Structural origin of the weak germanate anomaly in lead germanate glass properties

Binary PbO–GeO₂ glasses have been studied in detail from 5 to 75 mol% PbO using high-resolution neutron diffraction, high-energy X-ray diffraction, 207-Pb NMR, pycnometry, and thermal analysis. The Ge–O coordination number displays a broad maximum n_GeO = 4.14(3) close to 27 mol% PbO. This is smaller than the maximum n_GeO = 4.3 reported in CaO–GeO₂ glasses but occurs at a similar composition. This structural behavior appears to explain the relatively weak germanate anomaly manifest in lead germanate glasses, for example as a maximum in the measured atom number density and a plateau in the glass transition temperatures. The structural role of Pb(II) is complex. On the one hand, short covalent Pb–O bonds and small Pb–O coordination numbers of ∼3 to 4 indicate glass network former character for Pb(II), associated with a stereochemically active electron lone pair. On the other hand, the presence of some GeO₅ or GeO₆ units, in addition to the majority GeO₄ tetrahedral species, indicates some modifier character of Pb(II) at low PbO contents, giving rise to the observed weak germanate anomaly, as well as elongation and enhanced ionicity of the Pb–O bonds. Overall, the observed structural behavior of Pb(II) in lead germanate glasses appears as intermediate between that observed in lead silicate and lead borate glasses. Despite rapid quenching, at low PbO contents, the glasses studied exhibited nanoscale heterogeneity, evidenced by small-angle X-ray scattering consistent with the early stages of spinodal decomposition.     

Lead silicate glass structure: New insights from diffraction and modeling of probable lone pair locations

Structures of binary PbO-SiO₂ glasses have been studied in detail over the compositional range 35 to 80 mol% PbO using high-resolution neutron diffraction, high-energy X-ray diffraction, static ²⁰⁷Pb NMR, and structural modeling. The changes in the local environment of Pb(II) are subtle; it has a low coordination to oxygen (∼3 to 4) plus a stereochemically active electron lone pair and, thus, behaves as a glass network forming (or intermediate) cation over the entire composition range. This conclusion contradicts previous reports that Pb(II) is a network modifier at low concentrations, and is supported by an analysis of lead and alkaline earth silicate glass molar volumes. The Pb-O peak bond length shortens by 0.04 Å with increasing PbO content, indicating stronger, more covalent bonding, and consistent with an increase in the number of short (≤ 2.70 Å) Pb-O bonds, from 3.3 to 3.6. This is accompanied by increased axial symmetry of the Pb(II) sites, and is interpreted as a gradual transition toward square pyramidal [PbO₄] sites such as those found in crystalline PbO polymorphs. An attendant decrease in the periodicity associated with the first sharp diffraction peak (FSDP) toward that of β-PbO, accompanied by increases in the correlation lengths associated with the plumbite network (FSDP) and silicate anions (neutron prepeak), provides evidence of increased intermediate-range order and has implications for the glass forming limit imposed by crystallization. Pb(II) electron lone pairs occupy the natural voids within the silicate network at low PbO contents, while at high PbO contents they aggregate to create voids that form part of the plumbite network, analogous to the open channels in Pb₁₁Si₃O₁₇ and the layered structures of α- and β-PbO. Si-O and Pb-O bond lengths have been correlated with ²⁹Si and ²⁰⁷Pb NMR chemical shifts, respectively. This is the first time that such correlations have been demonstrated for glasses and attests to the accuracy with which pulsed neutron total scattering can measure average bond lengths.     

Spectroscopic and electrochemical investigations of lead–lead dioxide glasses and vitroceramics with applications for rechargeable lead–acid batteries

A new class of glass and vitroceramic electrodes with applications for rechargeable batteries was obtained by a melt quenching method. The structural characterization of the samples having the xPb·(100−x)PbO₂ composition, where x=0, 10, 20, 30, 40 and 50 mol% Pb, was performed by UV–vis and FTIR spectroscopies investigations.UV–vis and FTIR data reveal that the excess of lead content in the host matrix generates the transformation and/or disintegration of [PbO₆] octahedral structural units into [PbO₄] structural units or Pb²⁺ ions and non-bonding oxygen ions centers.The electrochemical performances of the glass and vitroceramics electrodes were investigated by cyclic voltammetry. The shapes of the cyclic voltammograms and redox peaks depend on the electrolyte solution concentration and the lead content in host matrix. Differences between these waves are determined by the type of electrochemically active species existing in the glass or glass ceramics. The improved performance of the vitroceramic electrodes is attributed to the presence of the lead metallic phase that seems to offer an easier route for the charge process of the electrodes. Thus, the presence of these phases generates more electrochemically active species, inhibits the secondary reactions implying PbO, takes up the ionic conduction of the larger electrolyte solution and increases the charge/discharge rate of the electrochemical processes.     

The basic lead nitrates I. Compounds formed by the reaction of orthorhombic lead monoxide with cold aqueous lead nitrate

Solid products of the reaction between orthorhombic lead monoxide and cold aqueous lead nitrate solutions in the range of molar proportions 1:3 to 3:1 PbO: Pb(NO₃)₂ have been studied by X-ray powder diffraction (X.R.P.D.). Three distinct crystalline phases were recognised. Reasonably pure samples of monobasic lead nitrate dihydrate [dilead (II) monoxide dinitrate dihydrate], PbO.Pb(NO₃)₂.2H₂O, were obtained at temperatures below 20 °C when the reactants were in the range of molar proportions 1:3 to 1:1 PbO: Pb(NO₃)₂. This compound seems to be stable below 20 °C, but it partially dehydrates at higher temperatures. It does not seem to have been reported elsewhere. Monobasic lead nitrate monohydrate [dilead (II) monoxide dinitrate monohydrate], PbO.Pb(NO₃)₂.H₂O, was formed in isolation at temperatures between 25 and 30 °C when the reactants were in the range of molar proportions 1:3 to 1:1 PbO: Pb(NO₃)₂. This compound is stable at room temperatures, and is identical to phases which have been reported by other authors. Mixtures of these two substances were obtained at temperatures between 20 and 25 °C. Tribasic lead nitrate trihydrate [tetra lead (II) trioxide dinitrate trihydrate], 3PbO.Pb(NO₃)₂.3H₂O, was formed in isolation at all temperatures in the range 15 to 30 °C when the reactants were in the molar proportion 3:1 PbO: Pb(NO₃)₂. This compound seems to be stable at room temperatures and has been reported elsewhere. When the reactants were in the molar proportion 2:1 PbO: Pb(NO₃)₂, mixtures of tribasic lead nitrate trihydrate with one or other (or both, depending on the temperature) of the monobasic lead nitrate hydrates were obtained. X.R.P.D. data are given for these three compounds, and a critical assessment is made of all the results in the cases of the two compounds for which published data already exists. Also, it is suggested that compounds of stoichiometries intermediate between that of a monobasic lead nitrate hydrate and that of a tribasic lead nitrate hydrate (and which have been described in the literature) can be only metastable in contact with water. The nomenclature used in this paper follows common industrial practise in naming basic lead compounds. However, scientific names are also given in parentheses when necessary.     

Improvement of the chemical composition and founding technology of high-lead glass in a high-efficiency furnace

A new composition for electrovacuum lead glass with a 20 wt. % PbO has been synthesized. The system of loading the charge and glass scrap into a furnace and a new system of tube shaping are described. The effect of the moisture content of the charge and the temperature on volatilization of PbO, Na₂O, and K₂O is investigated. It is shown that an artificially formed protective layer on the surfaces of discharge channels considerably reduces the volatilization of PbO, Na₂O, and K₂O from the liquid glass. Practical recommendations are presented.Translated from Steklo i Keramika, No. 8, pp. 3–6, August, 1995.     

Searching for correlations between vibrational spectral features and structural parameters of silicate glass network

Infrared (IR) and Raman spectroscopic features of silicate glasses are often interpreted based on the analogy with those of smaller molecules, molecular clusters, or crystalline counterparts; this study tests the accuracy and validity of these widely cited peak assignment schemes by comparing vibrational spectral features with bond parameters of the glass network created by molecular dynamics (MD) simulations. A series of sodium silicate glasses with compositions of [Na₂O]_x[Al₂O₃]₂[SiO₂]_98−x with x = 7, 12, 17, and 22 were synthesized and analyzed with IR and Raman. A silica glass substrate and a crystalline quartz were also analyzed for comparison. Glass structures with the same compositions were generated with MD simulations using three types of potentials: fixed partial charge pairwise (Teter), partial diffuse charge potential (MGFF), and bond order-based charge transfer potential (ReaxFF). The comparison of simulated and experimental IR spectra showed that, among these three potentials tested, ReaxFF reproduces the concentration dependence of spectral features closest to the experimentally observed trend. Thus, the bond length and angle distributions as well as Si–Qⁿ species and ring size distributions of silica and sodium silicate glasses were obtained from ReaxFF-MD simulations and further compared with the peak assignment or deconvolution schemes—which have been widely used since 1970s and 1980s—(a) correlation between the IR peak position in the Si–O stretch region (1050-1120 cm⁻¹) and the Si–O–Si bond angle; (b) deconvolution of the Raman bands in the Si–O stretch region with the Qⁿ speciation; and (c) assignment of the Raman bands in the 420-600 cm⁻¹ region to the bending modes of (SiO)_n rings with different sizes (typically, n = 3-6). The comparisons showed that none of these widely used methods is congruent with the bond parameters or structures of silicate glass networks produced via ReaxFF-MD simulations. This finding invokes that the adequacy of these spectral interpretation methods must be questioned. Alternative interpretations are proposed, which are to be tested independently in future studies.     

Vitrification, Properties, and Structure of Lead-Tellurite Borate Glasses

The vitrification, structure, and physicochemical properties of glasses in the PbO – ZnO – B₂O₃ – TeO₂ system are studied. The dual role of the lead ions in the glass structure is confirmed. It is demonstrated that the coordination transition of boron ions correlates with the concentration of PbO in glass. A nonlinear dependence of properties on the glass composition is due to the structural modifications in glass.     

Optical properties of alkali and alkaline-earth lead borate glasses doped with Nd<Superscript>3+</Superscript> Ions

Spectroscopic and physical properties of Nd³⁺-doped alkali lead borate glasses of type 20R ₂O · 30PbO · 49.5B₂O₃ · 0.5Nd₂O₃ (R = Li and K) and alkaline-earth lead borate glasses 20RO · 30PbO · 49.5B₂O₃ · 0.5Nd2O3 (R = Ca, Ba, and Pb) have been investigated. Optical absorption spectra have been used to determine the Slater-Condon (F₂, F₄, and F₆), spin orbit ξ_4f, and Racah parameters (E₁, E₂, and E₃). The oscillator strengths and the intensity parameters Ω₂, Ω₄, and Ω₆ have been determined by the Judd-Ofelt theory, which, in turn, provide the radiative transition probability (A), total transition probability (A _T ), radiative lifetime (τ _R ), and branching ratio (β _R , %) for the fluorescent levels. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω₄/Ω₆), the value of which is in the range 0.2–1.5, typical of Nd³⁺ in different laser hosts. A red shift of the peak wavelength is observed upon addition of alkali or alkaline-earth oxides to the lead borate glass. A higher value of the W₂ parameter for potassium-doped glass indicates a higher covalency for this glass matrix. The relative intensity of the peaks ⁴I_9/2 → ⁴F_7/2, ⁴S_3/2 has also been studied. The text was submitted by the authors in English.     

Medium-range order and physicochemical properties of (100 ? x)(0.5PbO · 0.5P2O5) · xTeO2 glasses in terms of the constant stoichiometry grouping concept

Glasses in the (100 − x)(0.5PbO · 0.5P₂O₅) · xTeO₂ section of the PbO-P₂O₅-TeO₂ system have been synthesized over the entire composition range for the first time and their properties (Raman spectra, refractive index n, density d, glass transition temperature T _g , and light scattering losses) have been investigated. It has been demonstrated that the Raman spectra can be represented as a superposition of constant spectral forms corresponding to constant stoichiometry groupings PbO · P₂O₅, TeO₂ · 2PbO · 2P₂O₅, TeO₂ · PbO · P₂O₅, 2TeO₂ · PbO · P₂O₅, and TeO₂. The existence of crystals of the corresponding stoichiometry has been predicted using the constant stoichiometry grouping concept. The diagram of the constant stoichiometry grouping contents (determined from the Raman spectra) in glasses of the system under investigation has made it possible to determine the partial properties of constant stoichiometry groupings, to calculate the dependences of the refractive index and density on the composition, and to refine the values of n and d for vitreous tellurium dioxide and lead metaphosphate. The practical importance of glasses in the system under consideration for the use in photonic devices has been discussed.     

The Reaction of Plumbonacrite (Basic Lead Carbonate) with Hot DOP,and the Stabilisation of Plasticised PVC

The basic lead carbonate ‘plumbonacrite’, 6PbCO₃.3Pb(OH)₂.PbO, has been reacted with di-2-ethyl hexyl phthalate (dioctyl phthalate, DOP), C₆H₄(COOC₈H₁₇)₂ at 180d?C under nitrogen. Anhydrous monobasic lead orthophthalate, PbO.Pb₆H₄(COO)₂, was the only product detected by X-ray powder diffraction (X.R.P.D.). These studies are related to previous work on reactions taking place in hot polyvinyl chloride (PVC) blends containing DOP plasticiser and basic lead stabilisers. It is concluded that plasticiser stabiliser interaction can play a significant role in stabilising PVC against thermal decomposition, and that efficient stabilisation takes place largely by a free-radical exchange mechanism. Characteristic X.R.P.D. data are tabulated for anhydrous monobasic lead orthophthalate, and for monobasic lead orthophthalate monohydrate, PbO. PbC₆H₄(COO)₂- H₂O, which can be made in aqueous suspension and which converts to the anhydrous salt at 180d?C. X.R.P.D. data are also given for dibasic lead orthophthalate, 2PbO.PbC₆H₄(COO)₂.1/2H₂O, which is well known as a stabiliser for PVC, and which might have been expected to form in these experiments, (but did not in fact do so).     

Lead-based systems as suitable anode materials for Li-ion batteries

Three lead-based materials formed by PbO₂, PbO and Pb as main phases were prepared by following different synthetic procedures and tested as anodic materials in Li-ion batteries by using potentiostatic and galvanostatic methods. While the reduction of Pb(IV) to Pb(II) takes place in a single step, that of Pb(II) to Pb is a complex process involving several steps. Both reduction reactions are irreversible. Lead, whether electrochemically or chemically formed, undergoes an electrochemical reaction with lithium that over the 1.0-0.0 V potential range yields Li_xPb alloys (0≤x≤4.4). The anodic and cathodic potentiostatic curves exhibit various signals that account for: (i) the formation of different intermediates with variable lithium contents; (ii) the reversibility of the alloying/de-alloying processes; (iii) the increase in complexity of such processes as the oxidation state of lead in them decreases. This results in capacity fading with cycling, particularly in the samples having Pb as the main component. One way of avoiding the capacity loss on cycling involves depositing the active material on lead sheets from spraying suspensions. These coatings exhibit a good capacity retention, which can be ascribed to the formation of a Li_xPb layer at the active material/substrate interface that facilitates electron and ion transfer across the electrode.     

Structure and disorder in Pb-Na metasilicate (PbO:Na2O:2SiO2) glasses: A view from high-resolution 17O solid-state NMR

Knowledge of the structure of lead (Pb)-bearing silicate glasses, such as degree of polymerization and arrangement among cations, provides improved prospects for understanding their macroscopic properties. Despite the importance, the detailed disorder in Pb-bearing silicate glasses with varying composition (i.e., Pb/alkali content) has not been systematically explored. Here, we reveal the first unambiguous structural information of PbO-Na₂O-SiO₂ glasses with varying PbO content [i.e., X_PbO = PbO/(Na₂O + PbO)], which are the fundamental model system for multicomponent Pb-bearing glasses, using high-resolution ¹⁷O solid-state NMR. ¹⁷O NMR spectra clearly show the resolved multiple oxygen sites, such as Na-O-Si, Si-O-Si, and [Na,Pb]-O-Si. As X_PbO increases, the fraction of [Na,Pb]-O-Si peak increases markedly at the expanse of substantial reduction in the fraction of Na-O-Si/total NBO. This trend indicates the relative predominance of the dissimilar pairs around non-bridging oxygen (NBO) and, therefore, can be explained well with the pronounced chemical ordering among Na⁺ and Pb²⁺. These results confirm that Pb is primarily a network-modifier in the glasses studied here. Atomic environments around both NBO and BO are affected by the change in Na/Pb ratio, while topological disorder due to cation mixing around NBO is much more prominent in Pb endmember. The structural details of short-range configurations around oxygen in alkali Pb-silicate glasses provide atomistic insights for understanding the properties of Pb-bearing multicomponent silicate glasses.     

Preparation and elastic moduli of germanate glass containing lead and bismuth

This paper reports the rapid melt quenching technique preparation for the new family of bismuth-lead germanate glass (BPG) systems in the form of (GeO₂)₆₀–(PbO)_40−x–(½Bi₂O₃)_x where x = 0 to 40 mol%. Their densities with respect of Bi₂O₃ concentration were determined using Archimedes’ method with acetone as a floatation medium. The current experimental data are compared with those of bismuth lead borate (B₂O₃)₂₀–(PbO)_80−x–(Bi₂O₃)_x. The elastic properties of BPG were studied using the ultrasonic pulse-echo technique where both longitudinal and transverse sound wave velocities have been measured in each glass samples at a frequency of 15 MHz and at room temperature. Experimental data shows that all the physical parameters of BPG including density and molar volume, both longitudinal and transverse velocities increase linearly with increasing of Bi₂O₃ content in the germanate glass network. Their elastic moduli such as longitudinal, shear and Young’s also increase linearly with addition of Bi₂O₃ but the bulk modulus did not. The Poisson’s ratio and fractal dimensionality are also found to vary linearly with the Bi₂O₃ concentration.     

EQCM study of electrodeposited PbO2: Investigation of the gel formation and discharge mechanisms

Lead dioxide thin films were electrodeposited on gold substrates and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mass change occurring upon immersion in a H₂SO₄ electrolyte and during electrochemical reduction was observed in situ by electrochemical quartz crystal microbalance (EQCM). A hydrated PbO₂ gel-type layer is formed at the surface of electrodeposited PbO₂. The concentration of the H₂SO₄ electrolyte does not affect the composition of the gel nor the amount of lead dioxide involved in the hydration process. It is established that 1.3 × 10⁻⁷ mol cm⁻² of β-PbO₂ are hydrated at the surface of an electrodeposited film and that the hydration reaction occurs according to the following reaction: PbO₂^(crystal) + xH₂O ↔ (PbO(OH)₂·(x − 1)H₂O)^(gel), where x = 8.1. The mass change occurring during the first and subsequent discharge of PbO₂ was recorded. It is shown that both PbO₂^(crystal) and PbO(OH)₂·(7.1)H₂O)^(gel) are reduced to PbSO₄ during the first discharge.     

Optical Spectroscopic Analysis of High Density Lead Borosilicate Glasses

Lead borosilicate glasses, of chemical composition 20SiO₂-xPbO-(15 + x)B₂O₃-5WO₂-10ZnO-(50-2x) Na₂O (where x = 5, 10, 15, 20, 25) were prepared using the normal melt-quenching technique. The samples were examined using a Philips Analytical X-ray diffraction system in order to check their amorphous nature. The effect of increasing B₂O₃ and PbO content on glass transition temperature was examined using Differential Thermal Analysis measurements (DTA). The results of DTA showed that both melting and glass transition temperatures decrease with increase of lead and boron oxides. Density and its related parameters have been determined to study the effect of lead-boron content on the structural properties of the prepared samples. Based on the density and DTA results, the network forming role of Pb and B ions was proved. The optical properties of the glass samples have been obtained using UV-VIS measurements. The optical parameters, such as optical band gap, Urbach energy, refractive index, and electronic polarizability were deduced based on the optical data. The observed increase in optical band gap and decrease in Urbach energy as well as the red shift in the absorption spectra arise due to the formation of non-bridging oxygen.     

Dependence of the phase composition of the anodic layer on oxygen evolution and anodic corrosion of lead electrode in lead dioxide potential region

At potentials more positive than 1300 than 1300 mV with respect to a Hg/Hg₂SO₄ electrode the partial currents of lead corrosion and oxygen evolution in 7_n H₂SO₄ follow the Tafel's dependence. X-ray investigations and wet analyses of the anodic layer show that it consists of tet-PbO and α PbO₂. Besides, at potentials more negative than 1530 mV, β PbO₂ forms at the oxide/solution interface.It is established that lead anodic corrosion proceeds in two stages. During the first Pb is oxidized to tet-PbO. During the second stage tet-PbP is oxidized to PbO₂. If this process is performed in solid state, α PbO₂ forms. If PbO is dissolved and then oxidized, β PbO₂ crystals are formed. The oxidation of tet-PbO to α PbO₂ proceeds at different rates in the bulk of the oxide and at its surface with the solution. At potentials more positive than 1530 mV the oxidation of tet-PbO to α PbO₂ at the surface of the oxide with the solution leads to the dropping off of part of the oxide layer.The oxidation of Pb and PbO is carried out under the action of O atoms and O^? radicals which evolve at the oxide/solution interface and penetrating the oxide reach the metal/oxide surface.     

Growth of whisker nanocrystals in the (1 ? x)In2O3 · xSeO2 system

PbSe and In films with surface areas of 3 × 3 mm² and thicknesses of 1?C1.5 ??m were consecutively deposited on substrates made of glass of S-29 grade using the vacuum deposition method. The films were oxidized in the dry air atmosphere at a temperature of 550°C. The possibility of forming whisker nanocrystals (1 ? x)In₂O₃ · xSeO₂ on glass substrates was demonstrated. The results of X-ray microanalysis demonstrated the presence of not only lead and indium selenide, but also (1 ? x)In₂O₃ · xSeO₂, PbSeO₃, PbO and SeO₂ on the surfaces of the films under study.     

Experimental phase equilibria studies of the PbO–SiO2 system

Phase equilibria of the PbO–SiO₂ system have been established for a wide range of compositions: (i) liquid in equilibrium with silica polymorphs (quartz, tridymite, and cristobalite) between 740°C and 1580°C, at 60‐90 mol% SiO₂; (ii) with lead silicates (PbSiO₃, Pb₂SiO₄, and Pb₁₁Si₃O₁₇) and lead oxide (PbO) between 700°C and 810°C. A high‐temperature equilibration/quenching/electron probe X‐ray microanalysis (EPMA) technique has been used to accurately determine the compositions of the phases in equilibrium in the system. Significantly, no liquid immiscibility has been found in the high‐silica range, and the liquidus in this high‐silica region has been accurately measured. The phase equilibria information in the PbO–SiO₂ system is of practical importance for the improvement of the existing thermodynamic database of lead‐containing slag systems (Pb–Zn–Fe–Cu–Si–Ca–Al–Mg–O).     

Interaction of lead and chromium with chitin and chitosan

The interaction of the natural marine polymer chitin and its deacetylated derivative chitosan with lead and chromium has been investigated. The uptake of lead and chromium was determined from changes in concentration as measured by atomic absorption spectroscopy. A significant uptake of Pb(II) on both chitosan and chitin was observed. However, the uptake of Pb(II) on chitin was approximately 21% of that on chitosan. The number of Natoms in chitin and chitosan and per number of Pb(II) ions sorbed was 115 and 29, respectively. The number density of flakes observed in the scanning electron microscope and characterized by an intense Pb signal in energy dispersive analysis of x rays (EDAX) was greater on the surface of chitosan [containing 1.7 × 10^?4 mole Pb(II)/g chitosan] than chitin [containing 3.5 × 10^?5 mole Pb(II)/g chitin] after equilibration with Pb(II) solution. The bonding state of lead on chitosan as determined by electron spectroscopy for chemical analysis (ESCA) is similar to the bonding of lead in PbO based on the Pb 4f_7/2 binding energy. A significant shift in the O 1s binding energy from 532.2 to 531.4 eV was observed for chitosen after equilibration with Pb(II) solution. The caculated values of the N/Pb ratio from ESCA spectra were 0.5 and 11, for chitosan and chitin, respectively. A significant uptake of Cr(III) on chitosan was observed and a significant increase in the pH of solutions of Cr(III) on equilibration with chitosan occurred. A high number density of nodules characterized by an intense Cr signal in EDAX was observed in chitosan [containing 2.5 mole Cr(III)/g chitosan] after equilibration with Cr(III) solution. The calculated values of the N/Cr ratio from ESCA spectra was 18 for chitosan.     

Effect of the Glass Structure on Emission of Rare‐Earth‐Doped Borate Glasses

A series of glasses composed of xB₂O₃–8Al₂O₃‐(90?x)Na₂O–R₂O₃ (x = 65, 70, 75, 80, 85; R = Dy³⁺, Tb³⁺, Sm³⁺) were prepared through melt‐quenching. Structural evolution was induced by varying the glass composition. Increasing the glass network former B₂O₃ enhanced the luminescence of rare‐earth ions, as observed in the emission spectra. The mechanism of the glass structural evolution was investigated by the NMR spectra analysis. The dispersant effect of the glass structure was believed to promote the better distribution of the rare‐earth ions in the matrix and reduced the concentration quenching between them. The relationship between the glass structure and its optical properties was established.