Narrow Results

Nanocomposites have many promising applications such as in hyperthermia and photodegradation. Laser ablation-assisted synthesis of nanocomposites offers several advantages such as it is a green synthesis method, cost-effective, ease of handling and absence of any by-products. This study included the fabrication of copper-silicon (Cu-Si) nanocomposites using liquid-phase laser ablation, followed by an investigation into their potential uses in photothermal hyperthermia and photodegradation. The surface properties, chemical composition and crystallinity were examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. Spherical, capsule-like and hexagonal nanoparticles with a size of 28nm were observed from transmission electron microscopy (TEM). The near-infrared (NIR) 808nm laser was used to obtain the optimum photothermal hyperthermia temperature. At increasing concentrations of nanocomposites and operating laser powers, the temperature trend of nanofluid was monitored and revealed a rising trend. Moreover, an increasing trend in degradation efficiency of methylene green dye was observed, with values of 46.4%, 81.7% and 95.7%, corresponding to photocatalyst doses of 10mg, 20mg and 30mg, respectively. These results shed light on the potential application of contamination-free nanocomposites for hyperthermia and photodegradation.

Nanodiamonds (NDs) have unique optical and mechanical characteristics, surface chemistry, extensive surface area and biocompatibility, and they are nontoxic, rendering them suitable for a diverse range of applications. Recently, NDs have received significant attention in nano-biomedical engineering. This review discusses the recent advancement of NDs’ biomedical engineering, historical background, basic introduction to nanoparticles and development. We summarize NDs’ synthesis technique, properties and applications. Two methodologies are used in ND synthesis: bottom-up and top-down. We cover synthesis methods, including detonation, ball milling, laser ablation, chemical vapor deposition (CVD) and high pressure and high temperature (HPHT); discuss the properties of NDs, such as fluorescence and biocompatibility. Due to these properties, NDs have potential applications in biomedical engineering, including bioimaging, biosensing, drug delivery, tissue engineering and protein mimics. Further, it provides an outlook for future progress, development and application of NDs in biological and biomedical areas.

ZnO nanobamboos and nanowires with diameters of 10–30 nm and lengths of 2–4 μm have been prepared by laser ablation in vacuum with precisely controlled pressure, growth and post-annealing temperature. XRD results show the annealed sample is hexagonal ZnO. Low-magnified TEM observation reveals the annealed sample includes ZnO nanobamboos and nanowires. High resolution TEM image and electron diffraction pattern confirm that the structure of ZnO nanobamboo is regular stacking of Zn and O layers with high crystal quality. The growth direction is determined as along [001] direction (c axis). TEM observations confirm that the formation of bamboo-shape ZnO is due to the stacking fault and cleavage. The bundle of those stacking faults seems to be the origin of the black contrast at the nodes. The uniformity of chemical composition for the nanobamboos is identified by EDS profiles. A strong-narrow UV band centred at 390 nm and a weak-broad green band centred at 515 nm are observed at room temperature in the PL spectrum recorded from the annealed ZnO nanobamboos and nanowires.

Pulsed laser deposition (PLD) is a unique method for growing highly stoichiometric, materials in the form of epitaxial thin films. Here we discuss the optimization of deposition parameters for laser ablation of multi-component La_0.7Ca_0.3MnO₃-YBa₂Cu₃O_7-δ (LCMO-YBCO) heterostructures grown in situ by sequential deposition of LCMO and YBCO on <100> LaAlO₃ (LAO) substrates using a PLD system. We discuss the growth of these multi-layers, from the device applications point of view.

We have developed a simplified molecular-dynamical model for simulating ablation of solid surfaces by laser pulses, and specifically investigated expansion of Cu cloud in vacuum vaporized on the surface, showing that the angular distributions of the plume depend on the shape of the laser spot on the surface. In particular, experimentally observed flipover effects have been obtained, and an adiabatic constant determined from our simulations via an adiabatic expansion model agrees well with previous measurements.

Work is reported on the characterizations of pulsed laser deposited aluminum–nitride thin films. The films were deposited on silicon substrate with a KrF 248 nm pulse laser operating in a Riber LDM-22 system. Optical reflection spectroscopy (400–900 nm) was carried out, which revealed that, under certain deposition conditions, the films could show strong periodic spectra with reflection gaps of about 50–100 nm in width. The microscopic structures, such as crystalline status and element composition, were also investigated with Auger electron spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and profilometry etc. Relations between the optical responses and the microscopic structures were established. The foundations underlying the relations were studied and discussed.

We have studied the effect of applying an external magnetic field on the characteristics of iron oxide (IO) nanoparticles (NPs) synthesized by pulsed laser ablation in dimethylformamide (DMF). The NPs synthesized with and without applying of magnetic field were characterized by Fourier transformation infrared spectroscopy (FT-IR), UV–Vis absorption, scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD). SEM results confirmed that the particle size was decreased after applying magnetic field.

In the present study, the field emission properties of multi-walled carbon nanotubes (MWCNTs) treated with laser ablation have been investigated. The MWCNTs were synthesized by chemical vapor deposition method. The laser ablation treatment was performed in liquid medium for laser ablation time of 40 min and 60 min. The morphology of MWCNTs films was characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The results exhibit that the field emission properties of MWCNTs are dependent on the laser ablation time. The Raman spectra of laser-ablated MWCNTs clearly showed disorder and increase in graphitic content. The SEM and TEM results clearly revealed the separation of MWCNTs after laser ablation treatment. The field emission characteristics of the MWCNTs showed that the turn-on fields and current density are improved for the nanotubes treated with laser ablation. The enhancement in the field emission characteristics of MWCNTs is attributed to the disorder as well as the increase in the aspect ratio which causes more pathways for electron emission.

The laser ablation of a noble target material in a liquid is known as an alternative physical method for nanostructure fabrication. In the present study, the nanosecond laser ablation is used to irradiate MoS₂ in water to produce MoS₂ nanosheets. The experiments of laser ablation time of 20 minutes and 120 minutes have been carried out to study their field emission properties. Transmission electron microscopy (TEM) and Raman spectroscopy have been used to reveal surface and structural morphology. It is observed that the laser ablation time is an important factor in determining the size of MoS₂ nanostructure. The Raman spectra of laser ablation confirm the formation of MoS₂ nanosheets and removal of molybdenum oxide species. The TEM shows the size of MoS₂ microsheet has been reduced from 2 $\mu$m to 400 nm after the laser ablation treatment. It is found that the turn-on fields are reduced and current densities of MoS₂ are increased after the laser ablation. The enhancement in the field emission characteristics of MoS₂ is due to the reduction in the size of MoS₂ and removal of molybdenum oxide species. The nanostructures produced by laser ablation may be used for optoelectronic application.

Growing interest in fundamental research on two-dimensional transition metal chalcogenides (TMDs) is rising rapidly due to their excellent physical and chemical properties. One such materials is Boron nitride (BN), an electrical insulator with a band gap of 5.5 eV, which possesses a high chemical stability, excellent mechanical properties and high thermal conductivity. Cubic BN (c-BN) and hexagonal BN (h-BN) are kinds of layered materials similar to that of graphite-like structure in which planar networks of BN hexagons are regularly stacked. In the present study, we report a general approach for the production of BN nanostructures using nanosecond laser ablation (Nd:YAG, 532 nm) in acetone at room-temperature. The laser ablation time was varied for 30, 120 and 240 min. The prepared BN nanostructures were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) to identify the formation of nanostructure. The presence of BN nanoparticle has been confirmed by SEM images and supported by XRD spectrum. It is expected that the BN nanoparticles have practical importance for optoelectronic devices and their applications in the near future.

The present study describes the results on the formation of WS₂ nanosheets using the nanosecond laser ablation in a liquid environment. The laser ablation in liquid is a well-known method and is widely used for the generation of nanostructure. The nanosecond laser ablation is used to irradiate WS₂ in a isopropyl alcohol to generate WS₂ nanosheets. The laser ablation time was 120 min. The field emission measurement of irradiated WS₂ nanostructures was performed. The Bulk and WS₂ were used to characterize the Transmission Electron Microscopy (TEM) and Raman spectroscopy to reveal their surface and structural morphology. It is found that the laser ablation time is an important parameter to transform the bulk WS₂ into WS₂ nanosheets. The generation of WS₂ nanosheets is revealed by the Raman spectra. Moreover, the TEM images indicate that the size of WS₂ microsheet has been reduced to 400 nm after the laser ablation treatment. It is also found that the field emission current density of WS₂ is increased after the laser ablation. The improvement in the field emission characteristics of WS₂ is due to the formation of WS₂ as well as the separation of layered WS₂ structure into few layers of WS₂. The formation of WS₂ nanosheets can be used for future optoelectronic devices.

In this study, we report, for the first time, on synthesis of lanthanum oxide ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ nanoparticles NPs by laser ablation in water without using surfactant. The effect of laser wavelength on the optical and structural properties of ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs was investigated. X-ray diffraction studies show formation of polycrystalline lanthanum oxide with pure cubic phase and the crystallinity of the nanoparticles synthesized with $\lambda =532$ nm was better than that prepared with $\lambda =1064$ nm. The optical absorption investigations reveal that a strong absorption peak at 234 nm was observed for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs prepared at 532 nm laser wavelength. The optical energy gap of ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs synthesized with 532 and 1064 nm laser wavelengths were 5 and 4.5 eV, respectively. Scanning electron microscope (SEM) investigation indicated the formation of nanoparticles with average particle size of 35 nm for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ prepared with 532 nm and was 75 nm for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ prepared with 1064 nm laser wavelength. The effect of laser wavelength on the optoelectronic properties of hybrid In/p-${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$/n-Si photodetector was studied. The responsivity studies of the photodetectors show the presence of two response peaks at 250 and 750 nm.

Two dimensional (2D) materials are widely attracting the interest of researchers due to their unique crystal structure and diverse properties. In the present work, tungsten disulfide (WS${}_2)$ nanorods were synthesized by a simple method of pulsed laser ablation in liquid (PLAL) environment. The prepared WS₂ are analyzed by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-visible spectroscopy (UV-vis) and Raman spectroscopy to confirm the surface morphology, phase and structure. A possible growth mechanism of WS₂ is proposed. This study indicates new door for the preparation of 2D materials with specific morphology.

This paper describes a simple approach for creating silver (Ag) nanocubes using pulsed laser ablation in a liquid medium. The development of nanocubical formations of Ag obtained by laser ablation using Nd: YAG laser was conducted for 5, 10, 15, and 20min. The surface morphological analysis was performed using field-emission scanning electron microscopy (FESEM) to show the formation of silver nanocubes with edge lengths ranging from 150nm to 250nm. The UV-visible spectroscopy demonstrates that the concentration of Ag nanostructures, evidenced by the characteristic localized surface plasmon resonance band near 400nm in the colloidal solution containing Ag nanoparticles, increased with the increasing laser ablation duration from 5min to 20min. The growth mechanism for Ag nanocubes can be easily understood with the change in laser ablation time from 5 to 10, 15, and then 20min. The Ag sheets with no specific shape start to develop after 5 min of laser ablation, and after 10min, larger particles form. Then, after 15min, a small number of cube-like nanostructures with rough and uneven edges was obtained. At the end of 20min, a complete cubic formed with fine and distinct edges and a very large amount of nanocubes. The elemental silver signal was present in Ag nanocubes, as revealed by the energy-dispersive X-ray spectroscopy (EDS) spectra. The produced Ag nanocubes may be used to construct two-dimensional nanocomposites with practical applications in the electrical, optoelectronic, electrochemical, and biological areas.

In recent years, vanadium pentoxide (V₂O₅) nanoparticles (NPs) have attracted considerable interest due to their potential medicinal applications, including cancer therapy, antibiotic resistance and antibacterial activity. Manufacturing V₂O₅ NPs is a crucial step in developing these applications, and laser ablation in solution has proven to be a particularly successful technique. Following fabrication, colloidal solutions were analyzed using ultraviolet–visible (UV–Vis) absorption spectra, Fourier transform infrared (FTIR) spectrum, transmission electron microscopy (TEM) and X-ray diffraction (XRD). In this work, XRD study revealed that the produced NPs had an orthorhombic phase. Based on the laser energy, nanosized vanadium pentoxide particles were created by laser irradiating a vanadium bulk submerged in a double deionized water (DDW), resulting in spherical particles with average sizes ranging from 15.4 to 33.8nm, as shown by TEM micrographs. Conforming to the quantum size concept, the bandgap energy of V₂O₅ NPs is higher than that of bulk V₂O₅ due to the decrease in particle size. This study examined the effectiveness of V₂O₅ NPs against pathogenic bacterial strains Staphylococcus aureus as Gram’s positive bacteria and Escherichia coli as negative Gram’s bacteria. Then, we evaluated anticancer activity of V₂O₅ NPs against a breast cancer cell line (MCF-7 cells) using MTT assay. The results reveal that the activity of prepared V₂O₅ NPs against S. aureus is greater than that of E. coli. The findings suggest that prepared NPs can act as an anti-proliferative agent against MCF-7 cells. Subsequently, the produced NPs might be exploited as a future strategy for other biomedical applications.

In this research, tantalum nanoparticles were prepared by the laser ablation method and the effect of an electric field on their structural properties was investigated. The optical absorption spectra were studied to comprehend the optical properties of nanoparticles. Size and morphology of nanoparticles are illustrated by TEM images. The average size of tantalum nanoparticles is 19 and 45nm for synthesized samples without and with electric fields, respectively. By applying an electric field, the morphology of nanoparticles changed from spherical to tangled shapes. XRD analysis showed the crystalline structure of nanoparticles. The investigation of bending and stretching of molecular functional groups and the measurement of the hydrodynamic radius were done by FTIR, RAMAN and DLS analyses, respectively. FTIR, RAMAN, XRD and DLS analyses confirm the structure. EDX spectra confirmed the existence of ingredients. The stability of colloidal is indicated by zeta potential analysis. Photoluminescence spectra reveal nanoparticle properties. As the electric field increases, the size of nanoparticles increased, morphology changes from spherical, and oxidation increases.

The component for photocatalyst is a developing field in energy production. Various photocatalysts can be synthesized using a variety of techniques. Numerous researchers have identified a wide range of photocatalysts. While ternary-based composite photocatalysts have received relatively little attention, plenty of reviews are available on photocatalysts. We provide a short summary of the most recent and a variety of ternary-based composite photocatalysts here. We discuss gold (Au)-based, silver (Ag) based, zinc oxide (ZnO) based, and other ternary-based composites in this paper. This quick summary will help future demonstrations of increased deterioration efficiency. This will provide insight for future research on ternary-based composite photocatalysts.

We report on the synthesis and characterization of silicon nanoparticles by ablating silicon wafer in an ambient atmosphere of helium at 1 Torr. The mean cluster size ranging from 1.8 nm to 4.4 nm deposited on silicon substrate at room temperature is observed to depend on the laser fluence. The size of the nanoparticles decreases with laser fluence. Photoluminescence of the deposited films using Nd:YAG laser and Ar⁺ ion laser at 355 nm and 457.9 nm respectively shows emission peaks at 1.7, 2.2, and 2.7 eV. The luminescence peak at 2.2 eV and 2.7 eV are attributed to oxygen related impurities and the peak at 1.7 eV is attributed to quantum confinement.

Current perpendicular-to-plane (CPP) magnetoresistance (MR) of La_0.7Ca_0.3MnO₃/LaNiO₃ superlattices sandwiched between two YBa₂Cu₃O₇ thin film electrodes is reported. The CPP-MR in the temperature window of 20 K to 80 K is larger by a factor of 7~15 compared to current-in-plane (CIP) MR. Both CPP and CIP-magnetoresistance decrease with temperature below ~ 20 K. The MR at T<40 K is also strongly hysteretic and does not saturate even at 4 Tesla. Measurements of saturation moment and modeling of the perpendicular-to-plane resistance suggest disorder at the ferromagnetic non-magnetic layer interfaces which dominate the MR. The relative orientation of magnetization in the ferromagnetic layers seems to play only a subservient role in the creation of magnetoresistance.

We have developed a theoretical model which studies the characteristics of laser-plasma interaction, the effect of plasma shielding and plasma radiation in the ablation process. The model is used to simulate 25 ns square pulsed laser irradiation on YBa₂Cu₃O₇ targets, and pulsed laser with the pulse width of 25 ns (FWHM) irradiation on Ni targets. The evolution of the plasma length and the transmitted intensity are performed. The model shows the variation of ablation depth with energy density. Moreover, we obtain the dependence of the ablation depth on the number of laser pulses. The satisfactorily good agreement between our results and experimental results confirms that plasma shielding plays a relevant role in the ablation process.