Papers by Keyword: Phosphate Glass

Abstract: Tantalum-containing phosphate invert glasses were prepared using a liquid phase method under ambient conditions. In our previous study, the ion-releasing behavior (i.e. chemical durability) of phosphate glasses was controlled by the amount of intermediate oxides. In this work, Ta₂O₅ (intermediate oxide) was used to improve the chemical durability of the glasses. Ta-containing phosphate invert glasses were prepared and their structures were characterized. X-ray diffraction (XRD) patterns of the glasses exhibited broad halos, indicating an amorphous state. The amount of P₂O₅ in the glasses increased with increasing Ta₂O₅ content, while the amount of CaO decreased. The glasses prepared with a nominal P : Ta molar ratio of 2 : 1 showed a value of 1.87 : 1. Thus, almost all the Ta used in the synthesis was contained in the resulting glass. Raman spectra showed bands corresponding to short phosphate units such as ortho-and pyrophosphate, and the P-O-P peak was blue-shifted with increasing Ta₂O₅ content. The P-O-Ta bonds were formed with TaO₄ tetrahedra, as new peaks at 970 cm^-1 (P-O-Ta bonds) and 825 cm^-1 (observed in YTaO₄) were observed. The glasses containing higher amounts of Ta₂O₅ exhibited TaO₆-rich phases, as shown by the Raman band at 630 cm^-1 (Ta-O-Ta bonds) and broad XRD peaks at 2θ = 5 ~ 10°. Therefore, Ta in the phosphate invert glasses prepared by the liquid-phase method crosslinks phosphate units in the form of TaO₄ tetrahedra, and the excess Ta exists in the form of TaO₆ octahedra as a network modifier and/or Ta₂O₅-rich phase.

Abstract: Phosphate invert glasses are mainly composed of ortho-and pyro-phosphate units and can stimulate cellular functions by releasing inorganic ions. Our group has succeeded in the synthesis of titanium-containing phosphate invert glasses with the liquid phase method at room temperature. ZnO is classified as an intermediate oxide in the glass network structure and improves the chemical durability of phosphate invert glasses. In addition, zinc ion exhibit a wide range of antibacterial ability. However, excess amounts of zinc ions can be toxic to cells. Hence, the dissolution behavior of zinc ions must be controlled for biomedical applications. In this work, ZnO-containing phosphate invert glasses (PIG-Zn) were prepared using the liquid phase method. The phosphate groups of PIG-Zn were composed of ortho-and pyro-phosphate groups, and the peaks were blue-shifted with increasing the ZnO content due to the field strength of Zn²⁺ being larger than that of Ca²⁺. Thus, phosphate groups may be cross-linked by Zn²⁺ to form P-O-Zn bonds. Meanwhile, ion-releasing amounts from PIG-Zn were decreased with increasing ZnO content. This is because the formation of P-O-Zn bonds can increase the chemical durability of PIG-Zn. In addition, PIG-Zn showed excellent antibacterial ability. Therefore, PIG-Zn is expected to exhibit antibacterial ability with controlled Zn²⁺ ion-releasing behavior for biomedical applications.

Abstract: In this work, the glass formula (70-x)P₂O₅: 15NaF: 5ZnF₂: 15AlF₃: xBaO where x is 0, 5, 10, 15 mol% were manufactured by the conventional melt-quenching technique at 1200 °C in 3 hours for photon shielding application. The effect of glasses was examined on the physical, gamma ray and x-ray shielding properties. The results revealed that the density was increased with increasing of BaO concentrations. The glass systems were calculated by using the experiment set up for estimating the radiation shielding properties in the content of mass attenuation coefficients (μ_m), effective atomic number (Z_eff), and effective electron density (N_eff), which were increased when concentrations of BaO increased, while the half value layer (HVL) was decreased. For result of using the x-ray source, the linear attenuation (μ) was increased with an accrue in BaO concentration. The HVL was decreased when concentrations of BaO increased. The HVL values of glass samples at 15 mol% has better shielding behavior than the standard materials at 120 kVp. The BaO glass systems can be candidate for radiation shielding materials in the future.

Abstract: Phosphate glasses, characterized by their high thermal expansion coefficients, low melting temperatures, and excellent transparency across a wide spectral range are ideal for optical applications. In particular, phosphate-based glasses are effective hosts for rare earth ions due to their ability to incorporate heavy metal oxides while retaining an amorphous structure. Building on these properties, a series of (50-x)P₂O₅-20ZnO-15SrO-15Li₂O-xSm₂O₃ where x = 0, 0.5, 1.0, 1.5 and 2.0 mol% were prepared by using melt-quenching technique to explore the effects of Sm₂O₃ concentration on structural and optical properties. This study addresses the challenge of optimizing Sm₂O₃ concentration in phosphate glasses to enhance properties such as density, structural stability and emission intensity for efficient green-orange-red luminescence. XRD spectra confirmed the amorphous nature and indicate that samples are glass. The physical measurements indicated that density and molar volume of increased with Sm₂O₃ concentration from 0 to 1.5 mol% and decreased when Sm₂O₃ further increase to 2.0 mol%. FTIR spectra revealed seven spectra bands within range 650 to 1500 nm. The emission spectra were recorded under 402 nm excitation, emits strong emission band at 562, 593, 644 and 705 nm which correspond to excitation from ⁶H_5/2 ground state. The optimal emission intensity was observed at 1.0 mol% Sm₂O₃, highlighting the potential of these glasses for applications in green-orange-red emitting materials.

Abstract: Glass doped with cerium is an attractive material for a variety of applications. The aluminium fluorophosphate glasses were made by the conventional melt-quenching technique. The glass samples were characterized by density, refractive index, FTIR and photoluminescence spectra. The density was shown to increase, but refractive and molar volume were shown to decrease. The FTIR spectra of these glasses showed mainly [PO₃] and [PO₄] structural units. Transparency of the glass samples is demonstrated by a transmission intensity in the 70-80% range. Regarding the optical properties, under 307 nm excitation, the emission peak around 348 nm of the CeF₃-doped aluminium fluorophosphate glasses was confirmed. The emission would be due to the 5d→4f transitions of Ce³⁺ ions.

Abstract: The effect of alkali fluoride on the photoluminescence properties of Tb³⁺ doped on the phosphate glass was discovered. However, the composition of the glass samples were 20Li₂O–10AlF₃–69P₂O₅–1Tb₂O₃ (LAPTb) and 20Li₂O–10AlF₃–10NaF–59P₂O₅–1Tb₂O₃ (LANPTb). To study optical properties were examined through their absorption and luminescence spectra. Luminescence spectra were investigated by photoluminescence. Characteristic luminescence bands corresponding to electronic transitions of terbium ions (Tb³⁺) were detected under two direct excitations of Tb³⁺ ions. Upon 377 nm excitation, the glass samples were obtained transition terbium ⁵D₄ → ⁷F₅ at 544 nm showed a green laser. The decay time Tb³⁺ for the ⁵D₄ level has been confirmed and the result was 2.865 ms and 2.982 ms corresponding to LAPTb was LANPTb, respectively. The green laser application has been investigated by a CIE-color-coordinates diagram with a color purity is ~73%.

Abstract: A glass system of composition 40P₂O₅-40ZnO-(20-x)Na₂O-xCdO (where, x = 1, 2, 3, 4, 5 and 6 mol%) was prepared using the conventional melt quenching technique. The glass formability of the prepared samples was inspected using XRD technique. Archimedes’ method was used to determine the density of the prepared glass samples then the molar volume was calculated. The optical spectroscopic investigations of the prepared glass samples were carried out over the spectral range (190-2500 nm). The proposed glass showed a successive transparency in both visible and near-IR ranges of spectrum till 2500 nm with considerably high transmission of about 78%. The refractive index of the glass samples with some other useful parameters such as dielectric constant, electric susceptibility and electronic polarizability of the prepared glass were evaluated. The results suggest the practicality of utilizing such new glass in the fabrication of optical supplies such as lenses and optical windows used for Nd:YAG lasers. The metallization criteria data of the prepared glass propose a good basis for predicting new nonlinear optical materials.

Abstract: The physical, optical and luminescence properties of lithium aluminium phosphate glasses different doping europium oxide have been investigated to evaluate their properties for solid-state lighting applications. The density and molar volume measurements were carried out at room temperature. The absorption spectra were investigated in the UV-Vis-NIR region from 250 to 2500 nm. The emission spectra, excited with 394 nm excitation wavelength showed four emission transitions corresponding to ⁵D₀→⁷F₁ (591 nm), ⁵D₀→⁷F₂ (612 nm), ⁵D₀→⁷F₃ (648 nm) and ⁵D₀→⁷F₄ (698 nm). The optimal concentration of Eu₂O₃ in lithium aluminium phosphate glasses was 1.00 mol%.

Abstract: Magnesium phosphate glasses co-doped with Er3+/Nd3+ concentration were prepared using melt quenching technique and thermal annealing process was proposed to control any defects found in the glass samples. The physical and optical properties of the samples were investigated. The amorphous nature of the samples were confirmed using X-ray diffraction pattern. It shows that all samples are in amorphous state. The optical band gaps and Urbach energies were obtained from the optical absorption spectra. The studyshows that the optical band gap energy,Eopt isincreasingas the Nd2O3 content increased. Meanwhile, Urbach energies, ΔE decreased due to increase of Nd2O3 content. The results obtained from this study shows that the optical band gap, Eopt and the Urbach energy, ΔE are intherange of 3.95 –3.98 eV and 0.367 –0.437 eV respectively.

Abstract: 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.