Crystallization Activation Energy Research Articles

[formula omitted] anomaly effect on crystallization and mechanical properties of soda-lime silicate glasses

In the present investigation, the effect of B2O3 is investigated on the theoretical mechanical properties and crystallization kinetics of (64-x)SiO2 - xB2O3 - 16Na2O - 12CaO - 2Al2O3 - 6MgO (x = 2, 4, and 6 mol%) glasses. To understand the mechanical properties elastic moduli are calculated using two theoretical models i.e., Makishima-Mackenzie and Rocherulle. Whereas, in crystallization kinetics, activation energies (Eg, Ec, and Ep) are computed using two distinct methods, i.e., the Kissinger model and the Augis and Bennett model. The replacement of SiO2 by B2O3 enhances the strengthening of the glass network which makes the B6-S58 glass network more rigid. The B6-S58 and B2-S62 glasses have the highest and lowest activation energy (Eg) for crystallization, respectively. B4-S60 glass shows non-linear behavior in characteristics temperature as well as in activation energy due to boron anomaly. The present finding could be helpful in designing windshield automobile glasses.

Rheological Behavior of a New Amorphous Alloy (Al74Cu16Mg10)99,7Zr0.3

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx = 168 ± 3.7 kJ/mol, was found to be higher than the activation energy of the glass transition Еg = 156 ± 1.4 kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg = 32 K and the low viscosity values in the same range ƞ(Тg) = 3.40E + 11 Pa.s and ƞ(Тx) = 1.87E + 10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt.

A novel Gd2O3–Al2O3–SiO2 glass-ceramics substrate material with comprehensive performance

A novel Gd2O3–Al2O3–SiO2 glass-ceramics (GAS GCS) for substrate application was prepared using the melt-quenching method. The present study pay attention to investigate the crystallization and sintering behaviors, phase compositions, micromorphology, dielectric and mechanical properties of GAS glass-ceramics. An appropriate amount of Gd2O3 diminished the glass viscosity while enhancing structural stability, thereby reducing the activation energy for crystallization and sintering. This contributed to the GAS GCS achieve dense microstructure and high crystallinity. X-ray diffraction (XRD) and Raman spectroscopy analyses confirmed the presence of high-density crystal phases, namely Gd2SiO5 and Gd2Si2O7, which significantly contribute to the enhanced density of the samples. Moreover, a positive correlation was observed between the dielectric constant and crystallinity. Notably, the GAS GCS composition of 41 wt% Gd2O3-21.3 wt% Al2O3-37.7 wt% SiO2 exhibited optimal properties, including a flexural strength of 243.4 MPa, Vickers hardness of 7.77 GPa, elastic modulus of 154.02 GPa, coefficient of thermal expansion of 5.9 × 10−6/°C, dielectric constant of 7.43, and dielectric loss of 4.05 × 10−3. These outstanding characteristics position it as a promising candidate for substrate materials.

Distinct Crystallization Pathways of Polyoxymethylene in Methanol System

Recrystallization of polyoxymethylene (POM) in solvent is an effective post-treatment method for manufacturing a better POM product. Herein, the crystallization process of POM in methanol was investigated with the use of a series of equipment. The results reveal that POM crystallization in methanol yields two kinds of particle morphologies, including small particles with lamellar structures branching and growing in all directions and large particles resulting from melt agglomeration. The mechanism of POM crystallization in methanol with two distinct pathways was proposed, in which solution cooling crystallization of POM at higher temperature yields small particles while melt crystallization yields large particles. Furthermore, both non-isothermal and isothermal crystallization kinetics of POM were determined. The Avrami equation was employed to derive the crystallization rate constant via data fitting. The activation energy of crystallization was then obtained using the Arrhenius formula. The kinetics suggest that recrystallization of POM in methanol may dissolve and remove substances hindering raw material crystallization, achieving a faster crystallization rate for products.

Crystallization Behavior of Copolyesters Containing Sulfonates.

The polar sulfonate groups in cationic dyeable polyester (CDP) lead to complex crystallization behavior, affecting CDP production's stability. In this study, cationic dyeable polyesters (CDP) with different sulfonate group contents were prepared via one-step feeding of sodium isophthalic acid-5-sulfonate (SIPA), terephthalic acid (PTA), and ethylene glycol (EG). The non-isothermal crystallization behavior of these copolyesters was analyzed by differential scanning calorimetry (DSC). Results show that the crystallization temperature of the sample shifts to lower values with the increase in SIPA content. The relaxation behavior of the molecular chain is enhanced due to the ionic aggregation effect of sulfonate groups in CDP. Therefore, at low cooling rates (2.5 °C/min and 5 °C/min), some molecular chain segments in CDP are still too late to orderly stack into the lattice, forming metastable crystals, and melting double peaks appear on the melting curve after crystallization. When the cooling rate increases (10-20 °C/min), the limited region of sulfonate aggregation in CDP increases, resulting in more random chain segments, and a cold crystallization peak appears on the melting curve after crystallization. The non-isothermal crystallization behavior of all samples was fitted and analyzed by the Jeziorny equation, Ozawa equation, and Mo equation. The results indicate that the nucleation density and nucleation growth rate of CDP decrease with the increase in SIPA content. Meanwhile, analysis of the Kissinger equation reveals that the activation energy of non-isothermal crystallization decreases gradually with the increase in SIPA content, and the addition of SIPA makes CDP crystallization more difficult.

Effect of high copper content in Cux(As2Se3)100-x glass on properties relevant for engineering of thermally induced processes

ABSTRACT Kinetic analysis of thermally induced processes was carried out in Cux(As2Se3)100-x glass with high copper content, x = 20 and 25 at.%. Non-isothermal differential scanning calorimetry at different heating rates was used to analyze the glass-transition and crystallization processes. It was shown that the glass-transition temperature increases with the increase in the copper content and that the examined glasses during the glass transition process do not show large configurational changes in the structure. Apparent activation energy of crystallization was determined using Kissinger method. In the composition with 25 at.% of copper the crystallization of three structural units was detected: CuAsSe2, Cu3AsSe4 and Cu2Se. Analysis of the crystallization mechanism and determination of parameters that depend on the morphology of nucleation and growth showed that volume nucleation and three-dimensional growth occur with a constant number of nucleation centers. Isoconversional analysis showed that the activation energy does not change significantly during the crystallization process.

Thermo-Structural Characterization of Phase Transitions in Amorphous Griseofulvin: From Sub-Tg Relaxation and Crystal Growth to High-Temperature Decomposition.

The processes of structural relaxation, crystal growth, and thermal decomposition were studied for amorphous griseofulvin (GSF) by means of thermo-analytical, microscopic, spectroscopic, and diffraction techniques. The activation energy of ~395 kJ·mol-1 can be attributed to the structural relaxation motions described in terms of the Tool-Narayanaswamy-Moynihan model. Whereas the bulk amorphous GSF is very stable, the presence of mechanical defects and micro-cracks results in partial crystallization initiated by the transition from the glassy to the under-cooled liquid state (at ~80 °C). A key aspect of this crystal growth mode is the presence of a sufficiently nucleated vicinity of the disrupted amorphous phase; the crystal growth itself is a rate-determining step. The main macroscopic (calorimetrically observed) crystallization process occurs in amorphous GSF at 115-135 °C. In both cases, the common polymorph I is dominantly formed. Whereas the macroscopic crystallization of coarse GSF powder exhibits similar activation energy (~235 kJ·mol-1) as that of microscopically observed growth in bulk material, the activation energy of the fine GSF powder macroscopic crystallization gradually changes (as temperature and/or heating rate increase) from the activation energy of microscopic surface growth (~105 kJ·mol-1) to that observed for the growth in bulk GSF. The macroscopic crystal growth kinetics can be accurately described in terms of the complex mechanism, utilizing two independent autocatalytic Šesták-Berggren processes. Thermal decomposition of GSF proceeds identically in N2 and in air atmospheres with the activation energy of ~105 kJ·mol-1. The coincidence of the GSF melting temperature and the onset of decomposition (both at 200 °C) indicates that evaporation may initiate or compete with the decomposition process.

Strengthening functional properties and competitive crystallization behavior of La2O3-BaO-CaO-Al2O3-B2O3-SiO2 glass-ceramic for solid oxide fuel cells: Agglomeration effect of rare-earth oxide

In this paper, the agglomeration effect of rare-earth oxide has been confirmed through that the thermal properties, viscosity, crystalline phase, and high temperature resistivity of the 35BaO-(15-x)CaO-5Al2O3–10B2O3–35SiO2-xLa2O3 (x = 1, 3, 5, 7, 9 mol%, BABSCLa) glass system were systematically investigated. With the increase of the La2O3/CaO molar ratio, the results of Raman and infrared spectra of the BABSCLa glass showed that the Q4, Q3, and Q2 units of [SiO4] decrease, while Q1 and Q0 units increased in the BABSCLa glass structure, because the La2O3 as the glass network modifier can create more non-bridging oxygen than the CaO. However, the "agglomeration" effect of La ions with the high field strength could adsorb the oxygen in glass to form the La–O–La (Si) bond, resulting that the glass transition temperature and softening temperature of the BABSCLa glass continued to increase with the addition of La2O3, and the coefficient of thermal expansion (CTE) of annealed glass decreased from 11.37 to 10.87 × 10–6K–1, respectively. Simultaneously, the main crystalline phase of the BABSCLa glass-ceramic gradually changed from the low crystallization activation energy BaSiO3 phase with 287 kJ/mol to Ba3La6(SiO4)6 phase with 454 kJ/mol duo to the "agglomeration" effect of La ions. The CTE of the BABSCLa glass-ceramic increased from 12.35 to 13.05 × 10–6K–1 and then decreased to 11.75 × 10–6K–1. The direct-current (DC) resistivity of the BABSCLa glass-ceramic was higher 105 Ω•cm at a high temperature of 750 °C, which had good high-temperature electrical insulation. This demonstrated the La2O3 strengthening BaOCaO-Al2O3-B2O3-SiO2 glass-ceramic system was an effective method for the preparation of hermetic glasses.

Isothermal and nonisothermal crystallization kinetics of modified hydroxyapatite-enhanced poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) is a biodegradable material, and efforts have been devoted to enhancing its mechanical properties and biocompatibility for biomedical applications. However, there is a lack of research confirming the influence of nucleating agents on its crystallization behavior. In this study, the isothermal crystallization process was described using the Avrami model. The non-isothermal crystallization process was investigated using the Avrami-Jeziorny and Mo models. The effects of different calcium hydroxyapatite (CA-HA) contents on the nucleation activity, crystallization activation energy, and equilibrium melting point of P34HB/CA-HA composites were compared. The impact of CA-HA on the crystallization rate, nucleation rate, and crystal growth rate of the polymer matrix was discussed. The results indicate that with an increase in CA-HA content, the crystallization rate initially decreases and then increases. The minimum crystallization rate is observed at a CA-HA content of 9 wt%. Moreover, as the CA-HA content increases, nucleation activity is enhanced, suggesting that CA-HA acts as a nucleating agent, facilitating the nucleation process. When the CA-HA content exceeds 9 wt%, the increase in crystallization rate may be attributed to the further enlargement of molecular clusters formed by CA-HA, leading to a reduced dispersion of CA-HA in the polymer matrix. Furthermore, when the CA-HA content surpasses 9%, a significant decrease in crystallization activation energy is observed, indicating a reduction in the mobility of polymer chain segments.

Kinetic analysis of the crystallization of Y2O3 and La2O3 doped Li2O-Al2O3-SiO2 glass.

Li2O-Al2O3-SiO2 (LAS) glass ceramics have a low coefficient of thermal expansion, high mechanical strength, and excellent chemical stability. With advancements in glass ceramics, researchers have explored using LAS glass ceramics with transition metal doping and rare earth doping. Most previous studies have studied the impact of rare earth element doping on crystallization primarily in the context of conventional nucleating agents present in glass. In this study, we aimed to investigate the impact of Y2O3 and La2O3 on LAS glasses in the presence of undoped nucleating agents. The crystallization mechanism of La2O3 and Y2O3 doped LAS glass ceramics was studied using differential scanning calorimetry. The crystallization kinetics of the glasses were analyzed using model-free and modeling methods. Moreover, the activation energy of crystallization and the indices of crystallization and growth of glass ceramics were calculated, and the crystalline phase and microstructure of the samples were characterized. All three fractions of the LAS glass showed consistent crystallization under different calculation methods. The glass doped with La2O3 and Y2O3 exhibited two- or three-dimensional growth during crystallization, promoting crystallization in the LAS glass. The Y3La0 sample demonstrated the most favorable crystallization effect. In the presence of an undoped nucleating agent, rare earth elements can enhance glass crystallization; this new idea can be utilized for the development of new materials.

Crystallization kinetics and structural development of Bi2GeO5 glass-ceramics fabricated by the modified incorporation technique

This study focuses on the fabrication and crystallization kinetics of bismuth germanate (Bi2GeO5) crystals in glass ceramics. Bismuth germanate glass-ceramics were produced from a base glass containing 58.4 mol% Bi2O3, 23.4 mol% GeO2, and 18.2 mol% B2O3 using a modified incorporation technique. Differential thermal analysis was used to determine the crystallization temperature. The X-ray diffraction results showed a dominant peak corresponding to the pure Bi2GeO5 phase, which has an orthorhombic crystal structure. The local Avrami exponent (n(x)) and local crystallization activation energy (Ec(x)) were determined using a non-isothermal method with heating rates ranging from 5 to 20 °C/min. The results indicated that the crystal growth process of the glass-ceramics occurred in all three dimensions, with Avrami exponent values ranging from 1.79 to 2.5. The microstructure also revealed uniform crystallization across the surface and bulk diffusion of crystallites. The modified incorporation method successfully enhanced the crystallization of Bi2GeO5 glass-ceramics, resulting in the transition from one-dimensional needle-like crystals to the desired crystal dimensions.

Modified Chalcogenide Glass Equations for the Activation Energy of Crystallization

For over six decades, chalcogenide glasses (ChGs) have played a pivotal role in the optical community, fostering innovations and new applications in photonics, electronics, and electro-optics. In the last decade, the exploration of novel applications, such as Gradient Index (GRIN) ChGs, has underscored the need for a nuanced comprehension and precise control of nucleation and crystallization kinetics in emerging infrared glass compositions. This article explores the activation energy of crystallization in amorphous materials, particularly focusing on ChGs. It identifies long-standing challenges associated with existing models used for crystal growth in nucleated glasses. Employing carefully outlined mathematical logic, our study critiques conventional models and introduces innovative equations centering around the need for balanced units and proper physical trends. These new models overcome some shortcomings of the established framework and provide a more accurate depiction of crystallization kinetics. To validate the efficacy of our proposed models, we conducted a comparative analysis using differential scanning calorimetry data from a recently published Sb-Te-Se chalcogenide glass composition. The numerical and graphical results clearly illustrate the improvements inherent in our models and their practical utility. Beyond ChGs, our models and equations have broader applications. They may extend to oxide, halide, oxy-halide, and fluoride glass compositions, as well as polymers, contributing new tools to the understanding of crystallization kinetics across diverse materials.

Nontoxic, precious-metal-free titanium-based metallic glasses with exceptional glass-forming ability and high specific strength

Titanium-based metallic glasses (TBMGs) are attracting broad interest due to their simultaneous light weight, superhigh strength, and specific strength, exceptional wear- and corrosion-resistance and biocompatibility, desirable for electronic, biomedical, and aerospace applications. However, the glass-forming ability (GFA) of TBMGs, except some containing significant amount of toxic (Be) or precious (Pd, Ag) elements, is disappointingly low, as manifested by a critical casting diameter (dc) not more than 6 mm, which significantly restricts their manufacturing and applications. Here, we report our discovery of a series of TBMGs in the (TiZrHf)x(CuNi)y(SnSi)z pseudo-ternary system. These alloys possess an exceptionally large dc, reaching up to 12 mm, doubling the current record for Be and precious-metal free TBMGs. Moreover, these alloys exhibit a low density (7.0–7.3 g/cm3), high fracture-strength (up to ∼2700 MPa), high specific fracture-strength (up to ∼370 N m g−1), and even good plasticity with a plastic strain of up to 9.4% upon compression. They also possess high activation energy for crystallization and high atomic packing efficiency, which provide an initial physical account for their exceptional GFA and manufacturability.

Unraveling influence of entropy on thermal stability and glass-forming ability of (Fe, Co)–(Ta)–B amorphous alloys: Insights from local atomic structure simulated by ab initio molecular dynamics

The thermal stability, glass-forming ability (GFA), and local atomic structure of (Fe, Co)–(Ta)–B amorphous alloys with different entropy values were investigated by experiments and ab initio molecular dynamics simulations, and the effects of entropy were elaborated from the perspective of the local atomic structure. The experimental results show that crystallization temperature, activation energy for crystallization, and undercooling degree all rise with the increase of configurational entropy (ΔSconf) of the alloys, whereas the critical thickness for amorphous samples shows a weak correlation with the ΔSconf. The simulations indicate that the short-range orders of the amorphous alloys are all dominated by B-centered tri-capped trigonal prisms (TTPs) and bi-capped square Archimedean antiprisms, and Fe-/Co-centered deformed body-centered cubic structures (BCCs) and icosahedral-like structures (ICOs) mainly with covalent-like B–Fe/Co and metallic Fe/Co–Fe/Co bonds. The increase in the ΔSconf results in shortened bond lengths and strengthened interactions between the main atomic pairs and sluggish diffusion of the atoms, thereby leading to enhanced thermal stability of both the amorphous phases and alloy melts. The GFA of the alloys shows a strong correlation with the characteristics of the short-range orders but not the entropy. The alloy containing the lowest fractions of the TTPs and BCCs but considerable ICOs possesses the best GFA.

Study on the Crystallization Behavior of Neodymium Rare-Earth Butadiene Rubber Blends and Its Effect on Dynamic Mechanical Properties.

Utilizing neodymium-based butadiene rubber as a baseline, this study examines the effect of eco-friendly aromatic TDAE oil, fillers, and crosslinking reactions on neodymium-based rare-earth butadiene rubber (Nd-BR) crystallization behavior. The findings suggest that TDAE oil hinders crystallization, resulting in decreased crystallization temperatures and heightened activation energies (Ea). The crystallization activation energies for 20 parts per hundreds of rubber (PHR) and 37.5 PHR oil stand at -116.8 kJ/mol and -48.1 kJ/mol, respectively, surpassing the -264.3 kJ/mol of the unadulterated rubber. Fillers act as nucleating agents, hastening crystallization, which in turn elevates crystallization temperatures and diminishes Ea. In samples containing 20 PHR and 37.5 PHR oil, the incorporation of carbon black and silica brought the Ea down to -224.9 kJ/mol and -239.1 kJ/mol, respectively. Crosslinking considerably restricts molecular motion and crystallization potential. In the examined conditions, butadiene rubber containing 37.5 PHR oil displayed no crystallization following crosslinking, albeit crystallization was discernible with filler inclusion. Simultaneously, the crystallinity level sharply declined, manifesting cold crystallization behavior. The crosslinking process elevates Ea, while the equilibrium melting point (Tm0) noticeably diminishes. For instance, the Tm0 of pure Nd-BR is approximately -0.135 °C. When blended with carbon black and silica, the Tm0 values are -3.13 °C and -5.23 °C, respectively. After vulcanization, these values decrease to -21.6 °C and -10.16 °C. Evaluating the isothermal crystallization kinetics of diverse materials via the Avrami equation revealed that both the oil and crosslinking process can bring about a decrease in n values, with the Avrami index n for various samples oscillating between 1.5 and 2.5. Assessing the dynamic mechanical attributes of different specimens reveals that Nd-BR crystallization notably curtails its glass transition, marked by a modulus shift in the transition domain and a decrement in loss factor. The modulus in the rubbery state also witnesses a substantial augmentation.

Sb induced effect on glass transition, crystallization kinetics and optical properties of Se96Sn4 alloy

Se96-xSn4Sbx (x = 0, 2, 4, 6, and 8) glassy alloys were prepared using the melt quench technique. Thermal measurements were carried out using differential scanning calorimetry (DSC) in non-isothermal mode. Kissinger and Moynihan methods are used for glass transition kinetics, while Kissinger, Takhor, and Augis-Bennet methods are used to study crystallization kinetics. The inclusion of Sb in the alloy increased the glass transition temperature (Tg), activation energy of the glass transition (Et), and activation energy of crystallisation (Ec). The chemical bond approach has been used to explain the results. The rising trend of Ec is explained by the production of SnSe4/2 structural units with energies greater than those of Se–Se and Se–Sb bonds, increasing the degree of cross-linking. The dimensionality of crystal growth changes from one to two with the addition of Sb to the Se-Sn alloy. The criterion for thermal stability was addressed by using the enthalpy emitted during the crystallization process. In addition, Kubelka-Munk transformation and Tauc plots were used to calculate the band gaps. The energy gap (Eg) decreases from 3.72 to 1.60 eV as the Sb concentration increases from 0 to 8 atm%.

Thermal stability of amorphous nimesulide: from glass formation to crystal growth and thermal degradation.

Thermally induced physico-chemical transformations in amorphous nimesulide were studied by means of differential scanning calorimetry (DSC), thermogravimetry, and Raman microscopy. The equilibrium glass transition temperature was found to be Tg0 = 10-15 °C, and the relaxation motions were found to be temperature-dependent. Crystal growth from the amorphous phase was found to be crucially dependent on the presence of mechanical defects that serve as centers for heterogeneous nucleation. The large amounts of mechanical defects significantly decrease the activation energy of the macroscopic crystallization; the positions of the crystallization peaks and their asymmetry/shape remain however almost unchanged. At laboratory temperature, powdered nimesulide fully crystallizes within several hours, with an absolute majority of the crystalline phase being formed as the thermodynamically stable form I polymorph. Amorphous nimesulide does not crystallize from the free smooth surface (no trace of formed crystallites was found by optical microscopy after 30 days at laboratory temperature). Nimesulide was found to be very stable at temperatures above its melting point of 147.5 °C; thermal degradation starts to proceed slowly at 200 °C. Mutual correlations between the macroscopic and microscopic crystal growth processes and between the viscous flow and structural relaxation motions were discussed based on the values of the corresponding activation energies. A link between the cooperativity of structural domains, parameters of the Tool-Narayanaswamy-Moynihan relaxation model, and microscopic crystal growth was proposed.

Analysis of the Non-isothermal Crystallization Kinetics of the Polyamide 6/M-lignin Composites

In this study, investigations of the non-isothermal crystallization kinetics of polyamide 6 (PA6) and PA6/m-lignin composites were conducted by differential scanning calorimetry (DSC). The crystallization kinetics of the PA6, including crystallization temperature and rate, were characterized by monitoring the heat flow during cooling. The study found that the crystallization temperature shifted to lower temperatures and the crystallization kinetics slowed down with increasing lignin. Besides, the Avrami equation modified by Jeziorny and Mo’s method were used to study the non-isothermal crystallization kinetics of the neat PA6 and PA6 composites. The curve fit resulting from the modified Avrami equation was not convincing. However, Mo’s method did successfully characterize the overall non-isothermal crystallization kinetics for neat PA6 and the PA6 composites. In addition, the activation energies of the non-isothermal crystallization were calculated by the Kissinger method. It was found that the PA6 composite crystallization rate increased when adding less than 10% lignin. However, the more the content of m-lignin, the slower the crystallization rate. The same conclusion was reached based on the fitting results of the non-isothermal crystallization activation energies.

The influence of B doping on phase formation and microstructural evolution in NHL during solid-state reactions

Natural Hydraulic Lime (NHL), was synthesized by doping B2O3 into calcium carbonate and silica aerogel. By introducing varying levels of B3+ ion doping (0/1/5/10/15/20/25 mol%), a range of NHL compositions were successfully prepared, thereby enabling regulation of the NHL phase composition. Furthermore, through the doping of 25 mol% B3+ ions, in-depth investigations employing XRD, SEM, and FT-IR were conducted to explore phase transitions and ion migration during NHL calcination at different temperatures. Thermal analysis kinetics studies further revealed the variation of activation energies for CaCO3 decomposition and C2S crystallization with changing levels of B3+ ion doping. The introduction of B ions was observed to stabilize the α’ phase of dicalcium silicate (C2S) and moderately enhance the reactivity of calcium oxide (CaO). B3+ ions significantly influenced the crystallization mechanism of C2S, shifting it from a diffusion-controlled process to a heterogeneous nucleation process. The application of the Kissinger and Flynn-Wall-Ozawa (FWO) methods assisted in elucidating the underlying reasons for these differences. Both approaches demonstrated a substantial decrease in activation energy, signifying the pronounced influence of B doping on the sintering regime and phase transition mechanism of NHL. In summary, the precise modulation of NHL phase composition and sintering regime was achieved through B doping. These findings not only deepen our understanding of the mechanistic role of B3+ ions in NHL preparation and application but also offer robust guidance for the production process of NHL.

Diopside-like based ceramics prepared via one-step sintering of extracted titanium slag and coal fly ash

Diopside-Like based ceramics as the main crystalline phase (expressed as ‘Diopside’) were prepared via one-step sintering using extracted titanium slag (ETS) and coal fly ash (CFA) as raw materials. The effects of CFA content and sintering temperature on the crystal phase composition, microstructure, properties and crystallization kinetics were studied by X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and inductively coupled plasma emission spectrometry. According to the findings, the addition of CFA supplemented the deficiency of Si and Al in ETS and balanced the Ca/Al/Si molar ratio in the system. Moreover, at the CFA doping of 20 %, melilite was gradually transformed into ‘diopside’ at 800–1100 °C that further remained stable at 1160–1200 °C. ‘Despite’ the fact that the crystallization activation energy increased and the Avrami index was at its lowest level (1.75), the crystallization temperature was reduced, whereas the crystallization rate increased, causing the ceramic body and surface to crystallize and thereby improving the properties of ceramics. Sintering at 1180 °C for 1 h resulted in ceramics with ‘diopside’ as the primary crystal phase composition. The water absorption, linear shrinkage, bulk density, bending strength, and acid resistance were respectively 1.3 %, 13 %, 2.89 g cm−3, 141.8 MPa, and 97.36 %. Finally, ‘diopside’ possessed the higher acid resistance than melilite and anorthite.