Predicting and optimizing the physical and spectroscopic properties of phosphate laser glasses using a phase diagram approach

Despite the significant technological applications of laser glasses, the quantitative prediction and optimization of their properties, particularly the spectroscopic properties, remain challenging. Here we address this problem by regarding the nearest-neighboring congruently melting compounds as the “component and structural motifs” based on the phase diagram approach. The composition–structure–property (CSP) relationships of Nd³⁺-doped ternary phosphate glasses are investigated. Spectroscopic properties are quantitatively predicted with an error of less than 10% compared to the experimental results. In particular, the fluorescence lifetime (τ_m) can be accurately calculated using the phase diagram approach, which is difficult to be predicted previously. Furthermore, the CSP databases with over 1000 compositions are established for the optimization of commercial laser glasses. This study enriches the CSP database of traditional laser glass and provides guiding significance for future research.     

Quantitative prediction of the glass-forming region and luminescence properties in Tm3+-doped germanate laser glasses

Germanate laser glasses have received much attention as a promising host materials for mid-infrared fiber lasers in recent years because of the outstanding infrared transparency, low phonon energy, and high rare earth solubility of such glasses. However, the development of high-performance germanate laser glasses is usually based on intuition and a trial-and-error method, which can involve long experimental periods and high costs, and thus, this approach is highly inefficient. Recently, with proposals for materials genome engineering, the concept of the “glass genome” has grown of interest to us. Herein, the structures of Tm³⁺-doped germanate laser glasses (BaO–GeO₂ and BaO–La₂O₃–GeO₂) were investigated by Fourier transform infrared spectra (FTIR) and Raman spectra analyses, which revealed that the resulting glass contains similar structural groups to the neighboring congruently melted glassy compounds (NCMGCs) in the composition diagram. What is more, the structure and properties of the resulting laser glasses largely depend on NCMGCs. Then, the glass-forming region, physical properties, and luminescence properties were calculated via the use of NCMGCs in Tm³⁺-doped BaO–GeO₂ binary and BaO–La₂O₃–GeO₂ ternary laser glass systems. The calculated results were in good agreement with the experimental results, thus demonstrating that our approach is practical for predicting the glass-forming region, physical properties, and luminescence properties in Tm³⁺-doped BaO–GeO₂ binary and BaO–La₂O₃–GeO₂ ternary laser glass systems. This work may provide an effective method to develop Tm³⁺-doped germanate laser glasses rapidly and at low cost.     

Mechanism for broadening and enhancing Nd3+ emission in zinc aluminophosphate laser glass by addition of Bi2O3

Nd³⁺-doped phosphate laser glasses have been attracting much attention and widespread investigation due to their high solubility of rare earth (RE) ions, excellent spectroscopic properties, and large damage threshold. However, the narrow NIR emission bandwidth (less than 30 nm) of these Nd³⁺-doped phosphate glasses limits their further application toward ultrahigh power field and efficient fiber laser in new region. Here, we demonstrate the broadening and enhancing of Nd³⁺ NIR emission in laser glass of zinc aluminophosphate through tuning the glass structure and covalency of Nd-O bond without limiting the radiative properties of Nd³⁺. The maximum bandwidth of 1.05 μm emission is broadened to 50 nm, which is comparable to that of Nd³⁺-doped aluminate laser glasses. Simultaneously, the lifetime of ⁴F_3/2 level is elongated nearly by two times. Structural and optical properties of prepared glasses were discussed systematically to reveal the mechanism. Detailed analysis on optical spectra and glass structure indicates that the bandwidth is affected by not only the covalency of Nd-O but also the compactness of glass structure. Our results could enrich our understanding about the relationship between local glass structure and luminescence behaviors of active centers, and may be helpful in designing new RE-doped laser glass systems.     

Quantitative prediction of the structure and luminescence properties of Nd3+ doped borate laser glasses

Although great advance has been made in glass science, predicting luminescence properties of laser glass poses a significant challenge for scientists due to the complex relationship between the composition, structure, and properties of the rare earth ions doped laser glasses. The development of high-performance laser glass usually relies on intuition and trial-and-error. Recently, with the proposal of the materials genome engineering, the “glass genome” has also attracted much attention. Here, the structure of the Nd³⁺ doped B₂O₃-Li₂O laser glasses was analyzed using Fourier transform infrared spectra and nuclear magnetic resonance, revealing that the glass contains similar glass-forming ion-centered coordination polyhedron structure groups to the neighbor congruent glassy compounds. The structure and properties of glass largely depend on the neighbor congruent glassy compounds. Therefore, the structure and luminescence properties of Nd³⁺ doped B₂O₃-Li₂O and B₂O₃-MgO-Li₂O laser glasses can be quantitatively predicted via the neighbor congruent glassy compounds. The predictive values are in good agreement with the experimental data, which indicates that our approach is an effective way to predict the structure and luminescence properties of Nd³⁺ doped borate laser glasses.     

Role of Nd3+ ions on the nucleation and growth of PbS quantum dots (QDs) in silicate glasses

The influence of Nd₂O₃ addition on the precipitation kinetics of lead chalcogenide (PbS) quantum dots (QDs) in silicate glasses was investigated. Energy dispersive X‐ray spectroscopy (EDS) indicated that the Nd³⁺ ions are preferentially located inside the PbS QDs rather than in the glass matrix. Changes in diameter (D) of PbS QDs exhibited smaller time dependencies (i.e., D≈t^{0.270‐0.286}) than that predicted by the classical Lifshitz–Slyozov–Wagner (LSW) theory. This is due to the limited concentrations of Pb²⁺ and S^2? ions and the large diffusion distance inside the glass matrix. In addition, extended X‐ray absorption fine structure (EXAFS) results indicated that the formation of PbS QDs was retarded due to the presence of Nd₂O₃ in the glasses, as the large NdO_x polyhedra interrupt the diffusion of Pb²⁺ and S^2? ions. We believe that these Nd³⁺ ions are primarily located in PbS QDs in the form of Nd–O clusters, and that the PbS QDs are built on top of these clusters.     

Experimental and theoretical studies on NIR luminescence of titanate-germanate glasses doped with Pr3+ and Tm3+ ions

Near-infrared (NIR) luminescence of Pr³⁺ and Tm³⁺ ions in titanate-germanate glasses has been studied for laser and fiber amplifier applications. The effect of the molar ratio GeO₂:TiO₂ (from 5:1 to 1:5) on spectroscopic properties of glass systems was studied by absorption, luminescence measurements, and theoretical calculations using the Judd–Ofelt theory. It was found that independent of the TiO₂ concentration, intense NIR emissions at 1.5 and 1.8 μm were observed for glasses doped with Pr³⁺ and Tm³⁺ ions, respectively. Moreover, several spectroscopic and NIR laser parameters for Pr³⁺ and Tm³⁺ ions, such as emission bandwidth, stimulated emission cross-section, quantum efficiency, gain bandwidth, and figure of merit, were determined. The results were discussed in detail and compared to the different laser glasses. Systematic investigations indicate that Pr³⁺-doped system with GeO₂:TiO₂ = 2:1 and Tm³⁺-doped glass with GeO₂:TiO₂ = 1:2 present profit laser parameters and could be successfully applied to NIR lasers and broadband optical amplifiers.     

Photodarkening mechanisms of Pr3+ singly doped and Pr3+/Ce3+ co-doped silicate glasses and fibers

In this work, we revealed the possible mechanisms of the photodarkening in Pr³⁺ ions singly doped and Pr³⁺/Ce³⁺ co-doped silicate glasses and fibers induced by X-ray and 488-nm laser radiations and studied the role of Ce³⁺ in increasing radiation resistance in Pr³⁺-doped silicate glasses and fibers. The absorption, emission, electron paramagnetic resonance (EPR), radiation induced attenuation spectra, and X-ray photoelectron spectroscopy (XPS) of Pr³⁺ singly doped and Pr³⁺/Ce³⁺ co-doped silicate glasses before and after X-ray radiation were measured and analyzed. The fluorescence intensity and photoinduced attenuation of Pr³⁺ singly doped and Pr³⁺/Ce³⁺ co-doped silicate fibers at visible wavelengths pumped by 488-nm laser were measured and analyzed. The influence of Ce³⁺ ions co-doping on the spectroscopic properties of Pr³⁺ ions as well as the radiation-induced defects in silicate glasses was studied. Results demonstrate that both X-ray and 488-nm laser radiations will induce photodamage in Pr³⁺ ions-doped silicate glasses and fibers. Co-doping Ce³⁺ (by up to 1 mol%) is efficient to suppress the darkening induced by both X-ray and 488-nm laser radiations without influence on the luminescence behavior of Pr³⁺ ions in silicate glasses and fibers. Our studies demonstrate the promising potential of Pr³⁺/Ce³⁺ co-doped silicate glasses for visible lasing applications.     

Direct Imaging of the Distribution of Nd3+ Ions in Glasses Containing PbS Quantum Dots

The influence of Nd³⁺ ions was investigated on the precipitation and optical properties of PbS quantum dots (QDs) inside silicate glasses. The diameters of the PbS QDs decreased as the concentration of Nd³⁺ in the glass increased as evidenced by blue shifts in the absorption and photoluminescence spectra. Electron energy loss spectroscopy shows that Nd³⁺ ions exist preferentially inside the PbS nanocrystals rather than in the glass matrix. We postulate that Nd–O clusters are preserved during heat treatment and serve as nucleation sites for PbS crystals. No change in the local bonding scheme of the Nd³⁺ ions was observed following heat treatment.     

Synthesis and Spectral Properties of Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>-Doped Sodium Silicophosphate Glass

Combined UV-visible and FTIR spectral studies of undoped and Nd₂O₃ –doped sodium silicophosphate glasses were carried out to characterize the optical and structural properties of such glasses. The base undoped silicophosphate glass exhibits strong UV absorption which is due to the presence of unavoidable trace iron impurities (mainly Fe³⁺ ions) present contaminated within the raw materials used for the preparation of such glasses. Nd₂O₃ –doped glasses show characteristic absorption bands extending in the entire visible region which are attributed to the contribution of Nd³⁺ ions with distinct peaks which are almost constant with the increase of dopant. This comes from the combined compact glass structure containing two glass forming units and the shielding of the rare-earth ions. Infrared absorption spectra of the studied glasses reveal characteristic IR bands due to the combination of both silicate and phosphate groups. The introduction of Nd₂O₃ within the dopant level (2 %) produces no variations in the IR vibrational bands due to the presence of the two structural silicate and phosphate groups giving compactness of the network structure. The deconvoluted spectra reveal the presence of phosphate groups in a slightly high ratio due to the high content of P₂O₅ in the composition.     

Spectroscopic properties of Yb2+ in aluminosilicate glass

In contrast to Yb³⁺ which is a well-investigated optically active ion, the spectroscopic properties of its divalent counterpart Yb²⁺ in glasses are hardly investigated, although Yb²⁺ might have a notable influence on the luminescence properties of Yb³⁺-doped glasses even at low Yb²⁺ concentrations because of its strong f-d transitions. In this paper, we report on the preparation and spectroscopic properties of Yb²⁺-doped aluminosilicate glasses that were produced using the normal melt-quench technique. The glass composition is 20CaO·20Al₂O₃·60SiO₂ (mol%). To achieve a sufficient amount of Yb²⁺ in the samples, different methods were applied to influence the red-ox equilibrium during glass melting: firstly, under argon atmosphere and additional argon bubbling, and secondly by the addition of metallic aluminum powder to the batch. The strongly reduced samples show a greenish to brownish yellow coloring which could be attributed to the strong absorption of Yb²⁺ ions in the UV to blue spectral range. The absolute Yb²⁺ concentration in the glass and the molar extinction coefficient of Yb²⁺ was obtained by spectroscopic measurements. If irradiated with UV light, the Yb²⁺-doped samples show a broad fluorescence emission in the wavelength range from 450 to 700 nm with a peak at around 515 nm.     

New Aluminosilicate Glasses as High-Power Laser Materials

In the past few years, aluminosilicate glasses of an extremely broad compositional range have been prepared and analyzed to scan this glass type for its potential use as high-power laser material. The tested network modifier ions included Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺, Pb²⁺, Y³⁺, and La³⁺. Preliminary investigations have been conducted with Sm³⁺- and Eu³⁺-doped glasses; selected glass compositions have also been prepared with Yb³⁺ doping for laser testing. It has been found that low refractive indices/low average molecular weights/low densities of the glasses in most cases support relatively long fluorescence lifetimes of the doped ions. It was further concluded that the phonon energy of the molecular network of the glasses does not affect the fluorescence properties of the doped samples. The mechanical properties such as Young's modulus, Vickers hardness, and fracture toughness generally increase with increasing field strength of the network modifier ion for constant stoichiometric ratios of the glass components. The lowest potential thermal stress values were found for zinc and magnesium aluminosilicate glasses, which also have relatively high field strengths. Taking all these facts into account, a ternary lithium aluminosilicate and a mixed lithium magnesium aluminosilicate glass doped with Yb³⁺ have been prepared in high optical quality and tested with respect to their laser performance. The fluorescence lifetime values are somewhat lower than in well-established Yb³⁺-doped laser materials, such as fluoride phosphate glass or single crystalline calcium fluoride. Nevertheless, the aluminosilicate glasses show exceptionally high absorption and emission cross sections, smooth and very broad amplification profiles, as well as much better thermomechanical properties. Quantum efficiencies close to unity could be reached by consequently removing dissolved OH from the glass melt.     

1.53 µm luminescence properties of Er3+-doped K–Sr–Al phosphate glasses

Trivalent erbium (Er³⁺)-doped K–Sr–Al phosphate glasses were prepared and studied their spectroscopic properties as a function of Er₂O₃ concentration. Judd–Ofelt analysis has been carried out for 1.0 mol% Er₂O₃-doped phosphate glass and in turn radiative properties have been evaluated for the excited levels of Er³⁺ ion. The radiative lifetime for the ⁴I_13/2 level was found to be higher for the present glass when compared to other Er³⁺-doped glasses. The Er³⁺-doped glasses exhibit intense near infrared emission at 1.53 µm corresponds to ⁴I_13/2→⁴I_15/2 transition as well as green emission at 546 nm corresponding to ⁴S_3/2→⁴I_15/2 under 980 nm and 488 nm excitations, respectively. The emission cross-section spectrum for 1.0 mol% of Er₂O₃-doped glass has been evaluated using McCumber theory. The gain cross-section has been evaluated as a function of population inversion, which revealed that the lasing action would be achieved at 1.53 µm for a population inversion about 40%. Decay curves for the ⁴I_13/2 level were measured and lifetimes have been determined for the studied glasses. The results indicate that the present glasses could be useful for laser as well as optical amplifiers at 1.53 µm.     

Factors Controlling Properties of Ca‐Mg,Ca‐Er,Ca‐Nd,or Ca‐Y‐Modified Aluminosilicate Glasses Containing Nitrogen and Fluorine

Glasses with composition (in eq.%) (30 ? x)Ca:xM:55Si:15Al:80O:15N:5F have been prepared with different levels of substitution of Ca²⁺ cations by Mg²⁺, Y³⁺, Er³⁺, or Nd³⁺. The properties of these glasses are examined in detail and changes observed in molar volume (MV), free volume, fractional glass compactness, Young's modulus, microhardness, glass transition temperature, and thermal expansion as a function of M content are presented. Using linear regression analysis, evidence is presented which clearly shows that these glass properties are either solely dependent on the effective cation field strength, if modifier cation valency is the same (e.g., Mg substitution for Ca), or dependent on the effective cation field strength and the number of (Si, Al) (O, N, F) tetrahedra associated with each modifier when Ca is replaced by the trivalent modifiers. Combining these correlations with those observed previously relating glass properties to N and F substitution for O, it becomes apparent that glass properties for Ca–M–Si–Al–O–N–F glasses can be described by correlations which involve independent, but additive contributions by N and F substitution levels, effective cation field strength, and the number of tetrahedra associated with each modifier ion.     

Quantitative prediction of the structure and properties of Li2O–Ta2O5–SiO2 glasses via phase diagram approach

Tantalum silicate glasses serve as laser host materials to take advantage of their high refractive index and the ability to tailor their physical properties in the design of high-performance photonic and photoelectric components. However, successful attainment of feature control in tantalum-doped materials remains a longstanding problem due to the limited understanding of local structure around the tantalum ions, a problem that lies at the heart of predicting the micro- and macroscopic properties of these glasses. Herein, we present a novel approach for predicting the local structural environments in tantalum silicate glass based on a phase diagram approach. The phase relations and glass formation region of Li₂O–Ta₂O₅–SiO₂ ternary systems are explored to calculate the structure and additive physical properties of lithium tantalum silicate glasses. These measured and calculated results are in good quantitative agreement, indicating that the phase diagram approach can be applied broadly to Li₂O–Ta₂O₅–SiO₂ ternary glass systems. Using the phase diagram approach, the local structure of tantalum can be directly obtained. Each Ta atom is surrounded by six atoms, and its polyhedron, the TaO₆ octahedron, bonds through oxygen to Li and Ta. As a network modifier, Ta⁵⁺ depolymerizes the silicate glass structure by modulating the local structure of lithium atoms in Li₂O–Ta₂O₅–SiO₂ ternary glass system. The compositional dependence of structure in lithium tantalum silicate glasses is quantitatively determined based on the structure of the nearest neighbor congruent compound through the lever rule. These findings offer a precise prediction of tantalum silicate glass properties with quantitative control over local structural environment of the disordered materials.     

Glass-forming regions and enhanced 2.7 μm emission by Er3+ heavily doping in TeO2–Ga2O3–R2O (or MO) glasses

Er³⁺-doped fiber lasers operating at 2.7 μm have attracted increasing interest because of their various important applications; however, the intrinsic self-terminating effect of Er³⁺ and the reliability of glass hosts hindered the development of Er³⁺-doped fiber lasers. Herein, the glass-forming regions of a series TeO₂–Ga₂O₃–R₂O (or MO) (R = Li, Na, and Rb; M = Mg, Sr, Ba, Pb, and Zn) glasses are predicted by the thermodynamic calculation method. On this basis, the physical and optical properties of TeO₂–Ga₂O₃–ZnO (TGZ) glass are investigated in detail as an example. Under the excitation of 980 nm laser diode, the fluorescence intensity at 2.7 μm reaches a maximum in the heavily Er³⁺-doped TGZ glass. By contrast, the accompanying near-infrared fluorescence at 1.5 μm and upconversion green emissions at 528 nm and 546 nm are all effectively weaken. Furthermore, the lifetime gap between the ⁴I_11/2 upper laser level and ⁴I_13/2 lower laser level is sharply narrowed from 2.81 ms to 0.59 ms, which is beneficial to overcome the population conversion bottleneck. All results demonstrate that these newly developed ternary tellurite glass systems are promising candidates for near-/mid-infrared laser glass fiber, fiber amplifiers, and fiber lasers.     

Structural,luminescence and NMR studies on Nd3+-doped sodium–calcium-borate glasses for lasing applications

In this work, Neodymium (Nd³⁺) -doped borate glasses were synthesised by melt-quenching method and their structural as well as optical properties were analysed through XRD, Raman, NMR, DSC, UV–Visible, luminescence and decay studies for the possible application as laser gain medium. DSC and XRD results revealed that the glasses have high transition temperature and are in amorphous nature, respectively. The vibrational characteristics of the host matrices as well as the effect of Nd³⁺ incorporation were analysed by using Raman spectra, which exhibit majorly borate groups as supported by NMR results. The band gap energy of the glasses decreases with an increase in Nd³⁺ concentration. Using Judd-Oflet theory the characteristic intensity parameters (Ω_λ, λ = 2, 4 and 6) were calculated and further used for calculating the various radiative parameters from the emission spectra. The emission cross-section (σ_em) was estimated as high as 1.15 × 10⁻²⁰ cm² from the Füchtbauer–Landenburg (FL) equation for the dominant ⁴F_3/2→⁴I_11/2 (1056 nm) transition. The effect of Nd³⁺ concentration on the lifetime of the ⁴F_3/2 luminescent level was analysed from the decay curve analyses. From which, the corresponding quantum efficiency (η) was estimated and found as high as 54%. The investigated result suggests the prepared glasses can be utilized as gain medium to generate laser at around 1.05 μm.     

Nd3+/Sm3+ codoped NaLa(WO4)2 glass ceramic: A novel optical heater

Transparent Nd³⁺/Sm³⁺ codoped tungstate silicate glass ceramics were prepared and used for the photothermal conversion process. XRD patterns, TEM image and the enhanced Raman signals confirm the appearance of the tetragonal scheelite NaLa(WO₄)₂ nanocrystals in the vitreous phase. In comparison to the precursor glass, the enhancement of photoluminescence of Nd³⁺ ions in the glass ceramics attributes to the enrichment of Nd³⁺ ion in the precipitated low phonon-energy tetragonal scheelite NaLa(WO₄)₂ nanocrystals. The rapid reduction of photoluminescence of Nd³⁺ ions in the Nd³⁺/Sm³⁺ codoped glass ceramics demonstrates that a strong energy transfer from Nd³⁺ to Sm³⁺ takes place, which provides more non-radiative relaxation channels and is beneficial for the improving the photothermal conversion efficiency. Under the irradiation of 808 nm laser diode, a significant temperature rise is observed in the Nd³⁺/Sm³⁺ codoped glass ceramics and may be used as a good optical heater.     

Effect of neodymium ions on upconversion fluorescence studies of oxyfluorosilicate glasses for optoelectronic devices

Effect of Nd₂O₃ concentrations on optical properties and upconversion studies were investigated for oxyfluorosilicate glasses with composition of SiO₂-Al₂O₃-Na₂CO₃-SrF₂-CaF₂. The Judd-Ofelt (JO) intensity parameters, Ω_λ (λ = 2, 4 and 6) as well as radiative properties for the ⁴F_3/2 level of Nd³⁺ ion have been evaluated from the absorption spectra of 1.0 mol% Nd₂O₃-doped glass. For all the glass samples, the strong NIR emissions were observed at 891, 1058 and 1330 nm and have been attributed to ⁴F_3/2 → ⁴I_{9/2, 11/2, 13/2} transitions respectively. The stimulated emission cross-section for the ⁴F_3/2 → ⁴I_11/2 transition is evaluated and found to be 4.24 × 10^–20 cm². From the decay curves, experimental lifetimes (τ_exp) of the ⁴F_3/2 level have been determined and are found to be 363, 340, 205, 134, 122 and 54 μs for 0.1, 0.5, 1.0, 1.5, 2.0 and 3.0 mol% Nd³⁺ ions doped glasses, respectively. By exciting the prepared glass samples at 808 nm, the upconversion of infrared light into blue, green, yellow and red emission have also observed. These results indicate that the present glasses could be useful for opto-electric devices and solid state laser applications.     

Structure and physical properties of Ba(PO3)2–AlF3–BaSO4 fluoro-sulfo-phosphate glasses

Alkali-earth-metaphosphate-based fluoro-sulfo-phosphate M(PO₃)₂–AlF₃–MSO₄ (MPFS, M = Ca, Sr, Ba) glasses have been developed via simultaneously incorporating fluoride and sulfate into metaphosphate glass. Their glass-forming regions were efficiently determined under the guidance of thermodynamic calculation method. The physical and structural properties of BaPFS glass were investigated in detail. Furthermore, near-infrared spectroscopic properties of Er³⁺-doped BaPFS (Er–BaPFS) glass were studied. Physical parameters, such as Abbe's number ν_d (55-75) and nonlinear refractive index n₂ (1.17-1.86 × 10⁻¹³ esu), of BaPFS glass are strongly depended on P/F/S ratio. The structure of BaPFS glass gradually depolymerizes and tends to become multianionic when Ba(PO₃)₂ is substituted by AlF₃ and BaSO₄. Anion-substitution strategy effectively modulates the property and structure of glass, providing a scheme to derive glass materials. In addition, enhanced emission at ~1.5 μm has been observed from Er–BaPFS glass along with large emission cross section (5.0-5.5 × 10⁻²¹ cm²) and long lifetime (6.7-7.3 ms), resulting in large figure of merit (3.46-3.84 × 10⁻²³ cm²·s), which is a promising candidate for solid-state laser.     

Effects of Difference in Ionic Radii on Chemical Ordering in Mixed‐Cation Silicate Glasses: Insights from Solid‐State 17O and 7Li NMR of Li–Ba Silicate Glasses

Understanding of the extent of cation disorder and its effect on the properties in glasses and melts is among the fundamental puzzles in glass sciences, materials sciences, physical chemistry, and geochemistry. Particularly, the nature of chemical ordering in mixed‐cation silicate glasses is not fully understood. The Li–Ba silicate glass with significant difference in the ionic radii of network‐modifying cations (~0.59 Å) is an ideal system for revealing unknown details of the effect of network modifiers on the extent of mixing and their contribution to the cation mobility. These glasses also find potential application as energy and battery materials. Here, we report the detailed atomic environments and the extent of cation mixing in Li–Ba silicate glasses with varying X_BaO [BaO/(Li₂O + BaO)] using high‐resolution solid‐state nuclear magnetic resonance (NMR) spectroscopy. The first ¹⁷O MAS and 3QMAS NMR spectra for Li–Ba silicate glasses reveal the well‐resolved peaks due to bridging oxygen (Si–O–Si) and those of the nonbridging oxygens including Li–O–Si and mixed {Li, Ba}–O–Si. The fraction of Li–O–Si decreases with an increase in X_BaO and is less than that predicted by a random Li–Ba distribution. The result demonstrates a nonrandom distribution of Li⁺ and Ba⁺ around NBOs characterized by a prevalence of the dissimilar Li–Ba pair. Considering the previously reported experimental results on chemical ordering in other mixed‐cation silicate glasses, the current results reveal a hierarchy in the degree of chemical order that increases with an increase in difference in ionic radius of the cation in the glasses [e.g., K–Mg (~0.66 Å) ≈Ba–Mg (~0.63 Å) ≈Li–Ba (~0.59 Å) > Na–Ba (~0.33 Å) > Na–Ca (~0.02 Å)]. The ⁷Li MAS NMR spectra of the Li–Ba silicate glasses show that the peak maximum increases with increasing X_BaO, suggesting that the average Li coordination number and thus Li–O distance decrease slightly with increasing X_BaO, potentially leading to an increased activation energy barrier for Li diffusion. Current experimental results confirm that the degree of chemical ordering due to a large difference in ionic radii controls the transport properties of the mixed‐cation silicate glasses.