Synchrotron Radiation Small-angle X-ray Scattering Research Articles

Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation.

The microstructure plays a crucial role in the manufacturing and application of polyacrylonitrile fibers, which serve as precursors for carbon fibers. Synchrotron radiation small angle x-ray scattering (SR-SAXS) is a non-destructive and precise technique for analyzing fiber structures. This study employed one-dimensional SR-SAXS mapping to extract key structural parameters such as periodicity, lamellae thickness, and the extent of amorphous regions, as well as the directional orientation in γ-irradiated, pre-oxidized polyacrylonitrile fibers. The analysis revealed a three-layered structure comprising a surface skin, a transitional layer, and a central core. Notably, the lamellar thickness exhibits a "U"-shaped distribution, while the long-period structures, amorphous regions, and orientational properties demonstrate a "wave-like" pattern. Within this structure, the skin exhibits a higher level of orientation, with the orientation decreasing progressively from the skin toward the core layer. The structure of the layered crystal was further corroborated by the morphological analysis. In addition, molecular simulations were performed to propose the mechanisms underlying the formation of this layered structure. This comprehensive investigation using SR-SAXS and one-dimensional mapping provides detailed insights into the microstructural and morphological characteristics of polyacrylonitrile fibers, which can inform future advancements in material processing and refinement techniques for the production of advanced fibers.

The long-lasting maintenance of the pore structure achieves the stability of lithium metal batteries

The separator is considered critical to the safety and performance of lithium metal batteries (LMBs), however, the separator structure fails under high temperature conditions due to damage resulting in decreased mechanical strength, which causes short-circuiting of the battery. This paper describes a novel process to prepare stable and uniform dispersions of aramid nanofibers (ANFs) by bottom-up low-temperature polymerization, and then crosslink the ANFs with N2 plasma-treated polypropylene (PP) separator through capping isocyanate crosslinkers. The composite separator not only has excellent mechanical properties with hardness and modulus of elasticity up to 0.35 and 2.26 GPa, which is three times higher than the PP separator, but also has high-temperature thermal stability, the size maintenance rate reaches 99.8 % at 200 °C. Meanwhile, real-time monitoring of the pore size at different temperatures by synchrotron radiation small-angle X-ray scattering (SR-SAXS) showed that the pore radius of gyration was kept at 8.81 nm and the size change rate was only 22.8 % at 200 °C, which demonstrated that the composite separator had an outstanding ability to maintain the pore structure to ensure the stability of the ionic transport channel. Therefore, the crosslinked composite separator has greater potential for improving the performance and safety of LMBs in extreme high-temperature environments.

Impact of Fractal Features on Gas Adsorption and Desorption Capacities and Ad-/Desorption Hysteresis in Coals Based on Synchrotron Radiation SAXS

Gas adsorption and desorption capacities and ad-/desorption hysteresis in coal are important for carbon capture and storage (CCS) and coalbed methane (CBM) development. To investigate the impact of fractal features on gas adsorption and desorption capacities and ad-/desorption hysteresis in coals, five coal samples were collected and carried out methane (CH4) and CO2 isothermal ad-/desorption experiments. Small angle X-ray scattering (SAXS) was applied to characterize the fractal features of the coal pore structure. The results show that five coal samples show surface fractal features, represented by surface fractal dimension (Ds). The adsorption and desorption capacities of CO2 are stronger than those of CH4. In the adsorption stage, Ds and Langmuir adsorption volume (VL-ad) show a positive relationship for CH4 and CO2, due to the van der Waals force and available adsorption sites. In the desorption stage, Ds and Langmuir desorption volume (VL-de) show a positive relationship for CH4 and CO2, because most adsorbed gas molecules can desorb and diffuse out of the pores when gas pressure decreases. No obvious correlation was found between Ds and Langmuir adsorption pressure (PL-ad) as well as between Ds and Langmuir desorption pressure (PL-de) for CO2 and CH4. An improved hysteresis index (IHI) was adopted to characterize the degree of gas ad-/desorption hysteresis. The IHI values of CO2 vary from 12.2 to 35.2%, and those of CH4 vary from 8.9 to 50.3%. The curves of Ds vs. IHI for CO2 and CH4 are like an irreversible “V” shape, which yields to be further studied. This work further extends SAXS application in exploring the impact of coal pore structure on gas adsorption related phenomena, which is beneficial for CCS technology and CBM development.

Synthesis, self-assembly and thermoresponsive behavior of Poly(lactide-co-glycolide)-b-Poly(ethylene glycol)-b-Poly(lactide-co-glycolide) copolymer in aqueous solution

Thermoresponsive block copolymer (BCP) micelles have attracted increasing attentions due to their potential in biological applications. Many studies have investigated facile strategies to tune the cloud point (Tcp) of thermoresponsive polymer, such as changing hydrophobic/hydrophilic block ratio, micelle concentration and addition of salt. Considering the dependence of properties and functions of BCPs on thermal-induced structural transition, it is necessary to understand the universal mechanism of structural changes during temperature-induced phase transition; whereas it is challenging to achieve precise structure and properties of BCP micelles with Tcp changes. Herein, we choose thermoresponsive poly (L-lactide-co-glycolide)-poly (ethylene glycol)-poly (L-lactide-co-glycolide) (PLGA-PEG-PLGA) block copolymer as a model system and utilize synchrotron-radiation small-angle X-ray scattering (SAXS) technique to systematically investigate the assembled structure of PLGA-PEG-PLGA and the mechanism for thermally induced structural transition of BCP micelle. With the increase of PLGA hydrophobic block, the Tcp significantly decreases, ascribed to the enhancement of the core size, aggregation number, as well as the packing density of PLGA in micelle core. Moreover, the increase of micelle concentration and the addition of salt also decreases the Tcp. Furthermore, temperature-induced drug release is also investigated, the release rate is much faster at above Tcp.

Modifying Y zeolite with chloropropyl for improving Cu load on Y zeolite as a super Cu/Y catalyst for toluene oxidation.

Developing an efficient catalyst is desirable when for example moving from a noble metal-based catalyst to a transition metal-based one for VOC removal. In this work, the chloropropyl-modified NaY zeolite (NaY-CPT) was first synthesized in an extremely dense system through introducing 3-chloropropyl-trimethoxysilane (CPT) in the aluminosilicate sol. Then the Cu/Y-CPT catalyst was fabricated by impregnating Cu species on the NaY-CPT zeolite and the highly effective Cu/Y based catalyst has been achieved for catalytic toluene oxidation. The structure evolution of CPT modified sol and its effect on texture properties of NaY-CPT and thereby reduction ability of Cu/Y catalyst were systematically investigated by synchrotron radiation small angle X-ray scattering (SR-SAXS), EXAFS and other characterization. The CPT modified sol can promote the formation of more active aluminosilicate species, greatly accelerating crystal growth and improving framework Si/Al ratio of NaY zeolite. Due to the presence of the CPT group, the Cu/Y-CPT catalyst enhanced the interaction between Cu species and the zeolite matrix, resulting in small sized CuO nanoparticles (2.0–4.0 nm) anchoring to NaY-CPT. The Cu/Y-CPT catalyst renders more isolated Cu2+ species and adsorbed oxygen species, which are reactive in the oxidation reaction due to their high reducibility and mobility. Finally, the Cu/Y-CPT catalyst exhibits 90% toluene conversion at 296 °C (T90), lower than the value of 375 °C on the conventional Cu/Y-con catalyst. Meanwhile, the optimal Cu/Y-CPT catalyst also gives higher toluene conversion and stability in moisture conditions.

Structural Changes in Spider Dragline Silk after Repeated Supercontraction-Stretching Processes.

Spider dragline silk is well-known for its excellent combination of strength and extensibility as well as another unique property called supercontraction. In our previous work, the changes in conformations of the Nephila edulis spider dragline silk when subjected to different supercontraction processes were extensively investigated. When a native spider dragline silk had free supercontraction, and then restretched to its original length, the content and molecular orientation of different conformations (β-sheet, helix, and random coil) changed but the mechanical properties remained almost the same. Therefore, herein, further supercontraction-stretching treatment was performed up to three cycles, and the corresponding structural changes were investigated. In addition to the synchrotron radiation FTIR (S-FTIR) microspectroscopy employed in our previous study, synchrotron radiation small-angle X-ray scattering (S-SAXS) and atomic force microscopy (AFM) were also used in this work to determine the structural changes of spider dragline silk in different scales. The results show that by repeating the supercontraction-stretching treatment, the β-sheet structure content in spider dragline silk was slightly increased, but its orientation degree remained almost the same. Also, with the increase in cycle of supercontraction-stretching treatments, a 10.5 nm long period perpendicular to the silk fiber axis gradually appeared, endowing the spider dragline silk with periodic structure both along (6.6 nm, already existed in native silk and did not change with the supercontraction-stretching treatment) and perpendicular to the silk fiber axis. After the third supercontraction-stretching cycle, the AFM images displayed a clear 210 nm × 80 nm corn kernel-like structure on the surface of nanofibrils in spider dragline silks, which may be related to the aggregation of 10.5 nm × 6.6 nm periodic structure observed via S-SAXS. Finally, although the structure of spider dragline silk became increasingly regular with the rise in supercontraction-stretching cycles, mechanical properties remained constant after every cycle of the supercontraction-stretching treatment. These findings can aid in further understanding the structural changes that are related to the supercontraction of spider dragline silk and provide useful guidance in fabrication of high-performance regenerated or artificial silk fibers.

Evaluation and comparison of bentonite surface fractal dimension and prediction of swelling deformation: Synchrotron radiation SAXS and N2-adsorption isotherms method

A key parameter for calculating the swelling deformation using fractal model is the fractal dimension. Small angle X-ray scattering (SAXS) and liquid nitrogen adsorption method (Frenkel-Halsey-Hill (FHH) and Neimark thermodynamic method) were employed to determine fractal dimension of four Chinese bentonite. Based on SAXS and the FHH method, fractal swelling deformation model was adopted to predict mechanical behavior. The result suggested that the fractal dimensions of #1, #2, #3 and #4 calculated by SAXS were 2.600, 2.650, 2.530 and 2.780, respectively. The fractal dimensions determined by FHH model were 2.636, 2.579, 2.612, and 2.892, respectively. These minor variations can be associcated with the different the test scales, difference between the open hole, closed hole and interlayer hole, and the different test mechanism. The SAXS method was based on the difference in electron density and can reach the interlayer pores of montmorillonite. It seemed that the reliability and stability of the Neimark thermodynamic method need to be further improved. Swelling deformation calculated by SAXS and FHH method was roughly in accordance with the experimental data. Compared with the liquid nitrogen adsorption method, the predicted value of the SAXS method was closer to the experimental value, which confirm that the fractal dimension calculated by SAXS was more accurate. This fills the gap of using SAXS to predict the swelling deformation of Gaomiaozi CaGMZ bentonite.

Simple carbon fiber graphitization device for in-situ measurement of small angle X-ray scattering (SAXS)

A small and simple device for the in-situ small angle X-ray scattering (SAXS) measurement of carbon fibers graphitization by direct electrical heating was developed. The graphitization process of polyacrylonitrile-based T700 carbon fibers from 1450 °C to 2100 °C with this device was followed in-situ by synchrotron radiation SAXS. The results show that there are needle-shaped voids oriented preferentially along the fibers axis with a surface fractal structure during graphitization of carbon fibers. The change in the fractal dimension as a function of temperature includes a dip with a minimum value at approximately 1700 °C. This short contribution briefly describes the device and analyzes the obtained experimental results.

Synchrotron radiation facility-based quantitative evaluation of pore structure heterogeneity and anisotropy in coal

Abstract In order to quantify coal pore structure heterogeneity and anisotropy, synchrotron radiation SAXS (Small Angle X-ray Scattering) was applied to obtain the SAXS images of two different rank coal samples. The surface fractal dimension (D1) and pore fractal dimension (D2) were obtained by processing the image data. The pore structure heterogeneity of two coal samples was quantified by pore fractal dimension (D2). Pore fractal dimension of Xinzhouyao coal is 2.74 and pore fractal dimension of Tangshan coal is 1.69. As a result, the pore structure heterogeneity of Xinzhouyao coal is stronger than that of Tangshan coal. 3D pore structure imaging was achieved by synchrotron radiation nano-CT. The selected Region of Interest (ROI) of coal sample was divided into a certain number of subvolumes. Pore structure heterogeneity was quantified by calculating the limit of the relative standard deviation of each subvolume's porosity. The heterogeneity value of Xinzhouyao coal pore structure is 3.21 and the heterogeneity value of Tangshan coal pore structure is 2.71. As a result, the pore structure heterogeneity of Xinzhouyao coal is also stronger than that of Tangshan coal, namely, pore structure heterogeneity from synchrotron radiation SAXS and synchrotron radiation nano-CT is consistent. Considering the corresponding relationship between the pore structure anisotropy and the permeability anisotropy, the quantification of pore structure anisotropy was realized by computing the permeability tensor of pore structure using the Lattice Boltzmann method (LBM), and the pore structure anisotropy was characterized by the eigenvalues and eigenvectors of the permeability tensor. The pore structure anisotropy obtained by the method proposed in this paper was validated by the pore structure geometrical morphology.

Crystallization and Phase Behavior in Block Copolymer Solution: An in Situ Small Angle X-ray Scattering Study

Amphiphilic diblock copolymers self-assemble into a variety of micellar structures with diverse shapes in selective solvents. Here, we study the concentration and temperature dependence of the packing structure of spherical micelles of a polyisoprene-b-poly(2-vinylpyridine) (PI-b-P2VP) diblock copolymer in toluene using synchrotron radiation small angle X-ray scattering (SR-SAXS) and atomic force microscopy (AFM) techniques. Randomly packed spherical micelles are detected in dilute solutions, while in concentrated solutions, face-centered cubic (FCC), body-centered cubic (BCC) mixed crystal structures, and pure BCC crystal structures are observed with an increase in concentration. In situ SAXS experiments on the FCC/BCC mixed crystal structures reveal a novel FCC/BCC → BCC → Disorder → BCC phase behavior during the thermal annealing process. These results demonstrated that the BCC phase is apparently more stable than the FCC phase in the current sphere-packing system and FCC/BCC is a metastable state. The incompatibility of the PI and P2VP blocks decreases at a higher temperature and renders the variation of domain spacing.

Effect of Side Chain Length on Segregation of Squalane between Smectic Layers Formed by Rod-Like Polysilanes

The segregation of spherical molecules (squalane) between the smectic layers of rod-like polymers (polysilanes) with narrow molecular weight distributions were investigated by synchrotron radiation small-angle X-ray scattering (SR-SAXS), atomic force microscopy (AFM) observations, and molecular dynamics simulations to elucidate the effect of the polymer side chain length on the segregation. It has been theoretically predicted that the smectic phase of the rod-like particles will be stabilized by inserting the spherical particles into the interstitial region between the smectic layers when the diameter of the spherical particles is smaller than that of the rod-like particles whose length is sufficiently long. We found that the segregation of squalane was unaffected by the molecular weight (Mw) of the polysilane in the range of 9,200-44,100 g/mol, and the diameter of the polysilane showed the optimal size of 5.64 nm for the segregation of squalane whose diameter is 6.57 nm although the origin of these inconsistencies between theory and experiment is currently not clear.

Nanostructures and space charge characteristics of MgO/LDPE nanocomposites

The electrical properties of nanocomposites are closely related to their nanostructures. In order to investigate the nanostructures and space charge characteristics of magnesium oxide (MgO)/low-density polyethylene (LDPE), samples of LDPE with nano-MgO from 0.1 to 2.0 wt% are prepared, as well as pure LDPE. The nanostructures of nanocomposites are investigated by the technology of synchrotron radiation small-angle x-ray scattering (SAXS), and the space charge distributions in nanocomposites and LDPE are measured by the pulsed electro-acoustic (PEA) method. Results of the synchrotron radiation SAXS experiments reveal that there is obvious interphase between the nano-MgO particle and the LDPE matrix, the thickness of which increases along with the increase in nano-MgO concentration. The agglomeration and mass fractal exist in all nanocomposites, and become more obvious at higher concentration. Results of space charge measurements indicate that the apparent trap-controlled mobilities and the apparent trap depths are respectively larger and smaller than those in LDPE during the initial phase of depolarization when the concentrations are 0.1 and 0.5 wt%, and are respectively smaller and larger than those in LDPE when the concentrations are 1.0 and 2.0 wt%. The space charge amount decreases after the addition of nano-MgO. This is mainly due to the introduction of shallow traps which promote the charge recombination in 0.1 and 0.5 wt% MgO/LDPE nanocomposites, and the introduction of deep traps which restrict the charge transportation in 1.0 and 2.0 wt% MgO/LDPE nanocomposites. The space charge characteristics of MgO/LDPE nanocomposites are explained combined with the nanostructures obtained from the synchrotron radiation SAXS experiments.

Surface-Enhanced Raman Spectroscopy on Liquid Interfacial Nanoparticle Arrays for Multiplex Detecting Drugs in Urine.

The design and application of liquid interfacial plasmonic platform is still in its infancy but is an exciting topic in tunable optical devices, sensors, and catalysis. Here, we developed an interfacial surface-enhanced Raman scattering (SERS) platform through the large-scale self-assembly of gold nanoparticle (GNP) arrays at the cyclohexane (CYH)/water interface for detecting trace drug molecules in the urine of humans. The molecules extracted by the CYH phase from a urine sample were directly localized into the self-organized plasmonic hotspots, yielded excellent Raman enhancement, and realized the substrate-free interfacial SERS detection. Synchrotron radiation small-angle X-ray scattering (SR-SAXS) experiments reveals a good uniformity of approximately 2-3 nm interparticle distance in the GNP arrays. SERS colocalization experiments demonstrated that amphetamine molecules of different concentration levels could be loaded into the interfacial GNP arrays and realized the coassembly together with nanoparticles at the liquid/liquid interface. Interfacial GNP arrays with dynamic nanogaps in liquid interfacial structure can make surrounding molecules easily diffuse into the nanogaps. In contrast, the fixed GNP arrays on Si wafer were more irregular, such as multilayer stack, random aggregates, and voids, during the drying process. When the drugs directly participate in the self-assembly process, it becomes easier for analytes diffusing into the nanogaps of GNP arrays, produces a concentration effect, and amplified the SERS sensitivity. This feature also enables molecules to be adsorbed evenly in the arrays and makes a more uniform distribution of both the analytes and GNPs in the liquid interface and realizes the significant increase in signal reproducibility. Interfacial SERS produced a standard deviation of 12.5% at 1001 cm(-1) peak of methamphetamine (MAMP) molecules under the concentration of 1 ppm, implying a good reproducibility. Moreover, dual-analyte detection at organic and aqueous phases was also realized and confirmed a good capability for analytes detection by liquid interfacial SERS platform, which promises nonengineering detection of analytes dissolved in often-inaccessible environments.

Characterization of Surface Microstructures on Bio-based Polymer Film Fabricated with Nano-imprint Lithography by Synchrotron Radiation Small Angle X-ray Scattering

Nano-imprint lithography (NIL) is a simple, low cost and high-resolution patterning method. However the precise evaluation method of nano-imprinted structure has not been established. Synchrotron radiation small angle X-ray scattering (SR-SAXS) measurement is a nondestructive and high resolution characterization method. In this study, we attempt to fabricate nanostructures on the poly(lactic acid) (PLA) film by NIL and evaluated with microscopic and scattering techniques. The mold with line/space pattern was used for NIL. Scanning electron microscope observation confirmed the formation of surface nano-structure in large areas. Also, nano-imprinted PLA film was evaluated using SR-SAXS measurement. The scattering patterns obtained from nano-imprinted PLA films were clearly observed up to higher order scattering spots. These results suggested that highly regular structure was fabricated on the surface of PLA films.

Combined Electrospray-Scanning Mobility Particle Sizer (ES-SMPS) and Time-Resolved Synchrotron Radiation-Small-Angle X-ray Scattering (SR-SAXS) Investigation of Colloidal Silica Aggregation. Part II. Influence of Aggregation Initiator on Gel Stability

The effect of ion specificity on the slow aggregation of silica nanoparticles with various initial morphology was investigated with an electrospray-scanning mobility particle sizer (ES-SMPS) and time-resolved synchrotron radiation-small-angle X-ray scattering (SR-SAXS). This combination provides a unique tool to monitor and resolve the early aggregate development in detail. Aggregation was induced by varying the K(2)CO(3) or KCl concentration to obtain a fixed gelation time of ∼40 min, and the results were compared with those obtained in a previous paper (Johnsson et al. J. Phys. Chem. B 2011, 115, 765-775) for NaCl. All dispersions produced gels that contained free primary particles well past the point of gelation (PoG). The initial aggregate formation and obtained gel morphologies were independent of the aggregation initiator. Nevertheless, ion-specific effects were observed for the rate of the stability increase of the 3-dimensional (3D) gel structure. The formation of a stable structure was fastest in the presence of the strongly hydrated counterions, and a clear anion effect was observed. The obtained gel stabilities were interpreted by relating the rate of formation of covalent siloxane bonds to the polarization of the water molecules surrounding structure-maker ions.

Combined Electrospray-SMPS and SR-SAXS Investigation of Colloidal Silica Aggregation. Part I. Influence of Starting Material on Gel Morphology

The slow aggregation of monodisperse, polydisperse, and preaggregated silica nanoparticles was studied with an electrospray-scanning mobility particle sizer (ES-SMPS) and time-resolved synchrotron radiation-small-angle X-ray scattering (SR-SAXS). Aggregation was induced by varying the NaCl concentration to obtain a fixed gelation time of ∼40 min. The combination of these techniques provides a unique tool to monitor and resolve the aggregate development in detail. The monodisperse spherical particles were converted to dimers, trimers, and eventually larger clusters as the aggregation proceeded, while the polydisperse spherical particles formed large clusters at an early stage. The initial particle shape and polydispersity had profound effects on the morphology of the aggregates; spherical primary particles produced compact spherical clusters, whereas the preaggregated dispersions formed open, elongated aggregates. All dispersions produced gels that contained free primary particles well past the point of gelation. The stability of the aggregates and the gel morphology were interpreted by relating to the structure of porous gel layers around the particles.

Entropically-Driven Formation of Smectic A1, A2, and A3 phases in Binary Mixtures of Rigid-Rod Helical Polysilanes with Different Molecular Weights

The smectic liquid crystal arrangements of binary mixtures of rod-like polymers, i.e., poly[n-decyl-(S)-2-methylbutylsilane]s, with narrow molecular weight distributions, were investigated by synchrotron radiation small-angle X-ray scattering (SR-SAXS) and atomic force microscopy (AFM) analyses. Depending on the molecular weight ratio, r (higher molecular weight/lower molecular weight), and the mixing ratio, three types of smectic phases are formed with different accommodations by two polymers. In the binary mixture of the shorter and longer polymers with the lower r values of 1.0−1.7, the two polymers are randomly mixed within a layer, forming the conventional smectic A1 phase with a layer thickness corresponding to an average length of the two polymers. In contrast, when two kinds of polymers with the higher r values of 1.7−2.8 are mixed, different types of smectic A structures are formed. Upon the addition of the shorter polymer to the abundant longer polymer, a smectic A2 phase in which a pair of smec...

Quaternary Structure of Flavorubredoxin as Revealed by Synchrotron Radiation Small-Angle X-Ray Scattering

Flavodiiron proteins (FDP) are modular enzymes which function as NO and/or O(2) reductases. Although the majority is composed of two structural domains, the homolog found in Escherichia coli, flavorubredoxin, possesses an extra C-terminal module consisting of a linker and a rubredoxin (Rd) domain necessary for interprotein redox processes. In order to investigate the location of the Rd domain with respect to the flavodiiron structural core, small-angle X-ray scattering was used to construct low-resolution structural models of flavorubredoxin. Scattering patterns from the Rd domain, the FDP core, and full-length flavorubredoxin were collected. The latter two species were found to be tetrameric in solution. Ab initio shape reconstruction and rigid-body modeling indicate a peripheral location for the Rd domains, which appear to have weak contacts with the FDP core. This finding suggests that Rd behaves as an independent domain and is freely available to participate in redox reactions with protein partners.

Characterization of Precipitation in Al-Zn-Mg-Cuand Li Containing Al-Zn-Mg-Cu Alloys after Isothermal Aging

The evolution of microstructure, precipitate size, volume fraction and integrated intensity of Al-8.0Zn-2.05Mg-1.76Cu (7055) and 7055-1.0Li alloys during isothermal ageing has been studied by transmission electron microscopy (TEM) and synchrotron-radiation small angle X-ray scattering (SAXS). According to the TEM results, referring to the thermodynamic phase diagram, it was found that the addition of Li changed the types of the precipitates. T1 phase was observed in the 7055-1.0Li alloy besides the GP zones, η' and η with variant orientations with matrix, η1、η2 and η4. The super-lattice spots of L12 (Cu3Au) structure were probably due to the existence of Al3Li (δ') or Al3(Zr,Li). Furthermore, the precipitation sequence has been modified in Li-containing Al-Zn-Mg-Cu alloys. The precipitate volume fraction derived from the integrated intensity for 7055 alloy reached an plateau except ageing at 120°C and the maximum was about 0.052-0.054 in the temperature range 140-160°C.

Structural Transition of Poly[(R)-3-hydroxybutyrate-co-(R)-3- hydroxyvalerate] Single Crystals on Heating As Revealed by Synchrotron Radiation SAXS and WAXD

The annealing behavior of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)) crystal was studied by synchrotron radiation small-angle X-ray scattering (SAXS) and wide-angle X-ray ...