Calcium Silicate Glasses Research Articles

Calcium Silicate Glass Ceramics Containing Chromium Sulfate: Structural, Optical, and Shielding Properties

Calcium Silicate Glass Ceramics Containing Chromium Sulfate: Structural, Optical, and Shielding Properties

Structure role of cesium bromide in calcium silicate glasses and glass ceramics

AbstractTo make the interpretation of the complex xCsBr.(100 − x)(CaO:SiO2) glasses easier to study, the structure of glasses in a binary composition CaO–SiO2 is being initially investigated. The changes in the crystallization behavior of glasses and the local environment surrounding silicon atoms could be easily followed using X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectroscopy. The XRD pattern of the binary 50CaO–50SiO2 glass showed that its structure was amorphous. But when (CaO:SiO2) is replaced with CsBr, some sharp diffraction lines appear in system of the ternary xCsBr.(100 − x)(CaO:SiO2) glass composition. A Polycrystalline Cs2Ca(SiO3)2 structure is the primary phase in CsBr rich glasses. The results based on transmission electron microscopy (TEM-EDP) and X-ray diffraction pattern (XRD) are in excellent agreement, indicating that crystalline-clustered species develop in glasses enriched with CsBr. Both the NMR and FTIR spectra are clearly defined, and they contain different features that distinguish between different silicate structural subunits. One and two bridging oxygen atoms (BO) can be found in the main SiO4 structural units. Such units become less shielded due to increasing of nonbridging oxygen atoms (NBO) in the silicate network by increasing CsBr at the expense of both SiO2 and CaO. There is a good correlation between the data obtained from FTIR and NMR spectroscopy. Both techniques could differentiate between BO and NBO involved in the silicate structural units.

Synthesis of biogenic calcium silicate glasses from biomass: Physical, dielectric and electrical properties

Biogenic calcium silicate glasses were synthesized from the biomass wastes by melt-quench technique at a high temperature of 1550 °C. XRD pattern showed the preferred orientation along the c-axis (002) regardless of the concentration of eggshell powder. The optical bandgap (Eg) decreased from 3.96 to 3.74 eV, and the refractive index (n) increased from 2.17 to 2.22 as ESP risen from 0 to 25 wt.%. The dielectric constant (ε′) of sintered glasses was measured at 1 kHz and 1 MHz to be 40–135 and 27–44, respectively. The decreasing, ε′ and tanδ with respect to concerning temperature is attributed to the most miniature hopping mechanism. The σac of SE-3(H) was observed to be the lowest (5.26 × 10−7 S/m) at 400 °C due to the lower volume of non-bridging oxygen. The study of silicate glasses suggests the major applications in the semiconductor industries, the sealing of energy harvesting and energy storage devices.

Nanofibrous hybrid scaffolds based on PCL-borosilicate system by a green sol-gel process

Tissue regeneration is yet a critical issue, and to mimic the natural extracellular matrix (ECM) innovative scaffolds need to be developed to ensure the functional and safe repair of the damaged organs or tissues. Hybrid biomaterials based on the combination of a biodegradable polymer and bioactive glasses (BGs) are potential candidates for tissue engineering (TE), since they exhibit tailored physical, biological, and mechanical properties, as well as controlled degradation behavior. Thus, the main purpose of this research was to develop by electrospinning (ES) a hybrid nanofibrous membrane composed of a synthetic polymeric matrix (PCL) and a boron and calcium silicate glass, formed via in situ sol-gel, and based on a non-aqueous and green fabrication route. Formic acid (FA) and glacial acetic acid (AA) were used as green solvents to dissolve the PCL. Different compositions were prepared: neat PCL and PCL/SiO2–B2O3–CaO with different sol-gel aging times and green solvent systems. All prepared hybrid solutions, except the composition with only AA, were spinnable. Structural features of the hybrids were assessed by ATR-FTIR spectroscopy, which confirmed the presence of siloxane (Si–O–Si) bonds of silica and carbonyl (CO) bonds characteristic of PCL polymer as well as intermolecular hydrogen-bonding interactions between the carbonyls of PCL and the silanol hydroxyls (Si–OH) of silica networks. Boron (B–O–B) and borosiloxane (B–O–Si) bonds were not visible due to the overlapping of PCL bands in the spectra. Only the solid state 11B NMR technique allowed to find peaks assigned to trigonal BO3 and tetrahedral BO4 groups, which evidence the boron linkages to silica. Thermal analysis showed a change in the crystallinity of PCL with the incorporation of inorganic domains, confirming the formation of chemical interactions between the polymer and the inorganic part. Microstructure and chemical analysis, by SEM/EDS, showed a homogenous distribution of Ca and Si elements into the fibers, as well as an increase of the fiber diameter with the incorporation of boron and calcium silicate glass in the PCL. The developed compositions of PCL/boron and calcium-containing silicate were feasible to electrospin into fibrous meshes, proving its potential for further design of multicomponent nanofibrous microstructures closer to extra cellular matrix architectures.

Influence of manganese ions in calcium silicate glass–ceramics on optical, mechanical, and magnetic properties

Nanocrystalline calcium silicate powder was synthesized by adding different ratios of MnO2 ranging from 0.00 to 2.00 wt% to detect its effect on the structure and physical properties. The pseudowollastonite triclinic and low combeite of hexagonal phase with nanocrystallite size less than 85.0 nm were confirmed by the XRD technique and average particle size ranging from 7.8 to 27.9 nm as detected by HR-TEM micrograph images. Stretching and bending vibration of the O–Si–O band were shifted to higher values upon the addition of MnO2 were verified by FT-IR. Increasing both the density and ultimate strength with a reduction in the porosity leads to an improvement in the mechanical properties with the addition of MnO2. Additionally, the increasing MnO2 content showed an improvement in magnetic and optical properties, which exhibited a decrement in the optical band gap Eg from 3.9 to 1.6 eV. Hence, the MnO2 acts as a structural network modifier of calcium silicate glass–ceramics. Furthermore, the estimated values of the Lande g-factor (2.01534–2.01731) for the d5 system of the Mn2+ displayed a negative shift from the free electron (2.0023), and the hyperfine splitting constant A value was 87 × 10−4 cm−1, indicating that the Mn2+ ions are in an ionic environment.

A comparative evaluation of light cure calcium silicate and resin-modified glass ionomer as indirect pulp capping agent in primary molars: A randomized clinical trial.

Minimally invasive techniques should be employed to maintain pulp vitality without affecting physiological tooth resorption for pediatric patients. This study aims to evaluate clinical and radiographic success of light cure calcium silicate and resin-modified glass ionomer (RMGI) as indirect pulp-capping agent in primary molars in children between 5 and 9 years. In this randomized clinical trial study, 40 primary molars with the International Caries Detection and Assessment System criteria 4-6 score were divided randomly into two groups after computerized randomization method. After caries excavation by minimally invasive dentistry principle, affected dentin was lined by either light cure calcium silicate (Group I) or RMGI (Group II) liner followed by composite restoration. Clinical success was determined with the absence of symptoms and bitewing radiographs were taken at baseline, 3, and 6 months' interval to measure increase in dentin increment using ImageJ software. Statistical analysis for intergroup comparison was done using Paired t-test, and Independent t-test was used for intragroup comparison. The level of statistical significance was set at P < 0.05. Change in dentin increment seen from baseline to 6 months in Group I was 0.19 mm and in Group II was 0.20 mm (P = 0.924). Intragroup increment was statistically significant during all follow-up intervals for both the groups (Group I - P ≤ 0.001, Group II - P = 0.009). For baseline remaining dentin thickness >1.5 mm, statistically significant increase was observed in the dentin increment at 3 months' interval between both the groups. Both TheraCal LC and Vitrebond show acceptable clinical and radiographic results when used in primary molars as indirect pulp treatment agents. Both the liners are equivalent to each other in terms of feasibility and cost-effectiveness but TheraCal LC can be preferred due to better handling and avoiding the manipulation step thereby reducing treatment time.

Optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses.

In this study, the indirect/direct optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses under different excitation wavelengths were investigated. Zinc calcium silicate glasses with the main compositions of SiO2-ZnO-CaF2-LaF3-TiO2 were prepared by the conventional melting method. EDS analysis was performed to determine the elemental composition existing in the zinc calcium silicate glasses. Visible (VIS)-, upconversion (UC)-, and near-infrared (NIR)-emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were also investigated. Indirect optical band gaps and direct optical band gaps of Bi m+-, Eu n+- single-doped, and Bi m+-Eu n+ co-doped SiO2-ZnO-CaF2-LaF3-TiO2-Bi2O3-EuF3-YbF3 zinc calcium silicate glasses were calculated and analyzed. CIE 1931(x, y) color coordinates for VIS and UC emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were determined. Besides, the mechanism of VIS-, UC-, NIR-emissions, and energy transfer (ET) processes between Bi m+ and Eu n+ ions were also proposed and discussed.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review.

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

The effect of V2O5/MgO substitution on SiO2-Na2O-CaO-ZnO–MgO glass structure

V2O5 incorporated sodium calcium silicate glasses of composition 55SiO2 - 25 Na2O - 5CaO - 10ZnO - 5MgO(1-x): V2O5(x) (x = 0, 0.01, 0.03, 0.05, and 0.1) have been prepared by melt-quench technique. In the determination of the glass network, a silicate glass structure was chosen for physical and chemical strength. It was preferred to use ZnO for high light transmittance and V2O5 to reduce the optical band gap. The structural and thermal properties of the samples were explored using Fourier transform infrared (FTIR) spectroscopy and differential thermal analysis (DTA), respectively. The optical properties of the glasses were detected by UV–VIS spectroscopy between the wavelength ranges of 200–1100 nm. The indirect band gap (Eg) and Urbach energy (Eo) values have been evaluated with the help of absorption spectra. Also, the refractive index values have been determined by spectroscopic ellipsometry. All data have been interpreted corresponding with V2O5 contributions.

Fabrication, structural, and physical properties of alumina doped calcium silicate glasses for carbon dioxide gas sensing applications

Attempts have been made to synthesize alumina doped calcium silicate glasses in the system 40SiO2–35K2O-(25-x)CaO (x = 0, 2, 4, and 6) via melt-quenching method. Density of the glasses were estimated by employing Archimedes’ principle and obtained within the range of 2.421±0.012 to 2.176±0.011 gm/cm3, the oxygen packing density (OPD) and ionic concentrations were estimated and found to be in the range of 58.818±0.294–54.161±0.271 × 10−3 gm-atom/cm3 and 0–195.725±0.979 ion/cm3 respectively. FTIR and Raman investigations showed the existence of numerous bonds of Si-O-Si, β-CaSiO3, Si-O−, C = O, CO32− and OH, which are due to diverse modes of vibrations. As doping concentration of Al2O3 increases optical band-gap increase from 1.5 to 2.5 eV. Refractive index (n), and optical dielectric constant (ε) were determined and lies within the range of 1.210±0.024–0.827±0.017 and 1.464±0.029- 0.684±0.014. CO2 gas sensing measurements were done at room temperature, 32 °C and maximum sensor response (9.93) was recorded for the glass SKCA6 at 1000 ppm.

Down- and up-conversion processes in Nd3+/Yb3+ co-doped sodium calcium silicate glasses with concomitant Yb2+ assessment

Novel Nd3+/Yb3+ co-doped sodium calcium silicate glasses were prepared by melting quenching method. Spectroscopic study was carried out as a function of doping content by fixing sensitizer (Nd3+) concentration to 0.2 mol% and adjusting activator (Yb3+) from 0 to 1.0 mol%. The energy transfer (ET) mechanisms between Nd3+ and Yb3+ are discussed based on their energy levels and excitation power-dependence emission intensity. Results show that the presence of Yb2+ might be considered for the Nd3+-free and co-doped samples. The ET was confirmed by the down-conversion NIR emission spectra of the doped and co-doped samples under excitation at 808 nm. The mechanisms observed seem to involve only one VIS absorbed photon for each NIR emitted via direct energy transfer between 4F3/2 of Nd2+ and 2F5/2 of Yb3+ compensated by phonon assistance due to energy gap between these levels. The efficiency of ET increases with the ytterbium content up to almost 90% for the sample with 1 mol% of Yb2O3, which was evaluated by lifetime measurements. Up-conversion photoluminescence by exciting trivalent ions of neodymium (808 nm) and ytterbium (975 nm) is reported. The observed up-converted emission bands are related to the 4f-4f transitions of Nd3+ and the spin-forbidden 5d-4f transition of Yb2+. Nd3+ up-conversion emission is observed under 975 nm excitation, presenting an almost quadratic emission dependence with power excitation, which suggests that two laser photons participate in the up-conversion (UC) process, showing that ET occurs by a phonon-assisted energy transfer and cooperative energy transfer.

Revisiting the Effect of the Interatomic Potentials in the Simulated Calcium Silicate Glasses

Revisiting the Effect of the Interatomic Potentials in the Simulated Calcium Silicate Glasses

Revisiting the Effect of the Interatomic Potentials in the Simulated Calcium Silicate Glasses

Revisiting the Effect of the Interatomic Potentials in the Simulated Calcium Silicate Glasses

Color tunability and synergistic effect of PiG materials based on YAG:Ce3+ phosphor in SCS:Eu3+ glass

Efficient white-emitting phosphor-in-glass (PiG) was successfully synthesized by synergistic complexation of Ce3+-doped YAG phosphor and Eu3+-doped sodium calcium silicate glass. The crystalline phosphor was obtained via sol-gel route using polyvinyl alcohol (PVA), whereas glasses were prepared by melting-quenching method. Rare-earth ions were successfully incorporated into the YAG and glass host lattices without changing their original structures. Through adjusting the Eu3+-doped glass and Ce3+:YAG phosphorus contents in the PiG, it was possible to optimize the chromaticity emission from yellow-green to orange-red in CIE 1931 diagram. Combination of a violet LED and samples emissions, allowed to achieve the chromaticity parameters closer to an ideal white light source [CIE-(0.33, 0.33); CCT 5000K]. Moreover, adjusting the luminescence intensity ratio between the LED and the PiG emission provides a tuning route for smart white light devices.

Eu2+-Nd3+ co-doped glasses for solar spectrum modification via NUV/visible to NIR downconversion

The challenge of modifying the solar spectrum intensifies efforts in the pursuit of enhanced materials and optical systems. In this work, we present novel and efficient near infrared-emitting Eu2+ and Nd3+ co-doped sodium calcium silicate glasses. Optical absorption, excitation spectra, emission decay time, were measured and discussed as a function of Nd2O3 content. Laser power-dependent emission intensity was used to evaluate the transfer mechanism, and an energy level diagram was proposed. For the sample doped with optimized neodymium content, energy transfer efficiency reached 70%. For co-doped samples, the excitation spectrum was broadly intense and perfectly overlapped with the solar spectrum in the NUV region. Therefore, NUV/Visible can be efficiently converted into NIR, precisely where the C-Si response is maximal, through the Eu2+→Nd3+ pathway. This work’s outcomes made the focused materials worthy for solar cell applications, optimizing energy conversion lost by thermalization, into useful energy.

Thermal, optical and structural properties of relatively depolymerized sodium calcium silicate glass and glass-ceramic containing CaF2

This paper reports on the synthesis and characterization of original sodium calcium silicate glass, with CaF2 as a nucleating agent, along with the successful transformation of the as-made matrix into glass-ceramic. Characteristic temperatures of thermal events were investigated by Differential Thermal Analysis. Volumetric density, refractive index, molar volume, and electronic polarizability of the newly developed glasses were determined and discussed as a function of Ca(O/F2) and Na2O content, fixing glass former SiO2 at 50 mol%. Transmittance and optical band gap energy were evaluated. Network structure was studied through Raman spectroscopy and X-Ray diffraction. Moreover, Eu3+ was used as a local structural probe in equivalent Eu2O3-doped samples. Luminescence properties (emission spectra and transition lifetimes) allowed us to investigate the local environment of precursor glass and glass-ceramic. Calcium fluoride nanostructured glass-ceramic, with 20 nm-sized crystals, was obtained with significant transparency (60–70% in VIS region). The refractive index of synthesized glasses was too close to that of precepted crystals, which is the requisite for high transmittance. The decay time of Eu3+ ions embedded into the matrix has shown that the glass-ceramics environment's phonon energy is lower than in as-made glass, making this matrix an excellent candidate for photonics applications.

Potential of tailored amorphous multiporous calcium silicate glass for pulp capping regenerative endodontics—A preliminary assessment

Introduction/ObjectiveThe tailored amorphous multi-porous (TAMP) material fabrication technology has led to a new class of bioactive materials possessing versatile characteristics. It has not been tested for dental applications. Thus, we aimed to assess its biocompatibility and ability to regenerate dental mineral tissue. Methods30CaO-70SiO2 model TAMP discs were fabricated by a sol-gel method followed by in vitro biocompatibility testing with isolated human or mini-swine dental pulp stem cells (DPSCs). TAMP scaffolds were tested in vivo as a pulp exposure (pin-point, 1 mm, 2 mm, and entire pulp chamber roof) capping material in the molar teeth of mini-swine. ResultsThe in vitro assays showed that DPSCs attached well onto the TAMP discs with comparable viability to those attached to culture plates. Pulp capping tests on mini-swine showed that after 4.5 months TAMP material was still present at the capping site, and mineral tissue (dentin bridge) had formed in all sizes of pulp exposure underneath the TAMP material. ConclusionsTAMP calcium silicate is biocompatible with both human and swine DPSCs in vitro and with pulp in vivo, it may help regenerate the dentin bridge after pulp exposure.

Rigidity theory of glass: Determining the onset temperature of topological constraints by molecular dynamics

Topological constraint theory has been extensively used to describe how the composition and structure of glasses and glass-forming melts control their properties. This approach relies on an accurate enumeration of the topological constraints acting in the atomic network. Such direct enumeration is challenging since constraints can be active or thermally-broken depending on temperature. Here, based on molecular dynamics simulations, we present a generic method aiming to predict the onset temperature below which constraints become active. We illustrate this method by considering the example of a series of binary calcium silicate glasses. We find that inter-polytope angular bond-bending constraints are associated with a lower onset temperature than intra-polytope angular constraints. Based on this, we show that the differing values of these two onset temperatures largely govern the glasses’ fictive temperature.

Insight into the structure-elastic property relationship of calcium silicate glasses: a multi-length scale approach.

Based on a combination of molecular dynamics simulations, and Raman and Brillouin light scattering spectroscopies, we investigate the structure and elastic properties relationship in an archetypical calcium silicate glass system. From molecular dynamics and Raman spectroscopy, we show that the atomic structure at the short and intermediate length scales is made up of long polymerized silicate chains, which adjusts itself by closing the Si-O-Si angles and leaving more space to [CaO]n edge shared polyhedra to strengthen the glass. Using Brillouin spectroscopy, we observe an increase of elastic constants of the glass with the calcium content, as the cohesion of the glass structure is enhanced through an increase of the binding between the cross-linked calcium-silicate frameworks. This result, albeit being simple in its nature, illustrates for the first time the implication of the calcium framework in the elastic behavior of the glass and will contribute substantially to the understanding of the composition-structure-property relationships in multi-component industrial glasses.

Application and research of nano-biomaterials in ankle sports injury rehabilitation

The ankle joint is an important weight-bearing joint of the lower limbs. It converts the vertical gravity of the human body into an arched structure. When the ankle joint is exposed to external reaction forces and cannot be effectively cushioned, injuries can easily occur. If improper and untimely treatment can cause joint instability, easy to repeatedly sprain in the future, secondary joint adhesions or traumatic arthritis can cause dysfunction. Therefore, strengthening the treatment of ankle joint injury repair is of great significance to improve prognosis and improve clinical effect. Clinically, the treatment of ankle joint injury is mainly based on protection, rest, cold compress, and drug intervention. It is difficult to achieve the expected therapeutic effect. From a large amount of research data, with the development of tissue engineering and bioengineering, currently the use of artificial biological materials to intervene in the healing and rehabilitation of bone injuries has become increasingly mature, but it is relatively rare in rehabilitation measures for ankle sports injuries. Therefore, in this study, 3D printing technology was used to mix PHBV, calcium silicate, and bioactive glass to successfully prepare a bioglass scaffold BG-Si-PHBV. The micromorphology, porosity, water absorption, weight loss analysis and biomechanical characteristics of the biomaterial scaffold were studied. At the same time, this study established an ankle joint sports injury model with Beagle dogs, implanted BG-Si-PHBV biological bone tissue scaffold material into the ankle joint defect area of the affected limb of Beagle dogs, and detected BG-Si-PHBV tissue engineering materials to repair the ankle joint Feasibility of sports injuries. The BG-Si-PHBV biological bone tissue scaffold material prepared in this research has good porosity, hydrophilicity and biomechanical properties, which can meet the conditions of artificial biological materials after ankle injury. Animal experiments show that BG-Si-PHBV biological bone tissue scaffold is ideal for the rehabilitation of ankle joint sports injuries. This helps to improve the biomechanical properties and has broad application prospects.