Glass Crystallization Temperature Research Articles

Understanding the dielectric properties of silicone rubber‐BN nanocomposites under DC voltage

AbstractThe present study explores the dielectric and structural properties of silicone rubber composites with low‐weight percentages of boron nitride (BN) fillers aimed at insulation applications. The incorporation of BN fillers into the silicone rubber matrix significantly enhances the glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc). Notably, the dielectric constant increases while the loss factor remains minimal with a low concentration of BN fillers with silicone rubber matrix. J–V characteristics from space charge limited current (SCLC) measurements were employed to evaluate trap density. The addition of 3 wt% BN filler notably improves the crossover voltage and trap density in the silicone rubber matrix. A strong correlation has been observed between trap density values derived from SCLC measurements and surface potential decay experiments. Furthermore, the SCLC measurements at different temperatures exhibit an Arrhenius behavior, providing insights into the charge transport and trapping mechanisms. Overall, the experiment results indicate that the inclusion of 3 wt % of BN filler has significant improvement in dielectric as well as charge trap characteristics.Highlights BN filler impacts permittivity and tan (δ) based on concentration levels. Differential scanning calorimetry shows crystallinity changes with increased BN filler in silicone rubber. Surface potential relates to J–V characteristics, following SCLC mechanism. Arrhenius relation to temperature‐based SCLC shows thermally activated conduction. Trap density trends align in SCLC and surface potential decay methods.

Optical, thermal, and radiation shielding characterization of bismuth-modified zinc-lithium-tungsten-borate glass

Abstract This study examines the optical, thermal, and radiation attenuation properties of zinc-tungsten-lithium-borate glass modified with Bi2O3, synthesized using melt-quench techniques. The resulting glass samples display a significant physical property, with density increasing from 3.22 g/cm³ to 4.84 g/cm³ as Bi2O3 concentration increase from 2 to 16 mol%. The optical band gap narrows from 2.9 eV to 2.55 eV, while the refractive index increases from 2.42 to 3.49, indicating a shift in absorption to lower energy levels. Higher Bi2O3 concentrations reduce optical non-linearity while enhancing the linear optical properties of the synthesized glasses. The formation of orthoborate anions suggests that Bi3+ ions in the glasses act as network modifiers, disrupting the borate framework and introducing structural disorder. Additionally, thermal properties, including glass transition temperature (T_g), crystallization temperature (T_c), and melting temperature (T_m), decrease with increasing Bi2O3 concentration. The radiation shielding effectiveness is significantly improved, with the linear attenuation coefficient (LAC) increasing from 0.56 cm⁻¹ to 1.35 cm⁻¹ at 0.284 MeV and from 0.127 cm⁻¹ to 0.186 cm⁻¹ at 2.506 MeV as Bi2O3 content rises from 2 mol% to 16 mol%. For a glass thickness of 1 cm, the radiation protection efficiency reaches approximately 74% for a photon energy of 0.284 MeV in the sample doped with 16 mol% Bi2O3. The glass's remarkable combination of high transparency and effective radiation attenuation, positions it as a promising option for radiation shielding applications.

Synthesis structural and thermal properties of 30Li2O-20ZnO-xB2O3-(50-x) P2O5 borophosphate glasses with varying B2O3 content

A borophosphate system with the composition 30Li2O-20ZnO-xB2O3-(50-x) P2O5 (where x = 0, 10, and 45 mol%) has been successfully synthesized using the conventional melt-quenching technique. The resulting materials were analyzed for their amorphous and vitreous properties using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The study focused on the impact of boron doping on thermal properties, specifically examining the glass transition temperature (Tg), crystallization temperature (Tc), and overall thermal stability. Structural analysis was further supported by Raman spectroscopy, providing insights into the network structure of the glasses. Morphological characteristics and elemental composition were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

Dipodal silane‐treated ramie woven matt reinforced polylactic acid biocomposites for improved mechanical and thermal properties

AbstractHot compression molding was used to produce biocomposites from ramie plain‐woven fabric‐reinforced polylactic acid (PLA). Prior to composite fabrication, alkali and dipodal silane (bis(3‐trimethoxysilylpropyl) amine) (BAS) were applied to improve fiber‐matrix adhesion. Mechanical tests revealed improvements in tensile and flexural strength due to interfacial adhesion. The flexural strength of ramie PLA composite samples treated only with silane (SR‐PLA) was the highest, at 136.35 MPa. Young's modulus was 7.51 GPa. BAS treatment was crucial for ensuring strong adhesion between the fabric and the PLA matrix. In combined alkali‐BAS‐treated composites (ASR‐PLA), the glass transition and crystallization temperatures disappeared completely, affecting PLA morphology. The maximum heat of absorption (373°C) was found in SR‐PLA composites, suggesting electrostatic interactions created a three‐dimensional network. In conclusion, the initial incorporation of dipodal silane resulted in the formation of six silanol linkages with ramie fabric, leading to enhancements in the mechanical and thermal characteristics of ramie–PLA composites.Highlights Alkali and BAS treated Fabrics ironed to remove treatment‐induced wrinkles. Carded PLA fiber with consistent density and weighted in four equal portions. Fabric and PLA lay alternatively in warp direction before compression molding. SR‐PLA composites exhibited improved thermal and mechanical properties.

Thermal analysis of mortar based on crushed dune sand

This study investigates the thermal decomposition behavior of mortars formulated using crushed dune sand and thixotropic polyester resin. Thermal analysis techniques, including Differential Scanning Calorimetry (DSC), Differential Thermal Analysis (DTA), and Gravimetric Thermal Analysis (GTA), were employed to characterize the thermal transitions, decomposition stages, and stability of these mortars. Results indicate that crushed dune sand maintains consistent glass transition (Tg) and crystallization temperatures (Tc) when integrated into the mortar matrix, highlighting its thermal stability. However, the melting point (Tm) varies due to the presence of the resin, which significantly influences the composite’s thermal behavior. Decomposition analysis reveals two major weight loss stages: water evaporation between 200°C to 400°C and organic decomposition of the resin between 700°C to 800°C, with minimal weight change beyond 800°C, indicating thermal stability. The DTA results exhibit distinct endothermic reactions related to dehydration and dehydroxylation, along with a pronounced exothermic peak around 400°C, signifying resin decomposition. Elemental analysis confirms that the crushed dune sand is predominantly silica with minimal impurities, making it suitable for construction applications. This research contributes to a deeper understanding of the thermal behavior of polymer-modified mortars, with implications for enhancing thermal and mechanical properties in construction materials.

Investigation of Elaeocarpus ganitrus seed (EGs) powder as a sustainable composite biomaterial: Effects of particle size on the mechanical, frictional, and thermal properties for potential biomedical applications

This study explores the potential of Elaeocarpus ganitrus seed (EGs) powder as a sustainable composite biomaterial, focusing on its particle size effects on the mechanical, frictional, and thermal properties of composite materials for potential biomedical applications such as prosthetics and implants. Composite specimens were produced using the compression hot molding method, utilizing EG powder particles of varying sizes (120, 140, and 200-mesh sieving). The influence of EG powder particle size on key properties was systematically investigated. The findings reveal that reducing the particle size of EGs leads to a decrease in density and hardness of the composite, with the largest particle size (BP1) resulting in the highest density and hardness. Friction coefficient measurements indicated suitability for biomedical applications where surface interaction and wear resistance are critical, such as joint prosthetics. Thermal analysis showed that BP1 exhibited superior thermal stability, with a maximum decomposition temperature (Tmax) exceeding 375 °C. Differential scanning calorimetry identified significant differences in glass transition temperature (Tg) and crystallization temperature (Tc) across specimens. The composites demonstrated exceptional thermal performance, surpassing previous benchmarks for biomaterials in high-temperature environments. The mechanical and thermal characteristics of Specimen BP1—2.725 g/cm3 density, 74 Shore D hardness, 0.159 coefficient of friction, 93.3% total residual, 378.14 °C Tmax, 426.25 °C Tc, and 376.87 °C Tg—suggest its potential for biomedical applications requiring durability and thermal resilience, such as in orthopedic devices and tissue engineering scaffolds.

Effect of ZnO/Li2O ratio on the structure and properties of Li2O-ZnO-SiO2-P2O5 glass-ceramics sealants

In order to meet the sealing temperature of copper alloy below 1000 °C, a kind of Li2O-ZnO-SiO2-P2O5-(B2O3+Al2O3+K2O) (LZS) glass-ceramics with high expansion coefficient and high resistivity was synthesized via the melting method and then crystallized through controlled cooling. The network structure, thermal properties, crystal phase transition, thermal expansion coefficient, and high-temperature resistivity have been investigated. As the mass ratio of ZnO/Li2O increases, the network structure of the LZS glass is strengthened, leading to an increase in the glass transition and crystallization temperature. Moreover, the predominant crystal phases in LZS glass-ceramics transit from Li2SiO3 to Zn[Zn0.1Li0.6Si0.3]SiO4 and subsequently to Zn2SiO4. At a ZnO/Li2O ratio of 3, a cristobalite phase with a high expansion coefficient emerges. The change in crystal phase results in a variation in the coefficient of thermal expansion (CTE) of glass-ceramics, ranging from 13.2 to 11.2 × 10−6 K−1. At a ZnO/Li2O ratio of 3, the softening temperature of glass-ceramics is minimized. Moreover, as the ZnO/Li2O mass ratio increases, the resistance of crystallized glass decreases first and then increases. The maximum resistivity is achieved at a ZnO/Li2O mass ratio of 5. By optimizing the mass ratio of ZnO/Li2O, it is determined that when the mass ratio of ZnO/Li2O is 3, the CTE is 12.4 × 10−6 K−1, and the softening temperature (Ts) is 679.8 °C, which is the best material for sealing applications.

Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses.

Silicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developments, the effect of SrO/CaO-CaO/SrO substitution on the local structure and dynamics of Si-Na-P-Ca-O oxide glasses has been studied in this work. Differential thermal analysis has been performed to determine the thermal stability of the glasses after the addition of strontium. The local structure has been studied by neutron diffraction augmented by Reverse Monte Carlo simulation, and the local dynamics by neutron Compton scattering and Raman spectroscopy. Differential thermal analysis has shown that SrO-containing glasses have lower glass transition, melting, and crystallisation temperatures. Moreover, the addition of the Sr2+ ions decreased the thermal stability of the glass structure. The total neutron diffraction augmented by the RMC simulation revealed that Sr played a similar role as Ca in the glass structure when substituted on a molar basis. The bond length and the coordination number distributions of the network modifiers and network formers did not change when SrO (x = 0.125, 0.25) was substituted for CaO (25-x). However, the network connectivity increased in glass with 12.5 mol% CaO due to the increased length of the Si-O-Si interconnected chain. The analysis of Raman spectra revealed that substituting CaO with SrO in the glass structure dramatically enhances the intensity of the high-frequency band of 1110-2000 cm-1. For all glasses under investigation, the changes in the relative intensities of Raman bands and the distributions of the bond lengths and coordination numbers upon the SrO substitution were correlated with the values of the widths of nuclear momentum distributions of Si, Na, P, Ca, O, and Sr. The widths of nuclear momentum distributions were observed to soften compared to the values observed and simulated in their parent metal-oxide crystals. The widths of nuclear momentum distributions, obtained from fitting the experimental data to neutron Compton spectra, were related to the amount of disorder of effective force constants acting on individual atomic species in the glasses.

Comparison of volatiles evolving from selected highland and mare lunar regolith simulants during vacuum sintering

Volatiles evolving from JSC-1A, NU-LHT-4M and CSM-LHT-1G lunar regolith simulants during in vacuo thermal processing were analyzed using mass spectrometry as a function of temperature. Two high-fidelity simulants, JSC-1A (mare) and NU-LHT-4M (highland), were compared to a newly developed CSM-LHT-1G highland simulant, modified to closely match lunar geochemistry. Large autogenous gas loads were observed for all investigated materials. Mineralogical knowledge was used to identify and attribute individual volatile species to reacting, transforming, or decomposing constituents (hydrates, carbonates, sulfates, sulfides, clays, etc.) of the respective regolith simulant in the self-generated gas environment. Cumulative mass losses for individual simulant components as a function of temperature were quantified using mass spectrometry in conjunction with thermogravimetric analysis. Investigation of the four components of CSM-LHT-1G – anorthosite, basalt, augite, and glass – aided the attribution of volatile species to specific compounds and their respective sources. The results showed significant decomposition of non-lunar phases present in the man-made regolith simulants below the typical glass crystallization temperatures, which paves the way to devising methods for enhancing the fidelity of the simulants. High gas loads and corrosive gases (HF and HCl) were recognized as potential hazards, pertaining to the development of large testbed facilities.

Influence of manufacturing parameters on bioactive glass 45S5: Structural analysis and applications in bone tissue engineering

Bioactive glass (BG-45S5) production through the melting process is affected by a wide variety of parameters. This study investigated the synthesis of BG-45S5 granules and the process variables to produce a bioactive and osteoinductive BG for bone grafting applications. The melting process was initially analyzed by varying parameters such as crucible type and pouring environment using P2O5 as phosphorus precursor. The obtained products were characterized by crystalline phases, characteristic chemical groups, particle size distribution, and chemical composition. Materials poured into graphite or steel molds resulted in particle sizes more suitable for applications in granular form. Using a platinum crucible yielded a chemical composition closer to the target when compared with another ceramic crucible. Subsequently, the melting process was evaluated to different phosphorus precursor (P2O5 or Na2HPO4) and melting duration (1 or 2 h) in a platinum crucible verifying their effects on the thermal behavior, chemical composition and structure of BG-45S5. Employing Na2HPO4 as a precursor led to higher glass transition and crystallization temperatures as compared to P2O5, enhancing glass homogeneity and structural stability. The product with better characteristics in terms of composition and structure was further characterized for bioactivity and cell culture behavior, showing a greater amount of mineralization nodules when compared to commercial hydroxyapatite. This is particularly due to its behavior as the solubility and interaction in biological environments.

Solid-state vitrification of LiPO3 through mechanical milling

A novel glass state of LiPO3 was obtained in powders produced by mechanical planetary ball milling of the crystal phase, in a direct room temperature solid-state process. X-ray diffraction shows that the amorphization develops through the compression along the [2 0 2] direction. This new material shows the calorimetric signatures of the glass state (glass transition and crystallization), and is produced in an excited state relaxing the excess of enthalpy through an exothermic event below the glass transition, akin to bulk glasses produced by hyperquenching of their melts. 31P nuclear magnetic resonance (NMR) reveals the progressive amorphization of the particles: the collapse of the resonances from P crystallographic sites and the appearance of broad resonances from amorphous domains. The nature of this glass is different from those obtained through melt-quench of bulk samples. The glass transition (Tg = 303 °C) and crystallization (Tc = 350 °C) temperatures are lower than in the melt-quenched glass (Tg = 330 °C, Tc = 379 °C). Also, 31P NMR shows a broader distribution of environments around Q2 phosphates, and higher populations of Q1 and Q3, suggesting differences in middle-range order. The amorphization can be fully reversed by recrystallization of the powders at 333 °C.

Polymer-derived coatings with La2Zr2O7 and glass fillers: Preparation and characterisation

This study investigated the impact of La2Zr2O7 (LZ) and different types of glass on the performance of polymer-derived ceramic (PDC) coatings on AISI 441 stainless steel substrates. Four double-layer PDC-based glass-ceramic coatings containing LZ and different glass fillers were prepared by dip coating. The LZ powder was synthesised by solid-state reaction (SSR): powder morphology, crystal structure, and thermal stability were analysed. X-ray diffraction (XRD) detected a LZ pyrochlore phase after annealing at 1300 and 1400 °C with a trace of t-ZrO2. Four different glass compositions, namely BaO-Al2O3-SiO2 (BAS), BaO-Al2O3-La2O3-B2O3-SiO2 (BALBS), CaO-B2O3-SiO2 (CBS), and BaO-ZnO-MgO-B2O3-SiO2 (BZMBS), were also synthesised as fillers for PDC coatings. The glass transition and crystallisation temperatures of the glasses were determined using differential scanning calorimetry (DSC). The coating systems, consisting of a Durazane 2250 bond coat and a top coat (Durazane 1800 + LZ filler + different glass sealants), were prepared. After pyrolysis of the coatings at 900 °C, some of the glasses partially crystallised. Scanning electron microscopy (SEM) revealed that the layers containing BAS, BALBS and CBS glass were dense, with good adhesion to the substrate, and with occasional presence of larger pores and cracks. Delamination of the upper layer was observed in the coating with the BZMBS glass filler.

Warm white light emitting thermally stable Dy3+ activated antimony fluoroborate glasses for n-UV based white LEDs

A transparent series of trivalent dysprosium (Dy3+) ions activated calcium antimony fluoroborate glass samples (CAFB) were synthesized by the aid of the melt quenching process. The thermogravimetric, structural, and spectroscopic characterizations were evaluated and investigated in detail. Thermogravimetric analysis was performed to determine the glass transition temperature Tg and crystallization temperature (Tc) of the prepared host CAFB glass. Raman Spectroscopy and Fourier transform infrared (FT-IR) analyzed the structural orientation as well as bonding formation in the prepared CAFB host and CAFBDy1.0 glass matrix. Furthermore, the optical absorption spectra exhibit various absorption peaks between the n-UV to NIR region (350 to 2000 nm). Under the different n-UV excitation wavelengths, photoluminescence (PL) spectra reflect three foremost emission centres located around 482, 575, and 663 nm in the Dy3+: CAFB glasses. The observed colour coordinates of the prepared CAFBDy glasses were marked in the standard white area of the CIE chart under different n-UV excitation wavelengths. Moreover, temperature-dependent PL (TDPL) studies demonstrate that these glass samples have significant thermal stability and also a large activation energy. Hence, the above-mentioned results prove the versatility of the CAFBDy glasses to make them potential candidates for usage in luminescent device applications.

Crystallization, structural, and optical properties of the 2BaF2·Al2O3·B2O3 glass in the presence of Er2O3 and SiO2

This study investigates the crystallization behavior and optical properties of the 2BaF2·Al2O3·B2O3 oxyfluoride glass in the presence of SiO2 and Er2O3 compositions. Samples were synthesized using the melt-quenching method. The amorphous nature of the prepared samples was characterized through X-ray diffraction (XRD) analysis. Differential thermal analysis (DTA) was subsequently employed to determine the glass transition temperature (Tg) and crystallization temperature (Tc). The presence of SiO2 and Er2O3 was found to enhance the glass forming ability and the crystallization temperature of the system. The optical bandgap was calculated by drawing Tauc plots from UV–Vis spectra. Notably, the presence of SiO2 caused a red-shift in the UV-absorbance edge of the glass, and resulting in a decrease in the optical bandgap. Molecular structure was further studied by Raman and FTIR analysis. Based on the DTA curves, glasses were heat-treated and the resulting glass-ceramics were analyzed using XRD, Photoluminescence and field emission scanning electron microscopy (FESEM). XRD analysis confirmed the crystallization of the BaAlBO3F2 crystalline phase within the glass matrix. Furthermore, the recorded down-shifted and upconversion photoluminescence spectra indicated that the Er3+ doped glass-ceramics have stronger emissions compared to glasses.

Novel phosphate bioglasses and bioglass-ceramics for bone regeneration

Bioactive glasses and glass-ceramics are biomaterials characterized by excellent bone bonding abilities. Many different bioactive glass formulations have been studied since the introduction of 45S5 bioglass by Larry Hench. Among silicate and borate bioglasses the phosphate-based ones seem to be interesting in drug delivery systems applications due to their high solubility and low toxicity. In this study novel phosphate bioactive glasses from the composition of P2O5 – CaO – Ca(OH)2 – KF – Na2O – TiO2 and P2O5 – CaO – Ca(OH)2 – ZnO – KF –TiO2 modified with 500 ppm or 2000 ppm of HAuCl4 – 3H2O were obtained by traditional melt-quenching technique. Glass crystallization temperature was measured by DSC calorimetry. The bioglasses were partially crystallized above the crystallization temperature and the bioactive glass-ceramic based on the composition of the parent glasses was obtained. The FT-IR structural studies were performed to detect the presence of structural units beneficial for bioactivity of the materials. Crystalline phases of the bioglass-ceramics were identified with XRD. All bioglass-ceramics contained bioactive β-pyrophosphate. The obtained bioglasses and glass-ceramics were incubated in SBF to evaluate their bioactivity. Only P2O5 – CaO – Ca(OH)2 – KF– Na2O–TiO2 bioglass-ceramics developed apatite-like layer on the surface after incubation in Simulated Body Fluid and was chosen as the material for future studies. The impact of the chemical composition of the bioglass, presence of particular structural units and bioglass-ceramic phase composition on the in vitro bioactivity was discussed.

Influence of BaTiO3 substitution on structural and thermal response of lead borosilicate glass for ultrasonic applications

An extensive examination of the impact of BaTiO3 doping on the mechanical and thermal characteristics of lead-borosilicate glasses is provided in this work. The glass density increases noticeably (from 6020 for BaTiO3 to 2533 kg/m3 for SiO2), and the molar volume decreases, suggesting a denser and more compact structural arrangement. The mechanical properties exhibited a notable improvement upon the addition of BaTiO3. Specifically, the longitudinal ultrasonic velocity (VL) increased from 3927 to 4458 m/s, and the shear velocity (VS) increased from 2317 to 2630 m/s, indicating a reinforced glass network. The bulk modulus increased from 35.71 to 58.06 GPa, and Young’s modulus increased from 57.2 to 92.98 GPa. These significant increases in elastic moduli were attributed to tighter atom packing and higher levels of cross-linking within the glass matrix. Furthermore, the glass structure’s increased rigidity and connectedness were further indicated by the Debye temperature (θD), which increased from 296.8 to 347.3 K. The influence of BaTiO3 on the thermal analysis is demonstrated, which revealed that increasing BaTiO3 content raises both the glass transition and crystallization temperatures. The results of the experiment demonstrate how much BaTiO3 doping can improve the physical characteristics of lead-borosilicate glasses, enabling them to be used in sophisticated optical and structural applications.

Evolution of microstructure and spectral characteristics of silver nanoparticles in photo-thermo-refractive glass

Photo-thermo-refractive (PTR) glass is widely used in volume holographic devices. After photo-thermo treatment, silver nanoparticles (Ag-NPs) and sodium fluoride (NaF) crystals can precipitate in the glass matrix to realize refractive index modulation (RIM). The Ag-NPs are the foundation for subsequent precipitation of NaF crystals and significantly affect the absorption and luminescence characteristics of PTR glass. Within the nucleation temperature range of 440 °C-480 °C, the Ag-NPs formed by photo-thermo-induced nucleation are within 5 nm. Increasing nucleation heat treatment time causes an increase in the average size of Ag-NPs and the thickness of AgBr shell. Increasing the UV exposure dose significantly increases the concentration of Ag-NPs. The long nucleation time and high UV exposure doses can both increase the content of luminescent silver molecular cluster [Agm]n+, while high nucleation temperatures over 500 °C cause fluorescence quenching of PTR glass due to the formation of large Ag-NPs over 10 nm and NaF crystals. The formation of Ag-NPs effectively reduces the crystallization temperature of PTR glass. The refractive index of PTR glass can be effectively controlled by adjusting the parameters of photo-thermo-induced nucleation. Under the condition of crystallization at 550 °C for 30 min, a maximum RIM value of 1500 ppm can be achieved.

Influence of Yb3+/Ho3+ codoping on optical and thermal properties of TeO2-ZnO glass

This paper reports the effect of incorporation of Yb3+ ions on the frequency downconversion luminescence and thermal properties of triply ionised Ho3+ doped zinc tellurite (TZ) glasses. The photoluminescence spectra of both the Ho3+/Yb3+ doped and codoped glasses have been recorded and observed a green emission band corresponding to the 5F4, 5S2 → 5I8 (∼550 nm) transition upon various excitations. In the downconversion (DC) emission process, the back energy transfer (BET) mechanism from Ho3+ ions to Yb3+ ions has also been explored. The colour emitted in the downconversion process is found to be non-tunable at different excitations. Thus, the Ho3+:TZ glass can be utilised for non-colour tunable optical devices under various UV excitations. Also the glass transition (Tg) and crystallisation (Tc) temperatures have been measured for both the doped and codoped glasses and found to be increased in the codoped glass. The singly Ho3+ions doped TZ glass shows better optical downconversion and glass forming ability.

Mixed alkali effect on the mechanical, thermal and biological properties of 58S bioactive glass

Bioactive glasses (BG) containing silicon, phosphorous, and boron have emerged as promising materials for bone tissue engineering. Modifying ions play a multifaceted role in BGs, influencing their structure, properties, and biological activity that depends on their size, charge, and coordination chemistry. This study investigates the addition of sodium borate (Na2B4O7) to the 58S BG and the mixed alkali effect (MAE) resulting from incorporating Na and B ions into the CaO–SiO2–P2O5 system. In specific concentrations, Na+ and Ca2+ ions function as network modifiers, introducing structural disruptions and generating defects that impact the glass transition temperature (Tg), crystallization temperature (Tc), hardness, and sintering characteristics. The physicochemical characterization of BGs confirms the incorporation of Na and B structures. Furthermore, the Na and B doped glass sample with a [Na/Si] ratio of 0.045 exhibits favorable properties for promoting cell attachment, including forming a hydroxyapatite (HAp) layer over the surface, thereby accelerating human placental mesenchymal stem cells (hPMSCs) proliferation. The findings demonstrate the potential of Na2B4O7 incorporation in BG for bone tissue engineering applications.

Novel Li2−2xK2xPbP2O7 glass system: Synthesis, thermal, structural and dielectric properties

Novel Li2−2xK2xPbP2O7 system (x = 0, 0.2, 0.4, 0.6, 0.8, and 1 mol%) was synthesized through the conventional melt-quenching method. The amorphous and crystalline characteristics of the resulting compounds were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The study assessed the effect of potassium doping on thermal parameters, including glass transition temperature (Tg), crystallization temperature (Tc), and overall thermal stability. The findings reveal that the stability does not consistently follow a single pattern with K2O doping. Notably, the Li1.6K0.4PbP2O7 glass exhibits the greatest stability. The addition of K2O led to a reduction of the density and an increase in the molar volume of the system. These observations align with FTIR results, which reveal that introducing additional potassium ions results in longer bond lengths and weaker bonds. The spectroscopic study was supported by Raman spectroscopy. Post-annealing XRD analysis revealed the presence of distinct crystalline phases that differed according to the K2O content The structure of the various phosphate groups in the synthesized materials after annealing was also analyzed using Fourier Transform Infrared (FTIR) spectroscopy. Moreover, dielectric studies were conducted over a range of frequencies, and the presence of the relaxation phenomenon as well as the influence of potassium content on dielectric features have been evidenced.