M.R. Sahar

The structural and conductivity characterization of P2O5-MgO-TiO2-Li2O glass ceramic embedded with nickel nanoparticles

Melt quenching technique (MQT) has been used to prepare the series of 75P2O5-17MgO-(3-x)TiO2-5Li2O glasses doped Nickel nanoparticles (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0), which was converted into glass-ceramic through heat treatment at 350 °C. In this study, the effects of NiO nanoparticle addition and heat treatment on microstructure were investigated through DTA and XRD. The frequency-dependent electrical data were used to study the conductivity mechanism. Preliminary experimental results from DTA measurement showed that the stability of the glasses are increased when the increment of TiO2 in the glasses. The XRD results showed the completely amorphous products were prepared by MQT and crystallite structured of glass ceramic were obtained via further heat treatment. Upon the increment of temperature, conductivities increased significantly.

Erbium concentration dependent absorbance in tellurite glass

Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er3+ ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states 4F7/2, 2H11/2, 4F9/2, 4I9/2, 2H11/2 and 4I13/2, respectively. The results are analyzed by means of optical band gap Eg and Urbach energy Eu. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er2O3 concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurit...

Luminescence spectra of TeO 2-PbO-Li 2O doped Nd 2O 3 glass

A tellurite glass of TeO2-PbO-Li2O doped with Nd2O3 has been successfully fabricated by using the conventional melt-quenched technique. The absorption and emission spectroscopy have been identified using UV-VIS-NIR and photoluminescence spectrometer, respectively. From the spectroscopy, ten significant spectra have been observed in the region of 400-900 nm. The absorption wavelength centered at 585 nm attributed to 4I9/2 → 4G5/2 transition is the predominant wavelength to be used as the excitation wavelength. Emission spectra have been determined by using 585 nm excitation wavelength at room temperature. From the emission spectra, seven distinctive upconversion bands contributed from Nd3+ were observed in the region of 400-1500 nm. It was found that the bands were centered at 450 nm (4G11/2 → 4I9/2), 485 nm (4G11/2 → 4I11/2), 605 nm (4G11/2 → 4I15/2), 665 nm (4G7/2 → 4I13/2), 880 nm (4F3/2 → 4I9/2), 1062 nm (4F3/2 → 4I11/2) and 1340 nm (4F3/2 → 4I11/2), respectively. Tthese emission bands showed the possibility of visible and near infrared emission spectra.

Absorption features and luminescence enhancement of tellurite glass embedded with metallic nanoparticles

This presentation provides a panoramic overview of the recent progress in nanoglass plasmonics, challenges, excitement, applied interests and the future promises. Enhanced optical properties of rare earth (RE) doped glasses for sundry applications are current challenges in materials science and technology. Nanoparticles (NPs) dispersed up-converted (UC) glasses seem to be the ideal candidates in terms of both efficiency and large area coverage provided the absorption cross-section be enhanced. The glasses containing gold NPs (AuNPs) and silver NPs (AgNPs) doped with optimum concentration of RE ions are of particular interest to us. We report the influence of embedded NPs on the luminescence and absorbance characteristics of RE ions doped tellurite glass prepared by melt-quenching method. The absorption and emission spectra displays several prominent peaks corresponding to the transitions from the ground state to the excited states of RE ion. The observed efficient enhancement of up-conversion emissions and absorbance in the entire visible region is attributed to strong localized electric field in vicinity of NPs. Improvements of radiative emissions suggests that the proposed glasses are potential for the development of solid state lasers, color displays and nanophotonic devices.

Tuning surface plasmon in erbium-boro-tellurite nanoglass via thermal annealing

The demand for tunable surface plasmon (SP) of embedded metal nanoparticles (NPs) in rare earth doped inorganic lasing glasses is ever-growing. Following melt quenching method Er3+ doped zinc-boro-tellurite glasses containing silver (Ag) NPs are prepared. Glasses are heat treated (thermally annealed) at varying temperatures and time duration to alter the NPs morphology which generates SP. The annealing assisted SP resonance mediated modification in spectral features is discerned. Samples heat treatment at 410 °C for 6 hrs duration ensures the reduction of Ag+ ions to Ago NPs. Thermally annealed glasses are characterized via XRD, UV–Vis-IR absorption, photoluminescence spectroscopy, and TEM imaging. XRD spectra confirm the amorphous nature of the glass and TEM image reveals the existence of homogeneously distributed spherically shaped silver NPs of average diameter ~4.5 nm. NPs are found to grow with the increase of both annealing time and temperature. The UV–Vis spectra exhibit seven absorption bands corresponding to 4f–4f transitions of Er3+ ions in the wavelength range of 500-650 nm. The localized SPR band is evidenced at 550 and 580 nm. Heat treatment causes a red shift of the plasmon peaks ascribed to the alteration in glass refractive index. Furthermore, the glass sample annealed for 6 hrs displays maximum enhancement in the emission intensity corresponding to the peaks centered at 536 (2H11/2→4I15/2), 550 (4S3/2→4I15/2) and 632 nm (4F9/2→4I15/2). This enhancement is primarily attributed to the local field effect of the silver NPs. Admirable features of the results suggest that our systematic method for heat treatment in tuning NPs size assisted SPR may contribute towards the development of functional glass.

Luminescence Features of Silver Nanoparticles Sensitized Samarium Doped Boro-Zinc Tellurite Glasses

Spectral features modification of rare earth (RE) doped tellurite glasses via controlled manipulation of metallic nanoparticles (NPs) is the current challenge in achieving enhanced lasing action. Triggering the localized surface plasmon resonance (SPR) of NPs in the glass generates tremendous applied interests especially in solid state lasers and nanophotonics. Despite several promising features of RE doped zinc-boro-tellurite glass, the low absorption and emission cross-section of RE ions prohibit them from fabricating efficient lasers. This drawback needed to overcome and significant enhancement of spectral features is required. Co-doping by rare earths and/or embedding metallic NPs (acts as sensitizer) are demonstrated to be the alternative route to surmount such shortcomings. Series of glass samples with composition 74TeO2–15B2O3–10ZnO– 1Sm2O3 – (x)Ag, where 0 ≤ x ≤ 0.1 mol% (in excess) are prepared using melt quenching method and the impacts of silver (Ag) NPs concentrations in altering their photoluminescence properties are inspected. The XRD spectra confirmed the amorphous nature of prepared glasses and the presence of Ag NPs are evidenced in EDX spectra. TEM micrographs revealed the distribution of Ag NPs with average size 7.2 nm. Absorption spectra revealed eight bands which most intense between 6F11/2 and 6F1/2. Photoluminescence spectra exhibited three prominent peaks corresponding to the transition from the excited state 4G5/2 to 6H5/2, 6H7/2, and 6H9/2 states, respectively. Our observation may be useful for the development of tellurite glass based nanophotonic devices.

Effect of Au NPs on the Spectral Modification of Er-Doped Zinc Sodium Tellurite Glass

Optimizing of the spectroscopic features of rare earth (RE) doped inorganic glasses via tuneable growth of metallic nanoparticles (NPs) is demanding in plasmonic based nanophotonics. We report the gold (Au) NPs assisted sizeable enhancements in Er3+ luminescence in zinc-sodium tellurite glass. Glasses of the form 70TeO2-20ZnO-10Na2O-(x)Er2O3-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0-0.6 mol% in excess) are synthesized via melt-quenching method and thoroughly characterized. Au concentration dependent variations in the physical and spectroscopic properties of glasses are determined. XRD data confirms the amorphous nature of all samples. UV-Vis-NIR spectra reveal seven absorption bands corresponding to the transitions from ground state (4I15/2) to 4I13/2, 4I11/2, 4I9/2, 4F9/2, 2H11/2, 4F7/2 and 4F5/2 excited states of Er3+. TEM micrograph manifests the existence of non-spherical Au NPs with average size of 8.6 nm. Prominent surface plasmon band of Au NPs is evidenced around 629 nm. Furthermore, Au NPs display a SPR mediated strong absorption in the visible region. Room temperature visible down-conversion emission (under 425 nm excitation) reveal three significant peaks centred at 532 (moderate green represent 2H11/2 → 4I15/2 transition), 550 (weak green represent 4S3/2 → 4I15/2 transition) and 588 nm (strong green represent 4S3/2 → 4I15/2 transition). Glass containing 0.4 mol% of Au exhibiting the highest luminescence intensity is ascribed to the NPs local field enhancement and energy transfer between RE ions and NPs. Variations in the physical properties of glass are explained in terms of the alteration in structures and ligand interactions with Au NPs present in the glass network. The intense field amplification discerned in the vicinity of Au NPs is attributed to the charge accumulation at the surface of the NPs. Surface plasmon resonance (SPR) of Au NPs and energy transfer (ET) from NPs to Er3+ ions are primarily attributed for the observed spectral modification. It is established that our glass composition displaying such significant enhancement may be beneficial for the development of up-converted solid state lasers and other plasmonic devices.

Magnetic Properties of Sm3+ Doped Zinc Phosphate Glass Containing Nickel Oxide Nanoparticles

Nickel nanoparticles are incorporated in Sm3+ doped zinc phosphate glass having a composition of 40ZnO-(58-x)P2O5-1Sm2O3-xNiO, with x = 0.0 and 2.0 mol% prepared by melt quenching technique. Sample characterizations are made by means of X-ray diffraction, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). X-ray diffraction shows that the glass is in amorphous state. The transmission electron microscopic (TEM) image reveals the existence of Nickel nanoparticles having a particles size in the range of 5.5 – 21.8 nm. The magnetization M(H) curve reveals that the glass displays an anomalous hysteresis behavior at room temperature. It is observed that the initial curve of magnetization lies positively as a function of magnetic field under 1000 H (O.e).

Gold Nanoparticles Stimulated Surface Plasmon Resonance Effects in Erbium-Zinc-Sodium-Tellurite Glass

Modifying the optical characteristics of rare earth (RE) doped inorganic glasses by stimulating surface plasmon resonance (SPR) via controlled growth of metal nanoparticles (NPs) is an outstanding quest in glass plasmonics. Glasses with composition 70TeO2-20ZnO-10Na2O-(x)Er2O3-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0 and 0.6 mol% both in excess) are synthesized using melt-quenching technique and characterized. Influences of heat treatment temperature on the growth of Au NPs and their subsequent impacts on Raman spectral features modifications are inspected. The amorphous nature of glass is confirmed by using XRD. TEM reveal the non-spherical Au NPs with average diameter vary from 7.4 to 10.3 nm. Surface plasmon band is evidenced around 627 - 632 nm. Raman spectra demonstrate the presence of Er-O and Zn-O bond, anti-symmetric vibrations of Te-O-Te bonds and stretching modes of non-bonded oxygen exists in TeO3 and TeO3+1 unit. The amplifications in Raman signals by a factor of 1.39, 1.40, 0.88 and 1.29 and 1.25 corresponding to the peak centered at 262, 382, 536, 670 and 725 cm-1 are attributed to the contribution of a surface plasmon (SP) generating a strong, localized and secondary field. The excellent features of the results suggest that our systematic method of controlled NPs growth may constitute a basis for improving the spectral features of tellurite glasses useful for the development of efficient and economic up-converted lasers.

The Ligand Fields Characterizations within Erbium-Tellurite Glass Network via Gold Nanoparticles Concentration Variation

Glass samples of composition 79TeO2 – 15PbO – 5PbCl2 – 1Er2O3 – (x)AuCl3 with (0.0 ≤ x ≤ 0.1 mol%) were successfully synthesized by using melt-quenching technique. The impacts of gold nanoparticles (GNPs) concentration in stimulating the ligand field interaction inside the erbium-tellurite glass network were inspected. Amorphous nature of the sample was confirmed through XRD pattern. TEM images display the existence of GNPs with average diameter ~1.24 nm. Optical absorption spectra were recorded in the UV-Visible range. The absorption displays several prominent peaks corresponding to the transitions from the ground state to the excited states of Er3+ ion. The compositional dependence of the ligand parameters in terms of crystal field strength and Racah parameter were determined.