Nanoscale Crystalline Phase Research Articles

Antiplatelet, cytotoxic activities and characterization of green-synthesized zinc oxide nanoparticles using aqueous extract of Nephrolepis exaltata.

The goal of the current study was to synthesize zinc oxide nanoparticles (ZnO-NPs) using ZnCl2.2H2O salt precursor and an aqueous extract of Nephrolepis exaltata (N. exaltata), which act as a capping and reducing agent. N. exaltata plant extract-mediated ZnO-NPs were further characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), UV-visible (UV-Vis), and energy-dispersive X-ray (EDX) analysis. The nanoscale crystalline phase of ZnO-NPs was analyzed by the XRD patterns. The FT-IR analysis revealed different functional groups of biomolecules involved in the reduction and stabilization of the ZnO-NPs. The light absorption and optical properties of ZnO-NPs were examined by UV-Vis spectroscopy at a wavelength of 380 nm. The spherical shape morphology of ZnO-NPs with mean particle size ranges between 60 and 80 nm was confirmed by SEM images. While the EDX analysis was used to identify the elemental composition of ZnO-NPs. Furthermore, the synthesized ZnO-NPs demonstrate potential antiplatelet activity by inhibiting the platelet aggregation induced by platelet activation factor (PAF) and arachidonic acid (AA). The results showed that synthesized ZnO-NPs were more effective in inhibiting platelet aggregation induced by AA with IC50 (56% and 10 μg/mL) and PAF (63% and 10 μg/mL), respectively. However, the biocompatibility of ZnO-NPs was assessed in human lung cancer cell line (A549) under in vitro conditions. The cytotoxicity of synthesized nanoparticles revealed that cell viability decreased and the IC50 was found to be 46.7% at a concentration of 75 μg/mL. The present work concluded the green synthesis of ZnO-NPs that was achieved by N. exaltata plant extract and showed good antiplatelet and cytotoxic activity, which demonstrates the lack of harmful effects making them more effective for use in pharmaceutical and medical fields to treat thrombotic disorders.

Heat Treatment-Induced Conductivity Enhancement in Sulfide-Based Solid Electrolytes: What is the Role of the Thio-LISICON II Phase and of Other Nanoscale Phases?

Sulfide-based solid Li+ electrolytes are one of the most promising electrolyte classes for solid-state battery applications. These solid electrolytes are typically prepared by means of high-energy ball milling, often followed by a heat treatment step for enhancing the Li+ ion conductivity. In many cases, heat treatment-induced conductivity enhancements have been attributed to the formation of a superionic thio-LISICON II phase. However, the chemical composition and structure of this phase as well as the origin of the conductivity enhancement are still under debate. Here, we have carried out a comprehensive study on the thiophosphate-based electrolyte system (1 – x) Li3PS4 + x LiI with x = 0–0.5. By combining electrochemical impedance spectroscopy, X-ray diffraction, and Raman spectroscopy as well as 7Li NMR line-shape analysis and high-resolution multidimensional 31P solid-state NMR measurements, we show that the widely used concept of a thio-LISICON II phase governing the ionic conductivity of heat-treated samples cannot explain the experimental observations. Double-quantum constant-time 31P NMR proves that P2S64– units are embedded in the amorphous phase of the ball-milled pristine samples. Upon heat treatment, the amorphous phase with the embedded P2S64– units is transformed into different nanoscale crystalline phases, a thio-LISICON II phase, a β-Li3PS4 phase, and a Li4PS4I-related phase. A structural model of the thio-LISICON II phase needs to explain the coupling pattern from two-dimensional double-quantum NMR presented here, showing two phosphorus environments with an approximate ratio of 2:1. Furthermore, our results indicate that in heat-treated samples, a highly disordered nanoscale Li4PS4I-related phase exists with an ionic conductivity even exceeding that of the thio-LISICON II phase.

Low-temperature mineralization sintering process for fabrication of fluoridated hydroxyapatite-containing bioactive glass

Bioactive glasses and glass-ceramics are receiving wide attention for their biomedical applications. We present a novel route to obtain fluoridated hydroxyapatite-containing bioactive glass (FHBG) through a low-temperature mineralization sintering process (LMSP). LMSP is a low-temperature densification procedure that can provide a functionalization of pristine materials through the formation and growth of new phases induced by mineralization. Here, SiO2–CaO–P2O5 bioactive glass nanoparticles (BGNPs) were prepared and mixed with fluorine-containing simulated body fluid (F–SBF) to induce mineralization. Under a uniaxial pressure of 330 MPa and temperature of 120 °C, BGNPs were densified up to 89% of their theoretical density, and the Vickers hardness and fracture toughness of the sintered BGNPs increased to 4.15 ± 0.11 GPa and 1.32 ± 0.12 MPa m1/2, respectively. This densification behavior was strongly influenced by the mineralization that forms nanoscale crystalline phase such as carbonated fluoridated hydroxyapatite (HAp), where part of PO43− and OH− in HAp (Ca10(PO4)6(OH)2) was replaced by CO32− and F−, respectively. The fluorides formed as minor phases in the sintered BGNPs by mineralization were identified as calcium fluorosilicate (CaSiF6) and calcium fluoride (CaF2). After an acid resistance test, because of the presence of fluorides, the sintered BGNPs containing fluorides presented a 38% weight loss, which is lower than that of sintered BGNPs containing no fluorides (54% weight loss). By employing LMSP, we successfully fabricated FHBG from non-fluoride-containing BGNPs and F–SBF at an extremely low temperature at 120 °C. Therefore, this study offers a more efficient method for the manufacturing of glasses and glass-ceramics.

Mechanical behavior of CuZr dual-phase nanocrystal-metallic glass composites

Molecular dynamics (MD) simulations are conducted to investigate the influence of various critical structural aspects such as crystallographic direction, spatial distribution and size/volume fraction of nanoscale crystalline secondary phase on the mechanical behavior of dual-phase nanocrystal-metallic glass composites (NCMGCs). The results of MD simulations show that the ‘softer’ amorphous matrix and amorphous-crystal interfaces serve as the nucleation sites of the shear transformation zones, and eventually developing into mature shear bands (SBs). We find that the different crystallographic directions of the nanocrystals have great influence on elastic modulus of composites. Moreover, the spatial distribution of nanocrystals plays an important role in SBs propagation direction. In particular, by increasing the volume fraction of the crystalline phase, plastic co-deformation of the SBs and stacking faults is achieved for the NCMGCs with nanocrystals of [1 1 0] and [1 1 1] directions. Moreover, the presence of stacking faults releases most of the stress of nanocrystals and retards the formation of a mature SB. By systematically varying the characteristics of the B2 CuZr nanoscale crystalline phase one can design composites with improved mechanical properties.

Applicability of Optical Scattering Model to β‐Quartz Solid Solution Glass–Ceramics with Nanoscale Crystalline Phase

The applicability of Rayleigh‐Gans and quasi‐continuum scattering models to β‐quartz solid solution (s.s.) glass–ceramics was studied. We evaluated the validity of these models using two specimens with different microstructures. The refractive indices of the crystalline and glass phases of the specimens were calculated by a method utilizing the transmittance change of the specimens due to structural relaxation. It was found that the quasi‐continuum model is applicable to the glass–ceramics for estimating scattering intensity and its microstructure dependence. We demonstrated that the optical transmittance of the glass–ceramics can be simulated as a function of the microstructure on the basis of this model. The result of this study provides a quantitative approach for controlling the optical transmittance of β‐quartz s.s. glass–ceramics.

Nanostructural pulse laser-deposited Ag(Tl)SbS semiconductor thin films: Growth dynamics, structural and electrical properties

Ag 3SbS 3 semiconductor material is an attractive substance for different optoelectronic and data storage applications [D. Adler, M.S. Shur, M. Silver, S.R. Ovchinsky, J. Appl. Phys. 51 (1979) 3289]. The most reliable way to get thin films with proper quality is the pulse laser deposition (PLD) technology. The paper reports data on growth dynamics (electron microscopic experiments (EME) performed in situ in order to clarify structural features of the films under PLD process), X-ray diffraction (XRD) investigations and room temperature current–voltage (IVC) characteristics. The sets of investigated samples were prepared by Nd:IAG laser. Films were deposited under substrate temperatures T = 300 K and T = 400 K and at different pulse repetition frequencies. EME studies revealed time-dependent changes of the grown films’ structure occurring under stationary pulse repetition frequency and the substrate temperature. The structure of the films was identified as an amorphous with nanoscale crystalline phase inclusions (there are results of the XRD studies). The IVCs investigations performed at the room temperature and under applied bias up to 10 V in both directions showed a domination of tunneling current for all samples under study.

Formation and chemical leaching of non-equilibrium Al 0.6(Co 75Cu 25) 0.4 alloy powders by rod milling

We report upon the formation of nanoscale crystalline Al 0.6(Co 75Cu 25) 0.4 alloy powders and leached non-equilibrium specimens, produced by employing a combination of rod milling and chemical leaching. X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) were used to characterize the as-milled and leached specimens. After 400 h of milling, bcc type peaks of the intermetallic compound AlCo were present in the XRD pattern. Leaching of the Al from the as-milled powders did not induce any significant change in the diffraction pattern. After annealing the leached specimen at 600 °C for 1 h, the nanoscale crystalline phase was transformed into the Co and fcc Cu phases, and this was accompanied by a change in the magnetic properties. Magnetization decreased gently upon heating from room temperature to 155.4 °C, then increased suddenly with rising temperatures up to 350.0 °C, as the Co and Cu atoms were rearranged, and finally decreased gently as heating continued to 850 °C. On cooling the specimen from 850 °C, the magnetization increased gently. The Curie temperature was about 570.7 °C for the as-milled powders.

Formation of non-equilibrium phase by leaching of rod-milled Al0.6(Co50Cu50)0.4 alloy powders

We report upon the formation of non-equilibrium phase by leaching of Al0.6(Co50Cu50)0.4 alloy powders produced by rod milling. X-ray diffractometry (XRD), scanning electron microscopy, differential scanning calorimetry, transmission electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400h of milling, bcc type peaks of the intermetallic compound AlCo were present in the XRD pattern. Leaching of the Al from the as-milled powders did not induce any significant change in the diffraction pattern. After annealing the leached specimen at 500°C for 1h, the nanoscale crystalline phase was transformed into the fcc Cu phase, and this was accompanied by a change in the magnetic properties. Magnetization decreased gently on heating from room temperature to 189.0°C, then increased suddenly with temperature rising to 514.0°C, as the Co and Cu atoms were rearranged, and finally decreased gently as heating continued to 800°C. On cooling the specimen from 800°C, the magnetization increased gently. The Curie temperature was about 564.2°C for the as-milled powders.

Formation of non-equilibrium phase by leaching of rod-milled Al0.6(Co50Cu50)0.4 alloy powders

We report upon the formation of non-equilibrium phase by leaching of Al 0.6 (Co 50 Cu 50 ) 0.4 alloy powders produced by rod milling. X-ray diffractometry (XRD), scanning electron microscopy, differential scanning calorimetry, transmission electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h of milling, bcc type peaks of the intermetallic compound AlCo were present in the XRD pattern. Leaching of the Al from the as-milled powders did not induce any significant change in the diffraction pattern. After annealing the leached specimen at 500 °C for 1 h, the nanoscale crystalline phase was transformed into the fcc Cu phase, and this was accompanied by a change in the magnetic properties. Magnetization decreased gently on heating from room temperature to 189.0 °C, then increased suddenly with temperature rising to 514.0 °C, as the Co and Cu atoms were rearranged, and finally decreased gently as heating continued to 800 °C. On cooling the specimen from 800 °C, the magnetization increased gently. The Curie temperature was about 564.2 °C for the as-milled powders.

Chemical Leaching of Non-Equilibrium Al(Fe-Co) Powder Produced by Rod Milling

We report on the formation and chemical leaching of non-equilibrium alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, decreased with increased milling time, the of the powders before milling was about 113.8 emu/g, the after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and phases. On cooling the specimen from 85, the degree of magnetization increased slightly, then increased sharply at approximately 364.8, indicating that the bcc phase had been transformed to the Fe and Co phases.

Chemical leaching and magnetic properties of non-equilibrium Al(Co–Cu) powders produced by rod milling

We report upon the chemical leaching and magnetic properties of nanoscale crystalline Al 0.6(Co 25Cu 75) 0.4 alloy powders produced by rod milling. X-Ray diffractometry (XRD), transmission electron microscopy, differential scanning calorimetry, vibrating sample magnetometry, and superconducting quantum interference device magnetometry were used to characterize the as-milled and leached specimens. After 400 h of milling, only the b.c.c. phase of the intermetallic compound γ-Al 3.892Cu 6.10808 was detected by XRD. After annealing the leached specimen at 600 °C for 1 h, the nanoscale crystalline phase was transformed into the f.c.c. Cu phase, and this was accompanied by a change in the magnetic properties. The peaks of the magnetization shifted towards lower temperature with increasing external field. The temperature behavior at T f (45 K) for direct current (d.c.) magnetic susceptibility measurements was quite different for field cooling and zero-field cooling. After cooling the leached specimen from 800 °C, magnetization increased gradually.

Formation and Properties of Amorphous and Nanocrystalline Phases in Mechanically Alloyed Fe-Based Multicomponent Alloys

ABSTRACTMulticomponent Fe-Al-P-C-B alloys have been prepared by mechanical alloying of elemental powder mixtures. X-ray diffraction data were recorded to monitor the structural development of the powders. Coexistent amorphous and nanoscale crystalline phases are found for a variety of alloys. Some alloys exhibit an extended supercooled liquid region before crystallization. The compositional dependence of glass formation and the thermal stability of the resulting phases were investigated by constant-rate heating differential scanning calorimetry (DSC), isothermal annealing experiments, and thermomechanical analysis (TMA). The results are compared with data for melt-spun ribbons.

Formation of nanocrystalline and amorphous phases in Cu80P20, Ni82P18 and Cu87Ni13 mechanically alloyed systems

Variations in the crystallite size and stored strain caused by mechanical milling of binary alloy systems of copper, nickel and phosphor were compared. During mechanical alloying process, an amorphous phase is partially produced in CuP and NiP alloy systems and only a nanoscale crystalline phase in CuNi alloy system. The CuP alloy system first forms a Cu 3 P intermetallic compound and then the partial amorphous phase by the reaction of primary copper phase and Cu 3 P intermetallic compound, while the NiP alloy system directly forms a partial amorphous phase by the reaction of primary nickel and phosphor phases. When the crystallite sizes of primary copper and nickel phases become of the order of a few nanometers in the CuP and NiP alloy systems, they are in an almost strain-free state.