Narrow Results

(La_2/3-xY_x) (Ca_1/3-ySr_y) MnO₃ (LYCSMO) thin films with x = 0.08 and y = 0.0868 deposited on SrTiO₃ (STO), Yttrium-stabilized ZrO₂ (YSZ), LaAlO₃ (LAO), and MgO substrates are fabricated. Atomic force microscopy measurements reveal that the morphology is quite different for all films. A two-dimensional growth mode is suitable for LYCSMO film on STO, while on LAO, YSZ, and MgO, an island growth mode may be a good description for the growth of LYCSMO films. X-ray diffraction studies show that the films epitaxially grow along c axis on STO, LAO, and MgO substrates, while grows along a axis on YSZ substrate. The in-plane and out-of-plane lattice parameters are also obtained for films grown on all substrates.

Molybdenum thin films were sputter deposited under different conditions of DC power and chamber pressure. The structure and topography of the films were investigated using AFM, SEM and XRD techniques. Van der Pauw method and tape test were employed to determine electrical resistivity and interfacial strength to the substrate, respectively. All the films are of sub-micron thickness with maximum growth rate of 78 nm/min and crystallite size in the range of 4 to 21 nm. The films produced at high power and low pressure exhibit compressive residual strains, low electrical resistivity and poor adhesion to the glass substrate, whereas the converse is true for films produced at high pressure.

In this work, we prepared LaNiO₃ (LNO) and Au-LaNiO₃ (Au-LNO) films using sol–gel multilayer coating method. The effects of lattice mismatch on the microstructure and electrical properties of the films were investigated by choosing different single-crystal substrate. XRD, SEM, and AFM results showed the high quality of LNO and Au-LNO films, indicating the successful epitaxial growth of the films on the single-crystal substrates. The room temperature resistivity of LNO films increased with the increase of lattice mismatch while different tendency was observed in Au-LNO films, suggesting that different mechanisms prevailed in the LNO and Au-LNO films. Both the transport behavior and the residual resistivity ratio were checked to explore the relationship between the lattice mismatch and the electrical properties of the films. Strain and defect concentration were proposed as the predominating factors for the changes in the resistivity of LNO and Au-LNO films under the influence of lattice mismatch.

A comprehensive theoretical study has been carried out to examine the electronic and thermoelectric properties of As$XY$ (where $X=\mathrm{\text{S}}$, Se; $Y=\mathrm{\text{Cl}}$, Br, and I) monolayers. The lattice constants of these monolayers are optimized to determine their most stable configurations. The electronic and thermoelectric characteristics of these monolayers are calculated using state-of-the-art computational methods. Specifically, the first-principles calculations in combination with semiclassical Boltzmann transport theory were employed to gain insights into their behavior. One of the crucial findings of the study is the observation of an indirect band nature in all the studied monolayers. This characteristic provides valuable information about the materials’ electronic behavior and potential applications. Furthermore, the impacts of tensile and compressive strains on these monolayers are investigated. Interestingly, we observed changes in the band value when strain is applied, which opens up exciting possibilities for engineering their electronic properties. Importantly, despite these changes, the band nature of the monolayers remains consistent. In particular, it is found that the AsSI monolayer exhibits a remarkable enhancement in the Seebeck coefficient, both in the unstrained state and under a compressive strain of 4% in the p-type region. This enhancement leads to a higher power factor (PF), suggesting that AsSI monolayers could be promising candidates for efficient thermoelectric devices. Overall, these findings highlight the potential of strain engineering to tailor the electronic properties of As$XY$ monolayers, offering exciting opportunities for their application in thermoelectric devices. This research contributes valuable insights into the design and optimization of novel materials for future energy conversion and electronic applications.

The results of pilot in situ studies of the responses of Nitinol surfaces to deformation are presented. It is shown that the mechanical behavior of Nitinol surfaces differs, depending on oxide thickness and its chemical composition. The corrosion resistance of the surfaces evaluated in strain-free and strained states using potentiodynamic and potentiostatic cyclic polarization at the body potentials demonstrated quite stable behavior.

Yttria nanoparticles are synthesized by co-precipitation method and as-prepared nanoparticles are annealed at various temperatures. The as-prepared and annealed particles are characterized by X-ray diffraction and transmission electron microscope (TEM). Here we estimated the lattice strain, crystallite size, deformation stress, and deformation energy density for annealed (800°C) yttrium oxide nanoparticles by Williamson-Hall-Isotropic Strain Model (W-H-ISM), W-H-Anisotropic Strain Model (W-H-ASM) and W-H-Energy Density Model (W-H-EDM) based on W-H plot from powder X-ray diffraction data. The shape and size of the nanoparticles are determined using TEM. The results of the estimated crystallite size of yttria nanoparticles by various methods agreed with the TEM results.

Partial oxalate route is an efficient method to synthesize complex perovskite ferroelectric ceramics, in which the synthesized (1 - x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (PMN–PT) ceramics exhibit rather pure perovskite structure, densified microstructure morphology, and excellent dielectric and piezoelectric properties. The PMN–PT ceramics synthesized by the partial oxalate route exhibit rather symmetric strain–electric (S–E) field hysteresis loops, where the strain is large and far less than saturated at 2 kV/mm. The PMN–PT ceramics exhibit excellent pyroelectric properties, in which the values of the pyroelectric coefficient and the calculated pyroelectric figures of merit maintain almost stable over the frequency range of 100 Hz–2000 Hz, and vary differently depending on composition with the increase of temperature. Such investigations reveal that high-performance piezoelectric and pyroelectric devices can be prepared by the partial oxalate route in low production cost.

The interplay between the linear elastic deformation up to 20% and the unique electronic properties of graphene nanostructures offers an attractive prospect to manipulate their properties by strain. Here we review the recent progress on the electronic response of graphene to the in-plane strains, including the strain-modulated electronic structure and the strain-modulated spin, valley and superconducting transports. A generalized Hamiltonian for a graphene was constructed subjected to arbitrary in-plane strains. The Hamiltonian is helpful to design and optimize the graphene-based nano-electromechanical systems (NEMS).

This paper presents a thorough study of the strain response of different types of electroceramics during dynamical electrical loading. It highlights important aspects to take into account in the experimental methodology and outlines general guidelines for the discussion and interpretation of the results. The contributions of piezoelectric effect, electrostriction and ferroelectric/ferroelastic domain switching to the strain produced during the application of an alternating electric field are discussed by describing the strain-electric field (S-E) loops of different dielectric ceramics in which each of these contributions are predominant. In particular, attention is given to the description of the strain evolution in the characteristic "butterfly loops" typically shown by ferroelectric materials. The strain-polarization loop is indicated as a useful means to reveal the interconnection between strain and polarization state during dynamical electrical loading. Strain rate is suggested as a powerful tool to obtain more detailed information regarding the mechanisms of the electric field-induced strain.

A three-dimensional mathematical model is proposed that describes the ferroelectric response of polycrystalline ferroelectrics to an electric field in the absence of mechanical stresses. It is based on the separation of the switching process into two related parts: the rotation of the spontaneous polarization vectors and the destruction of the domain wall fixing mechanisms. For each of the parts, the energy costs are calculated, which are the components of the energy balance in the real polarization process. The constitutive relations for the induced and residual components of the polarization vector of the representative volume are obtained. A number of numerical experiments were performed, which showed good agreement with the experimental data.

In this paper, we employ semiclassical Monte Carlo approach to study spin polarized transport in InP and strained InP nanowires on GaAs substrate. Due to higher spin relaxation lengths, InP is being researched as suitable III–V material for spintronics related applications. Spin relaxation in InP channel is as a result of D'yakonov–Perel (DP) relaxation and Elliott–Yafet (EY) relaxation. We have considered injection polarization along z-direction and the magnitude of ensemble averaged spin variation is studied along the x-direction i.e., along transport direction. The effect of strain on various scattering rates and spin relaxation length is studied. We then present the effect of variation of nanowire width on spin relaxation length for the case of both strained and unstrained InP nanowire. The wire cross-section is varied between 4 × 4 nm² and 10 × 10 nm².

While microalgae oil was perceived as the preferred feedstock to supply the inelastic global demand for biofuel, industry and academia attempts to create viable microalgae-oil production processes has not reach the desired goal yet. UniVerve Ltd. has developed an innovative technological process that provides a scalable, cost effective and sustainable solution for the production of microalgae-biomass. The oil, which can be extracted with off-the-shelf wet-extraction technologies and used as an excellent feedstock for all kinds of biofuel, is expected to be produced at up to US$50 per barrel. As the biomass also contains omega-3, proteins and other valuable biomaterials that can be commercialized in the food and feed markets, a microalgae farm can serve the biofuel, food and feed industries, which currently face an increasing lack of quality feedstock at an affordable price.

We have investigated the residual in-plane strain and width of the surface misfit dislocation free zone in linearly-graded GaAs_1-yP_y metamorphic buffer layers as approximated by a finite number of sublayers. For this purpose we have developed an electric circuit model approach for the equilibrium analysis of these structures, in which each sublayer may be represented by an analogous configuration involving a current source, a resistor, a voltage source, and an ideal diode. The resulting node voltages in the analogous electric circuit correspond to the equilibrium strains in the original epitaxial structure. Utilizing this new approach, we show that the residual surface strain in linearly-graded epitaxial structures increases monotonically with grading coefficient as well as the number of sublayers, and is strongly dependent on the width of the misfit dislocation free zone, which diminishes with an increasing grading coefficient.

Chirped superlattices are of interest as buffer layers in metamorphic semiconductor device structures, because they can combine the mismatch accommodating properties of compositionally-graded layers with the dislocation filtering properties of superlattices. Important practical aspects of the chirped superlattice as a buffer layer are the surface strain and surface in-plane lattice constant. In this work two basic types of InGaAs/GaAs chirped superlattice buffers have been studied. In design I (composition modulated), the average composition is varied by modulating the composition of one of the two layers in the superlattice period, but the individual layer thicknesses were fixed. In design II (thickness modulated), the individual layer thicknesses were modulated, but the compositions were fixed. In this paper the surface strain and surface in-plane lattice constant for these chirped superlattices are presented as functions of the top composition and period for each of these basic designs.