Shielding Behavior of Gamma-Irradiated MoO<Subscript>3</Subscript> or WO<Subscript>3</Subscript>-Doped Lead Phosphate Glasses Assessed by Optical and FT Infrared Absorption Spectral Measurements

Undoped and MoO₃- or WO₃- doped lead phosphate glasses were prepared by the melting-annealing technique. The glasses were characterized through UV-visible and infrared measurements which were repeated after gamma irradiation. Optical spectrum of binary lead phosphate glass shows distinct ultraviolet bands correlated with unavoidable trace iron impurities within the chemicals used for the preparation of the glasses. UV-visible absorption spectra of MoO₃- or WO₃- doped glasses exhibit additional UV-visible bands which are related to the presence of four oxidation states of the two transition metal (molybdenum or tungsten) ions (Mo³⁺, Mo⁴⁺, Mo⁵⁺, Mo⁶⁺, W³⁺, W⁴⁺, W⁵⁺, W⁶⁺). The extra UV band is related to hexavalent (5d⁰) state while the rest of the visible bands are related to (350–440 nm - trivalent state), (450, 550, 650 nm - tetravalent state) while the broad band centered at about 770 nm (pentavalent state). The intensities of the absorption bands are observed to change with the transition metal content and their valencies. Infrared absorption spectra reveal distinct vibrational bands which are assigned to phosphate groups with sharing of Pb-O vibrations within both the range 460–620 cm^-1 and the range 900–1100 cm^-1 revealing a compact network structure. Gamma irradiation causes a minor increase in intensity of one of the UV band due to suggested photo-oxidation of some trace ferrous ions to additional ferric ions but the remaining spectral curve remains unaffected which is obviously related to some shielding effects of heavy atomic weight of PbO. This heavy metal oxide (PbO) is assumed to retard or prohibit the free passage of free electrons or positive holes generated during the irradiation process.     

Alkali metal tungsten bronze-doped energy-saving glasses for near-infrared shielding applications

Tungsten bronze has attracted global attention for its applications in near-infrared (NIR)-shielding windows. Here, alkali metal tungsten bronze (M_xWO₃, M = one or two types of Li, Na, and K)-doped glasses are prepared by a simple melt-quenching method. Their structure and properties were characterized by XRD, Raman spectroscopy, XPS and UV–Vis–NIR spectrophotometry. The effects of M on their structure and the NIR shielding performance are investigated. The LiF sample has the best NIR shielding performance, but its visible transmittance is sacrificed due to its low quality. The glasses containing mixed Li⁺ and K⁺ cooperate to form a high-quality Li⁺/K⁺-codoped tungsten bronze, while the glasses containing mixed Li⁺ and Na⁺ compete for limited tungsten resources to form Li⁺- and Na⁺-doped tungsten bronzes separately. The research here is helpful for understanding the role of different alkali metal ions in bulk energy-saving glass and is hugely significant for the guidance of the future applications of energy-saving glass without films.     

Preparation and characterization of PVC/CsxWO3 composite film with excellent near-infrared light shielding and high visible light transmission

Near-infrared (NIR) shielding is essential not only in the building and automobile glass films but also in achieving energy conservation. However, effectively shielding NIR and maintaining high transmittance in the visible light region have been great challenges in the past decade. Recently, hexagonal cesium tungsten bronze (Cs_xWO₃) nanoparticles have been widely studied due to the excellent transparency in the visible light region and strong heat-shielding ability in the NIR region. Herein, a design concept of transparent polyvinyl chloride (PVC)/Cs_xWO₃ composite film, as a heat insulation material for glasses, was proposed. To achieve this purpose, the PVC/Cs_xWO₃ composite film was prepared by incorporating Cs_xWO₃ slurry with better dispersion than traditional Cs_xWO₃ nanoparticles powder into a transparent PVC matrix. By the UV-Vis-NIR spectrophotometer characterization, the PVC/Cs_xWO₃ composite film containing 2.1 phr Cs_xWO₃ slurry displays high blocking of NIR (78%) and high transmittance of visible light (76%). In order to further understand the actual heat insulation effect from the PVC/Cs_xWO₃ composite films, the indoor sunlight simulation test and outdoor cooling experiment with solar illumination variations were carried out, which both showed heat insulation that is superior to the antimony tin oxide and indium tin oxide thin films prepared in our previous work. In addition, the mechanical property of PVC/Cs_xWO₃ composite films shows almost no change with the increase of Cs_xWO₃ slurry. The PVC/Cs_xWO₃ composite films simultaneously achieve excellent shielding of NIR and high transmittance of visible light, which makes it an ideal material to alleviate the current building energy consumption issues.     

Synthesis,physical, optical,structural and radiation shielding characterization of borate glasses: A focus on the role of SrO/Al2O3 substitution

In a bid to expand the amount of information available on glass systems and their potential applications for radiation shielding design, glass samples with the compositions (30-x)SrO-xAl₂O₃–68B₂O₃–2V₂O₅(x = 5, 7.5, 10, 12.5&15 mol %) coded as SABV0 - 4 were prepared by the melt-quenching technique and analyzed for their optical, structural, physical, and radiation shielding features. The glassy (amorphous) nature of the SABV glass samples was affirmed by broad peaks of X-ray diffraction spectra. Calculated values of density and molar volume shown opposite behavior and the variation of these values were discussed as structural modifications in the glass matrix. From recorded optical absorption spectra optical band gap energy (Eg)-indirect transition, Urbach energy and optical basicity were estimated. FTIR spectra were recorded for all the samples in the range 400 cm^?1 to 4000 cm^?1. The FTIR absorbance spectra unveiled the SABV network structure mainly incorporating of BO₃ and BO₄ units. Raman spectroscopy is achieved to detect the structural changes and at higher wavenumber, B–O stretching modes in [BO₃] observed with one or two NBO's. The results of ESR spectra of glasses have indicated the highly covalent environment of vanadium ions. Analysis of the photon shielding parameters of the glasses which were obtained primarily from FLUKA Monte Carlo simulations and XCOM computations revealed photon energy and glass chemical composition dependence. The mass attenuation coefficient and effective atomic number ranged from 0.2668 to 0.3385 cm²g^-1 and 12.98–15.93 accordingly as the weight fraction of Sr increased from 16.06 to 26.72% in the glasses. Generally, photon shielding ability of the SABV glasses follows the trend: SABV0 > SABV1 > SABV2 > SABV3 > SABV4. The thermal neutron total cross section follows the same trend with values fluctuating between 71.9553 and 80.6268 cm^?1. However, SABV1 showed superior fast neutron moderating capacity among the glasses. The present SABV glasses showed outstanding photon shielding ability compared to common shields. The prepared glasses are thus suitable candidates for radiation protection applications.     

Structure,stability and optical parameters of cobalt zinc borate glasses

In this study, the impact of cobalt oxide (CoO) on the structure, stability, linear and nonlinear optical parameters of B₂O₃–Na₂O–ZnO glasses was scrutinized. A series of glass system (ZnCoNaB-glasses) was successfully prepared through the melt quenching approach. Optical absorbance, reflectance, transmittance and FTIR spectroscopy were performed for all ZnCoNaB-glasses. The FTIR results showed that the BO₄ units are enhanced while nonbridging oxygens are decreased with further CoO addition. Furthermore, ZnO exists as four-coordinated [ZnO₄] units and these units decreased with further doping of CoO. These structural variations produce a decreasing impact in Urbach energy and nonlinear refractive index, meanwhile enhance the glass stability. Further, the metallization criterion (M) values indicate that our glass samples can be used for a new generation of nonlinear optical glasses. The preceding results can predict that the investigated ZnCoNaB-glasses will be utilized in versatile applications; especially optical switching and computing.     

Effect of Surface Tungstate W<Superscript>5+</Superscript> Species on the Metathesis Activity of W-Doped Spherical Silica Catalysts

The high surface area W-doped spherical silica (SSP) catalysts were prepared with different sequences of W and Si addition (W–Si_(Alt), Si₁–W_2, and W₁–Si₂) by the sol–gel method with CTAB as a structure directing agent and compared with the impregnated one (W/SSP). All the catalysts exhibited high specific surface area (～?1100 m² g^?1) with a closely perfect spherical shape. The presence of surface/sub-surface tungstate W⁵⁺ species, crystalline bulk WO₃, and tetrahedral tungsten oxide species on the prepared catalysts was investigated by means of X-ray photoelectron spectroscopy depth profile analysis, X-ray diffraction, and Raman spectroscopy. Without in situ reduction by the reactants/products, tungstate W⁵⁺ species was found on the top surface of the as-prepared W–Si_(Alt) whereas for the Si₁–W₂, W/SSP, and W₁–Si₂, the W⁵⁺ appeared only on the sub-surface of the catalysts after 5 and 15 s Ar⁺ etching. The abundance of surface W⁵⁺ species is suggested to facilitate the establishment of the active tungsten carbenes and was correlated well to the catalytic activity in propene metathesis. The surface W⁵⁺-activity relationship of the WO₃-based metathesis catalysts is useful especially when the catalyst activity did not depend solely on the amount of active tetrahedral coordinated tungsten oxides.     

Preparation,characterization, and mechanical-optical properties of telluro-borate glasses containing tungsten

The current work is interested in the preparation, characterization, and mechanical-optical properties of the glasses in the (75-x)B₂O₃–10SrO–8TeO₂–7ZnO−xWO₃ system, with (x = 0 (BSTZW0), 1 (BSTZW1), 5 (BSTZW2), 10 (BSTZW3), 22 (BSTZW4), 27 (BSTZW5), 34 (BSTZW6), and 40 mol% (BSTZW7). The preparation of the glasses has involved the melt-quenching route. The new glasses are characterized by different characterization techniques using densimeter, microhardness, Raman spectroscopy, UV–visible absorption and emission, and X-ray diffraction. Photoluminescence can determine the impact of substituting B₂O₃ with WO₃ on the mechanical-optical parameters and the structure of the present glasses. The prepared samples’ X-ray patterns showed amorphous states. The density value rises from 2.88 to 4.50 g/cm3, with the amount of WO₃ rising from 0 to 40 mol% as a result of the difference in molecular weight between WO₃ and B₂O₃. The Vickers microhardness (Hv) rises as the amount of WO₃ increases as a result of a decrease in free volume and the formation of covalent bonds. The elastic moduli were found to increase when the WO₃ concentrations increased from 0 to 40 mol%. This increase depends on the formation of bridging oxygen atoms. The Raman bands are designed to correspond to the bonds that form the structure of the current glass and detect the insertion of WO₃ content by the attribution of the new W–O–W and W–O bonds. The UV–Visible spectroscopy analysis showed no band characteristic for the reduced species of W⁵⁺ ions identified by dark blue. However, the photoluminescence spectra showed emission bands (under excitation at 300 nm) that are associated with the active centers of W⁴⁺, W⁵⁺, and W⁶⁺ ions.     

Physical,thermal, optical,structural and nuclear radiation shielding properties of Sm2O3 reinforced borotellurite glasses

To observe direct effect of samarium (III) oxide reinforcement on physical, thermal, optical, structural and nuclear radiation attenuation properties, a broad-range experimental and numerical investigations were performed with a group of novel borotellurite glasses. FTIR spectra of powdered samples were taken at 250-4000 cm^-1. The transmittance and absorption characteristics, optical band gaps, and Urbach energies were measured. The glass transition temperatures, crystallization temperatures and melting temperature values of the samples were determined. Nuclear radiation shielding properties have been determined for gamma-ray, neutrons and heavy charged particles. The lowest transmittance and highest absorbance were reported for the TBVS1.5 sample with highest Sm₂O₃ additive. In addition, obtained results from the nuclear radiation shielding calculations have showed that TBVS1.5 sample has superior nuclear radiation shielding properties against gamma-ray, neutron and heavy charged particles. The increasing Sm2O3 additive has visibly improved the nuclear radiation attenuation properties by keeping other material properties within usable limits.     

Electrochromism and reversible changes in the position of fundamental absorption edge in cathodically deposited amorphous WO3

Amorphous WO₃ (a-WO₃) films have been produced by electrodeposition from a sodium tungstate-based aqueous electrolyte. Their coloration under the action of cathode current in 1N H₂SO₄ is accompanied by a reversible shift of ∼0.42 eV in the fundamental absorption edge of the oxide towards higher quantum energies. The shift of the edge is proportional to the change in the potential of the WO₃ electrode being colored and is caused by the sequential filling, by injected electrons, of levels in the energy spectrum of electronic states formed by the unoccupied d-orbitals of W⁶⁺ centers. The optical characteristics of the W⁵⁺ centers which are formed in this case (color centers of electrochromic material) depend on whether a particular tungsten atom has a double bond to the oxygen atom (WO type bond). At the initial stage of coloration, injected electrons are captured mainly by the W⁶⁺ centers that have no such bonds. Then, W⁶⁺ centers with WO bonds, which have a higher position of the unoccupied d-orbitals on the energy scale, are also filled; this is accompanied by the appearance of an extra absorption band with maximum at ∼2 eV in the optical spectrum of films.     

Energy-saving glasses based on sodium tungsten bronze-like (Na5W14O44) functional units: Facile synthesis,NIR-shielding performance,and formation mechanism

Near-infrared (NIR)-shielding glasses for energy-saving window applications were prepared by forming sodium tungsten bronze-like (Na₅W₁₄O₄₄) functional units in the 29SiO₂–43B₂O₃–28NaF glass matrix. The glasses were synthesized by a facile melt-quenching process where 4–8 mol.% H₂WO₄ was added as the W source. The optimal glass was produced using 6 mol.% H₂WO₄, which had a low NIR transmission of 15.4% and a high visible light transmission of 59.8%. The possible mechanism for the formation of Na₅W₁₄O₄₄ in glasses were discussed based on XRD, Raman, XPS, XANES and EXAFS characterization of the glass samples, the glass samples after further crystallization, and the samples produced by staged heating of the starting materials. Crystalline or amorphous Na₅W₁₄O₄₄ formed during heating partially due to the protection by molten B₂O₃. Subsequently, amorphous Na₅W₁₄O₄₄ clusters are present in the glass acting as NIR-shielding functional units. This study sheds a light on further development of non-film-based and highly efficiency energy-saving windows.     

Effect of laser power density on the electrochromic properties of WO3 films obtained by pulsed laser deposition

Pulsed laser deposition (PLD) was used to prepare tungsten trioxide (WO₃) films on ITO substrates with a varying laser power density of 4.0–5.5 W/cm². XPS indicated that when the laser power density decreased, the peak positions of the W 4f and O 1s orbits shifted slightly to low energy due to the difference in oxygen vacancies. As the laser power density decreased, W⁶⁺ gradually replaced the lattice position of O^2?, increasing oxygen vacancies in the lattice. The transmittance modulated values (ΔT) were over 44% at 830 nm, indicating strong absorption by the WO₃ thin films in the near-infrared ray. The switching time of the WO₃ thin films between bleached states and coloured states decreased as the laser power density increased due to the amorphous structure, morphology, and lower oxygen deficiency at a high power density. The high ΔT and very fast switching time of t_b (1.09 s) and t_c (6.01 s) demonstrated the excellent electrochromic (EC) properties of the WO₃ films prepared by PLD.     

Preparation and characterization of WO3/SiO2 catalysts

Two sets of WO₃/SiO₂ catalysts were prepared from (NH_{4 6}H₂W₁₂O₄₀ (aqueous method) and W(³-C₃H₅)₄ (non-aqueous method). The molecular structures and dispersions of the surface tungsten oxide species for the WO₃/SiO₂ catalysts under ambient and in situ dehydrated conditions were investigated by Raman spectroscopy. The samples prepared from (NH₄)₆H₂W₁₂O₄₀ (aqueous method) exhibit very strong Raman features due to the presence of crystalline WO₃ and the samples prepared from W(³-C₃H₅)₄ (non-aqueous method) do not possess crystalline WO₃. These results suggest that the preparation method exerts an influence on the dispersion of the surface tungsten oxide species on SiO₂. The surface tungsten oxide species under ambient conditions possess polytungstate clusters, W₁₂O ₄₂ ^12– , on the silica support. Upon dehydration at elevated temperatures, the hydrated polytungstate clusters decompose and interact with the silica support via the formation of isolated, octahedrally coordinated tungsten oxide species.     

Influence of Bi2O3/WO3 substitution on the optical,mechanical, chemical durability and gamma ray shielding properties of lithium-borate glasses

Six different lithium bismuth boro-tungstate glasses with chemical composition 20Li₂O-(20-x)Bi₂O₃-xWO₃-60B₂O₃ (x = 0, 1, 2, 3, 4 and 5 mol%) were produced by the quenching method. Then, the glasses were investigated by means of their optical, mechanical, chemical durability and gamma ray shielding properties. Measured values of density and ultrasonic velocities were used to determine the elastic properties of the glasses. The optical band gap determined using the absorbance spectrum fitting (ASF) model was found to decrease under Bi₂O₃/WO₃ substitution. The presence of BO₃, BO₄, BiO₆, and WO₄ structural groups in the glasses was confirmed by Fourier transform infrared spectroscopy (FTIR). The dissolution rate in the glass 20Li₂O–15Bi₂O₃–5WO₃–60B₂O₃ (LBWB5) was found to be 10 times lower than 20Li₂O-20Bi₂O₃– 60B₂O₃. Mass attenuation coefficients (MAC) values of the produced glasses were determined using the MCNPX Monte Carlo code and Phy-X/PSD program. The photon attenuation parameters such as half value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), exposure buildup factor (EBF) and energy absorption buildup factor (EABF) were also studied. The obtained results showed that Bi₂O₃/WO₃ substitution has a direct impact on the photon attenuation abilities of produced glasses. More specifically, HVL values increased from 0.252 × 10^?2 cm for LBWB0 glass to 0.275 × 10^?2 cm for LBWB5 glass. However, different trends were observed for the photon buildup factors for the produced glasses. It can be concluded that the produced glasses have promising structural, optical, and photon attenuation properties to be used for gamma shielding applications.     

Synthesis and characterization of mesostructured tungsten nitride by using tungstic acid as the precursor

Mesostructured tungsten nitride was firstly prepared from tungstic acid via the temperature programmed reaction with ammonia. The N₂ adsorption isotherm of as-synthesized tungsten nitride was of type IV with a type H-3 hysteresis loop. BJH pore size distribution was of bimodal distribution (2.5 and 3.5 nm), among which the latter was the main channel of tungsten nitride. The surface area of as-synthesized tungsten nitride was up to 89 m² g⁻¹. XRD pattern showed that the crystal phase of the product was β-W₂N. The effect of synthesis parameters on the surface area of tungsten nitride was investigated extensively. The nitridation mechanism was investigated by in-situ XRD and N₂ adsorption analysis. It was found that H₂WO₄ was initially transformed into WO₃ by eliminating the axial water molecules, and WO₃ retained the layered and porous structure of H₂WO₄. Below 773 K, WO₃ was just partially reduced to W₂₀O₅₈ and W₂₀O₄₀. Above 773 K, β-W₂N phase could be detected. It indicated that during nitridation, WO₃ was gradually reduced and then the homogeneous substitution of oxygen vacancies in the reduced oxides with nitrogen atoms occurred. Based on the experimental results, a reduction-nitridation mechanism was firstly proposed.     

The influence of irradiation on the microhardness and photoluminescence of SiO2

The microhardness and photoluminescence spectra excited with 337-nm laser radiation in commercial SiO₂ glasses (UV windows, substrates with BaTiO₃ film coatings) exposed to ⁶⁰Co gamma radiation and a mixed neutron flux from the reactor are investigated. It is revealed that initial samples contain nanocrystalline phases. An increase in the microhardness and the intensity of the excitonic UV luminescence due to ⁶⁰Co gamma irradiation and the quenching of the photoluminescence associated with the nonbridging oxygen centers result from healing of Si-O dangling bonds and microcracks in the surface layer at the nanocrystal-glass matrix and substrate-coating interfaces. It is demonstrated that reactor irradiation leads to the phase transformation of SiO₂ cristobalite into tridymite and BaO into BO₂, as well as to the decomposition of BaTiO₃ and BaCO₃. This brings about a decrease in the microhardness and photoluminescence quenching.     

Preparation of tungsten borides by combustion synthesis involving borothermic reduction of WO3

An experimental study on the preparation of two tungsten borides, WB and W₂B₅, was conducted by self-propagating high-temperature synthesis (SHS), during which borothermic reduction of WO₃ and elemental interaction of W with boron proceeded concurrently. Powder mixtures with two series of molar proportions of WO₃:B:W = 1:5.5:x (with x = 1.16–2.5) and 1:7.5:y (with y = 0.5–1.33) were adopted to fabricate WB and W₂B₅, respectively. The starting stoichiometry of the reactant compact substantially affected the combustion behavior and the phase composition of the final product. The increase of metallic tungsten and boron reduced the overall reaction exothermicity, leading to a decrease in both combustion temperature and reaction front velocity. The initial composition of the reactant compact was optimized for the synthesis of WB and W₂B₅. In addition to small amounts of W₂B and W₂B₅, the powder compact of WO₃ + 5.5B + 2 W produced WB dominantly. Optimum formation of W₂B₅ was observed in the sample of WO₃ + 7.5B + 0.85W. Experimental evidence indicates that an excess amount of boron about 10–13% is favorable for the formation of WB and W₂B₅.     

Effect of Y2O3 on the structural,optical and radiation shielding properties of transparent Na-rich borate glass with diluted and fixed Fe2O3

We study the impact of yttrium oxide (Y₂O₃) on the optical properties of iron-doped borate glasses. A series of borate glasses, with a diluted and constant amount of Fe₂O₃, doped with various amounts of Y₂O₃ (labeled as BNaFeY-glasses) was prepared and studied. The impact of Y₂O₃ doping on the optical transitions of BNaFeY-glasses was studied by analyzing the optical absorption spectra. The presence of Fe cations, with their Fe³⁺ state, leads to the appearance of absorption in the ultraviolet region. Furthermore, the optical transmittance spectra proved the transparency of all BNaFeY-glasses. Moreover, the transmittance of the sample with the highest Y₂O₃ content is about 93 % within the visible range. Because of the diluted Fe content within BNaFeY-glasses, the five absorption bands of Fe are not observed. So, these bands are detected by magnifying the spectra within the visible region. These bands are labeled ?₁, ?₂, ?₃, ?₄ and ?₅ at wavelengths 454.5, 518.4, 652.5, 707 and 808 nm respectively. These bands were used to calculate the crystal field splitting (10Dq) for all BNaFeY-glasses. The outstanding 10Dq increment with further Y₂O₃ doping was explained in terms of more interactions between Fe cations and their surroundings. On the other side, the shielding parameters were considered to examine the competence of these transparent glasses against nuclear radiation. We found that the sample doped with the highest amount of Y₂O₃ has the highest linear attenuation coefficient and the lowest half-value layer (HVL). From the HVL results, we need a thickness of 3.646 cm from the sample with 5 mol% of Y₂O₃ to get protection from 50% of the photons with energy of 0.662 MeV, and this thickness is increased to 5.137 cm when the energy is 1.333 MeV.     

Integration Between Optical and Structural Behavior of Heavy Metal Oxide Glasses Doped with Multiple Glass Formers

Heavy metal oxide glasses (composition 60 PbO, 20 Bi₂O₃ mol%) and containing 20 mol% conventional glass formers SiO₂, B₂O₃, and P₂O₅ were prepared. Combined optical and Fourier transform infrared absorption spectra were measured for the prepared glasses to justify the role of glass formers in the optical spectra together with the network structural groups in such glasses. Also, the density and molar volume values were calculated to obtain some insight on the compactness and arrangement in the network. Optical measurements have been used to determine the optical band gap (E_g), Urbach energy (ΔE) and the refractive index (n). Optical spectra of all the samples reveal strong UV absorption which is related to the presence of unavoidable trace iron impurities (Fe ³⁺ ions) contaminated within the raw materials which were used for the preparation of the studied glasses. Additional near visible bands are observed in all prepared glasses due to characteristic absorption of Pb ²⁺ and Bi ³⁺ ions. Furthermore, The variations of the luminescence intensity, values of the optical band gap, band tail, and refractive index can be understood and related in terms of the structural changes that take place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate or silicate or phosphate network (BO₃, BO₄, SiO₄, PO₄ groups) together with vibrational modes due to Bi-O and Pb-O groups.     

Effect of Al3+ on the photoluminescence and radioluminescence properties of Mn2+-Doped high silica glass

Mn²⁺/Al³⁺-, Eu²⁺/Mn²⁺-, and Eu²⁺/Mn²⁺/Al³⁺-doped high silica glasses were prepared to investigate their photoluminescence and radioluminescence properties. Particularly, the effect of Al³⁺ on the energy transfer from Eu²⁺ to Mn²⁺ and the regulation law of Mn²⁺ luminescence properties in Mn²⁺/Al³⁺- and Eu²⁺/Mn²⁺/Al³⁺-doped glasses were investigated. A strategy to improve the radioluminescence intensity of glasses was developed, and the radioluminescence intensity formula was improved. The dispersion caused by Al³⁺ improves the luminous intensity of Mn²⁺ and lowers the efficiency of the Eu²⁺→Mn²⁺ energy transfer in high silica glass. Al³⁺ can significantly broaden the excitation spectrum of Mn²⁺ by affecting the coordination number of Mn²⁺ and changing the field intensity around Mn²⁺ ions. Notably, the developed glass can potentially be applied in laser and LED lights. In addition, nonbridging oxygens (NBOs) are considered to be the main factor leading to the low efficiency of glass radioluminescence. Al³⁺ is able to reduce the relative amount of NBOs by forming [AlO_4/2]^?1 tetrahedra, thereby improving the radioluminescence intensity effectively.     

Tunable colors and applications of Dy3+/Eu3+ co-doped CaO-B2O3-SiO2 glasses

A series of Dy³⁺/Eu³⁺ single- and co-doped calcium borosilicate luminescent glasses were prepared by the conventional high temperature melt-quenching method. A compact glass structure is obtained by the addition of Dy³⁺/Eu³⁺ ions, which is verified by the physical properties of synthetic glasses. As network modifiers, Dy³⁺/Eu³⁺ fill in the interspaces of glass network and contribute to the conversion of [BO₃] to [BO₄]. Dy³⁺/Eu³⁺ co-doped calcium borosilicate glasses can emit white light, which consists of blue, yellow, and red light under 387 nm excitation. The emission spectra and decay curves of the white-emitting glasses have proved the existence of energy transfer. The average lifetime of Dy³⁺ decreases from 0.251 to 0.165 ms with the increasing Eu³⁺ concentration. Changing rare earth ions concentration, CIE color coordinates of Dy³⁺/Eu³⁺ co-doped glass shifts from cyan to white with increasing excitation wavelength. A white-light emission is obtained when the concentration of Dy³⁺ and Eu³⁺ equals to 4% and 2%, respectively. Moreover, the Dy³⁺/Eu³⁺ co-doped calcium borosilicate glass shows high-thermal stability and it may be applicable for high-quality white LEDs based on high power near ultraviolet (n-UV) LED chip in the future.