Solid State Phenomena Vol. 290

Abstract: Lanthanum and silver co-doped zinc borotellurite glasses having chemical composition of [{[(TeO₂)_0.7(B₂O₃)_0.3]_0.7(ZnO)_0.3}_0.96 (La NPs)_0.04]_1-x(Ag₂O)_x with 0.02 ≤ x ≤ 0.10 molar fraction were fabricated via melt-quenching technique. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the samples through the presence of broad hump instead of sharp peaks. Optical properties of the samples were determined through ultraviolet-visible spectroscopy (UV-Vis) in the range of 220 to 800 nm. Fundamental absorption edge observed in the optical absorption spectra shifts to longer wavelength as the concentration of silver in the glass system increases. Decreasing trend for indirect energy band gap and increasing trend of Urbach energy values with the increment of Ag content suggest the contribution of Ag to the formation of nonbridging oxygen. Enhanced optical properties of the prepared glass hints the possible application of the glass material as optical fiber in photonic field.

Abstract: In the present work, we studied the structural and optical properties of zinc-titania tellurite glass (75-x)TeO₂-20ZnO-5TiO₂-xEr₂O₃ doped with erbium ion Er³⁺ (where mol % : x= 0 (host), 0.5, 1, 1.5). The reported glasses were synthesized using tradition melt quench method. The X-ray diffraction and thermal profile were utilized to study the amorphous nature of the mentioned glass. Optical absorption UV-Visible-NIR spectra were measured for optical energy gap and Er³⁺ absorption bands analysis. Both visible and near infrared luminescence were performed at room temperature using 980 nm laser diode excitation where the optical transition mechanism of the Er³⁺ in the glass is finally proposed. Broad luminescence in the present glass suggests its potential for broadband optical application.

Abstract: The Er³⁺/Nd³⁺ doped glasses of the form (69-x)TeO₂-15Li₂CO₃-15Nb₂O₅-1Er₂O₃-(x)Nd₂O₃ with x=0.4, 0.8 and 1.0 mol % are successfully made by using conventional melt-quenching technique. It was found both the photoluminescence intensity and stimulated emission cross-section were found increase with Nd³⁺ codoping. Efficient blue (497 nm, ²G_9/2 → ⁴I_9/2), green (550 nm, ²G_7/2 → ⁴I_9/2), orange (618 nm, ²H_11/2→⁴I_9/2), and red (635 nm, ⁴F_9/2→⁴I_9/2) spectra were observed. The results suggest that the present glass shows the potential candidate of broadband amplifiers and lasers as it is comparable with other Nd³⁺ doped other host.

Abstract: This paper presents a small angle neutron scattering (SANS) study of a novel porous gehlenite-based ceramic, synthesised from a homogeneous powder mixture of soda-lime-silicate (SLS) glass, α-alumina, calcite and calcium fluoride via solid-state sintering at 1200 °C. The products of sintering at single temperatures from 600 to 1200 °C are examined by X-ray diffraction (XRD). Sintering of the mixture below 1200 °C forms two intermediate phases (Na₂CaSi₃O₈ and Ca₄Si₂O₇F₂). Nepheline and α-alumina are minor phases in the gehlenite-based ceramic fabricated through sintering at 1200 °C. The microstructure of the gehlenite-based ceramic is investigated using field-emission scanning electron microscopy (FESEM) and SANS at the Australian Centre for Neutron Scattering. This study also evaluated the specific surface area of the gehlenite-based ceramic (~3.0 m² cm^–3) from quantitative analysis of SANS data.

Abstract: Ceramics powders based on cerate-zirconate such as yttrium-doped barium cerate-zirconate, BaCe_0.54Zr_0.36Y_0.1O₃ (BCZY) have been used as electrolyte materials for proton-conducting fuel cell (PCFC) application. High purity of the ceramics powders are traditionally prepared by solid state reaction (SSR) method at a high processing temperature (> 1400 °C). Alternatively, sol-gel (SG) technique and high pressure – high temperature (HP-HT) batch wise reactor system using supercritical fluids (SCFs) method are introduced to synthesis the powders at a lower temperature. To achieve the goals in producing the ceramics powders with better properties than SSR method, few critical parameters for both SG and SG assisted SCFs methods are determined. This study reports the effects of different chemical agents (chelating agent and surfactant) in SG method and the effects of pressure and temperature of HP-HT batch wise reactor system using ethanol as solvent on the phase purity and microstructure of the BCZY powders. Chelating agent (triethylenetetramine, TETA) and surfactant (Brij-97) aided to produce a single perovskite phase of BCZY at calcination temperatures of 1100 °C and 950 °C, respectively. On the other hand, a single perovskite phase of BCZY was obtained via SCFs assisted with sol-gel (SG-SCFs) method. The optimum characteristics of BCZY powder was found in the one prepared at P = 2 MPa and T = 150 °C and 200 °C. Particles of the powders produced by SG and SG-SCFs methods are spherical in-shape. As proven, SG method is able to produce better phase purity and homogenize BCZY powder at lower processing temperature that meets criteria to be used as an electrolyte material.

Abstract: Tuning the concentration of nanoparticles (NPs) to accommodate wider application demanded a better understanding of the physicals and structural properties of the glass. A series of zinc phosphate glasses with the composition of (57-x) P₂O₅- 40ZnO-3Tb₂O₃ –xCuO, (0 ≤ x ≤ 2 mol %) has been prepared by melt quenching technique and their physical and optical characterization have been studied. The X-Ray Diffraction technique and UV-Vis Spectroscopy have been used to characterize the glass sample. The XRD confirms the amorphous nature of the prepared glasses. The physical properties of glasses with different CuO NPs such as density, molar volume, refractive index and electronic polarizability are determined. It is found that both density and molar volume decreases with increasing CuO NPs concentration. The optical band gap (4.54 eV-2.96 eV) and the Urbach energy (0.19 eV-0.54 eV) are showing a decreasing trend with the increasing amount of CuO NPs.This is due to the formation of non-bridging oxygen, (NBO) in the glass network. The glass exhibits high refractive index ~2.40 and polarizability ~1.12 ×10^-23 cm³ and is useful for solid-state laser and optoelectronic devices.

Abstract: Erbium ions (Er³⁺) doped zinc phosphate glass system with varying contents of natural ferrite (Fe₃O₄) nanoparticles were prepared using melt quenching method. The glass is characterized by x-ray diffraction (XRD) and UV-VIS NIR spectrometer. It is observed that the amorphous nature of the glass is confirmed by x-ray diffraction. The absorption spectra of the glass are recorded in the UV-Visible in the range of 400-1600 nm. The UV-VIS NIR spectra reveal ten absorption peaks centered at 376, 406, 420, 486, 522, 546, 652, 798, 976 and 1534 nm, correspond to the transitions from the ground state ⁴I_15/2 to higher ⁴I_13/2, ⁴I_11/2, ⁴I_9/2, ⁴F_9/2, ⁴S_3/2, ²H_11/2, ⁴F_7/2, ⁴F_3/2, ²H_9/2, ⁴G_11/2 levels, respectively. Effects of natural ferrite oxide nanoparticles on the absorption and emission properties of the synthesized glasses were analyzed via Judd-Ofelt (J-O) theory. The J-O intensity-parameters (W₂, W₄, W₆) analysis demonstrate a significant increase of spectroscopic quality factors.Keywords: Fe₃O₄ NPs, Absorption, Judd-Ofelt.

Abstract: Five distinguish glass samples were prepared by melt quenching technique of the composition (81-x)H₃BO₃-19BaCO₃-xDy₂O₃ with x = 0, 0.2, 0.4, 0.6 and 0.8 mol%. The effect of Dy³⁺ to the barium borate glass can be investigated in terms of their physical properties such as density, molar volume and oxygen packing density. The structural properties were analyzed by X-Ray Diffraction (XRD) technique and Fourier Transform Infrared Spectroscopy (FTIR). The result revealed that the increment of mol% of Dy³⁺ in the compound generally will increases the density and molar volume of the glass samples. The amorphous nature of the glass system was verified from the XRD spectra pattern. Meanwhile, the FTIR spectra shown the presence of Ba²⁺, BO₃, BO₄, B-O-B linkage, H-O-H and isolated borate in the glass network.

Abstract: Nd³⁺ doped lithium borotellurite glasses were successfully been prepared by conventional melt-quenching method with the chemical composition (70.0)B₂O₃-(5.0)TeO₂-(25.0-x) Li₂CO₃-xNd₂O₃ (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 2.0 mol%) by varying the Neodymium content. The physical properties such as density, molar volume and oxygen packing density were measured. The structural properties have been studied through X-ray diffraction (XRD) analysis and Fourier Transform Infrared (FTIR) spectroscopy. The XRD pattern has been used to confirm the amorphous nature of the glass samples. There are no sharp peaks were observed in XRD patterns of the glass samples which confirmed the amorphous nature of the glass. FTIR spectra were used to analyse the functional groups present in the glass samples. The FTIR spectra reveal the presence of B-O-B, B-O, BO_3, BO_4,Te-O and characteristic of the hydrogen bond in the prepared glass samples.