum showed a single broad band (green region) in octahedral symmetry at 582 nm as a result of transition from the upper 4T1g state to the 6A1g ground state of manganese ions. As the concentration of manganese ions increased, the emission band increased from 582 nm (green-light emission) to 650 nm (red-light emission). Apart from the spectral analysis, different physical properties of these glasses were also analyzed. Based on the physical and optical properties, we found the samples to be more promising for their use as novel luminescent optical materials.

The thermoluminescence response of Dy doped calcium borate glass subjected to 6MV photon irradiation

This paper presents the thermoluminescence (TL) response and sensitivity of various dopant concentration of Dy into borate glass. Borates glass present absorption coefficient that closely to human bone and teeth. This fact makes borate as an ideal material for TL material either for medical or environmental dosimeter. Therefore, a series of glasses based on xCaO-(100-x)B2O3 system (0 x 100) % weight has been prepared by using melt quenching method. In this research, Dy doped (0.01-0.4) mol% to 30CaO-70B2O3 glass sample were studied to investigate the TL properties in terms of dose-response relationship and sensitivity. Samples were irradiated to various doses range 0.5-4.0 Gy subjected to 6 MV photon irradiation by using LINAC Primus MLC 3339. The TL intensity of various dopant concentration were studied and it was founds that the 0.3 mol% Dy has the highest TL response and has linear dose response relationship. The highest sensitivity was calculated as 58 nC.mg-1.Gy-1 for 0.3 mol% Dy concentration.

Effects of Mg substitution on the structural and magnetic properties of Co0.5Ni0.5-xMgxFe2O4 nanoparticle ferrites

In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Co0.5Ni0.5-xMgxFe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of similar to 32 nm to similar to 36 nm. The lattice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2+ substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from similar to 57.35 emu/g to similar to 61.49 emu/g and similar to 603.26 Oe to similar to 684.11 Oe (1 Oe = 79.5775 A.m(-1)), respectively. The higher values of magnetization M-s and M-r suggest that the optimum composition is Co0.5Ni0.4Mg0.1Fe2O4 that can be applied to high-density recording media and microwave devices.

Structural and Luminescence Study of Rare Earth and Transition Metal Ions Doped Lead Zinc Borophosphate Glasses

A series of glasses with composition of xPbO-(50-x)ZnO-yB2O3-(50-y)P2O5 with 0 x 50 mol% and 10 y 20 mol% were prepared by melt quenching technique, with 30 minutes pre-heating and 10 minutes for melting. The structural properties of prepared samples were studied using Fourier Transform-Infrared spectroscopy. The glasses were mainly based on PO2, BOP and BO3 unit. In order to obtain luminescence properties, another series of sample at composition 20PbO-30ZnO-10B2O3-40P2O5 doped with Fe2+, Ti2+, Y2+ and Nd2+ were prepared. These samples were investigated using Photoluminescence Spectroscopy with different excitation wavelength to compare results. Results showed that with the presence of rare earth and transition metal ions as activator in lead zinc borophosphate glass system give rise to luminescence of visible light.