Crystalline Fraction Research Articles

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

Epitaxial Orientation-Controlled High Crystallinity and Ferroelectric Properties in Hf0.5Zr0.5O2 Films.

Hafnium-based binary oxides are essential for fabricating nanoscale high-density ferroelectric memory devices. However, effective strategies to control and improve their thin-film single crystallinity and metastable ferroelectricity remain elusive, hindering potential applications. Here, using NdGaO3 (NGO) substrates with four crystalline orientations, we report a systematic study of the structural characterizations and ferroelectric properties of epitaxial Hf0.5Zr0.5O2 (HZO) films, demonstrating orientation-controlled high crystallinity and enhanced ferroelectric properties. HZO films grown on NGO(001) and NGO(110) substrates exhibit relatively low crystallinity and a significant presence of the monoclinic phase. In contrast, HZO films grown on NGO(100) and NGO(010) possess high single crystallinity and a dominant ferroelectric phase. These differences are attributed to the surface symmetry of the NGO substrate, which favors the formation of 4- or 2-fold domain configurations. Moreover, the optimized HZO films exhibit a large polarization (2Pr) of ∼50 μC/cm2, enhanced fatigue behavior up to 1011 cycles, improved retention of 2Pr ∼ 40 μC/cm2 after 10 years, and characteristic polarization switching speeds in the submicrosecond range. Our results highlight the importance of modulating the single crystallinity and ferroelectric phase fraction of HfO2-based films to enhance ferroelectric properties, further revealing the potential of epitaxial symmetry engineering.

Analytical insight into caffeine extraction from typica coffee leaves based on crystallinity enhancement, optical phonon vibration upshift, and morphological evolution.

Caffeine extracted from callus cultures by in vitro technique induced from typica coffee (Coffea arabica L. var. typica) leaves was successfully carried out by a simple Soxhlet method. Analysis of X-ray diffraction patterns showed an increase in crystallinity fraction from leaves (13.56%) to callus (14.46%) and then to caffeine (39.18%). Crystallite size also varied, with average sizes of 18±6, 69±51, and 32.5±17 nm for leaves, callus, and caffeine, respectively. Fourier transmission infrared absorption data confirmed the presence of hydroxyl (OH) groups bound to carbon (C─COH), indicating caffeine content. The high stability of the C─COH is indicated by the broad optical phonon vibrations of the leaves: 247cm-1 to caffeine: 963cm-1. Quantitative analysis of dielectric function and electron loss function intensity peaks of each sample showed that leaves efficiently capture and store light energy while caffeine has less potency. Scanning electron microscopy analysis showed irregular shapes of leaves, oval round shapes for callus, and rectangular crystals for caffeine due to crystal orientation during transformation and had a strong correlation with crystallinity fraction. Finally, the structure-based identification, chemistry, optical-dielectric function, and micro-surface properties have been fully studied, thus unmasking the phenomenon of slow transformation from leaves to caffeine form. PRACTICAL APPLICATION: The result of this study can be applied to uncover new methodologies related to the classification, and biotechnological utilization of callus culture based on structural properties, optical-dielectric function, and micro-surface analysis. Methodologically, the resulting callus culture provides a sustainable and controllable supply of plant material for caffeine extraction, thereby reducing traditional methods involving field-grown plants and avoiding the use of pesticides.

Insights into the growth of GaN thin films through liquid gallium sputtering: A plasma-film combined analysis.

This study presents the detailed characterization of a magnetron-based Ar-N2 plasma discharge used to sputter a liquid Ga target for the deposition of gallium nitride (GaN) thin films. By utilizing in situ diagnostic techniques including optical emission spectroscopy and microwave interferometry, we determine different temperatures (rotational and vibrational of N2 molecules, and electronic excitation of Ar atoms) and electron density, respectively. Beyond providing insights into fundamental plasma physics, our research establishes a significant correlation between gas-phase dynamics, particularly those of gallium atoms (flux and average energy at the substrate) and deposited GaN thin film properties (growth rate and crystalline fraction). These findings underscore the role of plasma conditions in enhancing thin film quality, highlighting the importance of plasma characterization in understanding and optimizing GaN thin film growth processes.

A novel isolation technique for sweetpotato starch and its application in thermal property characterization.

The utilization of sweetpotato starch in the food industry is significantly influenced by the granule size of the starch. To isolate sweetpotato starch fractions with different sizes, an efficient isolation method is in demand. The differences in thermal properties of starch fractions with different sizes from various sweetpotato varieties were revealed insufficiently. In this study, we devised a time-saving isolation technique to effectively isolate sweetpotato starch fractions based on granule sizes. The new technique was proved applicable for sweetpotato varieties with different flesh colors. The amylose contents of the isolated starch fractions were in the range 16.49-23.27%. A positive association was observed between amylose content, relative crystallinity of starch fractions and their granule size. Conversely, both the swelling power and water solubility at 95 °C displayed a consistent decline from more than 30 g g-1 to lower than 20 g g-1 as the granule size increased. Tp, To and Tc decreased gradually with an increase of starch granule size, while the medium- or small-sized starch fractions showed higher ΔH. In the first stage of thermogravimetric analysis curves, the weight of the small-sized starch fractions decreased the slowest, but no definite pattern was detected in the second or third stage. Therefore, the newly established technique and the results of this study will help better understand the properties of sweetpotato starch fractions with different sizes and certainly provide guidelines for the utilization of sweetpotato starch in food processing and product development. © 2024 Society of Chemical Industry.

MIRI MRS Observations of Beta Pictoris. II. The Spectroscopic Case for a Recent Giant Collision

Modeling observations of the archetypal debris disk around β Pic, obtained in 2023 January with the MIRI Medium Resolution Spectrograph on board JWST, reveals significant differences compared with that obtained with the Infrared Spectrograph on board Spitzer. The bright 5–15 μm continuum excess modeled using a ∼600 K black body has disappeared. The previously prominent 18 and 23 μm crystalline forsterite emission features, arising from cold dust (∼100 K) in the Rayleigh limit, have disappeared and been replaced by very weak features arising from the hotter 500 K dust population. Finally, the shape of the 10 μm silicate feature has changed, consistent with a shift in the temperature of the warm dust population from ∼300 to ∼500 K and an increase in the crystalline fraction of the warm, silicate dust. Stellar radiation pressure may have blown both the hot and the cold crystalline dust particles observed in the Spitzer spectra out of the planetary system during the intervening 20 yr between the Spitzer and JWST observations. These results indicate that the β Pic system has a dynamic circumstellar environment, and that periods of enhanced collisions can create large clouds of dust that sweep through the planetary system.

Chain-Folded Lamellar Stacking Structure of the Crystalline Fraction of Bombyx mori Silk Fibroin with Silk II Form Studied by 2D 13C-13C Homonuclear Correlation NMR Spectroscopy.

The structure of Bombyx mori silk fibroin (SF) is a subject of significant interest due to its remarkable physical properties; however, its atomic-level structure is still not conclusive. We previously proposed a lamellar stacking structure for the crystalline fraction (Cp) with β-turns occurring every eighth amino acid. In this study, we took the following steps: At first, a model of the chain-folded lamellar stacking structure in antipolar and antiparallel β-sheet layers was constructed. Then, dipolar-assisted rotational resonance solid-state NMR spectra were observed to determine the effective internuclear distance (rj,keff) for the uniformly 13C-labeled Cp fraction sample. By comparing the experimentally obtained rj,keff (obs) values with the calculated rj,keff (calc) values from our structural model, a fairly good correlation between the observed and calculated values of the internuclear distances was obtained with a standard deviation of 0.37 Å. This supports the existence of the chain-folded lamellar stacking structure in the SF fiber. These findings contribute to our understanding of the atomic-level structure of SF and its exceptional properties.

Successive self-nucleation and Annealing technique applied to polypropylene/butyl rubber composites: Recycling alternatives for vacuum bagging materials

The aerospace sector uses butyl rubber to manufacture carbon fiber components through an autoclave or infusion. Both manufacturing techniques require a high vacuum to achieve adequate impregnation of the carbon fiber fabrics with epoxy resin, and butyl rubber is used as the sealant. The aerospace sector discontinues materials with shelf life expired, and butyl rubber is one of the materials most discontinued for not being used within the designated time. This work presents the development of composites using polypropylene and discontinued butyl tape. Composites with 30, 50, and 70 wt% of butyl rubber content were prepared using a twin-screw extruder. The structural analysis showed that the composites with 50 wt% and 70 wt% are similar to butyl rubber, while the compound with 30 wt% of butyl is similar to polypropylene. The degree of crystallinity of the compound with 50 wt% of butyl content was 18% higher than the PP, and the melting temperature decreased by 30% with the higher butyl content. SSA revealed that the highest enthalpic contribution occurred in the crystalline fraction of higher perfection, except for the compound with 50 wt% of butyl content, whose less perfect crystalline populations grew at the expense of the most perfect crystals. The reduction of the crystalline fraction implies that butyl interferes with the formation of crystals, developing populations with lower lamellar thickness that favors the overall crystallinity of the compound. Young’s modulus, yield strength, and nominal strain decreased with butyl rubber content. The composites showed rough failure surfaces with solid butyl rubber particles and poor adhesion to polypropylene. Butyl particles with diverse sizes and geometries lead to sudden failure of the composites and high dispersion in strain values.

Composite Nanoarchitectonics of Electrospun Piezoelectric PVDF/AgNPs for Biomedical Applications, Including Breast Cancer Treatment.

This study focused on preparing composite nanomats by incorporating silver nanoparticles (AgNPs) in polyvinylidene fluoride (PVDF) nanofibers through the electrospinning process. A short review of piezoelectric PVDF-related research is presented. PVDF is known for its biocompatibility and piezoelectric properties. Since electrical signals in biological tissues have been shown to be relevant for therapeutic applications, the influence of the addition of AgNPs to PVDF on its piezoelectricity is studied, due to the ability of AgNPs to increase the piezoelectric signal, along with providing antibacterial properties. The prepared samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. In addition, the biological activity of composites was examined using a cytotoxicity assay and an assessment of the antibacterial activity. The obtained results show that the incorporation of AgNPs into PVDF nanofibers further enhances the piezoelectricity (crystalline β-phase fraction), already improved by the electrospinning process, compared to solution-casted samples, but only with a AgNPs/PVDF concentration of up to 0.3%; a further increase in the nanoparticles led to a β-phase reduction. The cytotoxicity assay showed a promising effect of PVDF/AgNPs nanofibers on the MDA-MB-231 breast cancer cell line, following the non-toxicity displayed in regard to the healthy MRC-5 cell line. The antibacterial effect of PVDF/AgNPs nanofibers showed promising antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, as a result of the Ag content. The anticancer activity, combined with the electrical properties of nanofibers, presents new possibilities for smart, multifunctional materials for cancer treatment development.

Quantitative structural characterization of LiNbO3-SiO2 glass-ceramics by multinuclear solid-state NMR

This study presents a detailed structural analysis of the glass-to-crystal transition in the technologically important LiNbO3–SiO2 glass system, focusing on the composition 35Li2O–25Nb2O5–40SiO2 known for its exceptional second harmonic generation (SHG) response in glass-ceramics. We develop a comprehensive solid-state NMR protocol to quantify major and minor fractions of elusive nanocrystalline phases and the residual glass composition, overcoming limitations of techniques such as X-ray diffraction and Raman spectroscopy. By employing 7Li satellite transition difference spectroscopy and 93Nb magic-angle spinning (MAS) NMR, we achieve quantification of crystalline fractions down to 1%. By combining all the complementary 6Li, 7Li, 29Si, and 93Nb MAS NMR experiments, we also deduce the composition of the residual glass. Short crystallization times (up to 120 min) at 640 °C result in nanocrystalline LiNbO3, whereas crystallization for 1440 min at this temperature additionally yields two Li2Si2O5 polymorphs and Li2SiO3. 7Li spin echo and 7Li{93Nb} W-RESPDOR NMR spectroscopy indicate that LiNbO3 crystallizes in specific domains leaving behind SiO2-rich residual glassy domains. This work offers a time-efficient and versatile NMR protocol for characterizing crystalline and residual glass components in nanocrystalline glass-ceramics in the LiNbO3–SiO2 system and beyond, providing valuable insights into the crystallization process which is not possible with other techniques.

Synthesis and characterization of biobased copolyesters based on pentanediol: (1) Poly(pentylene dodecanoate‐co‐furandicarboxylate)

AbstractA series of biobased aliphatic‐aromatic copolyesters, poly(pentylene dodecanoate‐co‐furandicarboxylates) (PPeDFs) were synthesized via an esterification and polycondensation melt process. The copolyesters were characterized using gel permeation chromatography, Fourier transform infrared spectroscopy, 1H NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, wide angle x‐ray scattering, and tensile testing. The thermal transition behavior was strongly dependent on composition, with the melting and glass transition temperatures reaching a minimum at approximately equimolar ratio of D to F. All copolyesters were stable below 300°C with their R600 (the weight of material remaining at 600°C) values increasing with F fraction. PPeD to PPeDF30 (e.g., mole ratio D/F = 7:3) show sharp PPeD crystalline reflections only while broad PPeF reflections are shown in PPeF and PPeDF90. PPeDF40 to PPeDF80 showed both crystal structures. The fractional crystallinity for the PPeD was much higher than PPeF and the fractional crystallinity of the copolymers showed a minimum at D/F ratios closer to the latter. The stress at break and modulus both exhibited maxima at D/F ratios that were either high or low, but somewhat surprisingly a strong maximum in percent elongation at break of over 600% occurs at PPeDF40. For this composition, a typical plastic behavior curve was found including a yield point, high elongation at break, and strain hardening.Highlights Poly(pentylene dodecanoate‐co‐furandicarboxylates) (PPeDFs) are synthesized Mechanical properties, a function of D:F ratio. High elongation at 40 mol% F. Two melting temperatures/crystal structures, one PPeD, the other PPeF Glass transition temperature minimum at intermediate D:F ratios

Tailoring the stress-free two-way shape memory effect in sol–gel crosslinked poly(ϵ-caprolactone)-based semicrystalline networks

Two-way shape memory polymers are stimulus-responsive materials capable of changing their shape between two configurations based on an on/off thermal stimulus. While the traditional effect has been studied under the application of an external mechanical load, it was demonstrated also in the absence of an external load. Such a response only relies on a carefully tailored macromolecular architecture of the polymer combined with a specific thermo-mechanical protocol. In particular, semicrystalline networks, either consisting of a multi-phase copolymer network or a homopolymer based network with broad phase transitions, have been proposed to this aim under ad hoc thermo-mechanical histories. In this work, the two-way shape memory behavior is studied on a poly(ϵ-caprolactone)-based network, crosslinked by means of a sol–gel approach and tailored on the selection of the molecular weight of the precursor polymer. Changing the prepolymer precursor allowed to tune the melting/crystallization regions of the networks, thus the thermal region of the reversible shape memory effect. The application of properly designed thermo-mechanical cycles allowed to study the two-way shape memory effect without the application of an external load under tensile conditions. Given a specific network, the stress-free actuation of the reversible elongation-contraction cycle under tensile conditions was induced across its specific melting/crystallization region. The extent of the effect was found to depend on the crystalline fraction remaining for the given actuation temperature and on the tensile stretched state imposed on the materials during the training step. The results were compared with the response achieved under the traditional two-way shape memory protocol under stress. The stress-free two-way shape memory effect was also successfully demonstrated and emphasized, under flexural conditions, which suggests the potential of these materials as intrinsically reversible actuators, promising for applications in the biomedical field and/or for soft robotics.

Petrographic and chemical characterization and carbon and nitrogen isotopic compositions of cometary IDPs and their GEMS amorphous silicates

GEMS (glass with embedded metal and sulfides) are the dominant carrier of amorphous silicates in anhydrous interplanetary dust particles (IDPs) and one of the most suitable materials to study early solar system processes. Amorphous silicates in 105 GEMS from eight IDPs were analyzed regarding texture and chemical composition to reassess GEMS formation theories and genetic relationships to amorphous silicate material in meteorites. Petrography of bulk IDPs was investigated to understand GEMS’ relationships to other IDP components. Furthermore, carbon and nitrogen isotopic compositions were measured. Nearly all GEMS are aggregates of several subgrains with variable amount of nanophase inclusions and different Mg- and Si-contents, while single GEMS are rare. The subgrains within aggregates are typically surrounded by one or more carbon rims with high density. The chemical compositions of GEMS amorphous silicates are subsolar for all major element/Si ratios but exhibit wide heterogeneity. This is not influenced by silicon oil from the capturing process of IDPs as assumed before, as a penetration of the silicon oil is excluded by high resolution EELS (electron energy loss spectroscopy) areal density maps of silicon. Furthermore, low Fe-content in GEMS amorphous silicates shows that these are not altered by aqueous activity on the parent body as it is the case for amorphous silicate material in primitive meteorites. The subsolar element/Si ratios and the wide chemical heterogeneity point to a non-equilibrium fractional condensation origin either in the early solar nebula or in a circumstellar environment and are not in agreement with homogenization via sputtering in the ISM. The close association with carbon around GEMS subgrains and as double-rims around GEMS aggregates argue for a multi-step aggregation after formation of the smallest GEMS subgrains in the ISM or the early solar nebula. Carbon acting as matrix material connecting GEMS and other IDP components has lower areal density as seen from carbon EELS areal density maps and isotopic anomalies varying at the nanometer scale, pointing to different origins and processing of materials to varying extent or at changing temperatures.To balance GEMS’ subsolar element/Si ratios, a supersolar component in IDPs was assumed to account for the overall chondritic composition of bulk IDPs. Nevertheless, our bulk IDP analyses revealed subsolar, but variable, element/Si ratios for complete particles as well, depending on type and amount of mineral phases in each particle. Pyroxenes in the investigated particles can occur as elongated euhedral crystals, but are overall rare. The dominant crystalline fraction in the investigated IDP samples are equilibrated aggregates (EAs) that show the same chemical compositions as GEMS, indicating that the EAs are recrystallized GEMS grains and formed after GEMS formation as secondary phases.

Synergistic effects of silicon and goethite co-application in alleviating cadmium stress in rice (Oryza sativa L.): Insights into plant growth and iron plaque formation mechanisms

Rice is one of the most important staple food crops; however, it is prone to cadmium (Cd) accumulation, which has negative health effects. Therefore, methods to reduce Cd uptake by rice are necessary. At present, there is limited research on the effects of co-application of silicon (Si) and goethite in mitigating Cd stress in rice. Furthermore, the specific mechanisms underlying the effects of their combined application on iron plaque formation in rice roots remain unclear. Therefore, this study analyzed the effects of the combined application of Si and goethite on the biomass, physiological stress indicators, Cd concentration, and iron plaques of rice using hydroponic experiments. The results revealed that co-treatment with both Si and goethite increased the plant height and dry weight, superoxide dismutase and catalase activities, photosynthetic pigment concentration, and root activity. Moreover, this treatment decreased the malondialdehyde concentration, repaired epidermal cells, reduced the Cd concentration in the roots by 57.2 %, and increased the number of iron plaques and Cd concentration by 150.9 % and 266.2 % in the amorphous and crystalline fractions, respectively. The Cd/Fe ratio in amorphous iron plaques also increased. Our findings suggest that goethite serves as a raw material for iron plaque formation, while Si enhances the oxidation capacity of rice roots. The application of a combination of Si and goethite increases the quantity and quality of iron plaques, enhancing its Cd fixation capacity. This study provides theoretical evidence for the effective inhibition of Cd uptake by iron plaques in rice, providing insights into methods for the remediation of Cd contamination.

Highly stable mesoporous-controlled corncob biochar confined paraffinic material with exceptional latent heat retention performance

Bio-based composites fabricated from bio-sourced waste feedstocks have attracted increasing interest and have shown potential applications in sustainable energy infrastructure development. Thermal management using phase-change materials (PCMs) has appeared as an innovative approach for energy storage and cooling, where pure PCMs that lack thermal stability are encapsulated in solid matrices to ensure the charge/discharge of the latent heat of the composite. However, their energy storage density, thermal stability, and durability are reduced after multiple thermal cycles, besides the complicated and expensive nonrenewable fossil feedstock utilization. Biochar, mostly used for soil remediation, can be redirected and repurposed for the encapsulation of PCMs in renewable energy storage infrastructures. In this study, a “greener” biochar-based composite was fabricated from agricultural corncob-derived biochar (88.9 % mesopore proportion) and a commercially available paraffinic PCM (n-hexadecane) following vacuum impregnation strategies. Corncob biochar combined with hexadecane exhibited an efficient energy per unit mass of 250.6 kJ kg−1 and a latent heat retention of 110.3 % after 500 consecutive thermal cycles. In addition, the corncob biochar/hexadecane composite demonstrated high fractional crystallinity and relative latent heat efficiency (98.9 %). The composite exhibited promising chemical compatibility with composite components, stability, and competitive energy density even compared with a composite made of nonrenewable fossil-based materials, like exfoliated graphene nanoplatelets, which demonstrated reduced latent heat retention after multiple heating-cooling cycles. Intermolecular interactions, such as hydrogen bonding, between the guest molecular chains and host materials played a significant role in the thermal performance of the as-synthesized composite materials. This approach will contribute to overcoming the complexities and costs of composite PCM development in thermal management and thermal energy storage applications and support and advance the UN's sustainable development goal (affordable and clean energy).

Recyclability of elastomer toughened recycled poly(ethylene terephthalate): The effect of grinding-extrusion-injection moulding on the mechanical and morphological properties of the blend

Reprocessing potential of recycled poly(ethylene-terephthalate) (RPET)/ethylene-butyl-acrylate-glycidyl methacrylate (EBA-GMA) blends was investigated. PET flakes from food packaging were compounded with 0, 5, 10, 15 and 20 % EBA-GMA. Injection moulded specimens were produced, and some of the specimens were grinded, and reproduced to simulate real reprocessing. It was revealed by scanning electron microscopy that the distribution and particle size of the elastomer did not change notably after recycling. Noticeable degradation of the polymer matrix was observable after every processing step. Such deterioration of PET resulted in higher crystallinity and rigid amorphous fraction, as found by differential scanning calorimetry, which ultimately led to higher storage modulus, while the notched impact strength and elongation at break decreased. Nevertheless, the mechanical performance of the reprocessed RPET/EBA-GMA blends still significantly outperforms that of the neat PET recyclate. The degree of chain breakage was found to be the primary factor determining the recyclability of RPET/EBA-GMA blends.

Tunable Near-Infrared Transparent Bands Based on Cascaded Fabry–Perot Cavities Containing Phase Change Materials

In this paper, we construct a near-infrared Fabry–Perot cavity composed of two sodium (Na) layers and an antimony trisulfide (Sb2S3) layer. By cascading two Fabry–Perot cavities, the transmittance peak splits into two transmittance peaks due to the coupling between two Fabry–Perot modes. We utilize a coupled oscillator model to describe the mode coupling and obtain a Rabi splitting of 60.0 meV. By cascading four Fabry–Perot cavities, the transmittance peak splits into four transmittance peaks, leading to a near-infrared transparent band. The near-infrared transparent band can be flexibly tuned by the crystalline fraction of the Sb2S3 layers. In addition, the effects of the layer thickness and incident angle on the near-infrared transparent band and the mode coupling are investigated. As the thickness of the Na layer increases, the coupling strength between the Fabry–Perot modes becomes weaker, leading to a narrower transparent band. As the thickness of the Sb2S3 layer increases, the round-trip propagating of the Sb2S3 layer increases, leading to the redshift of the transparent band. As the incident angle increases, the round-trip propagating of the Sb2S3 layer decreases, leading to the blueshift of the transparent band. This work not only provides a viable route to achieving tunable near-infrared transparent bands, but also possesses potential applications in high-performance display, filtering, and sensing.

Development of high conducting phosphorous doped nanocrystalline thin silicon films for silicon heterojunction solar cells application

We have investigated the plasma-enhanced chemical vapor deposition growth of the phosphorus-doped hydrogenated nanocrystalline silicon (n-nc-Si:H) film as an electron-selective layer in silicon heterojunction (SHJ) solar cells. The effect of power densities on the precursor gas dissociation are investigated using optical emission spectra and the crystalline fraction in n-nc-Si:H films are correlated with the dark conductivity. With the P d of 122 mW cm−2 and ∼2% phosphorus doping, we observed Raman crystallinity of 53%, high dark conductivity of 43 S cm−1, and activation energy of ∼23 meV from the ∼30 nm n-nc-Si:H film. The n-nc-Si:H layer improves the textured c-Si surface passivation by two-fold to ∼2 ms compared to the phosphorus-doped hydrogenated amorphous silicon (n-a-Si:H) layers. An enhancement in the open-circuit voltage and external quantum efficiency (from >650 nm) due to the better passivation at the rear side of the cell after integrating the n-nc-Si:H layer compared to its n-a-Si:H counterpart. An improvement in the charge carrier transport is also observed with an increase in fill factor from ∼71% to ∼75%, mainly due to a reduction in electron-selective contact resistivity from ∼271 to ∼61 mΩ-cm2. Finally, with the relatively better c-Si surface passivation and carrier selectivity, a power conversion efficiency of ∼19.90% and pseudo-efficiency of ∼21.90% have been realized from the SHJ cells.

Obtaining extremely low coercivity of high Bs FeCoBSiCPCu nanocrystalline alloys through modulation of magnetic anisotropy

Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe75Co8(B10Si3C3P1)1-x/17Cux (x = 0.5, 0.75, 1, 1.25) nanocrystalline alloys. All of the magnetic field-annealed nanocrystalline alloys with Cu content more than 0.5 at.% exhibit significantly improved soft-magnetic properties, including high saturation magnetic flux density up to 1.87 T, effective permeability of 13,000–16,000 under the condition of 1 A/m and 1 kHz, coercivity as low as 1.6 A/m, and core loss of 0.11–0.45 W/kg under the condition of 1.0 T and 50 Hz. The application of a magnetic field promotes the nucleation and inhibits the growth of grains, leading to an increase in the number density of nanocrystals and the crystalline volume fraction, and a reduction in the grain size. The magnetic field annealing reduces the effective magneto-crystalline anisotropy energy to 2–4 J/m3, and induces longitudinal magnetic anisotropy with anisotropy energy density of 400–900 J/m3 which shows dependence on the crystalline volume fraction. The field-induced magnetic anisotropy dominates over the random local magnetic anisotropies, and results in the formation of regular magnetic domains aligned longitudinally, pinning-free domain wall displacement, and thus enhanced soft-magnetic properties.