The effect of the different doses of γ irradiation on Cu–23.36Al–2.78Be (at.%) shape memory alloy (SMA) has been investigated in this study. The effect of irradiated dose on characteristic transition temperatures was determined by differential scanning calorimetry (DSC). The diffraction planes which depend on irradiation dose were analyzed by X-ray diffraction (XRD), and crystallite size was calculated for alloy samples. In order to observe changes in the structure with increasing irradiation dose, optical microscope investigations were performed. The transformation temperatures and activation energies decreased after irradiation, and some changes occurred in the forming latent gas. The sample of the heat treated but unirradiated alloy includes the β (DO3) structure as matrix phase at room temperature. With increasing irradiation dose, 18 R martensite structure is observed. Microhardness values and crystallite size values of the alloy samples changed significantly with increasing irradiation dose. The average crystallite size was found as 42.99 × 103 ± 18.71 nm for Cu–23.36Al–2.78Be (at.%) SMA. The thermal measurements showed a non-monotonous change on transition temperatures by the increase in applied dose value. Radiation hardening is about the beginning of spot defects in the metal structure. The basis of the mechanism is the interaction of the defects with movement of dislocations. Under the effect of radiation, very fast moving atomic particles strike the atoms that make up the crystal structure and force them out of their balanced position. As a result, atomic cavities and some defect atoms are formed in the lattice because of the gamma radiation.

The effect of substituting sodium by potassium on electrical and dielectric properties is investigated in details for the GdFeO3-type Pr0.8Na0.2-xKxMnO3 (x = 0.00, 0.05, 0.1, 0.15 and 0.2) manganites. The electrical measurements indicate that the parent compound exhibits a metal behavior. When introducing potassium, all samples show a metal–semiconductor transition. Then, the increase of K content reduces the resistivity in the whole temperature range but doesn’t affect the metal–semiconductor temperature transition (TMS). At a specific temperature TS, a saturation region was marked in the resistivity curve. It is found that TS values shift toward lower temperatures when the potassium content rises. The TS value approaches to room temperature for x = 0.2. The temperature coefficient of resistance (TCR) of the investigated manganites shows significant value, especially for x = 0, indicating that these ceramics can be used for a specific application such as bolometer technology. The frequency dependence of conductance was investigated through Jonscher's universal power law and the electrical conduction mechanism well interpreted by the correlated barrier hopping (CBH) model. Impedance spectroscopy measurements indicate that the electrical behavior of these perovskites is primarily dominated by the grain boundary response. The dependence of the dielectric constant on the frequency and the temperature confirms that the investigated samples are of a classical dielectric type.

Structured light, where optical beams are tailored in amplitude, phase and polarisation to some desired profile, has become topical of late, fuelled by the ease at which such fields can be created internal and external to the source. In this treatise, part I of a two part series, we consider the thermal effects (stress, lensing and phase aberrations) associated with high-power structured light, where the structure may be the pump, optically inducing the thermal effects in the medium, or the probe, experiencing thermally induced optical aberrations. We outline a general theory for arbitrary structured light pumps and probes, reducing to the prior studies of Gaussian and flat-top beams as special cases. We illustrate the power of the model using the structure of light as a new degree of freedom with which to mitigate thermally induced optical aberrations. Finally, in part II of this composite work (Scholes and Forbes, Appl Phys B, 2021. https://doi.org/10.1007/s00340-021-07656-z), we experimentally demonstrate the phase aberration predictions using a digital micro-mirror device for real-time simulation of such high-power thermal effects in a cheap, fast and versatile manner, without the need for elaborate high-power experiments. Our work brings together the disparate fields of thermal modelling and structured light, providing a framework for future work in the creation and delivery of high-power structured light fields.

Magneto-plasmonic nanoparticles have gained increasing interest, especially for the synergistic response study of hyperthermia applications. However, some challenges, including the synthesis process, dose optimization of laser, and magnetic field strength besides its frequency, need significant attention. Herein, we prepared magneto-plasmonic Ag/Co nanomaterials for photothermal performance evaluation using dual-beam of the Q-switched Nd:YAG 1064 nm pulsed laser ablation in distilled water, which can avoid any additive, contaminations, complicated route, and multiple purifications processes as they may occur in chemical synthesis processes. Properties, morphologies, and compositions of synthesized nanomaterials were studied, and results suggested that the main constituents of NPs were Ag/Co. The detailed theoretical calculation of the photothermal performance of nanofluid is described, along with an experimental study of nanofluid and the water as a reference medium using NIR 808 nm laser. The overall results suggest that the higher temperatures for Ag/Co nanofluid compared with water alone were recorded as 16.5 °C, 20.9 °C, 24.7 °C, 24.5 °C, 27.7 °C, and 30.2 °C during 808 nm laser irradiation operating at different corresponding powers, respectively. The possible reason for the higher temperature profiles and the rapid temperature rise of nanofluid than water alone is the localized surface plasmon effects of nanoparticles. These results evidence that silver and cobalt nanomaterials composite structures could significantly increase hyperthermia based on an effective and simple synthesis approach.

Tungsten bronze structure-based PbNb2O6 ceramics are functional materials and are usually known as low-density ceramics. The low-density property may limit their practical applications. In this study, Cu-substituted PbNb2O6, with different concentrations, was prepared by a well-known solgel auto-combustion method. X-ray diffraction analysis confirmed the formation of rhombohedral perovskite phase for PbNb2O6 which is transformed to monoclinic phase upon complete replacement of Pb by Cu. The surface morphology of all the samples suggested that, with the increase in copper content, the grain size decreased, which resulted in an increase in the density of these ceramics. Energy-dispersive X-ray spectroscopy assured the presence of all the elements in the samples in accordance with their empirical formulae. Fourier transform infrared spectroscopy confirmed complete combustion, and the downward peaks in the corresponding spectra were purely related to perovskites. Frequency-dependent dielectric analysis showed that the dielectric constant and conductivity of PbNb2O6 improved with increasing Cu contents and less than 1% dielectric loss was achieved. In addition, complex impedance spectroscopy and complex modulus analysis revealed the existence of non-Debye-type relaxation in these compositions.

In this work, pure and Al-doped zinc oxide (AZO) thin films were grown on glass substrates by sol–gel spin coating method. Structural, morphological, optical and waveguiding properties are investigated for different Al concentration (0–4 at. %). X-ray diffraction confirmed the hexagonal ZnO Würtzite structure of the films with a high c-axis preferred orientation. The crystallite size decreased from 30 to 20 nm with increasing Al content. Atomic force microscopy showed that Al-doped ZnO films presented a smooth and uniform surface and their roughness values depend on dopant concentration.The AZO films showed a high optical transparency more than 95% in the visible region and the optical band gap increased by increasing Al content. The optical waveguiding characterization demonstrated that our films have planar waveguide structure. All the AZO films supported only a well-guided fundamental mode for both transverse electric and transverse magnetic polarizations. Both ordinary and extraordinary refractive indices are found to decrease with Al doping content. Best performing thin films have been obtained with 2 at. % of Al.

Titania nanotubes (TNTs) are attractive for a variety of applications. In this study, amorphous TNTs have been synthesized by anodization. Annealing of anodized TNTs has been performed to get the anatase phase. Amorphous and annealed TNTs have been electrochemically reduced using 1 M KOH solution. For characterization of amorphous, annealed, electrochemically reduced amorphous and annealed TNTs, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques were used. The presence of C, F and K is detected from the full scan of X-ray photoelectron spectroscopy (XPS) analysis. The effect of electrochemical reduction on optical properties of TNTs under ambient conditions is studied using photoluminescence (PL) spectroscopy. The electrochemical reduction does not cause any appreciable morphological changes (evident from SEM images). However, XRD results show that this treatment produces strain in the anatase phase as a result of the increase in ‘d’ spacing between (101) and (202) planes. Photoluminescence spectroscopy of TNTs indicates that the defect states lie in the visible region for all the samples. These defects states have been found at 2.93 eV, 2.67 eV, 2.53 eV and 2.35 eV energies for amorphous TNTs. For annealed TNTs, these states have been observed at 2.67 eV and 2.35 eV. PL signal for amorphous TNTs is higher than the annealed TNTs. The electrochemical reduction treatment of the amorphous TNTs efficiently removes defects like F, K and C in addition to creating oxygen vacancies as compared to annealed TNTs. As these electrochemically reduced amorphous TNTs are exposed to ambient air for 7 days, the oxygen vacancies are filled. Moreover, in addition to removal of oxygen vacancies, these exposed and electrochemically reduced amorphous TNTs are devoid of other defects like F, K and C. This results in the significant reduction in PL intensity for such amorphous TNTs samples 7 days after electrochemical reduction. Due to the oxygen scavenging ability of electrochemically reduced TNTs, they could be used for vacuum improvement in various devices. This type of electrochemical reduction/recovery cycle makes these TNTs useful for the solar cell application under special (reduced/absence of oxygen) conditions.

In this study, pure KNN and Ba/Sr co-doped KNN with and without nano-CuO (nCuO) as sintering aid (0.5 mol%) were prepared by the solid-state method. The results showed that both Ba/Sr co-doping and nCuO sintering aid efficiently improved the densification process, piezoelectric and dielectric properties of the KNN ceramic. The Ba/Sr co-doped KNN samples with nCuO showed a high piezoelectric coefficient (d33 = 176 pC/N), a high dielectric constant (εr = 623), a low dielectric loss (tanδ = 0.009) and a high remnant polarization (33 µC/cm2). The Ba/Sr dopants and nCuO sintering aid could transform the tetragonal phase to orthorhombic ones for KNN ceramics and by the substitution of Cu2+ at the B-site of the perovskite structure formed the oxygen vacancies that could improve the densification. Furthermore, it was found out that the density has a significant effect on the electrical properties of sintered samples. With increase in the relative density, the d33, and εr of KNN ceramics expansively increased, and the tanδ of the samples linearly decreased.

Nickel-based thin film electrodes were electrodeposited onto copper substrate using a deep eutectic solvent. The supercapacitor performance of these electrodes in alkaline KOH solution was greatly enhanced by altering surface roughness of coatings. In order to create a rougher surface, two paths were followed. In the first path, Ni-only coatings were prepared at different deposition potentials and smooth-to-rough transition in surface morphology took place at higher potentials due to increasing emission of hydrogen bubbles. In the second path, Ni–Zn binary coatings with varying zinc concentration were electrodeposited and surface roughness was formed by dealloying zinc element from the electrodes as corroborated by Scanning Electron Microscopy and Atomic Force Microscopy results. In both paths, noticeable improvements in the capacitance of nickel electrodes were observed upon the apperance of rougher surface. A linear relationship was discovered between cathodic peak currents and polarization values in the cyclic voltammetry scans of electrodes, possibly for the first time here in literature. The increase in polarization was explained by the decrease in electrode conductivity proved by dwindling of metallic nickel peaks in X-ray diffraction upon electrochemical testing.

Herein, we demonstrate a simple one-step method for synthesizing Ag NPs embedded free-standing PVA/chitosan (PVA/Cs) films. The influence of gamma radiation on the dielectric constants, dispersion, and optical characteristics of PVA/Cs/Ag nanocomposite films was studied. The results confirmed the successful formation of silver NPs in the matrix through the appearance of the surface plasmon absorption at 420 nm. The indirect energy gap decreases from 2.11 to 2.01 eV, while the direct energy gap decreases from 2.6 to 2.5 eV by increasing the irradiation doses. Besides, the oscillator energy and the dispersion energy are varied by increasing the irradiation doses. Furthermore, the optical conductivity increases by the increase in γ-doses but decreases at 15 kGy due to the degradation process. Overall, the optical characteristics of PVA/Cs/Ag nanocomposite films make them promising materials for flexible optoelectronic devices.