Crystallization Activation Energy Research Articles

Thermal behavior of gadolinium-silica gels prepared via sol–gel route combined to γ-irradiation process

Gadolinium-silica (Gd-silica) gels were prepared via sol–gel route combined to γ-irradiation (0–30 kGy), starting from Tetra-Ethyl-Orthosilicate (Si(OCH2CH3)4, TEOS) and gadolinium nitrate Gd(NO3).6H2O used as raw materials. The phase transformation and morphology of the gels derived from both precursors were characterized by XRD and TEM analysis. Differential scanning calorimetry (DSC) under non-isothermal conditions was used to determine the crystallization activation energy (E c) at different γ-doses (0, 8, 15, 25 and 30 kGy), using the methods suggested by Kissinger, Moynihan and Ozawa. XRD analysis of the samples calcined up to 1100°C for 2 h reveals the formation of gadolinium silicate (Gd4.67 (SiO4)3O) apatite crystalline phase with the presence of small traces of gadolinium pyrosilicate (Gd2Si2O7), the average particle sizes about 50 nm. TEM observations show spherical Gd-silicate nanoparticles homogeneously dispersed in silica matrix, the mean diameter size is about 40 nm. From DSC analysis, it was observed that the onset crystallization temperature (T x) and peak crystallization temperature (T c) both increase with increasing γ-dose. According to Kissinger, Moynihan and Ozawa models, the crystallization activation energies for Gd-silicate phase formation were found to be 465.2, 474.5 and 465.7 kJ mol−1, respectively for unirradiated samples and 429.1, 447 and 438 kJ mol−1 when the γ-irradiation reaches 30 kGy respectively. Results revealed that the values of E c decreased when the γ-dose increases and attains the minimum value at the dose of 15 kGy and then increase at higher doses. The crystallization rate factor (K) was also seen to decrease with increasing of γ-dose. Gamma irradiation increases the crystallization peak temperature (T c). The crystallization activation energy (E c) estimated from the three models is in good agreement and much well with those reported for silicate systems. Gamma irradiation decreases the E c and crystallization rate factor (K). These preliminary results can provide useful technical information for a better understanding and control of the crystallization process of this type of nanomaterial.

The kinetic characteristics of mullite crystallization in slag with high SiO2 and Al2O3 content at gasification condition of solid fuel

Mullite crystallization leading to poor slag discharge, is the bottleneck of solid fuel gasification. In order to quantify the crystallization behavior and prevent slag blocking, the crystallization thermodynamics and kinetics of slags in the main crystalline phase region of mullite were studied using FactSage, XRD, SEM-EDS and DSC. Mullite crystallization temperatures ranged from 1189 °C to 1325 °C, and an increase in the cooling rate reduced the mullite onset crystallization temperature as detected by DSC. Kinetic analysis showed that mullite possesses strong nucleation capacity and crystallize tendency, and the minimum activation energy of crystallization of slags was 304.4 kJ/mol. The Si-O-Al structure was regarded as the key short-range ordered structure for mullite crystallization ability, and its concentration was reduced by increasing SiO2/Al2O3. Then the crystallization tendency could be weakened by adjustment of SiO2/Al2O3. Meanwhile, slags with SiO2/Al2O3 = 2.0 or Fe2O3 ≤ 15 wt% showed weak crystallization tendency or glassy slag, which was favorable for slagging operation. The results of this study can provide theoretical guidance for the smooth slagging of ash slag in the main crystalline phase of mullite.

Crystallization of sodium calcium silicate glass for highly transparent glass-ceramics

Sodium-calcium-silicate glasses are the most widely used glasses in architectures, photovoltaics, etc. Development of highly transparent sodium-calcium-silicate glass-ceramics is important to extend the application areas. This work investigates the effect of glass composition on the crystallization and transmittance of sodium-calcium-silicate glasses containing ZrO2. It is found that concentration of Na2O in the glasses has large effect on the crystallization behaviors and transmittance of the glass-ceramics obtained. Higher concentration of Na2O in glasses leads to lower glass transition temperature and crystallization activation energy, facilitating the bulk crystallization. Lower concentration of Na2O in glasses results in the surface crystallization of glasses. Similarity in composition of crystalline grains and glass improves the transmittance of glass-ceramics up to above 75% in the visible region, even when the grain size is as large as ~150 μm. Results reported in this work are full of significance for the development of transparent sodium-calcium-silicate glass-ceramics.

Non-isothermal crystallization kinetics and memory switching properties of Tl-Se-Ge-Sb chalcogenide semiconductor alloy for thermally stable phase change memory applications

Quaternary (Tl20Se70Ge10)0.85Sb0.15 chalcogenide glass was synthesized using melt-quenching and thermal evaporation techniques for bulk and thin film samples, and its amorphous character was confirmed by XRD. Based on different models of non-isothermal crystallization kinetics, the average values of the glass transition and the crystallization activation energies are 121.33 and 82.94 kJ mol−1, respectively. The crystallization mechanism in the examined composition is 2D nucleation growth, according to Avrami exponent Thermal parameters of the studied quaternary glass, like fragility fluctuation free volume reduced glass transition temperature thermal stability and glass formation ability were investigated and indicated that the (Tl20Se70Ge10)0.85Sb0.15 ChG exhibits a good ability of glass formation and thermal stability. The obtained results of the dc electrical conductivity are found to increase with temperature and decrease with film thickness. The electrical conduction activation energy (0.583 ± 0.004 eV) is thickness independent and the predominant conduction mechanism is the hopping of charge carriers in the band tail localized states. The () curves of (Tl20Se70Ge10)0.85Sb0.15 chalcogenide glass film samples were analyzed and shown to be appropriate for a memory switch. The mean value of the threshold voltage decreases exponentially as temperature increases, whereas it increases linearly as film thickness increases. The values of threshold voltage and threshold resistance activation energies are 0.282 ± 0.003 and 0.521 ± 0.004 eV, respectively. The obtained switching characteristics data were discussed in view of the electrothermal model motivated by current channel Joule heating. These findings highlight the suitability of the investigated composition for various optoelectronic applications, such as memory switching devices, optical data storage, phase-change memories and optical fibres sensing devices.

Crystallization kinetics of iron (oxyhydr)oxides from zinc leaching solution at 95–150°C based on the Avrami equation

ABSTRACT Here, the Avrami equation was employed to investigate the crystallisation process of iron (oxyhydr)oxides from the ZnSO4–FeSO4 solution. Hydrothermal conditions were as follows: initial Fe2+ concentration = 5–15 g L−1, Zn2+ concentration = 130 g L−1, temperature = 95–150°C, oxygen partial pressure (PO2) = 0.03–0.73 MPa, agitation speed = 300–600 rpm, seed addition = 5 g L−1. Results showed that increasing temperature, PO2, and agitation speed can increase the crystallisation efficiency. The crystallisation activation energy of iron (oxyhydr)oxides is about 104.2 kJ mol−1. During crystallisation, the goethite phase first transforms to hydro-haematite, then to haematite. In contrast, aggregates (precipitated at PO2 = 0.73 MPa) with high-density acicular crystal have more holes that can adsorb the ZnSO4 solution than spherical crystal aggregates (precipitated at PO2 = 0.03–0.33 MPa). Therefore, to produce high-grade crystallisation products while improving iron removal efficiency, the optimal conditions were controlled as follows: T = 150°C, PO2 = 0.3–0.4 MPa, agitation speed = 500 rpm, t = 180 min and adding seeds of 5 g L−1. The resultant (oxyhydr)oxides products containing > 55% Fe, < 1% Zn and < 3% S. Moreover, adding neutralisers can significantly increase the crystallisation efficiency and thus improve iron removal efficiency.

Crystallization kinetics and nanoindentation studies of Cu46Zr40Ti8.5Al5.5 glassy alloy

Crystallization kinetics of Cu46Zr40Ti8.5Al5.5 metallic glass is investigated in non-isothermal and isothermal conditions. In non-isothermal condition, the crystallization activation energy is determined using Kissinger's method. Further, activation energy of reported Cu-Zr-Al metallic glasses are compared with Cu46Zr40Ti8.5Al5.5 alloy to understand the effect of Ti addition on crystallization kinetics. Detailed investigation on activation energy through the crystallization process is studied. To understand the influence of nucleation and growth mechanism during the crystallization steps, samples are heated in isothermal conditions at various annealing temperatures in supercooled liquid region to determine the local Avrami's exponent using Johnson-Mehl-Avrami equation. Additionally, small scale mechanical response is noted on metallic glass sample to determine the influence of structure on hardness and elastic modulus. Nanoindentation results showed hardness value of 5.39 ± 0.09 GPa and Young's modulus of 92.81± 0.52 GPa.

Phase behavior-microstructure-crystallization kinetics correlations in semi-crystalline/amorphous PCL/SAN mixtures filled with nanosilica

In this study, the effects of poly(ε-caprolactone) (PCL) molecular weight and the type and presence of nanosilica on the non-isothermal crystallization behavior of PCL in the PCL/poly(styrene-co-acrylonitrile) (SAN)/nanosilica systems have been quantitatively investigated. The PCL/SAN system have been chosen as an ideal model system because of the special phase behavior of the blends, which include a lower-critical solution temperature (LCST) phase diagram over a virtual upper-critical solution temperature. By this choose, the great importance of phase separation, mutual phase dissolution and preferential nanoparticle migration to one of the polymeric phases on the crystallization behavior during a commercial production process has been highlighted. The addition of both hydrophilic (Si) and hydrophobic (SiR) silica nanoparticles to virgin PCLs with different molecular weights retards the crystallization process. However, the presence of these nanoparticles in PCL/SAN blends impacts the PCL crystallization kinetics in opposite ways, depending on the nanosilica type, PCL molecular weight and melt cooling rate. The reasons for the observed opposite trends are the changes in the LCST-type phase diagram position by altering the PCL molecular weight and nanosilica type, the selective migration of nanoparticles as well as the dispersion state of nanofillers. The presence of both Si and SiR nanosilicas increases the crystallization activation energy, respectively, by 4.2% and 2.4% for the PCL/SAN blend conatining the PCL with lower molecular weight. While the addition of both Si (11%) and SiR (6.7%) reduces this energy for the blend conatining the PCL with higher molecular weight.

Effect of Zn/B molar ratio on the structure, crystallization mechanism and properties of ZnO-B2O3-SiO2 glasses for LTCC applications

ZnO-B2O3-SiO2 glass-ceramics, with the same Si/B molar ratio (0.7) and different Zn/B molar ratios (1.6–2.1) have been prepared by quenching glass melt and heat treatment between 680 °C and 720 °C. DSC analysis has demonstrated that the crystallization activation energy (Ea) of the Zn2SiO4 phase increased with increasing Zn/B ratio, and the glass crystallization process was transformed from a two-dimensional to a one-dimensional growth. DSC curves are consistent with the deformation and viscosity curves and can be attributed to the crystallization behavior of glass. The glass-ceramic with Zn/B = 1.7 sintered at 700 °C for 30 min exhibited the best properties: εr = 6.35; tanδ = 4.3 × 10−3 (11.39 GHz); CTE = 3.8 × 10−6 /K.

Thermal performance of glass-based seals for reversible solid oxide cell: Effect of Al2O3 ceramic addition on the crystallization behavior

Al2O3 ceramic addition in glass significantly influenced thermal performance during sealing process in RSOC stack. The effect of Al2O3 ceramic on crystallization behavior, phase compositions, microstructure, and viscosity of glass were discussed. With increasing Al2O3 ceramic content, the crystallization activation energy of glass gradually increased. The crystallization behavior of glass was effectively suppressed with Al2O3 ceramic addition. The glass with 20 wt% Al2O3 ceramic exhibited that the content of BaAl2Si2O8 crystallization phase remained at around 45 wt% after heat-treated at 750 °C for 300 h. The controlled hexagonal BaAl2Si2O8 crystallization content combining with Al2O3 ceramic in seals effectively adjusted viscosity at about 105.1 Pa s and 107.2 Pa s during 700 °C–900 °C. During sealing process, the moderate Al2O3 ceramic and BaAl2Si2O8 were embedded in glass matrix acting as frame to enhance structural stability. Simultaneously, the glass phase owned proper fluidity, which could infiltrate components and ceramic without wide flow and release thermal stress during sealing.

Effect of hyperfine structure on crystallization, microstructure and magnetic properties of amorphous Nd9Fe85B6 alloy

Crystallization of amorphous alloy is a commonly used method to fabricate nanocomposite permanent magnets. However, the effect of the hyperfine structures of amorphous alloy on microstructure evolution and magnetic properties of the obtained nanocomposites is far from understood. Here, amorphous Nd9Fe85B6 alloys with different hyperfine structures, i.e., different short-range orders (Rs = 0.80–0.91 nm), were prepared via melt spinning. The effects of the hyperfine structure on crystallization behavior, microstructure, and magnetic properties of the material upon thermal annealing were investigated in depth. Crystallization kinetics calculations show that a larger Rs leads to a smaller apparent crystallization activation energy, which leads to higher volume fractions of α-Fe and Nd2Fe14B. At the same time, a crystallizaition process dependent stage crystallization activation energy of Nd2Fe14B has been obtained, which is low at nucleation stage and increases with crystallization process, i.e. easy for nucleation but hard for growth, which leads to a smaller grain size of Nd2Fe14B. As a result, optimized magnetic properties were obtained in the sample with Rs = 0.91 nm.

Effect of boron content on microstructure evolution and crystallization behavior of Fe7(CoNi)93-xBx (x=15, 18, 21) eutectic high-entropy alloys

The effect of boron content on microstructure evolution, glass-forming ability and crystallization behavior of Fe7(CoNi)93-xBx (x = 15, 18, 21) eutectic high-entropy alloys (EHEAs) was investigated. Bulk Fe7(CoNi)93-xBx EHEAs and ribbons were prepared by vacuum frequency induction melting furnace and melt-spinning method, respectively. The results show that the microstructure of as-cast hypoeutectic Fe7(CoNi)78B15 alloy consists of primary (Fe, Co, Ni) dendrite and lamellar eutectic. The eutectic Fe7(CoNi)75B18 alloy shows a fully lamellar eutectic structure consisting of (Fe, Co, Ni) phase and B-rich phase. The microstructure of hypereutectic Fe7(CoNi)72B21 alloy exhibits primary B-rich dendrite and lamellar eutectic. The as-spun Fe7(CoNi)75B18 and Fe7(CoNi)72B21 alloys show an amorphous structure. By comparison, the hypereutectic Fe7(CoNi)72B21 alloy shows an excellent glass-forming ability and thermal stability, which is attributed to the increase of crystallization activation energy induced by B addition. In addition, the increase of B addition inhibits the crystallization behavior, which is caused by the formation of stable covalent bonds between boron and other elements. This work provides an alternative route for the preparation of metallic glass by introducing the non-metallic boron component.

Preparation of rigidity toughness balance and stable poly(glycolic acid) based on chain extension reaction

AbstractAs a completely degradable material, poly(glycolic acid) (PGA) has excellent rigidity, barrier properties, degradability and biocompatibility. However, the inherent brittleness and easily hydrolysable characteristics limit its widespread application. Herein, we introduced chain extension ADR to modify PGA to ameliorate these defects. The results showed that ADR could react with PGA to form “comb‐like” and “cross‐linked” chain extension structures resulting in the improvement of complex viscosity and formation of gel. Because of the chain entanglement of chain extension structures, the toughness of modified PGA was improved (which was verified by the impact strength value of 4.3 kJ/m2 that was about 126% of virgin PGA) without sacrificing its rigidity. Furthermore, the hydrolysis results indicated that the representative PGA/1.0ADR had better hydrolysis stability, it had more complete morphology and slower degradation rate than virgin PGA in the 17‐day hydrolysis experiment. Apart from better toughness and hydrolysis stability, there was also improvements in crystallization performance, the sample PGA/1.0ADR endowed with higher crystallization peak temperature (2.3°C higher than virgin PGA) and lower crystallization activation energy. In short, this work prepared a kind of modified PGA with rigidity toughness balance and better hydrolysis stability, which could expand the application range of PGA‐based materials.

Influence of samarium modification on the phase-change performance and phase structure of tin antimonide

This work presents the optimization of the crystallization behavior and reliability of Sn15Sb85 thin films by doping Sm element. The phase transition behaviors induced by thermal were investigated by in situ resistance measurement. With the addition of Sm element, Sn15Sb85 film exhibits the superior crystallization temperature (232 °C) and data conservation (172.32 °C for 10 years), larger activation energy of crystallization (4.91 eV) and crystalline resistance (∼103 Ω), which contributes to the increased thermal stability of the amorphous state and decrease in the programming energy. The Sm-doping can broaden the energy band gap from 0.55 to 1.07 eV. The amorphous Sm and Sn compositions could retard grain growth and refine grain size from 21.13 to 11.13 nm, combining with x-ray diffraction and x-ray photoelectron spectroscopy. The surface morphology of Sn15Sb85 film becomes smoother after Sm doping as determined by atomic force microscopy images, resulting in the improved interfacial reliability. Phase change memory devices based on Sm0.095(Sn15Sb85)0.905 films can successfully achieve the complete SET and RESET reversible operation process with high operating speed (200 ns) and low power consumption (1.6 × 10−10 J). The results suggest that doping the proper concentration of Sm element will be an effectual solution to adapt and optimize the crystallization properties of Sn15Sb85 phase change material.

Impact of non-bridging oxygens on the thermal, electrical and optical properties of germanate glasses and exploration of the germanate anomaly

In this study, we successfully prepared quaternary germanate glasses (Bax/3Srx/3Cax/3)Ge(1-x)O3 (x = 0.1–0.5) using a containerless solidification method. The structure of the germanate amorphous materials was characterized using techniques such as XRD, SEM, TEM and Raman. We evaluated the thermodynamic properties of the amorphous materials using differential scanning calorimetry and investigated their crystallization activation energies. In terms of application performance, we measured electrical conductivity and impedance spectra for the electrical properties, while the optical properties were assessed through the refractive index and transmittance. The results revealed that the (Ba0.2/3Sr0.2/3Ca0.2/3)Ge0.8O3 system represented the germanium anomaly point. Due to the highest number of ternary rings and the most compact structure within this system, the values of density, glass transition temperature, refractive index, and bandgap all reached their maximum. As the content of alkaline earth oxides increased, the glass network structure gradually fractured, leading to an increase in non-bridging oxygens and corresponding changes in properties.

The crystallization kinetics analysis and the new prediction index of melilite-bearing slag under solid fuel gasification condition

Melilite represents a prevalent crystalline phase precipitated from the gasification slag produced by various solid fuels, including coal and biomass. The crystallization of melilite can lead to gasifier blockage, posing significant challenges. This study investigated the crystallization behavior of melilite-bearing slags during slag tapping. To achieve this, FactSage, XRD, SEM-EDS, and DSC were employed to investigate the crystallization thermodynamics and kinetics of 12 synthetic melilite-bearing slag samples. The results revealed that the crystallization temperatures of slags with the mass fraction of SiO2 + Al2O3 is 50 wt% (SiO2 + Al2O3 = 50 wt%) ranged between 1150 and 1100 °C. Slags with the SiO2 + Al2O3 = 60 wt% and mass ratio of SiO2 to Al2O3 > 1.0 (Si/Al > 1.0) showed no crystals precipitate, which is conducive to slag tapping. Thermodynamics plays a crucial role in melilite crystallization, as it involved the uphill diffusion of Ca and Al. To quantify the thermodynamic crystallization ability, a parameter called Thermodynamic Crystallization Ability (TCA) is defined. Increasing Si/Al contributes significantly to reducing TCA. When the TCA is less than 0.33 wt%/K, the melilite-bearing slag will not crystallize. Furthermore, the kinetic analysis results demonstrated that the crystallization activation energy (EC) of melilite-bearing slag ranged from 310.64 to 458.54 kJ/mol. Moreover, the rate-determining step is the surface reaction, which was influenced by cluster structure. The essential short-range ordered structure that composes the melilite crystal is Al-O-Al; however, due to higher Si/Al, the concentration of the Al-O-Al structure in the slag decreases, resulting in higher EC value. These findings provide theoretical guidance for the stable operation of the gasifier.

Effect of substituting Na2O with B2O3 on the crystallization and properties of MgO–Al2O3–SiO2 transparent glass-ceramics

MgO–Al2O3–SiO2 (MAS) transparent glass-ceramics were prepared with ZrO2 as a nucleating agent, and the substitution of B2O3 for Na2O on the properties of the MAS glass-ceramics was investigated systematically. The results show that the substitution of B2O3 increased the glass transition temperature, crystallization temperature, and crystallization activation energy. Additionally, there was no change in the main crystal phase of the glass-ceramics, which were ZrO2 (JCPDS PDF#.50-1089) and Al0.52Zr0.48O1.74 (JCPDS PDF#.53-0294). The crystal growth mode shifted from three-dimensional growth to two-dimensional growth, and the crystal morphology transformed from a spherical appearance to a star-shaped appearance. Moreover, the mechanisms of the property changes induced by B2O3 substitution are revealed and discussed. The transmittance of MAS glass-ceramics without B2O3 decreased from 88 % to 32 % as the crystallization temperature increased from 800 °C to 920 °C, and decreased from 90 % to 8 % when B2O3 was added. Additionally, the Vickers hardness of MAS glass-ceramics decreased from 6.37 GPa to 6.13 GPa, after the introduction of B2O3, while, the fracture toughness increased from 1.48 MPa m1/2 to 1.55 MPa m1/2. The scratch behaviour of glass-ceramics exhibits a negative correlation with the applied load, but a positive correlation with the crystallization temperature. In particular, the incorporation of B2O3 substantially enhances the scratch resistance of glass-ceramics. The conclusions provide researchers with the roles of B2O3 in crystallization kinetics, microstructure, transmittance, and mechanical properties of MAS transparent glass-ceramics for various applications such as covers.

Glass‐ceramic: Controlled crystallization of glasses obtained from biomass ash

AbstractIn this work, vitreous material was produced, using ash from burning wood in a boiler, to obtain a glass‐ceramic with the gehlenite phase. The glass obtained by melt‐quenching at 1450°C was characterized by differential scanning calorimetry and other techniques to determine the glass transition and crystallization temperatures, and crystallization kinetics were investigated using the Kissinger model. Tablets prepared with glass powder were treated at 970, 990, 1074, and 1120°C for 1 h, to obtain the glass‐ceramic material. The phase identified by X‐ray diffraction was gehlenite, with two crystalline structures coexisting in the sample. According to the kinetics study, the phase with a tetragonal structure had a lower crystallization activation energy, and therefore, it may have been the first phase to be formed in the material. Scanning electron microscopy images revealed crystalline regions within the glassy matrix with a lamellar microstructure, with no geometrically defined morphology and no morphological or microstructural distinction, suggesting that both gehlenite phases coexist without apparent distinctions in the glass‐ceramic. The best results for water absorption, apparent porosity, and apparent density were for the glass‐ceramic sample sintered at 990°C, whose values were respectively 0.1, 0.29, and 2.89 g/cm3.

Crystallization behavior and properties of quartz glass-ceramics synthesized from desert sand

Quartz glass-ceramics were synthesized with desert sand as the main raw material. The effects of pretreatment technology of desert sand and various cations on the glass stability (GS) parameters (KH, KLL,KW, KZW, KLX), crystallization kinetic parameters (crystallization activation energy (Ec), reaction rate (k), the effective frequency factor(ν) and the Avrami parameter (n)), phase transition, microstructure and properties of glass-ceramics were investigated. The results show that the chemical composition of desert sand is greatly changed by sieving and magnetic separation, and the glass stability, phase transition and crystallization ability of glass are controlled by the mixed mobile ion effect (MMIE), in which the ionic field intensity determined by ionic valence and radius plays a major role. Finally, the crystallization of glass is dominated by the surface crystallization mechanism, and the obtained glass-ceramics mainly consist of α-quartz, β-cristobalite and glass phases, which have excellent comprehensive properties.

Samarium addition-mediated simultaneous achievement of excellent resistance drift and superior thermal stability in phase-change compound antimony-selenium thin film

The Sm-doped Sb7Se3 thin films were systematically investigated, including phase change behavior, phase structure, microstructure, and electrical properties. The in-situ resistance test displays that the addition of Sm element leads to a significant increase in the crystallization temperature, decadal data retention and crystallization activation energy, implying better thermal stability. Crystallization kinetic analysis indicates a one-dimensional growth crystallization pattern, exhibiting an ultra-fast crystallization speed. The change in optical bandgap reflects that the exotic Sm atoms enhance the bandgap energy, which facilitates the reduction of the threshold current. Resistance drift test highlights the suppression of structural relaxation by Sm atoms, which would greatly improve the reliability of the information readout. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, and transmission electron microscopy demonstrate that the addition of Sm retards the crystallization process and refines the grain size. Energy dispersive spectroscopy shows that the Sm dopant has incorporated into Sb7Se3 thin film. The phase change memory cell based on Sm-doped Sb7Se3 film exhibits faster running speed (100 ns) and lower power consumption (3.0 × 10−11 J) than the conventional Ge2Sb2Te5 material. All the results prove that incorporating appropriate amounts of Sm into Sb7Se3 material is an ideal technique for optimizing resistance drift and thermal stability of Sb7Se3 thin films.

Accelerated nonisothermal crystallization and improved material properties of biobased poly(butylene 2,5-furandicarboxylate)/talc composites

Biobased poly(butylene 2,5-furandicarboxylate) (PBF) reflects the much poorer crystallizability than its petroleum-based counterpart poly(butylene terephthalate). By introducing talc platelets into PBF matrix to fabricate composites, the effects of low loadings’ layered filler upon nonisothermal melt crystallization and material properties of PBF/talc composites are investigated for the first time. Obviously accelerated crystallization of the composites relative to pure PBF is first evidenced by the simultaneous increase of crystallization temperature and decline of crystallization half-time, and further supported by both the crystallization rate coefficient and crystallization rate parameter. Nonisothermal crystallization kinetics are analyzed by both the Jeziorny model and Mo equations, and the intensifying effect of talc upon PBF's crystallization is attributed to the coupling of enlarging nucleation activity and lowering crystallization activation energy. Meanwhile, the incorporation of layered talc doesn't modify the crystal structure of PBF. Moreover, both the thermal and mechanical properties of PBF/talc composites are reinforced slightly.