Transparent highly ce 3+ - doped boron-aluminosilicate glass for advanced photonic applications

Abstract

Methods, devices and systems for producing a trivalent cerium doped material are described. One method of stabilizing trivalent cerium ion includes using a melting crucible to synthesize a glass melt from a mixture of compounds that includes trivalent cerium oxide by heating the mixture inside a synthesis chamber substantially free of oxygen for a predetermined amount of time. In one example, the crucible includes graphite or glassy graphite that reduces oxygen in the glass melt. Next, oxygen-reducing components are introduced into the synthesis chamber that mitigate energy state transitions of trivalent cerium ions obtained from the trivalent cerium oxide. The method further includes obtaining a glass composition that includes trivalent cerium ions in stabilized form by annealing the glass melt. The concentration of the trivalent cerium ions in stabilized form in the glass composition is based on capabilities of oxygen-containing compounds included in the mixture to dissolve trivalent cerium oxide.

Description

U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) TRANSPARENT HIGHLY CE3+- DOPED BORON-ALUMINOSILICATE GLASS FOR ADVANCED PHOTONIC APPLICATIONS CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to the provisional application with serial number 63 / 650,272 titled “TRANSPARENT HIGHLY CE3+ - DOPED BORON-ALUMINOSILICATE GLASS FOR ADVANCED PHOTONIC APPLICATIONS,” filed May 21, 2024. The entire contents of the above noted provisional application are incorporated by reference as part of the disclosure of this document. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with Government support under grant No. DMR-2310284 awarded by the National Science Foundation. The Government has certain rights in the invention. TECHNICAL FIELD

[0003] The disclosure of this patent document relates to methods and system for producing glass and specifically cerium doped glass. SUMMARY

[0004] The disclosed embodiments relate to systems and methods, that among other features and benefits, stabilize trivalent cerium (Ce3+) ions in silicate glass using high-purity Ce2O3as the source of cerium and deoxidation additives during the synthesis of the silicate glass. The systems and methods can be implemented to create a stable boron-aluminosilicate-lanthanum (BASL) glass with the highest Ce3+concentration among currently known glass materials. In some implementations, a glass composition comprising a concentration of stabilized Ce3+ions can be fabricated in a controlled, heated environment from a glass melt with an optimized chemical composition. Certain properties (e.g., optical or magneto-optical properties) of Ce3+-doped glass compositions based on the disclosed technology can be tuned by modifying the concentration of Ce3+ions in the glass composition using the disclosed techniques. Trivalent cerium doped optical materials have multiple special applications, such as high energy radiation and particle detection, medical imaging, radiation-resistance components and devices, illumination, laser technologies, amplifiers, and magneto-optic devices. Additionally, highly Ce3+-doped glasses present exciting opportunities for the development of advanced photonic devices.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0005] Systems and methods described herein stabilize cerium ions in trivalent form during high-temperature synthesis of glass systems using a graphite melting crucible that acts as a container and a reducing agent that depletes the glass melt of oxygen, thus preventing Ce3+^Ce4+transitions. Advantages of the disclosed embodiments includeconcentration quenching and Ce3+oxidation in Ce3+-doped BASL glass. Among glass materials, only silicate glasses generally show favorable properties. However, their doping level is limited to ≤ 3.7×1020Ce3+ions / cm3due to the facile transition from Ce3+to Ce4+during glass melting. The disclosed systems and methods can be used to create a stable BASL with the highest Ce3+concentration among currently known glass materials.

[0006] In one aspect, a method of stabilizing trivalent cerium ions is provided. The method comprises: synthesizing a glass melt, using a melting crucible comprising graphite or glassy graphite, from a mixture of compounds that includes trivalent cerium oxide by heating the mixture inside a synthesis chamber substantially free of oxygen for a predetermined amount of time, wherein the melting crucible comprising graphite or glassy graphite reduces oxygen in the glass melt; introducing oxygen-reducing components into the synthesis chamber that mitigate energy state transitions of trivalent cerium ions obtained from the trivalent cerium oxide; and obtaining a glass composition comprising a concentration of the trivalent cerium ions in stabilized form by annealing the glass melt, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on capabilities of oxygen-containing compounds included in the mixture to dissolve trivalent cerium oxide.

[0007] In another aspect, a system for producing a trivalent cerium doped material is provided. The system comprises: a synthesis chamber substantially free of oxygen and configured to receive a mixture of compounds comprising trivalent cerium oxide and silicon dioxide and to heat the mixture to a first temperature; a glassy graphite melting crucible configured to contain the mixture within the synthesis chamber during the heating of the mixture to the first temperature, the glassy graphite melting crucible operable to provide carbon to the mixture during the heating of the mixture and to absorb oxygen in the mixture and the synthesis chamber such that the mixture comprises trivalent cerium ions in stabilized form after the heating; and a mold configured to receive the mixture comprising trivalent cerium ions in stabilized form, the mold annealed in an oxygen-reduced atmosphere at a second temperature that is lower than the first temperature toU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) allow the mixture comprising trivalent cerium ions in stabilized form to become glassy.

[0008] In yet another aspect, a method of producing a trivalent cerium doped glass is provided. The method comprises: synthesizing a mixture of compounds including trivalent cerium oxide and a rare-earth containing compound, wherein the mixture of compounds comprises a predetermined ratio of trivalent cerium oxide to the rare-earth containing compound; forming a glass melt by heating the mixture to a first temperature; and annealing the glass melt to a second temperature that is different from the first temperature such that a glass composition comprising a concentration of trivalent cerium ions in stabilized form is obtained, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on the predetermined ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIGS.1A and 1B show example properties of Ce3+-doped materials.

[0010] FIG.2 shows an example transmission spectrum of a Ce2O3 doped silicate glass.

[0011] FIGS. 3A, 3B, and 3C show example ternary phase diagrams of some BASL glass systems.

[0012] FIG.4 shows a comparison of example doping levels in Ce3+-doped materials.

[0013] FIG.5 shows an example photo of undoped and Ce3+-doped BASL glasses.

[0014] FIG. 6 shows example spectra of Ce3+-doped BASL glasses obtained by X-ray photoelectron spectroscopy (XPS).

[0015] FIGS. 7A and 7B show high resolution scanning electron microscopy with energy dispersive X-ray spectroscopy images of example Ce3+-doped BASL glasses.

[0016] FIGS. 8A and 8B show example characterizations of thermodynamical properties of Ce3+-doped BASL glasses describing the behavior and stability of the glasses as influenced by temperature.

[0017] FIG.9A shows an example of a refractive index dispersion of some Ce3+-doped BASL glasses and FIG.9B shows example attenuation spectra for the visible to the near-infrared region of some Ce3+-doped BASL glasses to describe losses in the material.

[0018] FIG.10 shows example magneto-optical properties of some Ce3+-doped BASL glasses described in terms of the Verdet constant.

[0019] FIG.11 shows example magneto-optical properties of some Ce3+-doped BASL glasses described in terms of the Verdet constant.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0020] FIG.12 shows example luminescence properties of some Ce3+-doped BASL glasses.

[0021] FIG.13 shows example fluorescence spectra of some Ce3+-doped BASL glasses.

[0022] FIG.14 shows example fluorescence spectra of some Ce3+-doped BASL glasses.

[0023] FIG.15 shows example lifetimes of some Ce3+-doped BASL glasses.

[0024] FIG.16 shows example absolute quantum yields of some Ce3+-doped BASL glasses.

[0025] FIG. 17 illustrates a set of operations that can be carried out for stabilizing trivalent cerium ions in accordance with an example embodiment.

[0026] FIG.18 illustrates a set of operations that can be carried out for producing a trivalent cerium doped glass in accordance with an example embodiment.

[0027] FIG.19 shows example x-ray diffraction patterns of BASL-Ce glass powders.

[0028] FIG. 20 shows example high resolution SEM-EDX images of BASL-Ce3+ glass samples under 110000x magnification.

[0029] FIG.21 shows a configuration of an example Verdet constant measurement apparatus.

[0030] FIG. 22 shows a block diagram of a system for producing a trivalent cerium doped material in accordance with an example embodiment. DETAILED DESCRIPTION

[0031] Trivalent cerium doped materials possess extraordinary optical and physical properties including no absorption transitions across the entire visible and near-infrared wavelength region (400-3500 nm), broadband UV and visible luminescence (250-700 nm), large Verdet constant, high resistance to radiation and photo-darkening, and high scintillation yield. These unique properties are attributed to the simple energy level structure of Ce3+with a large energy gap of ~30 000 cm-1between the highest 4f state (2F7 / 2) and the lowest 5d state (2D3 / 2) as shown in FIG.1A. When Ce3+doped materials are irradiated by ultraviolet (UV) light, ionizing radiation or high- energy particles, they generally emit light in 250-700 nm region through an electronic transition between the 5d and 4f levels. The luminescence of Ce3+ions in most host materials is characterized by fast rise and decay times of < 0.5 ns and < 50 ns, respectively, making Ce3+-doped materials very favorable for scintillation applications. Their scintillation yields are also very high due to the large hole-capturing cross-section of Ce3+ions. This property also results in the exceptional radiation hardness of Ce3+-doped materials because Ce3+can trap the holes and electrons induced by radiation and significantly reduce the formation of other defect centers on hole and electronU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) traps and non-radiative decay as illustrated in FIG.1B. On the other hand, due to the high transition moment of Ce3+, Ce3+-doped materials usually have large Verdet constants, making them very attractive for magneto-optic (MO) applications. Most importantly, compared to other rare-earth ions with large Verdet constants, such as terbium (Tb3+), praseodymium (Pr3+), and dysprosium (Dy3+), Ce3+is the only one without any absorption transitions over the visible, near-infrared, and mid-infrared (400-3500 nm). FIG.2 shows the transmission spectrum of a 10-mm-thick 1 mol.% Ce2O3silicate glass, which shows the hydroxyl group band edge starting from 2.1 µm. These unique properties make Ce3+-doped materials very attractive for a wide range of applications, such as high energy radiation and particle visualization, radiation-resistant optics, illumination, laser technologies, amplifiers, magneto-optics, and holography.

[0032] Highly Ce3+-doped materials have always been pursued for enabling photonic devices with outstanding size, weight, and power (SWaP). Most existing highly Ce3+-doped materials for the above-mentioned applications are based on crystals and films because of their high solubility for the Ce3+ion. For instance, LYSO / LSO: Ce3+and LaBr3: Ce3+crystals with doping levels of up to ~1.0×1021and ~2.4×1021ions / cm3, respectively, have been widely used in state-of-the-art scintillators. Highly Ce3+-doped YAG and other crystalline materials have been used for white light luminophores and wide wavelength-tunable solid state lasers in the UV and visible. Highly Ce3+-doped films and crystals have also been used in advanced magneto-optic devices. Although photonic devices based on highly Ce3+-doped crystals and films have seen significant progress, their fabrication processes are expensive, complex and time-consuming particularly when compared with glass, and their applications are also restricted by the drawbacks of crystals and films, such as small apertures, brittleness, and anisotropy.

[0033] In example embodiments described herein, the aforementioned shortcomings can be addressed with highly Ce3+-doped robust silicate glass materials because inorganic glass has favorable mechanical properties, chemical durability and thermal stability and can be made into large-scale and complex shapes (e.g., 3D printed optical components) or even be drawn into optical fibers, which have been extensively used in current photonic systems.

[0034] Usually it is very challenging to make highly stable Ce3+-doped glass with a doping level as high as that of the Ce3+-doped crystals because the possibility of Ce3+^ Ce4+oxidation state change increases with increasing Ce3+concentration in glass materials as oxygen is present.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) However, Ce3+^ Ce4+is inhibited in crystals because the lattice energy is minimized when the R3+ions in the crystal unit cell are replaced by Ce3+ions. Since glass is a homogenous mixture without anisotropy, there is no preference to either the Ce3+or Ce4+state and optimizing the oxidation-reduction conditions is thus the only approach to making highly Ce3+-doped glass with low Ce4+content.

[0035] Cerium-doped glass materials can be used for scintillation applications. Silicate glass has the highest mechanical strength and lowest hygroscopicity among oxide glass materials. However, so far, the maximum concentration of Ce3+in silicate glass, the only commercially available inorganic glass scintillator, is ^3.7×1020 / cm3due to the low stability. The issue can be solved by tailoring the silicate glass composition. For example, aluminosilicate and boron- aluminosilicate glass not only have significantly improved trivalent rare-earth ion solubility, but also maintain other outstanding properties including high mechanical strength, low hygroscopicity, and high thermal shock resistance.

[0036] In the description that follows, the synthesis and characterization of a highly Ce3+doped 89(0.4B2O3-0.2Al2O3-0.4SiO2)-11La2O3 (BASL) glass system is presented as an example. In this example, a stable Ce3+-doped BASL glass (BASL-25) with Ce3+ion concentration as high as 9.5×1021ions / cm3(25 mol.%) was successfully fabricated by optimizing the batch composition and precisely controlling the reduction conditions during glass fabrication. In some implementations of the techniques disclosed in this patent document, a stable Ce3+-doped glass with a Ce3+ion concentration higher than 9.5×1021ions / cm3can be synthesized. In some embodiment, a concentration of up to 1.31 × 1022ions / cm3 can be achieved.

[0037] As shown in Table 1, BASL-25 has the largest Ce3+concentration among current glass materials. Its decay time is 39 ns, which is smaller than the 50 ns decay time of low-concentration Ce3+-doped lithium-silicate glass. Its density is ^4.3 g / cm3, which is second to than that of HMF glass. Moreover, the emission peak wavelength of the BASL-25 glass is 452 nm, in the high sensitivity region of both photomultiplier tubes (PMT) and silicon photodiodes, making BASL-25 glass very efficient for radiation and particle visualization. Most importantly, like lithium-silicate glass, BASL-25 glass has low hygroscopicity. All these outstanding properties make BASL-25 as an excellent alternative to current highly Ce3+- doped crystalline materials.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0038] Table 1: Property summary of highly Ce3+-doped glass materials Material NCe3+, cm-3^, g / cm-3^max, ^, nsHygroscopicity

[0039] k position, ^- average luminescence decay time.

[0040] Example Results

[0041] Example Glass Fabrication

[0042] In the examples described herein, the development of stable highly Ce3+- doped BASL glass (FIG. 5) was accomplished in two steps. The first step was to identify B2O3-Al2O3-SiO2 compositions capable of dissolving 11 mol.% of La2O3. A series of 89(B2O3-Al2O3-SiO2)-11La2O3 glasses were synthesized with traditional glass synthesis techniques. As shown in FIG. 3A, the recipe for making stable 89(B2O3-Al2O3-SiO2)-11La2O3 glass is very limited and the glass with a composition of 89(0.4B2O3-0.2Al2O3-0.4SiO2)-11La2O3 has exhibited the highest stability.

[0043] The second step was to dope the BASL glass with Ce3+. Two glass systems 89(0.4B2O3- 0.2Al2O3-0.4SiO2)-(11-x)La2O3-xCe2O3(0<x≤11) (FIG. 3B) and (100-x)(0.4B2O3-0.2Al2O3- 0.4SiO2)-xCe2O3 (11<x≤25) (FIG.3C) were developed. Highly stable Ce3+ions were obtained in the BASL glass by using high purity Ce2O3 (99.9%) instead of the traditionally chosen CeO2 as a precursor23–29,35and adding deoxidation compounds, such as graphite, sugar, and metal halides. Because Ce2O3 can pass into CeO2 even under standard ambient conditions and Ce3+^Ce4+is mainly caused by oxygen from ambient and impurities of metal ions with mixed valence, synthesis of Ce3+-doped BASL glass was conducted in a carefully controlled environment. A series of Ce3+- doped BASL glass samples with a maximum Ce3+concentration of 25 mol% and without traceable Ce4+were successfully fabricated. We refer to the glasses as BASL-X, where X is the Ce2O3concentration in mol.%. BASL-25 has the largest Ce3+concentration for current glass materials and state-of-the-art crystalline materials (FIG.4). A vitreous state was confirmed for the BASL-U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) Ce samples, with no presence of crystalline phases observed in the X-ray diffraction (XRD) analysis of powder glass samples (see Appendix A, Note 1).

[0044] Example Methods

[0045] Example methods to synthesize Ce3+-doped BASL glass samples are described herein. Boron-aluminosilicate glass systems with 89(B2O3-Al2O3-SiO2)-11La2O3, 89(0.4B2O3-0.2Al2O3- 0.4SiO2)-(11-x)La2O3-xCe2O3 (0<x≤11) and (100-x)(0.4B2O3-0.2Al2O3-0.4SiO2)-xCe2O3 (11<x≤25) compositions were synthesized by a conventual glass melting method from stoichiometric amounts of H3BO3(4N), Al2O3(4N), SiO2(4N), La2O3(4N) and Ce2O3(3N). Small 30 to 70 g batches of these materials were mixed in an agate mortar in air for 30 min. The mixed batches were loaded into a preheated 1400-1500oC electrical furnace with Mo-Si heating elements. In some implementations, the mixed batches are loaded into a preheated 1400-1600oC electrical furnace. The furnace was purged with Ar at 10 l / m with the gas being directed to the bottom of the heating zone and to the melt-atmosphere interface. It is well known that boron oxide tends to volatize while glass is melted at high temperatures; however, the loss of boron oxide is usually less than 10%.

[0046] The glass melts were held in the furnace for 30 minutes to let batches melt and vitrify, as well as to refine the melt. Next, the melts were poured into a stainless steel mold and annealed 10oC above the glass transition temperature (Tg) for 1 h and slowly (10oC / h) cooled to 25oC.

[0047] To stabilize cerium ions in trivalent form during the glasses synthesis, an oxygen free inert and / or reducing atmosphere was established in the synthesis chamber and trivalent cerium oxide was used instead of traditionally used tetravalent cerium oxide. Additionally, a glassy graphite melting crucible that acts as a container and as a reducing agent that depletes the melt of oxygen, thus preventing Ce3+^ Ce4+transition, was used. Deoxidation techniques were also implemented. For example,halides, metals, metal nitrides, metal carbides, graphite and graphite containing precursors and other components ready to react with oxygen were used in glass fabrication. The addition of 0.1 – 2.5 wt.% of the above components was shown to significantly mitigate Ce3+^ Ce4+transition. The use of trivalent cerium oxide and the graphite melting crucible during synthesis allow for increased doping levels of up to 25 times or more without affecting transmission in visible and near infrared regions.

[0048] It should be noted that the above method of Ce3+ions stabilization is applicable for allU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) oxide glass systems, thus allowing fabrication of highly Ce3+doped oxide, oxynitride, oxyhalide glasses of various compositions and / or co-doped with rare-earth elements and transitional metals. Possible glass modifiers include but are not limited to GeO2, Ga2O3, PbO, alkaline and alkaline earth oxides, as well as other metal oxides. In some implementations of the disclosed techniques, glass modifiers are included in a form in which they cannot release oxygen when heated.

[0049] After annealing, all the samples were visually inspected for the presence of inclusions, cords and brown coloration. The fine glass samples were then cut into 1 mm thick plates and ^ 7^7^15 mm3rectangular samples for property characterization.

[0050] It should be noted that, because of the imperfect insulation of the furnace, some traces of oxygen can be found in the synthesis chamber. Thus, it is necessary to include additives that readily react with oxygen and mitigate the oxidation of Ce3+. In our experiments, we found that adding small amounts of conventional reduction agents, such as graphite, sugar, or metal halides on the order of 0-0.1 wt.%, 0-1 wt.% and 0.5-2 wt.% to the batch improved the Ce3+stability. In some implementations, metal halides, metals, metal nitrides, metal carbides, graphite and graphite containing precursors and other components ready to react with oxygen can be used to help mitigate leaks in the synthesis chamber.

[0051] A vitreous state and the absence of crystallinity in the glass samples were using an X- ray diffractometer with Cu Kα radiation as the source. The diffraction pattern of the glass powder samples was measured in the Bragg-Brentano geometry with 0.05omeasurement steps in the 10– 80orange.

[0052] The Ce4+ / Ce3+ratio was evaluated by X-ray photoelectron spectrometry (XPS) of the glass powder samples using monochromatic Al Kα X-ray excitation at 300W (20 mA / 15 keV). All elemental regions were measured at a pass energy of 20 eV with base pressure below 1 x 10-8torr. Each sample was mounted in an XPS stub with multiple 4 mm diameter cups to prevent seeing any carbon, nitrogen or oxygen from the mounting surface. The background spectra were approximated with the “Tougaard background” which is based on a physical model for the inelastic scattering properties of the material.

[0053] The glass transition and crystallization temperatures of the BASL glass samples were determined from the thermal property curves measured on a differential scanning calorimeter with thermo-gravimetric analysis for ^80 mg bulk and powder samples in a temperature range of 200–U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) 1100oC at a scanning rate of 10oC / min. The linear thermal expansion coefficient was determined using a thermomechanical analyzer in a temperature range of 50–800oC at a scanning rate of 10oC / min.

[0054] The Vickers’s micro-hardness was tested on a microhardness testing system under 0.3 kgf load with loading speed of 40 µm / s and loading time of 10 sec.

[0055] The mass of each sample was measured to an accuracy of 1 mg on an analytical balance. The glass density ρ was determined by the hydrostatic weighing method with an accuracy of 0.0005 g / cm3using distilled water with a density of 0.9978 g / cm3as the immersive liquid at room temperature.

[0056] The number of Ce ions per cubic centimeter was calculated using Equation (2) ^^^^ൌ^^^∗ேೌ∗ఘெ^^∗^^^(2)where ^^^^, ^^, ^^^ and ^^^^ are thenumber (mol-1), and molar weight (g / mol) of ceria, respectively.

[0057] The BASL-Ce glass sample surface morphology and element maps were observed on a scanning electron microscope at 400 W (20 mA / 20 kV). To allow for charge dissipation the glass samples were coated with a 4 nm layer of Pt on a sputter coater.

[0058] The refractive indices (RI) of the glass samples were measured at 532, 633, 816, 1305 and 1555 nm by the prism coupling method with a prism coupler. The RI values were approximated with the Cauchy equation that was later used to estimate reflectance R using Equation (3): ^^ ൌ ^^ି^ ^ଶ ^ ^1 െ ^^ି^ ^ଶ^ ∗ ^^ି^ଶ^ା^ ^ା^ ^ା^ ^ (3) where ^^ is the reflectance foundby a least squares method.

[0059] UV–Vis–NIR absorption spectra of the glass samples were measured with a spectrophotometer in the 0.2-3 µm range with 1 nm steps. The glass attenuation coefficient, a, was calculated from the absorption spectrum with Equation (4): ି୪୭^^శೃ ^ ^^ ൌ భబ^ ^బ(4) where ^^^and ^^ are the intensities of incidentand ^^ is sample thickness.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0060] The Verdet constants of BASL-Ce glass samples at 460, 532, 633, 795, 976, 1550 and 1940 nm were obtained by measuring the Faraday rotation of the linearly polarized light as it went through glass samples that were placed in a solenoid capable of producing a magnetic field as high as 100 mT. The output beam after the glass samples was separated into two orthogonal polarization components adjusted to have equivalent power when the magnetic field of the solenoid is zero (see FIG.21). The rotation angle of the linearly polarized beam at a given applied magnetic field was obtained by measuring the power levels for the two spatially separated polarization components (Psand Pp) and using Equation (5): ^^ ൌ^ೞି^^ଶ^^ೞା^^^(5) where ^^ is the rotation angle, and ^^^and ^^^components. The Verdet constant was then determine by using the relationship in Equation (6): ^^ ൌ ఏℬ∗^ (6) where ℬ is the magnetic flux, and ^^ is the

[0061] The photoluminescence spectra and absolute quantum yield were measured on an Absolute PL Quantum Yield Measurement System consisting of a multichannel analyzer with an InGaAs sensor (200–950 nm range with 2 nm resolution), integrated sphere unit, a monochromatic light source with a 150 W Xenon lamp and a monochromator (250–950 nm range, bandwidth from 2 to 5 nm).

[0062] The decay lifetimes were obtained by measuring the fluorescence decay of the BASL- Ce glass samples that were pumped by a solid-state pulsed laser source at 355 nm with a pulse duration of 5 ns and repetition rate of 10 Hz. The fluorescence emission from the BASL-Ce glass samples was collected with an aspheric lens. A set of filters were used to filter out the pump light and obtain the fluorescence produced due to the transition between the targeted energy levels. The filtered light was focused onto a detector via another aspheric lens. The time-resolved fluorescence decay curves were measured with an oscilloscope. The lifetime of an energy level was obtained by fitting the time-resolved fluorescence decay curve with a second order exponential decay function.

[0063] Example Glass Characterization

[0064] In the examples described herein, X-ray photoelectron spectroscopy (XPS) was usedU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) to detect traces of Ce4+in the BASL-Ce glass samples. The XPS results for BASL-1, BASL-11, and BASL-25 are shown in FIG.6. Because there is no detectable peak at a binding energy of 916 eV, which corresponds to one of three Ce4+3d3 / 2–3d5 / 2 spin–orbit split doublets, we confirmed that the BASL-Ce glass samples don’t contain detectable levels of Ce4+ions. The peaks of the two doublets (t0, t1) at binding energies of 882 and 886 eV, and 900 and 904 eV correspond to Ce3+transitions.

[0065] The homogeneity of the BASL-25 glass was checked on a scanning electron microscope with energy dispersive X-ray spectroscopy (EXD) (see Appendix A, Note 2). As shown in FIGS. 7A and 7B, there are no signs of phase separation or crystallization and the distributions of Ce and Si are uniform.

[0066] High thermal stability of the BASL-Ce glass samples was confirmed with differential scanning calorimetry (DSC). DSC data for bulk and powder glass samples are shown in FIGS.8A and 8B, respectively. Separation between the glass transition and the crystallization temperatures (Tc– Tg) of ^ 200oC was measured with the bulk samples. However, the DSC of the powder glass samples exhibits a smaller Tc– Tgof ^ 100oC and some exothermic peaks at high temperatures. The first exothermic peak of powder BASL-Ce samples can be attributed to glass nucleation and crystal seed formation, whereas the exothermic peaks of BASL-25 at 850oC and 940oC can be assigned to glass crystallization. Considering the difference between the thermograms of the bulk and powder BASL-Ce samples, the glass crystallization is strongly dependent on the surface area and thus can be classified as surface crystallization (see Appendix A, Note 3).

[0067] The densities of the BASL-Ce glass samples were measured to be 3.26 - 4.27 g / cm3as shown in Table A1 of Appendix A with the immersion method. Their thermal expansion coefficients and Vickers hardnesses were measured to be approximately ^8ppm / oC and ^540 Hv with a thermomechanical analyzer and a microhardness testing system, respectively.

[0068] Example Optical Properties

[0069] In the examples described herein, the refractive indices of the BASL-Ce3+glass samples at 532, 633, 816, 1305 and 1555 nm were measured with the prism coupler technique and were fitted with a Cauchy equation (see Appendix A, Table A3) as shown FIG.9A. It is clear that highly Ce3+-doped silicate glasses exhibit high refractive indices of 1.6-1.8. It should be noted that the refractive index decreases slightly with the increasing Ce3+concentration for 89(0.4B2O3-U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) 0.2Al2O3-0.4SiO2)-(11-x)La2O3-xCe2O3(0<x≤11) system because the molar polarizability of Ce3+is smaller than that of La3+, while it increases significantly with increasing Ce3+concentration for the (100-x)(0.4B2O3-0.2Al2O3-0.4SiO2)-xCe2O3 (11<x≤25) system due to the higher polarizability of rare-earths and their ligands compare to the glass matrix components. The Abbe numbers of the BASL-Ce3+glass samples were calculated based on the refractive indices. Since the Abbe numbers are greater than 60, the BASL-Ce3+glass can be classified as lanthanum crown with low dispersion according to the Schott Abbe diagram. The attenuation spectra (including absorption and scattering loss) of the BASL-Ce3+glass samples were measured with a UV-Vis NIR spectrophotometer and are shown in FIG.9B. The UV edge shifts from 220 nm to 420 nm as the Ce3+concentration increases from 0 and 25 mol% due to the strong ground-state absorption of Ce3+(4f ^ 5d) peaked at 309 nm in silicate glass. Whereas attenuation losses at 532 nm do not exceed 0.008 cm-1, decreasing with Ce3+content increase (see Appendix A, Table A1), and mostly originating from scattering from inhomogeneities. Despite high molar absorptivity, no spectroscopic evidence of Ce4+ions presence can be seen that correlates with XPS data. It should be noted that the attenuation loss increase in the 0.7—2 µm region is mostly attributed to transition metals impurities in the starting materials, particularly Cu2+which has an intense broad peak around 1µm and divalent iron (Fe2+). The rise in loss beyond 2µm wavelength can be attributed to Fe2+and the absorption of hydroxyl groups having a broad peak centered near 2.7µm in silicates, whereas the multiphonon edge of boron oxide limits transmission beyond 3.2 µm.

[0070] Example Magneto-Optical Properties

[0071] In the examples described herein, the Verdet (V) constants of the BASL-Ce3+glass samples at 460, 532, 633, 795, 976, 1550 and 1940 nm were measured at room temperature and are shown in FIG. 10. The experimental results were fitted with the Van Vleck-Hebb single oscillator model for paramagnetic optical materials described by Equation (1) below. The modeling and experimental results are in good agreement in the visible and short-wave near-IR but become inconsistent in the long-wave near-IR due to the limitation of the single oscillator model. ^^^^^^ ൌ ாఒమିఒమబ(1) where V, λ, and λ0are the Verdet resonantwavelength of the material, respectively; E a constant.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0072] It should be noted that in experimental data the BASL-1 glass diamagnetic contribution of the BASL glass matrix overwhelms the contribution from the Ce3+ions. The E and λ0 for the BASL glass samples with Ce3+concentrations ^ 6 mol% were obtained by fitting with the least squares method and are presented in Table 1. When the Ce3+concentration is ≥ 11 mol.%, the λ0 is ^ 250 nm, which is close to that of most prevalent Ce3+-doped materials. The λ0of the BASL-6 glass, however, is at 288 nm due to the influence of the diamagnetic glass matrix. The Verdet constants of BASL-25 and the terbium gallium garnet (TGG) are plotted in FIG.11. It is clear that BASL-25 glass outperforms the state-of-the-art paramagnetic crystal in the visible and near-IR.

[0073] Example Luminescence Properties

[0074] In the examples described herein, the luminescence properties of Ce3+- doped BASL glass samples were investigated. As shown in FIG.12, all the Ce3+- doped BASL glass samples emit blue light when they are excited with UV light. The normalized luminescence spectra of BASL-1, BASL-15 and BASL-25 glass samples excited at 370 nm are shown in FIG.13. All Ce- doped BASL glasses emit broad UV-visible luminescence with full-width half-maximum (FWHM) of ^ 4750 cm-1, which is similar to that of low Ce3+-doped silicate glass. However, the luminescence peak shifts from 418 nm to 452 nm as the Ce2O3 content changes from 1 mol.% to 25 mol.% due to increased reabsorption. In the experiment, it was also found that the luminescence peak shifts to longer wavelength with increasing excitation wavelength as shown in FIG.14.

[0075] The luminescence spectra of the BASL-25 glass excited at different wavelengths are shown in the inset of FIG.14. As the excitation wavelength changes from 330 nm to 370 nm, the luminescence spectrum exhibits a very small red-shift. The red-shift of the luminescence becomes much larger and the luminescence peak shifts from 448 nm to 512 nm as the excitation wavelength changes from 370 nm to 430 nm. The excitation-wavelength dependence of the luminescence spectrum is attributed to the high sensitivity of the 5d ^ 4f transition to the surrounding environment and thus variations in the local ligands surrounding Ce3+ions.

[0076] The 5d-state lifetimes of the BASL-Ce3+glass samples were obtained by measuring the intensity decay of the fluorescence excited by a short pulse laser and fitting the decay curve with decaying exponentials as shown in the inset of FIG.15. We found that the fluorescence decay is fits very well to a two-component exponential decay function. The time constants of all BASL- Ce3+glass samples are presented in FIG. 15. The slow time constant (^2) corresponding to theU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) spontaneous decay decreases with increasing Ce3+concentration due to concentration quenching. Nevertheless, the slow time constants are still in a range of 30-50 ns that is comparable with that of other Ce3+materials. The fast time constant (^1) increases with increasing Ce3+concentration, indicating significant energy transfer among Ce3+ions.

[0077] The luminescence absolute quantum yields of BASL-1, BASL-15, and BASL-25 glasses excited at different wavelengths were measured with an absolute quantum yield spectrometer and are shown in FIG.16. The BASL-1 glass has the highest quantum yield of up to 82±5% at the excitation wavelengths of 330–360 nm, which is similar to those of high performance Ce3+-doped crystalline materials (80±10% for 1 - 5 mol.% of Ce2O3) Due to concentration quenching, the maximum quantum yields of BASL-15 and BASL-25 decrease to 62±5% at 370 nm and 45±5% at 380 nm, respectively. The quantum yields of all the BASL-Ce3+glass samples decrease at long excitation wavelength because of the diminished absorption compared to parasitic losses.

[0078] Example properties of the BASL-Ce3+glasses are summarized in Table A1 of Appendix A.

[0079] Highly Ce3+-doped oxide glass has been pursued by material scientists for decades for many specific applications where cost-intensive and compact Ce3+-doped crystals and thin films are currently used but cannot meet all the requirements. Based on a novel BASL system, a stable oxide glass with Ce3+ion concentration up to 25 mol% was successfully synthesized for the first time, to the best of our knowledge. Systematic investigations on Ce3+-doped BASL glass samples with different concentrations confirm that oxidation of Ce3+during glass melting can be significantly mitigated by the use of high purity Ce2O3and a deoxidation technique. The highly Ce3+-doped BASL glass exhibits outstanding properties including high absolute quantum yield comparable to Ce3+-doped crystals (LYSO, YAG, LaBr3), large Verdet constant, high density of up to 4.27g / cm3, and lifetime of close to 50 ns, making it a very attractive material for advanced photonic devices that can be used for medical imaging, high-energy particles and radiation visualization, colliding beam experiments, neutrino and dark matter detectors, and highly radiation resistant passive and active optics for critical infrastructure and communication, as well as various laser developments.

[0080] FIG. 17 illustrates a set of operations that can be carried out for stabilizing trivalentU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) cerium ions in accordance with an example embodiment. At 1702, using a melting crucible comprising graphite or glassy graphite, a glass melt is synthesized from a mixture of compounds that includes trivalent cerium oxide by heating the mixture inside a synthesis chamber substantially free of oxygen for a predetermined amount of time, wherein the melting crucible comprising graphite or glassy graphite reduces oxygen in the glass melt. At 1704, oxygen-reducing components are introduced into the synthesis chamber that mitigate energy state transitions of trivalent cerium ions obtained from the trivalent cerium oxide. At 1706, a glass composition is obtained that includes a concentration of the trivalent cerium ions in stabilized form by annealing the glass melt, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on capabilities of oxygen-containing compounds included in the mixture to dissolve trivalent cerium oxide.

[0081] In one example embodiment, the annealing is performed below a glass transition temperature, wherein the glass composition is ramped to a temperature lower than the glass transition temperature following the annealing. In another example embodiment, the synthesis chamber is heated to a temperature between 1400-1600°C and held at the temperature for the predetermined amount of time during the synthesizing. In some embodiments, the temperature range can be 1120-1600oC. In yet another example embodiment, the glass melt is synthesized from stoichiometric amounts of H3BO3(4N), Al2O3(4N), SiO2(4N), La2O3(4N) and Ce2O3(3N). In still another example embodiment, the glass composition is a B2O3-Al2O3-SiO2 composition capable of dissolving lanthanide oxides, such as La2O3.

[0082] According to another example embodiment, the concentration of the trivalent cerium ions in stabilized form is controlled by including trivalent cerium oxide in the mixture is an amount that is between 1 and 25 mol.%. In some embodiments, the trivalent cerium oxide in the mixture is between 1 and 35 mol.%. In one example embodiment, the melting crucible that comprises graphite or glassy graphite partially dissolves into the glass melt during the synthesizing such that carbon from the graphite or glassy graphite is provided to the glass melt. In another example embodiment, the glass composition is non-crystalline. In still another example embodiment, the synthesis chamber is purged with an inert gas prior to synthesizing the glass melt. In yet another example embodiment, the glass composition comprises oxide, oxynitride, or oxyhalide glasses of various compositions. In another example embodiment, the glass composition is co-doped withU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) rare-earth elements and transitional metals.

[0083] In yet another example embodiment, the glass composition includes glass modifiers comprising GeO2, Ga2O3, PbO, alkaline and alkaline earth oxides, or metal oxides. In still another example embodiment, the oxygen-reducing components include one or more of metal halides, sugar, metals, metal nitrides, metal carbides, graphite, or graphite containing components. In one example embodiment, one or more luminescence properties, optical properties, or magneto-optical properties of the glass composition are controlled by modifying the concentration.

[0084] Another aspect of the disclosed embodiments relates to a system for producing a trivalent cerium doped material that includes a synthesis chamber substantially free of oxygen and configured to receive a mixture of compounds comprising trivalent cerium oxide and silicon dioxide and to heat the mixture to a first temperature. The system also includes a glassy graphite melting crucible configured to contain the mixture within the synthesis chamber during the heating of the mixture to the first temperature, wherein the glassy graphite melting crucible is operable to provide carbon to the mixture during the heating of the mixture and to absorb oxygen in the mixture and the synthesis chamber such that the mixture comprises trivalent cerium ions in stabilized form after the heating. The system also includes a mold configured to receive the mixture comprising trivalent cerium ions in stabilized form, wherein the mold is annealed in an oxygen-reduced atmosphere at a second temperature that is lower than the first temperature to allow the mixture comprising trivalent cerium ions in stabilized form to become glassy.

[0085] In one example embodiment, the synthesis chamber is configured to receive oxygen- reducing components during the heating of the mixture to the first temperature, wherein the oxygen-reducing components include metal halides, sugar, metals, metal nitrides, metal carbides, graphite, or graphite containing components. In another example embodiment, the synthesis chamber operable to receive an inert gas prior to the heating of the mixture to the first temperature to purge the synthesis chamber. In yet another example embodiment, the first temperature is between 1400-1600°C, wherein the second temperature is near 690°C. In some embodiments, the first temperature range can be 1400-1600°C. In still another example embodiment, the mold comprises a metal, stainless steel, graphite, or a material capable to withstand heating to the first temperature.

[0086] FIG.18 illustrates a set of operations that can be carried out for producing a trivalentU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) cerium doped glass in accordance with an example embodiment. At 1802, a mixture of compounds is synthesized that includes trivalent cerium oxide and a rare-earth containing compound, wherein the mixture of compounds comprises a predetermined ratio of trivalent cerium oxide to the rare- earth containing compound. At 1804, a glass melt is formed by heating the mixture to a first temperature. At 1806, the glass melt is annealed to a second temperature that is different from the first temperature such that a glass composition comprising a concentration of trivalent cerium ions in stabilized form is obtained, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on the predetermined ratio.

[0087] In one example embodiment, one or more luminescence properties, optical properties, or magneto-optical properties of the glass composition are tunable by modifying the predetermined ratio. In another example embodiment, the glass composition is a silicate glass composition capable of dissolving lanthanide oxides, such as La2O3. In yet another example embodiment, the glass melt is contained by a graphite melting crucible during the heating of the mixture to the first temperature, wherein the graphite melting crucible causes oxygen to be depleted from the glass melt.

[0088] In some embodiments, the crucible materials can also include boron nitride and other nitrides, as well as carbides such as silicon carbide—provided they are capable of absorbing oxygen by forming volatile components. Accordingly, the glass batch (chemical mix) is melted at high temperatures in these crucibles and then is annealed from around 690 C. Subsequently, the glass quality can be improved by remelting the obtained glass in conventional refractory crucibles made of materials like Al2O3, ZrO2, or other oxides (e.g., mullite (SiO2 + Al2O3 ceramic)), under strictly controlled environments with no oxygen access. For example, in one embodiment, the glass melt is contained by a melting crucible made of a material comprising a nitride or a carbide compound that is capable of absorbing oxygen, and the disclosed method further includes, subsequent to the annealing, remelting the trivalent cerium doped glass in a refractory crucible that is made of a material comprising an oxide compound under a controlled environment with no oxygen access, and then annealing the remelted trivalent cerium doped glass. For instance, the nitride compound is boron nitride, the carbide compound is silicon carbide, and the oxide compound is one of Al2O3 or ZrO2.

[0089] An example aspect of the disclosed embodiments relates to a system for producing aU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) trivalent cerium doped material that includes a synthesis chamber substantially free of oxygen and configured to receive a mixture of compounds comprising trivalent cerium oxide and silicon dioxide and to heat the mixture to a first temperature, and a crucible made of a material comprising a nitride compound or a carbide compound and configured to contain the mixture within the synthesis chamber during the heating of the mixture to the first temperature. The system further includes one or more molds configured to receive the mixture from the crucible to enable annealing of the mixture, and a refractory crucible made of a material comprising an oxide compound, the refractory crucible operable under a controlled environment with no oxygen access and configured to receive and re-melt the annealed mixture. The material is then annealed again to release the internal stresses.

[0090] While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0091] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document. APPENDIX A

[0092] Further details and examples of the disclosed embodiments are described herein.

[0093] NOTE 1: Vitreous state verification of the BASL-Ce samples

[0094] As glass is amorphous with an intrinsically disordered structure, while crystals exhibit periodicity over large volumes, the crystalline state can easily be distinguished from glassy state by using x-ray diffraction (XRD). The glass samples for this analysis were ground into powder form in order to perform bulk characterization. The XRD pattern of a glass exhibits broad peaksU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) with a full-width at half-maximum (FWHM) of a few to tens of degrees while the FWHM for a crystal is << 1 degree. The XRD patterns of BALS-0, BALS-11, and BALS-25 are shown in FIG. 19. All patterns only exhibit broad peaks corresponding to the glass phase and do not exhibit any sharp features characteristic of crystalline phases. Therefore, we can conclude that the BASL-Ce glass samples are completely vitrified.

[0095] NOTE 2: Homogeneity and elements distribution in BASL-Ce glass

[0096] It is known that during synthesis or thermal treatment near its glass transition temperature, borosilicate glass may undergo phase separation, resulting in some regions rich in silicon and others that are rich in boron. This liquid-liquid phase separation is an unwanted phenomenon for transparent optical glass materials because it can result in noticeable scattering losses. Various techniques such as small-angle X-ray scattering (SAXS) and electron microscopy with energy-dispersive X-ray (EDX) spectroscopy can be used to detect phase separation. Scanning electron microscopy (SEM) complemented with EDX analysis is an effective method because it offers high-resolution images of the sample surface to be observed, supported by an elemental distribution profile. Based on EDX data, it is possible to detect element clustering and thus draw conclusions on the material homogeneity. Although boron cannot be detected with EDX, an uneven silicon distribution can indicate if phase separation is present.

[0097] A study of the BASL- Ce3+glass surface and elemental distribution, using high- resolution SEM / EDX, revealed no signs of phase separation or elemental clustering at magnifications up to 110,000x (as illustrated in FIG.20 and FIGS.7A and B). Notably, FIG.20 illustrates high resolution SEM-EDX images of BASL-Ce3+ glass samples under 110000x magnification. Panel (a) shows STEM image of a BASL-1 glass; panel (b) shoes STEM / EDX maps of Ce and Si ions in BASL-1 glass; panel (c) shows STEM image of a BASL-11 glass; and panel (d) shows STEM / EDX maps of Ce and Si ions in BASL-11 glass. From the figures, it is evident that the glass surface is homogeneous and free from crystalline inclusions across all Ce2O3 concentration ranges. Only nano-scale cracks, which are typical for glass, are visible.

[0098] NOTE 3: Glass forming ability of the BASL-Ce glass system

[0099] Glass forming ability (GFA) refers to the capability of a material to form a glass or amorphous solid upon cooling from a high temperature liquid. A material with high GFA can retain its disordered atomic arrangement in a glassy state, even when it is cooled down slowly, whereasU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) a material with low GFA is more prone to crystallize when the temperature decreases. The GFA of a material is influenced by several factors including its chemical composition, atomic structure, cooling rate, and the presence of impurities or additives. Enhancing understanding and increasing GFA is critical for glass production. The GFA can be determined from material characteristic temperatures such as the glass transition (Tg), crystallization onset (Tx), crystallization (Tc), melting (Tm) and liquidus (Tl). A number of approaches have been proposed to estimate GPA, but only a few have been shown to be consistent with experimental data for oxide systems. In our work we used (SE1) to estimate GFA (^^ᇱ^ of BASL-Ce glass, where Tgand Tcare glass transition and crystallization temperatures,in kelvins. ^^ᇱ ൌ ^்ି ^்(A1)

[0100] Glass crystallization cancrystallization. Volume crystallization occurs when crystals grow within a material volume, whereas surface crystallization occurs when crystals grow on the material’s surface. A variety of techniques, including differential scanning calorimetry (DSC), differential thermal analysis, and microscopy, among others, can be employed to determine the type of crystallization. When using DSC, signals from two types of samples - powder and bulk - should be compared. In the case of volume crystallization, there should be no difference in the DSC when comparing bulk and powder species. However, if a glass undergoes surface crystallization, one can anticipate a significant shift of the crystallization peak toward lower temperatures and an increase in signal intensity for the powder sample. This is due to the considerably higher surface area of a powder compared to bulk samples. DSC thermograms of powdered and bulk BASL-Ce glass samples are shown in FIGS. 8A and 8B.

[0101] All BASL-Ce glass samples have a glass transition around 690oC regardless of Ce2O3content and the method of species preparation. When analyzing the DSC thermograms, a notable correlation between the positions and intensities of the peaks and the form of the sample becomes evident. Thermograms of the bulk samples show well-separated glass transition and crystallization peaks with Tc – Tg of ^ 200oC. In contrast, powder samples show crystallization closer to the Tg (Tc – Tg of ^ 100oC) with the emergence of additional peaks. The BASL-Ce glass characteristic temperatures and GFA are summarized in Table A2 below.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158)

[0102] The first exothermic peak on the thermogram of powder BASL-Ce samples can be attributed to glass nucleation and first seed formation. Meanwhile, exothermic peaks near 970oC, 853oC and 940oC for BASL-25 can be assigned to the glass crystallization, similar to BASL- Dy3+ / Er3+glass developed in our pervious study. The high ^^ᇱvalue of the bulk BASL-Ce glass supports it’s ability to vitrify and form large form factor samples. For instance, optical BGG glass, which can be cast into large windows and domes exceeding 18 inches in diameter, has an ^^ᇱof 0.216 measured for bulk glass. This observation, in combination with the absence of phase separation, underscores the high stability and potential of the developed glass system. In contrast to the bulk, the GFA of the powder samples was shown to be relatively low and similar to ZBLAN glass, which is known for its susceptibility to crystallization, with an ^^ᇱof 0.147 measured for bulk glass. The high tendency toward crystallization in the powder BASL-Ce samples limits applicability of the glass in fiber production as high surface area has been shown to promote glass crystallization.

[0103] FIG.21 illustrates an example configuration of an apparatus for measuring the Verdet constant. The apparatus of FIG. 21 includes a light source, followed by a lens, a polarizer, and half-wave plate, and a solenoid within which the sample can be positioned. The light from the sample is received by a polarizer (e.g., a Wollaston polarizer) and is split into two polarized components (p- and s-polarized light) that are received and detected at the two detectors.

[0104] FIG. 22 shows a block diagram of a system for producing a trivalent cerium doped material in accordance with an example embodiment. As shown, the system includes a synthesis chamber 2202 and one or more inlets to allow a mixture of compounds, such as trivalent cerium oxide and silicon dioxide, to be provided to the synthesis chamber 2202. The system further includes a melting crucible, such as a glassy graphite crucible, that is configured to contain the mixture within the synthesis chamber while the mixture is being heated. FIG. 22 also shows a temperature control unit 2208 that controls the temperature of the synthesis chamber 2202 and its crucible 2204. During the heating, crucible 2204 can be configured to receive additional material, such as carbon, through the one or more inlets. The system further includes a mold 2206 configured to receive the mixture from the synthesis chamber 2202 or the crucible 2204 through one or more outlets. The mold 2208 is also coupled to the temperature control unit 2208 (the same or a different temperature control circuitry that controls the temperature of the crucible) that allowsU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) the material to be annealed.

[0105] Table A1: Summarized properties of the BASL-Ce glass samples Glass NCe3+, ^, cm-1n ^, ^o, E, 10-11^max, ^1, ^2, 50ns cm-3(^=532nm) (^=532nm) g / cm-3nm rad / T^m nm ns ns output, % B N / AB 65B 68B 69B 73B 75B 80[0 ns in1 cm3; - absorbtion coefficient; n – refractive index; - density; o and E – magnetooptical parameters as the average resonant wavelength of the material and wavelength independent constant; ^max - emission peak position,; ^1 and ^2 - decay times; 50ns output – persentage of light emitted in first 50ns.

[0107] Table A2: Characteristic temperatures of the BASL-Ce glass samples Sample Bulk Powder T* (K) T (K) T (K) H' T* (K) T** (K) T** (K) H' 120113125134114102088[0 [0a e : aucy coe cens o e - e gass sampes Sample A B C BASL-0 1.6129 0.01071 -0.0008189

Claims

U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) CLAIMS WHAT IS CLAIMED IS:

1. A method of stabilizing trivalent cerium ions, comprising: synthesizing a glass melt, using a melting crucible comprising graphite or glassy graphite, from a mixture of compounds that includes trivalent cerium oxide by heating the mixture inside a synthesis chamber substantially free of oxygen for a predetermined amount of time, wherein the melting crucible comprising graphite or glassy graphite reduces oxygen in the glass melt; introducing oxygen-reducing components into the synthesis chamber that mitigate energy state transitions of trivalent cerium ions obtained from the trivalent cerium oxide; and obtaining a glass composition comprising a concentration of the trivalent cerium ions in stabilized form by annealing the glass melt, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on capabilities of oxygen-containing compounds included in the mixture to dissolve trivalent cerium oxide.

2. The method of claim 1, wherein the annealing is performed below a glass transition temperature, wherein the glass composition is further ramped to a temperature lower than the glass transition temperature following the annealing.

3. The method of claim 1, wherein the synthesis chamber is heated to a temperature between 1400-1600oC and held at the temperature for the predetermined amount of time during the synthesizing.

4. The method of claim 1, wherein the glass melt is synthesized from H3BO3(4N), Al2O3(4N), SiO2 (4N), La2O3(4N) and Ce2O3(3N).

5. The method of claim 1, wherein the glass composition is a B2O3-Al2O3-SiO2composition capable of dissolving lanthanide oxides.

6. The method of claim 1, wherein the concentration of the trivalent cerium ions inU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) stabilized form is controlled by including trivalent cerium oxide in the mixture in an amount that is between 1 and 25 mol.%.

7. The method of claim 1, wherein the melting crucible comprising graphite or glassy graphite partially dissolves into the glass melt during the synthesizing such that carbon from the graphite or glassy graphite is provided to the glass melt.

8. The method of claim 1, wherein the glass composition is non-crystalline.

9. The method of claim 1, wherein the synthesis chamber is purged with an inert gas prior to synthesizing the glass melt.

10. The method of claim 1, wherein the glass composition comprises oxide, oxynitride, or oxyhalide glasses of various compositions.

11. The method of claim 1, wherein the glass composition is co-doped with rare-earth elements and transitional metals.

12. The method of claim 1, wherein the glass composition includes glass modifiers comprising GeO2, Ga2O3, PbO, alkaline and alkaline earth oxides, or metal oxides.

13. The method of claim 1, wherein the oxygen-reducing components include one or more of metal halides, sugar, metals, metal nitrides, metal carbides, graphite, or graphite containing components.

14. The method of claim 1, wherein one or more luminescence properties, optical properties, or magneto-optical properties of the glass composition are controlled by modifying the concentration.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) 15. A system for producing a trivalent cerium doped material, comprising: a synthesis chamber substantially free of oxygen and configured to receive a mixture of compounds comprising trivalent cerium oxide and silicon dioxide and to heat the mixture to a first temperature; a glassy graphite melting crucible configured to contain the mixture within the synthesis chamber during the heating of the mixture to the first temperature, the glassy graphite melting crucible operable to provide carbon to the mixture during the heating of the mixture and to absorb oxygen in the mixture and the synthesis chamber such that the mixture comprises trivalent cerium ions in stabilized form after the heating; and a mold configured to receive the mixture comprising trivalent cerium ions in stabilized form, the mold annealed in an oxygen-reduced atmosphere at a second temperature that is lower than the first temperature to allow the mixture comprising trivalent cerium ions in stabilized form to become glassy.

16. The system of claim 15, wherein synthesis chamber is configured to receive oxygen- reducing components during the heating of the mixture to the first temperature, wherein the oxygen-reducing components include metal halides, sugar, metals, metal nitrides, metal carbides, graphite, or graphite containing components.

17. The system of claim 15, wherein the synthesis chamber operable to receive an inert gas prior to the heating of the mixture to the first temperature to purge the synthesis chamber.

18. The system of claim 15, wherein the first temperature is between 1400-1600oC, wherein the second temperature is near 690oC.

19. The system of claim 18, wherein the mold comprises a metal, stainless steel, graphite, or a material capable to withstand heating to the first temperature.

20. A method of producing a trivalent cerium doped glass, comprising: synthesizing a mixture of compounds including trivalent cerium oxide and a rare-earthU.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) containing compound, wherein the mixture of compounds comprises a predetermined ratio of trivalent cerium oxide to the rare-earth containing compound; forming a glass melt by heating the mixture to a first temperature; and annealing the glass melt to a second temperature that is different from the first temperature such that a glass composition comprising a concentration of trivalent cerium ions in stabilized form is obtained, wherein the concentration of the trivalent cerium ions in stabilized form in the glass composition is based on the predetermined ratio.

21. The method of claim 20, wherein one or more luminescence properties, optical properties, or magneto-optical properties of the glass composition are tunable by modifying the predetermined ratio.

22. The method of claim 20, wherein the glass composition is a silicate glass composition capable of dissolving lanthanide oxides.

23. The method of claim 20, wherein the glass melt is contained by a graphite melting crucible during the heating of the mixture to the first temperature, wherein the graphite melting crucible causes oxygen to be depleted from the glass melt.

24. The method of claim 20, wherein, during the heating of the mixture to the first temperature, the glass melt is contained by a melting crucible made of a material comprising a nitride or a carbide compound that is capable of absorbing oxygen, and wherein the method further comprises: subsequent to the annealing, remelting the trivalent cerium doped glass in a refractory crucible that is made of a material comprising an oxide compound under a controlled environment with no oxygen access, and annealing the remelted trivalent cerium doped glass.

25. The method of claim 24, wherein the nitride compound is boron nitride, the carbide compound is silicon carbide, and the oxide compound is one of Al2O3or ZrO2.U.S. Provisional Patent Application 044974.8131.WO00 (UA24-158) 26. A system for producing a trivalent cerium doped material, comprising: a synthesis chamber substantially free of oxygen and configured to receive a mixture of compounds comprising trivalent cerium oxide and silicon dioxide and to heat the mixture to a first temperature; a crucible made of a material comprising a nitride compound or a carbide compound and configured to contain the mixture within the synthesis chamber during the heating of the mixture to the first temperature; one or more molds configured to receive the mixture from the crucible to enable annealing of the mixture; a refractory crucible made of a material comprising an oxide compound, the refractory crucible operable under a controlled environment with no oxygen access and configured to receive and re-melt the annealed mixture.

Images