Mixed-Alkali Effect on Thermal Property and Elastic Behavior in Borosilicate Glasses

We investigated the mixed alkali effect on the thermal properties and elastic response to temperature in the borosilicate glasses system with the composition of 70.65Si O_(2)·21.09B_(2)O_(3)·1.88Al_(2)O_(3)·(6.38-x)Li_(2)O·x Na_(2)O glasses,where x=0.00,1.595,3.19,4.785,and 6.38.Except for the expected positive and negative deviations from linearity for the coefficients of thermal expansion,room temperature E and G,we observed a new mixed alkali efiect on the response of elastic moduli to temperature.Fourier transform infrared spectra were obtained to elucidate the possible structural origin of the mixed alkali efiects.This work provides a valuable insight into the structural and mechanical properties of mixed-alkali borosilicate glasses.

Visible to deep ultraviolet range optical absorption of electron irradiated borosilicate glass

To study the room-temperature stable defects induced by electron irradiation, commercial borosilicate glasses were irradiated by 1.2 MeV electrons and then ultraviolet（UV） optical absorption（OA） spectra were measured. Two characteristic bands were revealed before irradiation, and they were attributed to silicon dangling bond（E＇-center） and Fe^3＋species,respectively. The existence of Fe3＋was confirmed by electron paramagnetic resonance（EPR） measurements. After irradiation, the absorption spectra revealed irradiation-induced changes, while the content of E＇-center did not change in the deep ultraviolet（DUV） region. The slightly reduced OA spectra at 4.9 eV was supposed to transform Fe3＋species to Fe^2＋species and this transformation leads to the appearance of 4.3 eV OA band. By calculating intensity variation, the transformation of Fe was estimated to be about 5% and the optical absorption cross section of Fe2＋species is calculated to be 2.2 times larger than that of Fe^3＋species. Peroxy linkage（POL, ≡Si–O–O–Si≡）, which results in a 3.7 eV OA band, is speculated not to be from Si–O bond break but from Si–O–B bond, Si–O–Al bond, or Si–O–Na bond break. The co-presence defect with POL is probably responsible for 2.9-eV OA band.

The Coordination State of B and Al of Borosilicate Glass by IR Spectra

The IR spectra of R2O-RO-B2O3-SiO2 and R2O-RO-B2O3-Al2O3-SiO2 glasses were tested for the study of coordination state of B, Al and their content. The results show that no matter Na2O/B2O3〉1, =1, or〈1, both [BO3] and destroyed Si-O bond exist in glass structure; the addition of Al2O3 to borosilicate glass reduced both the number of non-bridging oxygen in the silicate network and the number of [BO4] units.

Preparation and Optical Properties of Er^(3+)-Doped Gadolinium Borosilicate Glasses

Er^(3+)-doped Gd_2O_3 -SiO_2 -B_2O_3 -Na_2O glasses were prepared, and formation range of glass of Gd_2O_3 -SiO_2 -B_2O_3 system was experimentally obtained. It is found that the glass phase can be formed only when the content of SiO_2 is 0～50%(molar fraction), Gd_2O_3 is 0～30%(molar fraction) and B_2O_3 is above 20%(molar fraction) in this glass system. The glass can also be obtained but becomes translucent at the contents of 60%(molar fraction) SiO_2 and 30% Gd_2O_3 , or at the contents of 60%(molar fraction) SiO_2 and 30%(molar fraction) B_2O_3. There is no glass phase formed in other glass components. Glass forming ability for Gd_2O_3 content of 10%, was characterized by the value of β, the parameter of crystallization tendency, which is 0.32～1.76, obtained from the differential thermal analysis. The absorption and emission cross section, the J-O parameters Ωt_((2,4,6)) and radiative transition probabilities were calculated by using the theory of McCumber and Judd-Ofelt. The emission properties at 1.5 μm of the samples are discussed with the product of full width at half maximum and stimulated emission cross section. It can be seen that the value of the FWHM×σ_e^(peak) product in the prepared glass is more than those of germanate, silicate and phosphate glasses. Furthermore, the maximum value of the product among these glasses reported in this work is close to that of oxyfluoride silicate glass. Therefore, the Er^(3+)-doped gadolinium borosilicate glass in this paper is a candidate for broadband erbium doped fiber amplifiers.

Effect of SiO_2/B_2O_3 Ratio on the Property of Borosilicate Glass Applied in Parabolic Trough Solar Power Plant

This work aimed to analyze the glass material used for sealing the end of a thermal collector in a parabolic trough solar power plant. Based on matched sealing requirements and application performance of glass and Kovar alloy 4J29, one borosilicate glass material （GD480S）, whose expansion coefficient was similar to that of Kovar alloy 4J29, was studied. Moreover, the effect of the ratio of SiO2 to B203 on the glass properties was explored in detail by Fourier transform infrared spectroscopy. As the SiO2 to B203 ratio in the glass increased from 4.18 to 5.77, the expansion coefficient showed a decreasing trend from 4.95×10-6/℃ to 4.55℃ 10-6/℃. In addition, the water resistance performance improved, enabling the glass material to seal well with the alloy for application in a trough solar power plant. Thus, the increase in the SiO2 to B2O3 ratio made the glass structure more compact and improved the glass performance to meet the requirements of an industrial tubular receiver.

Thermal Analysis and Immobilisation of Spent Ion Exchange Resin in Borosilicate Glass

The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. The thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) were used in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG-3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical works and shows that it is possible to minimise the volume of the waste while keeping the required safety levels, however further research needs to be carried out in this area.

The Effect of Sm_2O_3 on the Chemical Stability of Borosilicate Glass and Glass Ceramics

Sm2O3 containing zinc-borosilicate glass and glass ceramics were prepared by melt quenching method, and the effect of Sm2O3 and micro-crystallization on the chemical stability of borosilicate glass was explored. DTA analysis showed that the endothermic peak and exothermic peak of basic glass changed from 635 ℃ and 834 ℃ to 630 ℃ and 828 ℃ respectively as a result of the doping of Sm2O3. XRD analysis showed the promoting effect of Sm2O3 on crystallization ability of this glass. The cumulative mass loss of base glass, Sm2O3 containing glass, glass ceramic and Sm2O3 containing glass ceramic was 0.289, 0.253, 0.329, 0.269 mg/mm2 respectively after 26 days corrosion in alkali solution, and 1.293, 1.290, 0.999, 1.040 mg/mm2 respectively in acidic erosion medium. Micro-crystallization decreased and improved the alkali and acid resistance of borosilicate glass respectively, the addition of Sm2O3 increased the alkali resistance of base glass and glass ceramics, and the slight effect of Sm2O3 on the acid resistance of borosilicate glass was also observed.

Effects of energy deposition on mechanical properties of sodium borosilicate glass irradiated by three heavy ions: P, Kr, and Xe

Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification;therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 10^20 keV/cm^3 and 1.8 × 10^20 keV/cm^3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 10^22 keV/cm^3 in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.

Effects of SnO on Structure and Propertiesof Borosilicate Glasses

Tin was found in the bottom of float borosilicate glasses. To simulate the enriched amounts of SnO found on the surface of the float borosilicate glasses, a series of glasses were produced in which the stannous concentration was varied from 0.1 wt% to 9.0 wt%, while the relative concentration of other components were held constant. Infrared spectra were obtained to probe the effect of increased amounts of SnO on the structure of the glass samples. The results show that SnO plays the role of an intermediate in glasses studied. When FO/SnO〉1.0, SnO takes the role of network-former. And when FO/SnO〈1.0, SnO can give the free oxygen as network-modifier. Besides, SnO has intensive effect on thermal performance of borosilicate glasses.

Up-conversion photoluminescence characteristics of Yb^(3+):Er^(3+):Tm^(3+) co-doped borosilicate glasses

Yb^3＋：Er^3＋：Tm^3＋co-doped borosilicate glasses are prepared. Their strong up-conversion photoluminescence spectra in a range from ultra-violet to near-infrared, which are excited by a 978-nm laser diode, are measured, and the mechanisms of energy transfer among Yb^3＋ Er^3＋ and Tm^3＋ ions are discussed. The results show that there is an unexpected wavelength at 900-nm emission from Yb^3＋ Stark splitting levels to pump Tm^3＋ ions and there exists an optimum pump power. The concentration of the Tm^3＋ dopant gives rise to a prominent effect on the intensity of visible and near-infrared emissions for the yb^3＋：Er^3＋：Tm^3＋ co-doped borosilicate glasses.

Morphological and Structural Investigations on Iron Borosilicate Glasses

Borosilicate glasses and glass ceramics in the system 30Na2O-2Al2O3-25SiO2-xFe2O3(43-x)B2O3 (x = 0 - 20 mol%) have been prepared and studied by distinguished techniques. X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction pattern (EDP) and SEM experiments are applied to explore the induced structural changes. Nanometer-sized species of polycrystalline structure are formed particularly in low Fe2O3 containing glasses. The size of the crystallites is found to depend on Fe2O3 concentrations. It is ranged from 10 to 33 nanometers. Structurally, these materials are suggested to contain different components, crystalline component and an interfacial component which situated between the crystallized domains. Presence of these components affects the atomic arrangement without short- or long-range order. An intermediate range ordered structure is dominant in glass ceramics of Fe2O3 2O3 concentration, since more disordered structure of lower size is present. These structural changes are found to be connected with the role of Fe2O3 and Na2O in glasses. Na2O is the strong glass modifier in the studied composition region, while Fe2O3 is consumed also as a modifier in composition of 2O3 is mainly dominant in the composition region of higher iron oxide concentration (8 - 20 mol%).

Studies of Preparation and Characteristics in Borosilicate Photosensitive Glass-Ceramics

Photosensitive glass-ceramics have been extensively studied in recent years in that it is an attractive high diffraction efficiency grating materials. It is based on Stookey’s mixed fluoride sodium glass system for us to adopt, design prescriptions on the basis of SiO2-Na2O-Al2O3-ZnO for the glass main component and a series of glass doped with CeO2, AgNO3 and NaF etc. melted at about 1450?C, and the glass have good optical property (homogeneity, without bubble and stripe, high transparency). The borosilicate glass was exposed by ultraviolet light, and then after the heat treatment of the sample, the measurement of ultraviolet-visible-near infrared absorption spectrum and the X ray diffraction of exposure part was performed.

Mechanism of Cluster Formation on Cerium Borosilicate Glasses Based on TEM-EDP and SEM-EDEX Investigations

Cerium oxide has a great capacity to remove nonbridging oxygen atoms (NBO) from the glass network and serves as glass former units. The well formed CeO4 units played the role of decreasing NBO from the silicate network and cause a reduction in the concentration of tetrahedral boron groups (N4). The highest content of NBO in glass of lower CeO2 (1 mol%) has a dominant role in constructing crystalline clusters in the glass. Higher CeO2 concentration leads to formation of an amorphous glass network as documented by XRD and TEM-EDP spectra. Coordination of cerium with oxygen atoms gives uniform units of spherical morphology in the pure CeO2 as well as in cerium rich glass. Clustered species has a great benefit in the field of application, used as a shielding material for ionized radiations.

Regulating effect of borosilicate bioglass extract on the osteoblast proliferation activity and osteogenesis signaling pathway function

Objective: To study the regulating effect of borosilicate bioglass extract on the osteoblast proliferation activity and osteogenesis signaling pathway function. Methods: Osteoblasts MG-63 were cultured and divided into borosilicate group and control group that were treated with the culture medium containing borosilicate bioglass extract and the culture medium without extract respectively. After 24 h of treatment, the cell proliferation activity as well as the expression of proliferation activity markers, Wnt signaling pathway molecules and PI3K/AKT signaling pathway molecules was measured. Results: After 24 h of treatment, MTT cell viability of borosilicate group was significantly higher than that of control group, and ALP, OC, OPN, COL-I, Runx2, Wnt1, Wnt3a, β-catenin, LRP5, LRP6, p-PI3K, p-AKT, Bcl-2 and BMP protein expression in cells were significantly higher than those of control group. Conclusion: Borosilicate bioglass extract can enhance the proliferation activity of osteoblasts by activating Wnt pathway and PI3K/AKT pathway.

Spontaneous immunomodulation and regulation of angiogenesis and osteogenesis by Sr/Cu-borosilicate glass (BSG) bone cement to repair critical bone defects

Injectable bone biomaterials like bone cement should be designed and fabricated with certain biological criteria,which include:1)recruitment and polarization of the macrophages from M1(pro-inflammatory)to M2(anti-inflammatory)phenotype,2)enhance vascularization,and 3)activate osteogenic differentiation of bone marrow-derived stem cells to promote bone healing.So far,no injectable biomaterials could spontaneously regulate the entire bone healing process that involves inflammation,angiogenesis,and osteogenesis.Therefore,in this study,we designed bone cement comprised of strontium and copper-incorporated borosilicate glass(Sr/Cu-BSG)in the liquid phase of chitosan to modulate bone healing.In vitro studies showed that the controlled release of Sr and Cu ions up-regulated anti-inflammatory genes(IL-1Ra and TGF-β1)while down-regulating pro-inflammatory genes(IL-1βand IL-6)in macrophages at 3 days.Sr and Cu ions also increased the expressions of angiogenic genes(VEGF and bFGF)in HUVECs at 5 days and osteogenic genes(Runx-2,OCN,and OPN)in hBMSCs at 7,14,and 21 days.5Sr3Cu-BSG bone cement exhibited the best anti-inflammatory,angiogenic,and osteogenic properties among the bone cement groups with different Sr and Cu ratios.Short-term and long-term implantation of Sr/Cu-BSGs in femoral condylar bone defects of rats and rabbits confirmed the in vitro results,where the degradation rate of Sr/Cu-BSG matched the bone healing rate.Similar to in vitro,the 5Sr3Cu-BSG group also showed the highest bone formation in vivo.Excellent physical and chemical properties,along with its bone repairing ability,make the Sr/Cu-BSG bone cement a good candidate biomaterial for treating bone defects.

Dual stimulus responsive borosilicate glass(BSG)scaffolds promote diabetic alveolar bone defectsrepair by modulating macrophage phenotype

The regeneration of alveolar bone is still clinical challenge,particularly accompanied with diabetes,causing metabolic disorder with a protracted low-grade inflammatory phenotype.As a result,the anticipated loading of biomaterials is highly suspicious in spontaneous modulation of cells function,which is mostly disturbed by constant inflammation.In this study,we developed glucose and hydrogen peroxide dual-responsive borosilicate glass(BSG)scaffolds loaded with epigallocatechin gallate(EGCG)to synergistically modulate the abnormal inflammation of diabetic alveolar bone defects.It was found that the release of EGCG by BSG could directly regulate the shift of macrophages from M1 to the M2 phenotype by promoting autophagy and lessening the inhibition of autophagic flux.Moreover,EGCG can also indirectly regulate the polarization phenotype of macrophages by reducing the activation of NF-κb in stem cells and restoring its immunoregulatory capacity.Therefore,the addition of EGCG to BSG scaffold in diabetes allows for a more striking modulation of the macrophage phenotype in a timely manner.The altered macrophage phenotype reduces local inflammation and thus increases the ability to repair diabetic alveolar bone,showing promise for the treatment of alveolar defect in diabetic patients.

Tb^(3+)-doped borosilicate glass scintillators for highresolution X-ray imaging

Scintillators are the vital component in X-ray perspective image technology that is applied in medical imaging,industrial nondestructive testing,and safety testing.But the high cost and small size of single-crystal commercialized scintillators limit their practical application.Here,a series of Tb^(3+)-doped borosilicate glass(BSG)scintillators with big production size,low cost,and high spatial resolution are designed and fabricated.The structural,photoluminescent,and scintillant properties are systematically investigated.Benefiting from excellent transmittance(87%at 600 nm),high interquantum efficiency(60.7%),and high X-ray excited luminescence(217%of Bi4Ge3O12),the optimal sample shows superhigh spatial resolution(exceeding 20 lp/mm).This research suggests that Tb^(3+)-doped BSG scintillators have potential applications in the static X-ray imaging field.

Strontium modulates osteogenic activity of bone cement composed of bioactive borosilicate glass particles by activating Wnt/β-catenin signaling pathway

There is a need for synthetic grafts to reconstruct large bone defects using minimal invasive surgery.Our previous study showed that incorporation of Sr into bioactive borate glass cement enhanced the osteogenic capacity in vivo.However,the amount of Sr in the cement to provide an optimal combination of physicochemical properties and capacity to stimulate bone regeneration and the underlying molecular mechanism of this stimulation is yet to be determined.In this study,bone cements composed of bioactive borosilicate glass particles substituted with varying amounts of Sr(0 mol%to 12 mol%SrO)were created and evaluated in vitro and in vivo.The setting time of the cement increased with Sr substitution of the glass.Upon immersion in PBS,the cement degraded and converted more slowly to HA(hydroxyapatite)with increasing Sr substitution.The released Sr2+modulated the proliferation,differentiation,and mineralization of hBMSCs(human bone marrow mesenchymal stem cells)in vitro.Osteogenic characteristics were optimally enhanced with cement(designated BG6Sr)composed of particles substituted with 6mol%SrO.When implanted in rabbit femoral condyle defects,BG6Sr cement supported better peri-implant bone formation and bone-implant contact,comparing to cements substituted with 0mol%or 9mol%SrO.The underlying mechanism is involved in the activation of Wnt/β-catenin signaling pathway in osteogenic differentiation of hBMSCs.These results indicate that BG6Sr cement has a promising combination of physicochemical properties and biological performance for minimally invasive healing of bone defects.

Research on upconversion luminescence in new Er^(3+)/Yb^(3+) codoped oxyfluoride borosilicate glass ceramics

The upconversion luminescence of Er^3＋/Yb^3＋ ions is researched in a novel transparent oxyfluoride borosil- icate glass and glass ceramics under 980-nm excitation. Fluoride nanocrystals Ba2YF7 are successfully precipitated in glass matrix, which is affirmed by the X-ray diffraction results. Compared with the parent glasses, significant enhancement of upconversion luminescence is observed in the Er^3＋/Yb^3＋ codoped transparent glass-ceramics, which may be due to the variation of coordination environment around Er^3＋ and Yb^3＋ ions after crystallization. The possible upconversion mechanism is also discussed.

Osteogenic and anti-tumor Cu and Mn-doped borosilicate nanoparticles for syncretic bone repair and chemodynamic therapy in bone tumor treatment

Critical bone defects caused by extensive excision of malignant bone tumor and the probability of tumor recurrence due to residual tumor cells make malignant bone tumor treatment a major clinical challenge.The present therapeutic strategy concentrates on implanting bone substitutes for defect filling but suffers from failures in both enhancing bone regeneration and inhibiting the growth of tumor cells.Herein,Cu and Mn-doped borosilicate nanoparticles(BSNs)were developed for syncretic bone repairing and anti-tumor treatment,which can enhance bone regeneration through the osteogenic effects of Cu^(2+) and Mn^(3+) ions and meanwhile induce tumor cells apoptosis through the hydroxyl radicals produced by the Fenton-like reactions of Cu^(2+) and Mn^(3+) ions.In vitro study showed that both osteogenic differentiation of BMSCs and angiogenesis of endothelial cells were promoted by BSNs,and consistently the critical bone defects of rats were efficiently repaired by BSNs through in vivo evaluation.Meanwhile,BSNs could generate hydroxyl radicals through Fenton-like reactions in the simulated tumor microenvironment,promote the generation of intracellular reactive oxygen species,and eventually induce tumor cell apoptosis.Besides,subcutaneous tumors of mice were effectively inhibited by BSNs without causing toxic side effects to normal tissues and organs.Altogether,Cu and Mn-doped BSNs developed in this work performed dual functions of enhancing osteogenesis and angiogenesis for bone regeneration,and inhibiting tumor growth for chemodynamic therapy,thus holding a great potential for syncretic bone repairing and anti-tumor therapy.