Crystallization Activation Energy Research Articles

Revealing the effect of annealing at Tg on the crystal growth in Au49Ag5.5Pd2.3Cu26.9Si16.3 metallic glass via nanocalorimetry

In this study, Au49Ag5.5Pd2.3Cu26.9Si16.3 metallic glass is annealed at Tg and its impact on crystal growth is demonstrated with nanocalorimetry. With annealing following the rapid quenching, an amorphous phase free of nuclei, a relaxed amorphous phase, an amorphous phase with nuclei, and an amorphous phase with crystals are sequentially produced. With the reheating at rates ranging from 100 to 50,000 K/s, these four stages are quantitatively distinguished. Additionally, crystal growth behaviors of these four stages are demonstrated by the Kissinger and Mauro-Yue-Ellison-Gupta-Allan model. For the quenched and relaxed amorphous phases, the apparent crystallization activation energy (Ea) decreases with increasing heating rate, with a noticeable upward deviation at ultrahigh heating rates. When nuclei and crystals form in the amorphous phase, Ea keeps decreasing with the heating rate. As the annealing time increases, the maximum growth rate (umax) exhibits a monotonic increase while the temperature corresponding to umax displays a maximum.

Kinetics of crystallization and soft magnetic properties of Co72Fe8B10Si10 amorphous alloys

Co72Fe8B10Si10 amorphous alloy was prepared in an Ar atmosphere using a single roller rapid quenching technique at a wheel speed of 25 m/s. The prepared ribbons were annealed for 1 h at temperatures ranging from 473 to 773 K. X-ray diffractometer was used to observe the microstructure transformation. Field emission scanning electron micrographs exhibit mosaic type structures that become more prominent with increasing annealing temperature. Energy dispersive X-ray spectroscopy was also utilized to observe the concentrations of elements. The Kissinger and Ozawa equations were utilized to determine the amorphous alloy's crystallization activation energy. The two methods revealed consistent findings in their calculations. At 473 K, the obtained maximum real initial permeability (μ′max) is 376 which remains unchanged up to 10 kHz, whereas for 573 K, μ′max is noted to be 361 to 100 kHz. Other magnetic parameters such as loss factor, quality factor, and relative quality factor were also investigated for the Co72Fe8B10Si10 amorphous alloy to elucidate its suitability in such materials based devices.

Transition mechanism and thermokinetic analysis of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics for nuclear waste forms based on in-situ synthesis

In this study, the novelly designed Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics were utilized as nuclear waste form to simultaneously immobilize simulated fission products Sr and actinide nuclides. The phase transition mechanism, thermokinetics and densification behavior of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics based on in-situ synthesis were systemically analyzed by XRD, in-situ XPS, TG-DSC, SEM and density measurements. The results demonstrate that the formation of Ce0.5Sm0.5PO4 solid solution phase preceded that of Sr0.5Zr2(PO4)3 phase, of which there is a valence change of Ce from Ce4+ to Ce3+ before 1023 K. Additionally, as for the exothermic crystallization enthalpy, change of exothermic crystallization enthalpy and activation energy, the values of Sr0.5Zr2(PO4)3 and Ce0.5Sm0.5PO4 phases in composite ceramics are 286.17 – 515.61 mJ, 19.11 – 35.38 J/g, 702.45 kJ/mol and 145.21 – 232.44 mJ, 9.26 – 15.44 J/g, 450.04 kJ/mol, respectively. It is then indicated that the formation of Ce0.5Sm0.5PO4 phase is definitely more favorable than that of Sr0.5Zr2(PO4)3 phase. Simultaneously, the relative densities of Sr0.5Zr2(PO4)3–Ce0.5Sm0.5PO4 composite ceramics are more than 95 % when the sintering temperature exceeds 1273 K.

Preparation of high-performance multilayer circuits by controlling the diffusion of Ag in borosilicate glass-ceramics through the addition of SiO2

Due to its superior reliability and performance, thick film technology is extensively employed in various applications, including automotive electronics, consumer electronics, communication engineering, and aerospace. However, a challenge arises from the mutual diffusion during the electronic paste production process, which leads to a decline in insulation performance and hinders the production of three-dimensional equipment. Inspired by the principles of low-temperature co-fired ceramic technology, a multi-layered ceramic structure has been successfully bonded using thick film technology by introducing a borosilicate glass-ceramics layer. To further enhance the properties of this multi-layered ceramic structure, approximately 8 wt% SiO2 was incorporated into the borosilicate glass-ceramics. This addition effectively inhibits silver diffusion and reduces the diffusion depth within the glass-ceramic film. The key mechanisms behind this improvement are the increased activation energy for crystallization, resulting in a slower crystallization rate due to the addition of SiO2. Moreover, the multi-layered ceramic with a sandwich structure exhibits remarkable properties. Notably, the dielectric strength of this system has been significantly enhanced to 13.9 kV/mm, accompanied by a high adhesion strength of 790 N. These enhanced properties of the optimized system indicate promising characteristics for multi-layer circuit applications.

Influence of high field strength ions on the crystallization characteristics and properties of slag glass-ceramics

Blast furnace slag glass–ceramics were prepared by melting using rare-earth-containing blast furnace slag (REBFS) as the main raw material and Fe2O3 and Cr2O3 as composite nucleating agents. By adding different TiO2 contents, the study comprehensively revealed the effects of high field strength ions on the glass network structure, crystalline properties, elemental distribution and physicochemical properties. Raman spectroscopy and differential scanning calorimetry revealed that TiO2 acted primarily as a network modifier in the glass network. The appropriate TiO2 content disrupted the glass network, decreasing the crystallization activation energy (EC) of the glass–ceramic. However, excess TiO2 repaired the network structure, thereby increasing the EC. The combined effect of the Cr and Ti substantially improved the crystallization characteristics of the glass-ceramics. Cr2O3 induced the formation of spinel, which promoted the crystallization of the main crystalline augite phase. The self-aggregation of the high field strength Ti4+ ion induced the formation of a titanium- and cerium-containing titanite phase, which also contributed to grain refinement. This titanite phase effectively increased the Vickers hardness and acid and alkali resistances of the glass-ceramics to 9.16 GPa and over 98.5 %, respectively. The excellent physicochemical properties render REBFS glass–ceramics as being promising materials for various construction applications. This research provides theoretical support for comprehensively utilizing blast furnace slag and provides theoretical guidance for preparing slag glass–ceramics possessing desirable physicochemical properties.

Preparation of enstatite-spinel based glass-ceramics from ferronickel slag and iron ore tailings by microwave-assisted one-step crystallization

A novel method to prepare high-quality enstatite-spinel based glass-ceramics by co-utilization of ferronickel slag (FNS) and iron ore tailings (IOT) via microwave-assisted one-step crystallization was proposed with an emphasis on the effect of IOT content on the preparation process. The thermodynamic analysis demonstrated that incorporating appropriate amounts of IOT into FNS can effectively transform olivine in FNS into enstatite. The experimental exploration revealed that the crystallization activation energy of parent glass, obtained after mixing, melting, casting, annealing and cooling of the mixture of FNS and IOT, decreased from 564.6 kJ/mol to 351.93 kJ/mol when the IOT content increased from 30 wt% to 45 wt%. Meanwhile, the crystallization index of parent glass increased from 3.88 to 4.81, indicating less depolymerization. In the subsequent crystallization process, with increasing content of IOT, the main phase remained enstatite, accompanied by small amounts of spinel phases which acted as nucleation sites promoting enstatite formation. Due to the decreased depolymerization degree that resulted in fewer nucleation sites, the average grain size of enstatite increased from 123 nm to 196 nm. By controlling crystallization of the melted mixture of 65 wt% FNS and 35 wt% IOT at 863 °C for 20 min, the resulting enstatite-spinel based glass-ceramics had excellent comprehensive properties, namely density of 3.13 g/cm3, bending strength of 153.53 MPa, hardness of 9.22 GPa, and acid resistance of 99.89% and alkali resistance of 99.72%. With a much shorter crystallization time (1/6 of conventional one), the product obtained by microwave-assisted one-step crystallization had properties comparable to those derived from similar wastes.

Reversible Glass‐Crystal Transition in a New Type of 2D Metal Halide Perovskites

AbstractCrystalline metal halide perovskites (MHPs) have ushered in remarkable advancements across diverse fields, including materials, electronics, and photonics. While the advantages of crystallinity are well‐established, the ability to transition to a glassy state with unique properties presents unprecedented opportunities to expand the structure‐property relationship and broaden the application scope for 2D MHPs. Up until now, the exploration of amorphous analogs for MHPs is confined to high‐pressure conditions, limiting in‐depth studies and practical applications. In this context, a new type of 2D MHPs is synthesized by incorporating halogen substituted organic cations, resulting in a remarkable combination of low melting temperature and inhibited crystallization. This new type of 2D MHPs can be effectively melt‐quenched into a glassy state except for (DMIEA)3Pb2I7 (DMIEA = N, N‐dimethyl iodoethylammonium) counterpart. Analysis of the crystallization activation energy for (DMIPA)4Pb3I10 (DMIPA = N, N‐dimethyl iodopropylammonium) reveals a low crystallization activation energy of 60.7 ± 4.0 kJ mol−1, which indicates a fast glass‐crystal transition. The type of atypical 2D MHP showcases facile and reversible switching between glassy and crystalline states and opens up novel possibilities for applications, such as nonvolatile memory, optical communication, and neuromorphic computing.

Crystallization behavior and structural characteristics of Cr-doped Sb70Se30 thin films for phase change memory

In this study, we prepare Cr-doped Sb70Se30 (SS) thin films via the magnetron sputtering. The influence of Cr doping on the crystallization behavior and structure characteristics of the SS thin films is systematically studied using a combination of experimental analyzes and theoretical calculations. The results reveal that compared with SS thin films, Cr-doped SS thin films exhibit higher crystallization temperature, better data retention capability, larger crystallization activation energy, and reduced resistance drift coefficient. In addition, the incorporation of Cr effectively suppresses grain growth in the SS thin films and refines the grain size. The electrical transport properties of the Cr-doped SS thin films are analyzed using a Hall system. Both X-ray photoelectron spectroscopy and first-principles calculations indicate that Cr is more prone to occupy Sb atoms and form stronger Cr–Se bonds, consequently enhancing the stability of the SS thin films. Raman spectroscopy confirms that the introduction of Cr leads to a decrease in bond length and an increase in bond energy. Moreover, the Cr-doped SS thin film exhibits minimal volume fluctuations and a smoother surface morphology, resulting in enhanced interface performance and reliability. Taken together, these results indicate that the introduction of Cr is an effective strategy for optimizing the properties and modifying the structures of SS phase-change materials.

Research on Improved Crystallization Properties and Underlying Mechanism of the Sb2Te3 Phase-Change Thin Film by Inserting Sn15Sb85 Layers.

As a non-volatile semiconductor memory technology, phase-change memory has a wide range of application prospects as a result of the excellent comprehensive performance. In this paper, multilayer thin films based on Sb2Te3 material were designed and prepared by inserting the Sn15Sb85 layer. The thermal and electrical properties of superlattice-like Sb2Te3/Sn15Sb85 phase-change films can be adjusted by controlling the thickness ratio of Sb2Te3/Sn15Sb85. In comparison to the monolayer Sb2Te3 film, the multilayer layer Sb2Te3/Sn15Sb85 materials have a higher crystallization temperature, larger crystallization activation energy, and longer data lifetime, indicating the great improvement of thermal stability. The changes in the phase structure and vibrational modes of multilayer Sb2Te3/Sn15Sb85 films were characterized by X-ray diffraction and Raman spectroscopy, respectively. The presence of Sn15Sb85 layers restrains grain growth and refines the grain size. The multilayer Sb2Te3/Sn15Sb85 films exhibit better surface flatness, smaller surface potential undulation, and lower thickness variations than single-layer Sb2Te3. Phase-change memory cells based on the [Sb2Te3 (1 nm)/Sn15Sb85 (9 nm)]5 thin film has a lower threshold voltage (1.9 V) and threshold current (3.1 μA) compared to the Ge2Sb2Te5 film. Meanwhile, the electrical heating model of a phase-change memory cell based on a [Sb2Te3 (1 nm)/Sn15Sb85 (9 nm)]5 multilayer structure was established by multiphysics coupling analysis, proving the great improvement in heat transfer performance and efficiency. The experimental and theoretical studies confirm that the insertion of the Sn15Sb85 layer can significantly improve the crystallization properties of Sb2Te3 films, paving the way for optimizing the phase-change materials by regulating the microstructural parameters.

Low-temperature β-relaxation promotes crystallization in oxide glasses

Primary (α) structural relaxation is known to influence the nucleation behavior in glasses and it has recently been proposed to account for the so-called classical nucleation theory “breakdown” in oxide glasses around the glass transition temperature. However, it is unclear whether secondary (β-) relaxation, predominant at lower temperatures, also plays a role in promoting crystallization. Here, we study the correlation between crystallization kinetics and β-relaxation of three types of oxide glasses with distinct chemical bonds by subjecting the glasses to low-temperature annealing. We find that the activation energy of crystallization (Ea) exhibits an exponential decay with increasing annealing duration for all studied glasses. Such a decrease in Ea is found to be associated with the structural rearrangements in the glasses, especially showing a negative correlation with the enhanced atomistic interplays around modifying cations. Our findings thus point to a universal linkage between β-relaxation and nucleation kinetics in oxide network glasses.

[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.