Rahim Sahar

Luminescence Enhancement of Samarium-Doped Tellurite Glass Containing Silver Nanoparticles

Samarium-doped tellurite glass embedded with silver nanoparticles are synthesized by melt quenching technique and optically characterized. The effect of silver nanoparticles on the luminescent properties of the samarium-doped sodium tellurite glass is investigated. Upon pumping with 406 nm radiation, it is found that there are four distinctive emission bands centered at 562 nm, 599 nm, 645 nm and 705 nm. In the presence of silver nanoparticles in the glass substrates, we observe significant enhancement in the intensity of these emission bands. The enhancement tends to increase with the increasing of silver nanoparticles concentration. The mechanism of luminescence enhancement is discussed in terms of localized surface plasmon resonance.

Optical Absorption of Erbium Doped Tellurite Glass

Improving the optical behavior of tellurite glass with controlled rare earth doping is an important issue from device perspectives. The Er3+ -doped tellurite glasses having composition (75-x)TeO2-20ZnO-5Na2O-xEr2O3 where (0 x 0.7) mol% are prepared by melt quenching technique and their structural and optical properties are investigated. Amorphous nature of the samples is confirmed through X-ray diffraction technique. The optical absorption recorded at room temperature in the wavelength range from 400 to 1000 nm exhibits five broad bands. The value of the optical band gap and the Urbach energy (ΔE) are calculated from the absorption edge data. The value of optical band gap lies between 2.18 eV and 2.89 eV for the indirect transition whereas the value of Urbach energy varies from 0.15 to 0.53 eV. The optical band gap and Urbach energy values are found to dependent strongly on the erbium concentration.

Enhanced Luminescence from Erbium Doped Phosphate Glass Containing ZnO Nanoparticles

Enhancing the up-conversion luminescence and nonlinear optical properties by incorporating various metallic nanoparticles (NPs) into rare earth (RE) doped glass oxides is the key issue towards the fabrication of photonic devices. Series of erbium doped phosphate glasses containing ZnO NPs with composition (78.5-x)P2O5 10Li2O 10ZnO 1.5Er2O3 (x)ZnO, where 0 x 1.2 are prepared by melt quenching technique and their spectroscopic characterization are made. The amorphous nature of the glass is confirmed by XRD spectra. The influence of NPs on the luminescence characteristics using 357 nm excitations is studied and the mechanisms involved in the enhancement on emission intensity are examined. The emission spectra exhibit eight peaks in which the peak intensity of the violet and blue band (413 and 458 nm) shows gradual increment with increasing concentration of ZnO NPs added to the host matrix. The enhancement in the emission peak intensity for the transition is attributed to the effects of quantum confinement and local field of ZnO NPs. The effect of NPs within the glass matrix in influencing the optical properties are analysed and discussed. Our observation may contribute towards the development of nanophotonics.

Structural and Thermal Behavior of Sm3+ Ions Doped Sodium Tellutite Glasses

The effect of Sm +3 ions concentration doped TeO 2 -Na 2 O glasses on structural and thermal parameters have been discussed. Glass samples with molar composition (80- x ) TeO 2 -20Na 2 O- x Sm 2 O 3 glasses ( x =0, 0.3, 0.6, 1, 1.2, 1.5) are prepared by melt quenching technique. Crystallization temperature ( T c ) , melting temperature ( T m ) and glass transition temperature ( T g ) are measured by using differential thermal analysis (DTA), it is found that the stability factor ( ΔT ) increases from (58.5-97.8) oC with the increasing of Sm 2 O 3 . The amorphous phase nature of the glass samples are observed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectrometer are applied to study the structural properties of the glass samples. Values of density ( ρ ), molar volume ( V M ), and ionic packing density ( V t ) were calculated for each of the glass compositions. The effect of the Sm 2 O 3 on the glass structure have been investigated by using FTIR and Raman spectroscopies, the FTIR spectra are characterized by a band of 637 cm -1 for the telluride glass, high frequency peak at 668 cm -1 presented by Raman spectra which indicates that these glasses network are basically consists of TeO 4 and TeO 3 /TeO 3+1 structural units. The spectra of Raman shows the presence of Sm-O bond, Na-O bond, Te-O-Te bridging configurations, vibrations of Te-O-Te bonds and stretching modes of non-bonding oxygen found on the TeO 3 /TeO 3+1 structural unit.

Effect of Rare Earth Co-Doping On Physical and Optical Characterization of Zinc Tellurite Glass Embedded Ag NPs

A series of Silver Nanoparticles embedded in Neodymium/Erbium ions co-doped in the system of zinc-tellurite nanocomposites with the composition of (69.5-2.x)TeO 2 – 30ZnCl 2 – xNd 2 O 3 – xEr 2 O 3 – (0.5+0.5x) AgCl concentration from 0.0 to 3.0 mol% (x=0, 1, 2 and 3) have successfully been synthesized by melt-quenching techniques.. The amorphous nature of the glass was confirmed from x-ray diffraction technique. From the absorption edge studies, the value of the optical band gap E opt. and Urbach energy (D E ) have been evaluated. The value of E opt. lies between 2.35 and 2.85eV for the indirect transition while the Urbach energy values lies between 0.005 to 1.295eV. The experimental results indicate that Nd 3+ /Er 3+ rare earth ions co-doped in the system of zinc-tellurite glasses embaded silver nanoparticles are a good candidates for solid state laser active medium

DC and Thermal Conductivity of Lithium Zinc Phosphate Glasses

The phosphate glasses, with composition (60-x)P2O5-25ZnO-(15+x)Li2O where 0.0 ≤ x ≤ 5.0 mol% are prepared by conventional melt quenching method. The amorphous nature of the glass is determined by X-Ray Diffraction (XRD). The physical properties are measured in term of their density and molar volume. Glass density is found to increase from 2.700 to 2.785 g cm-3 whereas molar volume is found to decrease from 40.735 to 37.488 cm3 mol-1 with respect to Li2O content. The DC measurements are done by using four point probes and the activation energies are determined. Arrhenius plot shows straight line behavior as observed that confirmed the conductivity increased with Li2O content. The activation energy is found to decreases from 0.75 to 0.08 eV as Li2O content is increased in the temperature range from 310 to 420 K. Measurements of the thermal conductivity using Lee’s disc apparatus have been made. It is observed that the maximum and minimum thermal conductivity are 0.2679 and 0.2168 W m-1 K-1 respectively.

Luminescence Studies of Erbium Doped Sodium Magnesium Boro-Tellurite Glass

The optical behaviour of Er3+ (1.0 – 2.0 mol %) doped B2O3-TeO2- Na2O-MgO glasses synthesized by conventional melt-quenching technique was studied through luminescence measurements. The X-ray diffraction (XRD) pattern confirms the amorphous nature of the glasses without the existence of any sharp peak. The emission spectra at 378 nm excitation displayed three emission peaks corresponding to 2H11/2-4I15/2, 4S3/2-4I15/2 and4I9/2-4I15/2 transitions. Hence, a schematic energy level diagram was proposed. The luminescence properties of the prepared glasses was found to be strongly affected by varying the concentration of Er3+ ions.

Influence of Eu3+ on Physical and Thermal Properties of Borotellurite Glass Containing Manganese Oxides Nanoparticles

The influence of the europium concentration on the physical and thermal properties of manganese nanoparticles (Mn3O4 NPs) ) embedded borotellurite glass are studied. Glasses with composition (59-x)TeO2-30B2O3-10MgO-xEu2O3-1Mn3O4 (where x = 0.5, 1.0 and 1.5 mol%) are prepared by melt-quenching method and characterized using XRD and Differential Thermal Analysis (DTA). The XRD pattern confirms the amorphous nature of all samples.The physical properties such as density (ρ) and molar volume (Vm) are calculated. The thermal properties of borotellurite glasses show that the glass with 1.0 mol % of Eu2O3 possess the highest stability.

Effect of ZrF4 on the Physical and Absorption Properties of Magnesium Tellurite Glass

Tellurite glass containing zirconium fluoride (ZrF4) with composition of (90-x)TeO2-10MgO-(x)ZrF4,where 0.0 ≤ x ≤ 6.0 in mol% has successfully been prepared by melt quenching technique. X-Ray Diffraction (XRD) pattern verified the amorphous nature of the glass. In this study, the physical and optical properties were investigated in term of density and absorption properties by using Archimedes method and UV-Vis Spectroscopy. It was found that glass density decreases in the range of 4.842 – 4.995 g cm-3 with the increase of ZrF4 concentration. Meanwhile, the molar volume is increased in the range from 29.566 to 30.593 cm3/mol with increase of ZrF4. The absorption edge is found to shift toward a higher wavelength as the ZrF4 concentration is increased. On the other hand, the optical energy band gap shows the decrement from 2.573 to 2.212 eV for indirect transition and from 3.044 to 2.927 eV for direct transition with the addition of ZrF4 concentration while the Urbach energy, increases from 0.302 to 0.498 eV with the increase of ZrF4. All the results will be discussed with respect to the glass composition.

Influence of NiO Nanoparticles on Magnetic Properties of Neodymium Doped Tellurite Glasses

Series of glass samples with composition (72.5-x)TeO2-15MgO-10Na2O-2.5Nd2O3-xNiO where 1.0 ≤ x ≤ 2.5 mol% are prepared using melt quenching method. The glasses are characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The XRD spectra confirmed the amorphous nature of prepared glasses. TEM images manifest the existence of NiO NPs which are homogeneously distributed in the glass matrix. The magnetization M(H) curve reveals that the glass displays an anomalous hysteresis behavior at room temperature. It is observed that M(H) is dependent on the NiO content. The initial curve of magnetization lies positively as a function of the magnetic field under 1000 H (O.e).