La2O3 Glass Research Articles

Environmental impacts of La2O3 on the optical and ligand field parameters of Ni ions inside Na2O-B2O3 glass

In this work, a glass system of La2O3, NiO, and Na2O borate glass was prepared by changing the concentrations of La2O3/B2O3 contents. Further, the internal structure, optical absorbance, and ligand field parameters of Ni ions were studied. The internal structure was investigated using the Fourier transform infrared technique. The optical absorbance was measured, and the optical band gaps were obtained using Tauc's plot. According to the internal structure studies, BO4 contents increase with increasing La2O3/B2O3 concentrations, while BO3 contents decrease. Furthermore, the brown color and the absorption band at 424–428 nm of the prepared glass samples confirm the existence of Ni2+ cations in the form of NiO4 species and they act as glass formers. Additionally, the observed bands at 424–428, 490–500 and 798–806 nm are associated with the spin-allowed electron transitions of Ni2+ in octahedral coordination. Furthermore, the observed bands at 710–718 and 940–950 nm are related to the electronic transitions for Ni2+ in tetrahedral coordination. Moreover, the positions of all absorption bands shift toward higher wavelengths (redshift) with higher La2O3 concentrations. Additionally, the fundamental glass absorption edges move toward lower energy values as La2O3/B2O3 contents increase, confirming the band gaps behavior. Also, with increasing La2O3/B2O3 contents, the linear and nonlinear refractive indices increase. These behaviors were justified by the optical basicity and the electronic polarizability increase. On the other hand, the ligand field parameters of Ni ions; the crystal field splitting and Racah parameters (B and C), show opposite behaviors with further La2O3 additions. In detail, the crystal field splitting shows decreasing values and Racah parameters show increasing values. These results reflect the tendency of the bonds between the Ni cations and their surroundings towards a higher ionic nature (lower covalent nature).

Radiation shielding and nuclear security functions of Na2O–Fe2O3–B2O3–La2O3 glass system

The radiation shielding parameters of Fe3+ hybrid 20Na2O–5.0Fe2O3–(75- x) B2O3–xLa2O3 (where x = 0.0 (NBFL1), 0.5 (NBFL2), 1.0 (NBFL3), 1.5 (NBFL4), and 2.0 (NBFL5) mol%) were estimated and analysed in this report. The photon, neutron, and charged radiation interaction quantities of the glasses were estimated with the aid of the FLUKA Monte Carlo code, the XCOM calculator, and well-known theoretical expressions. The photon and charged particle shielding quantities were estimated for the particle's energy up to 15 MeV. The mass attenuation coefficient ranged from 0.0189 to 6.1457 cm2/g for NBFL1, 0.0194–7.3041 cm2/g for NBFL2, 0.0199–8.4231 cm2/g for NBFL3, 0.0204–9.5046 cm2/g for NBFL4, and 0.0209–10.5504 cm2/g for NBFL5. At 15 MeV the half value layer was 18.08 cm, 16.54 cm, 14.63 cm, 14.05 cm and 13.03 cm for NBFL1, NBFL2, NBFL3, NBFL4 and NBFL5, respectively. NBFL5 has the highest shielding efficiency for charged radiation due to its higher density and La2O3 content. The value of ΣR for NBFL1, NBFL2, NBFL3, NBFL4, and NBFL5 is 0.0842 cm−1, 0.0884 cm−1, 0,0961 cm−1, 0.0965 cm−1, and 0.1004 cm−1, respectively. There was also a steady increase in the total cross section for thermal neutrons as the density and La2O3 content of the glasses increased. In addition to advanced optical functions, the NBFLX glasses possess good radiation absorption qualities, which makes them attractive for radiation absorption roles in radiation environments, among other functions.

Modification of CaO–B2O3–La2O3 glass powder and its application in low-temperature co-fired ceramic substrate

CaO–B2O3–La2O3 (CBL) glass is widely used in high-frequency packaging and co-firing with highly conductive metal electrodes as a new lead-free glass/ceramic system in low-temperature co-fired ceramic (LTCC) materials due to its multiple advantages, such as low softening point, controllable crystallisation properties, and chemical stability. The silane coupling agent, KH-570, was used as a surface modifier for preparing modified CBL glass powder to obtain a tape-casting slurry with low viscosity and excellent stability in a polymethyl methacrylate binder system; this system achieved better co-firing compatibility between the composite and Ag electrodes. In this study, the modification mechanism of the silane coupling agent with the powder is elucidated. The effects of the modified powder on the kinetic stability and rheological properties of the slurries were investigated. A slurry with a solid content of 39.6 vol% and lowest viscosity of 1500 mPa s could be obtained with the addition of 2 wt% KH-570. In particular, the uniformity of tape-casting slurry was observed during tape casting, leading to a difference in the density of green tapes, which increased from 2.45 (without KH-570) to 2.61 g/cm3 (with 2 wt% KH-570), and the tensile strength increased to 5.11 MPa. Simultaneously, the micromorphology and surface roughness of the green tapes and substrate were analysed by scanning electron microscopy and atomic force microscopy. The results showed an improvement in densification and a decrease in Ra after modification, resulting in the sintered substrate obtaining a higher density of 3.06 g/cm3 and a lower dielectric loss of 9.8 × 10−4 (12 GHz). The excellent co-firing compatibility between green tapes and silver paste at 850 °C was confirmed by energy-dispersive X-ray spectroscopy. In this study, high-quality LTCC materials were manufactured by coupling modification, with their stable performance ensuring their wide application.

Spectral investigations of Nd3+:Ba(PO3)2+La2O3 glasses for infrared laser gain media applications

The investigation of the concentration dependent spectroscopic characteristics of Nd3+ ion in Ba(PO3)2+La2O3 (PBaLa) glasses have been carried out. Based on prominent Judd-Ofelt (JO) formalism, the three JO phenomenological quantitative intensity parameters (Ωλ = 2,4,6) were determined by using absorption levels. The very high Ω6 intensity parameter value reveals greater degree of structural distortion of the Nd3+ sites in PBaLa glass. From Ωλ, required radiative characteristics such as radiative emission probability, lifetime (τr), branching ratio (βr) and emission cross-section (σ(λ)) for excited fluorescent levels have been predicted to assess the potentiality of the glasses. The de-excitation (radiative emission) spectra observed for these glasses yield three prominent levels of 4F3/2 → 4I13/2,11/2,9/2 and their related effective bandwidths and de-excitation cross-sections have been quantified. The lifetimes of the 4F3/2 fluorescent state in Nd3+:PBLa for different concentrations (0.1–2.0 mol %) of Nd3+ ion have been determined by exciting with diode laser (808 nm). The quenching of lifetime could be attributed to the enhanced energy transfer phenomenon via cross-relaxation between pairs of the Nd3+ ions. The crucial spectroscopic characteristics that include Ωλ parameters, radiative properties, effective bandwidths, stimulated emission cross-section, gain bandwidth, figure of merit and optical gain of 4F3/2 → 4I11/2 transitions of PBaLaNd1.0 glass are determined which are also compared with other reported 85 Nd3+: glasses which include 63 Nd3+:phosphate glasses. These systematic analysis and critical comparison with similar results reveal that Nd3+:PBaLa glasses with a wide bandwidth of fluorescence can also be useful for optical amplifiers or laser gain media applications.

Glass-forming region and optical properties of TeO2 – MoO3 – La2O3 glasses

Several properties of TeO2 – MoO3 – La2O3 glasses were studied. The glass-forming region in the TeO2 – MoO3 – La2O3 system covers the composition range from 7 to 78 mol.% TeO2, from 7 to 78 mol.% MoO3 and from 0 to 30 mol.% LaO1.5. Optical transmission of glasses was investigated in the wavelength range from 450 to 2000 nm. In this spectral region, the bands of Mo+5 atoms cause the main contribution to light absorption. The presence of these atoms was confirmed by electron paramagnetic resonance method. The specific absorption coefficient attributed to Mo+5 atoms was found (0.009 ± 0.002) cm−1/ppm ((140 ± 30) cm−1/wt.%.) at 990 nm.

Optical and gamma-ray absorption features of newly developed P2O5−Ce2O3−La2O3 glass system

Optical and gamma-ray absorption features of newly developed P2O5−Ce2O3−La2O3 glass system

Optical temperature sensing performance of Er3+/Yb3+ co-doped TiO2–ZrO2–La2O3 glasses

Er3+/Yb3+ co-doped TiO2–ZrO2–La2O3 glasses were prepared by aerodynamic levitation method. The transmittance spectrum shows that the transmittance of the glass before and after irradiation decreases from 75.46% to 71.13% in visible and near-infrared bands. The absorption and emission cross sections of the glasses at 525 nm were studied. The glasses were thermally treated at various temperatures and then investigated by x-ray diffraction, Scanning Electron Microscope and Transmission Electron Microscope. Optical spectra were measured as a function of temperature in the range of 298–498 K. The maximum relative sensitivity was determined to be 1.47% K−1 at 298 K. These results imply that the obtained glass may have the potential to be the matrix material for temperature sensing that requires to employed in a complex environment.

Optical, thermal and radiation shielding properties of B2O3–NaF–PbO–BaO–La2O3 glasses

The techniques of melt-quenching have been used to generate 53B2O3—2NaF—27PbO – \((20-x)\) BaO—\(x\) La2O3 \((0\le x \ge 15) glass system\). XRD patterns have been established the amorphous character of glass samples. There is a clear evidence of the role of the La2O3 modifier in the glass network. The thermal characteristics have been identified to increase with an increase in La2O3 content. Increasing La2O3 increases the linear and non-linear optical bandgap energy and the Urbach energy. By adding La2O3 to the glass samples, the refractive index, molar polarizability, polarizability, and optical basicity increased. The bulk modulus and the glass transition temperature increased because of the increase in bond strength. The number of bonds per unit increased with the increase in La2O3 content because of the modifier character of La2O3 in the glass samples. Many optical parameters (ε \(\boldsymbol{\infty }\)), (εo), \({\chi }^{(1)}\), \(\left({\chi }^{(3)}\right)\) and \({(n}_{2})\) as a function of linear and non-linear \({E}_{opt}\) have been obtained. The extent of shielding in this article has been examined with the increment in La2O3 at the expense of BaO. The results correspond with similar studies conducted before.

TeO2–B2O3–ZnO–La2O3 glasses: γ-ray and neutron attenuation characteristics analysis by WinXCOM program, MCNP5, Geant4, and Penelope simulation codes

γ-ray, fast and thermal neutrons shielding features for five Pb-free {[(TeO2)0.70(B2O3)0.30]0.7 (ZnO)0.30}(1-x)(La2O3)x (x = 0.01, 0.02, 0.03, 0.04, and 0.05 mol%) glasses have been inspected in this work. For all samples, within the photon energy range of 0.015–15 MeV, linear attenuation coefficients (μ) and mass attenuation coefficients (μ/ρ) were estimated using WinXCOM program (theoretical approach), and obtained μ/ρ values are in fine agreement with computed μ/ρ results of respective MCNP5, Geant4, and Penelope codes. By utilizing μ/ρ values of WinXCOM, γ-ray attenuation parameters like effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), and mean free path (MFP) were assessed within 0.015–15 MeV photon energy range, for all samples. Additionally, exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) were calculated for all samples by applying a five parameter geometric progression (G‒P) fitting method as a function of various penetration depths (1, 5, 10, 15, 20, 25, 30, 35, and 40 mfp) within 0.015–15 MeV photon energy range. The derived radiation protection efficiency (RPE) results indicate all samples' effective attenuation competence for lower energy γ-rays. Among all glasses, 46.55TeO2-19.95B2O3-28.5ZnO–5La2O3 (mol%) sample, by having relatively bigger μ/ρ and Zeff, minimal HVL and MFP, and lowest EBF and EABF, endorse its' excellent γ-ray shielding effectiveness. Further, neutron shielding parameters such as macroscopic removal cross-section for fast neutrons (ΣR), coherent and incoherent scattering cross-sections (σcs & σics), absorption cross-section (σA), and total cross-section (σT) for thermal neutrons were explored. By using the Geant4 code, ‘σT’ values have been deduced within 10−4‒10−8 MeV neutron energy range. The 46.55TeO2-19.95B2O3-28.5ZnO–5La2O3 (mol%) glass owns relatively larger ΣR (0.1474 cm−1) for fast neutrons attenuation and ‘σT’ (10.1444 cm−1 at 0.0253 eV neutron energy, 15.9824 cm−1 → 0.551 cm−1 from 1 × 10−8 MeV →1 × 10−4 MeV neutron energy) for thermal neutrons absorption, respectively, revealing its' superior neutrons shielding ability.

Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 glass with a high fluorescence intensity ratio for an all-fiber temperature sensor

Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 (TZZL) glasses with different concentrations of Er3+ ions were fabricated. Strong green upconversion emission bands centered at 523 and 545 nm induced by 980 nm excitation were observed. The maximum emission intensity of the TZZL glasses was obtained at the Er3+ ion concentration of 0.2 mol%. High-temperature difference (ΔT = 131.8 °C) between the transition and onset crystallization temperatures was confirmed by differential thermal analysis curve. The relationship between fluorescence intensity ratio value and temperature was examined within 303–560 K. The maximum absolute sensitivity (Sa) and the maximum relative sensitivity (Sr) was 0.006 K−1 at 560 K and 0.012 K−1 at 303 K, respectively. A prototype of an all-fiber temperature sensor was designed, and its temperature-sensing performance within 293–383 K was evaluated. Results showed that the absolute errors were within ±1 K, and the largest value of relative standard deviation was approximately 0.2%, suggesting that Er3+/Yb3+ co-doped TZZL glasses have potential applications in optical-fiber temperature sensors.

The effective role of La2O3 contribution on zinc borate glasses: radiation shielding and mechanical properties

In this theoretical study, the zinc borate glasses have been modified with lanthanum oxide (La2O3) in a different amount (0, 1, 2, 3 and 4%).The mechanical and shielding properties change after adding of lanthanum oxide in zinc borate glasses depending on the bond compression and Makishima-Mackenzie models. The mass attenuation coefficients have been calculated using the XCOM program and MCNPX simulation code. The results present that La2O3 increment in the glass density modifies the glass mechanical properties and improves the radiation attenuation performances. The variations in the mechanical properties are resulting from the formation of bridging oxygen. The density of the ZnO–B2O3–La2O3 glass system is proportional to La2O3 concentration, which is attributable to the highest molecular weight of La2O3 than those of ZnO and B2O3. Furthermore, the mass attenuation coefficients, effective atomic numbers and effective removal cross-section of the glasses increases as La2O3 contains increase. The half-value layer, tenth value layer, mean free path, buildup factors and mass stopping power of the glasses decrease as La2O3 contain increases. Present results explained the characteristic of ZnO–B2O3–La2O3 glass as a novel nominee for radiation attenuation barrier in the chosen energy zone.

Luminescence and scintillation properties of CuO-doped SiO2–B2O3–La2O3 glass

A CuO-doped SiO2–B2O3–La2O3 glass system was prepared through high-temperature melting and the Si powders were used as reducing agent to reduce Cu2+ to Cu+. The spectral properties, electron paramagnetic resonance spectra, and scintillation luminescence under X-ray irradiation were measured. The Cu+ ions in the borosilicate glasses exhibited both luminescent centers under ultraviolet light excitation, which are isolated Cu+ ions and Cu+–Cu+ ion pairs, respectively. There is an energy transfer process from isolated Cu+ ions to Cu+-Cu+ ion pairs, which strongly affects radioluminescence. The luminescent intensity of the Cu+–Cu+ ion pairs became increasingly apparent with the increase in CuO doping concentration, and the optimum concentration was 0.4 mol% for the photoluminescence and radioluminescence.

Enhanced luminescence at 2.88 and 2.04 μm from Ho3+/Yb3+ codoped low phonon energy TeO2–TiO2–La2O3 glass

The high phonon energy and short infrared cut-off wavelength of conventional oxide glass (or crystal) hosts are the limitations to achieve mid-infrared (MIR, λ≥2.5μm) luminescence. In present study, the luminescence performance of low phonon and non-conventional TeO2-TiO2-La2O3-based glass (TTL) host doped with Ho3+ and Ho3+/Yb3+ has been investigated, for visible to MIR range. The MIR emission band with peak at 2.88μm (Ho3+:5I6→5I7) and NIR band at 2.04μm (Ho3+:5I7→5I8) has been realized from Ho3+ singly doped TTL glass due to low phonon energy and extended transmission window of the host. Intensity of MIR and NIR emission bands have enhanced significantly in Ho3+/Yb3+: TTL glass under Yb3+ excitation, signifying an efficient Yb3+→Ho3+ energy transfer. The Judd-Ofelt analysis, on Ho3+ absorption characteristics reveals relatively better radiative transition probability (34.4s−1) and branching ratio (10.5%), which is associated to Ho3+:5I6→5I7 transition. The effective bandwidth of 2.88μm emission band is 180nm, with stimulated emission cross-section is 4.26×10-21cm2 and its gain bandwidth has been evaluated as 7.67×10-26cm3. For 2.04μm (Ho3+:5I7→5I8) emission band, the effective bandwidth of 160.5nm and gain bandwidth of 7.26×10-26cm3 have been accomplished. The non-resonant Förster-Dexter method has been applied to Ho3+/Yb3+: TTL glass on emission (donor, Yb3+) and absorption (acceptor, Ho3+) cross sections. The evaluated donor-donor (CDD) and donor-acceptor (CDA) energy transfer micro-parameters are 1.02×10-38 and 5.88×10-41cm6/s respectively while, maximum energy transfer efficiency has been 80%. In concise, Ho3+/Yb3+ codoped TeO2–TiO2–La2O3 glass host has revealed its potential for MIR to NIR photonic applications.

Frequency upconversion mechanism in Ho3+/Yb3+-codoped TeO2–TiO2–La2O3 glasses

Frequency upconversion from Ho3+/Yb3+-codoped glass or crystal under Yb3+ sensitization is a known phenomenon. However, inconsistencies are prevalent in the understanding of double energy transfer mechanisms for Ho3+/Yb3+-codoped systems. In this context, rate equations are proposed for Ho3+/Yb3+-codoped low-phonon TeO2–TiO2–La2O3 glass under Yb3+ sensitization with continuous and pulsed excitations. The proposed rate equations are validated with experimental results to elucidate the mechanisms responsible for populating 5(S2, F4) and 5F5 energy levels of Ho3+ ion. The solutions of rate equations with experimental results are substantiating the occurrence of both excited state absorption (ESA) and energy transfer upconversion (ETU) mechanisms in populating Ho3+:5(S2, F4) level, though higher concentration of Ho3+ ion would decrease the probability of ETU and increase of ESA. In contrast, Ho3+:5F5 level has been populated via ETU only. Numerical solutions to the rate equations are also proposed to elucidate the mechanics for populating 5(S2, F4) and 5F5 levels of Ho3+ ion. The proposed rate equation for pulsed excitation explains the characteristics of respective decay curves, which are further used to quantify energy transfer coefficient (W02) as (1.77 ± 0.12) × 10− 17cm3 s−1 for Ho3+/Yb3+-codoped TTL glass host.

Structural study of Na2O-B2O3-SiO2-La2O3 glasses from molecular simulations using a polarizable force field

The properties of Na2O-B2O3-SiO2+La2O3 glasses (NBS_La) are not well understood. In particular the influence of the lanthanides on the polymerized network structure and organization are not well known. In this work, we use a Polarizable Ion Model (PIM) that was fitted on electronic structure calculations to simulate a series of NBS_La glasses using molecular dynamics. The simulations account well for the main structural characteristics of NBS_La glasses such as the structure factors and the ionic local environments despite minor discrepancies with experiments about the Si-O distance and the B coordination. In particular, we examine the impact of La2O3 addition to Na2O-B2O3-SiO2 glasses in term of structural changes and in the Na migration paths which become more homogeneous.

Comparative investigations of gamma and neutron radiation shielding parameters for different borate and tellurite glass systems using WinXCom program and MCNPX code

In the present article, for different chemical compositions of B2O3‒Bi2O3, B2O3‒Sb2O3, B2O3‒WO3‒La2O3, B2O3‒MoO3‒ZnO, and TeO2‒MO (M = Mg, Ba, and Zn) glasses, by applying WinXCom program we calculated the mass attenuation coefficient (μ/ρ) values, and from these values, the effective atomic number (Zeff), electron density (Ne), mean free path (MFP), half-value layer (HVL), and exposure buildup factor (EBF) values using Geometric progression (G‒P) fitting method, including macroscopic effective removal cross-section (ΣR) values for fast neutrons are evaluated for their potential applications as γ-ray and neutron radiation shielding materials. Moreover, the μ/ρ values of all the studied different glass compositions were computed using MCNPX simulation code and compared with WinXCom results. BBi65 glass has the highest μ/ρ, and Zeff values in the B2O3‒Bi2O3 glasses and lower values of MFP, HVL, and EBF. The maximum values of μ/ρ and Zeff are recorded for BSb70 in the B2O3‒ Sb2O3 glasses. It is found that the Zeff for B2O3‒Bi2O3 glasses is higher than those for B2O3‒ Sb2O3 glasses, which reveal that the B2O3‒Bi2O3 glasses have better shielding properties than the B2O3‒Sb2O3 glasses. The μ/ρ values of B2O3‒WO3‒La2O3 glasses are higher than those B2O3‒MoO3‒ZnO glasses, which indicate that B2O3‒WO3‒La2O3 glasses show preferable radiation shielding effectiveness comparing with B2O3‒MoO3‒ZnO glasses. The variation of different shielding parameters for the selected glasses was discussed according to the three photon interactions with matter (Photoelectric effect, Compton scattering, and pair production). The calculated μ/ρ and Zeff for the selected glasses have been compared with different glasses. HVL values are compared with ordinary, hematite-serpentine, ilmenite, steel-scrap and ilmenite-limonite concretes. It is found that ΣR values for B2O3‒Bi2O3, B2O3‒Sb2O3, B2O3‒WO3‒La2O3, B2O3‒MoO3‒ZnO, and TeO2‒MO (M = Mg, Ba, and Zn) glasses lie within the range 0.1312–0.2823 cm−1, 0.0876–0.0957 cm−1, 0.1180–0.1085 cm−1, 0.1066–0.1002 cm−1, and 0.1040–0.1075 cm−1, respectively.

Optical features of novel fluorotellurite glasses based on TeO2- LiNbO3- BaF2- La2O3- (Nb2O5 or TiO2)

New families from fluorotellurite glasses with composition 7.53 TeO2-7.31 LiNbO3-4.16 Nb2O5-10 BaF2-1.0La2O3, 72.53 TeO2-7.31 LiNbO3-10 Nb2O5-10 BaF2-1.0La2O3 and 77.53 TeO2-7.31 LiNbO3-5 TiO2-10 BaF2-1.0La2O3 in mol% were prepared. The thermal characterization and optical properties of these glasses were estimated by using differential scanning calorimetric, DSC, and UV–vis-NIR spectroscopy respectively. The results of thermal analysis indicate that 77.53 TeO2-7.31 LiNbO3-5 TiO2-10 BaF2-1.0La2O3 glasses has high thermal stability and high factor against crystallization. The density and linear refractive index, n, of present glasses were measured. Also, the physical parameters such as; oxygen packing density, molar volumes, oxygen molar volume, molar refraction, metallization criterion, molar polarizability, third-order non-linear susceptibility and two photon absorption coefficients were calculated. It was found that, the linear refractive index increases otherwise decrease in the optical energy gap with increase Nb2O5 concentration. On the basis on thermal and optical results of these glasses it can be concluded that fluorotellurite glasses tested can be used in optical application.

All-optical dynamic photonic bandgap control in an all-solid double-clad tellurite photonic bandgap fiber.

All-optical dynamic photonic bandgap (PBG) control by an optical Kerr effect (OKE) is investigated in an all-solid double-clad tellurite photonic bandgap fiber (PBGF) which is fabricated based on TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN, high-index rod) glass, TeO2-ZnO-Na2O-La2O3 (TZNL, inner cladding) glass, and TeO2-ZnO-Li2O-K2O-Al2O3-P2O5 (TZLKAP, outer cladding) glass. To the best of our knowledge, this is the first demonstration of all-optical dynamic PBG control in optical fibers. This PBGF has a high nonlinear refractive index which can lead to a significant OKE and induce the generation of all-optical dynamic PBG control. The transmission spectrum is simulated with the pump peak power increasing from 0 to 300kW, which shows an obvious PBG shift. Dynamic PBG control is demonstrated both numerically and experimentally at the pump peak power of 200kW (ON or OFF) at the signal of 1570nm.

Judd-Ofelt analysis of Nd3+ doped phosphate glass: The effect of Ba/Sr ratio

ABSTRACTHere we disclosed the substantial effect of the local medium in the vicinity of the excited Nd3+ions on the optical properties and the laser characteristics of glasses. The UV-Vis absorption of the laser BaO/SrO–P2O5–Al2O3–K2O–B2O3–La2O3 glasses doped with Nd3+ ions is measured at 25 °C. Judd-Ofelt (JO) theoretical analysis of 4f electron transitions in the Nd3+ absorption spectra was performed. From the JO intensity parameters, a set of the laser 4F3/2→4I11/2 transitions characteristics are found and stimulated emission cross-sections are characterized. The effect of different Ba/Sr ratio on the structure-properties relationships in the glasses is shown.

Phase Separation, Crystallization, and Microwave Dielectric Properties of MgO‐Al2O3‐SiO2‐TiO2‐La2O3 Glass‐Ceramic

The effects of heat treatment on phase separation, crystallization, and microwave dielectric properties of the 1MgO·1.2Al2O3·2.8SiO2·1.4TiO2·0.4La2O3 (in molar ratio) glass and glass‐ceramic were investigated. The results show that the parent glass has a two‐liquid phase separation structure, with a droplet phase rich in Al & Ti embedded in the matrix rich in Si. Heat treatment of the glass at 770°C leads to the enlargement of the liquid droplets and promotes the formation of crystals from the droplets. The initial crystalline phase perrierite appears after heat treatment of the parent glass at 850°C, and it is analyzed to precipitate from the Al&Ti‐rich droplet phase. With increasing heat‐treatment temperature from 850°C to 1250°C, the crystallization degree of the glass increases as the other main crystal phases rutile, cordierite and magnesium aluminotitanate precipitate successively from the material. As a summation of the phases present, the dielectric constant εr of the material after heat treatment at 950°C–1250°C fluctuates between 11.3 and 12.3, while the quality factor Q × f and the temperature coefficient τf go up firstly and then decrease with the peak at 1200°C, ranging from 8200 to 19,500 GHz and −57ppm/°C to 24 ppm/°C, respectively.