Table of contents

Novel plasma-assisted inkjet printing, where inks during flight and after landing on a substrate are irradiated by atmospheric-pressure nonequilibrium plasma, is developed as a rapid one-step process without any pre-/post-treatments. A silver line with good electrical conductivity was fabricated on a polyimide. Compared with heat treatment, the line shows lower electrical resistivity and a narrower line width even with a much shorter treatment time.

Harvesting energy from ambient mechanical sources in our environment has attracted considerable interest due to its potential to power applications such as ubiquitous wireless sensors and Internet of Things devices. In this context, piezoelectric and/or triboelectric materials offer a relatively simple means of directly converting mechanical energy from ubiquitous ambient vibrating sources into electrical power for microscale/nanoscale device applications. In particular, nanoscale energy harvesters, or nanogenerators, are capable of converting low-level ambient vibrations into electrical energy, thus are vital to the realization of the next generation of self-powered devices. Polymer-based nanogenerators are attractive as they are inherently flexible and robust, making them less prone to mechanical failure which is a key requirement for vibrational energy harvesters. They are also lightweight, easy and cheap to fabricate, lead-free and biocompatible, but in many cases their energy harvesting performance is found lacking in comparison to more commonly studied inorganic materials. Recent advances have been made in developing scalable nanofabrication techniques for flexible and low-cost polymer-based nanogenerators with improved energy conversion efficiency, including the incorporation of high-quality polymer nanowires with enhanced crystallinity, piezoelectric and/or surface charge properties. In this review, we discuss aspects of nanomaterials growth and energy harvester device design, including those involving nanowires of polymers of polyvinylidene fluoride and its co-polymers, nylon-11, and poly-lactic acid for scalable piezoelectric and triboelectric nanogenerator applications, as well as the design and performance of polymer-ceramic nanocomposite nanogenerators. In particular, we highlight the effects of growth parameters, nanoconfinement, self-poling, surface polarization, crystalline phases, and device assembly on the energy harvesting performance of a range of recently reported nanostructured polymer-based materials and devices.

Yttrium aluminum garnet (YAG) (chemical composition Y₃Al₅O₁₂) is a well-known host material for obtaining highly efficient luminescent materials (phosphor) that offer unprecedented applications in the science and technology community. The structure of Y₃Al₅O₁₂ permits facile doping of lanthanide ions, leading to the formation of different compositions possessing emission properties in a wide range (ultraviolet–near infrared). The ease of emission tuning and high chemical stability of YAG hosts lead to their wide applicability in various applications, including lasers, biomedical theranostic platforms, thermoluminescence dosimetry, nanothermometry, and long persistent luminescence. We present an overview of YAG-based nanophosphors and their synthesis pathways-related morphology and luminescence properties. In addition, we explore various fields where the YAG-based nanophosphors have been implemented, and also discuss their possible future applications.

A detailed theoretical investigation of the effect of scattering of electrons and phonons by lattice vacancies in molybdenum disulfide (MoS₂) monolayers (MLs) on diffusion, S_d, and phonon-drag, S_g, components of thermoelectric power (TEP), S, is presented over a wide-temperature range (1  <  T  <  300 K) using the Boltzmann transport formalism. The diffusion component is assumed to be influenced, not only by vacancies via short-range and Coulomb disorder scattering, but also by charged impurities (CIs) and acoustic and optical phonons. In the case of S_g, the phonons are considered to be scattered, besides the vacancies, by sample boundaries, substitutional isotopic impurities, as well as other phonons via both N- and U-processes. Numerical calculations of S_d and S_g, as functions of temperature and vacancy defect density are presented for MoS₂ MLs with n_s  =  10¹⁷ m⁻² supported on SiO₂/Si substrates. The role of carrier scatterings by mono-sulfur and mono-molybdenum vacancies in influencing the overall electron and phonon relaxation rates and in determining S_d and S_g are investigated. The behavior of S_d and S_g is found to be noticeably influenced by vacancy scattering. The influence on S_d is seen to be more for mono-sulfur vacancies for densities lesser than 1%. The influence, is to enhance S_d slightly for MLs with realizable CI concentrations. On the other hand, S_g is found to depend sensitively on the vacancy disorder for T  <  50 K; a S-vacancy density of 0.1% is found to suppress the characteristic peak of S_g by almost 60%. The extent of reduction in the characteristic peak of S_g, observable in low temperature measurements of S, can provide information about defect density. The calculations demonstrate that defect engineering of MoS₂ ML systems can be used to tune their thermoelectric performance. A need for detailed experimental studies is suggested.

Nanoparticles—both natural and engineered—are ubiquitous in their interactions with cells and especially their membranes. Beneficial aspects of such interactions range from targeted drug delivery to imaging applications while the major concern in terms of the potential hazards of such interactions is to understand their cytotoxic effects. It is well documented that of the various classes of nanoparticles, charged nanoparticles, especially cationic, have a significantly higher penetrating capability of cell membranes and in most cases also lead to enhanced cytotoxicity. However, a microscopic physical understanding of the mechanism of interaction, membrane re-organization and penetration by such charged nanoparticles is absent. Recently, we have initiated a concerted effort towards achieving this goal by studying various classes of charged nanoparticles interacting with model lipid bilayer membranes of varied composition using various real and reciprocal space high-resolution techniques as well as atomistic molecular dynamics simulations. In this article, we describe the process of membrane re-organization and pattern formation due to interaction of charged polymer capped quantum dots and dendrimers with single component lipid bilayer membranes. The size of the nanoparticles, as well as their concentration, determines the nature of membrane re-organization and shape of these patterns formed. Depending on the nanoparticle size, smaller particles generate membrane-bound disc like complexes whereas comparatively larger particles drive the formation of loosely bound aggregates ranging from discs to tubules. Diffusion studies on these structures suggest the presence of fluidized aggregates in the former case whereas fluidized membrane surround these structures in case of the latter. A consequence of this membrane re-organization is reflected through calcein leakage experiments. Understanding of these processes would go a long way in delineating the pathways for cytotoxicity or their efficacy in drug delivery and imaging applications.

Driven colloids are out of equilibrium systems, which self-organise into diverse complex structures, and have been one of the major driving themes in materials science. We report experimental studies on the evaporation driven self-assembly of colloidal nanoplatelets of montmorillonite and laponite. The sol-gel transition is studied using a rheometer and imaging by confocal laser scanning fluorescence microscope and an electron microscope to probe the microstructures. Evaporation driven thin films prepared from the bicontinuous gel state show increasing transparency and decreasing surface roughness with increasing concentration of laponite. Polarising optical microscope shows a microstructure with string-like birefringent domains. The scanning electron microscope reveals nacre-like structure of the films and decreasing inter-layer spacing with increasing concentration of laponite. The composite films showed superior flame-shielding property compared to the films made of individual components.

The growth of cell colonies is determined by the migration and proliferation of the individual cells. This is often modeled with the Fisher–Kolmogorov (FK) equation, which assumes that cells diffuse independently from each other, but stop to proliferate when their density reaches a critial limit. However, when using measured, cell-line specific parameters, we find that the FK equation drastically underestimates the experimentally observed increase of colony radius with time. Moreover, cells in real colonies migrate radially outward with superdiffusive trajectories, in contrast to the assumption of random diffusion. We demonstrate that both dicrepancies can be resolved by assuming that cells in dense colonies are driven apart by repulsive, pressure-like forces. Using this model of proliferating repelling particles, we find that colony growth exhibits different dynamical regimes, depending on the ratio between a pressure-related equilibrium cell density and the critial density of proliferation arrest.

Considering electrical control of electrostatic precipitation, this paper discusses particle collection in terms of corona ionic wind, gas flow pattern and high-voltage power sources. Experiments and simulations were conducted with lab-scale and industrial electrostatic precipitators. In general, a larger electrostatic precipitator (ESP) index value leads to better ESP performance. To maintain the voltage, simulation results show that a three-phase power source could operate at a lower ripple factor of 0.8% and a shorter recovery time of 5 ms after spark-over than single-phase or high frequency transformer rectifiers. For an industrial ESP with several electric fields, optimal voltage or electric field strength drops from its inlet to outlet fields. It is normally around 3.3 kV cm⁻¹ with a large corona input power for the inlet field, and it drops to about 2.3 kV cm⁻¹ with a small input power to limit ionic wind induced reentrainment for the last field. For a typical Chinese 660 MW coal-fired boiler with a four-field colder-side ESP, its outlet ash concentration and its PM₁₀ and PM_2.5 are usually around 15 mg m⁻³, 12 mg m⁻³ and 2 mg m⁻³, respectively. According to particle image velocimetry observation and particle collection measurements, we found that the corona wind generated vortex can result in not only enhancement of collection but also particle reentrainment and/or the so-called 'bypass flow'. An optimum electric field inside the ESP exists to save energy and collect particles. For present ESPs, a higher electric field (>3.5 kV cm⁻¹) generates strong electrohydrodynamic flow, which consequently undermines the collection due to turbulent flow. Advanced industrial automatic voltage controllers for three-phase transformer rectifier and double-wire ESPs have been developed according to those experimental results for both reducing emission and corona energy consumption.

We consider the beam-plasma formed by an energetic electron beam at fore-vacuum pressure, when the beam is terminated by an electron collector plate. We show that in the pressure range of 1–10 Pa, the dependence of beam-plasma density n on the electron beam collector potential φ has a maximum. The maximum plasma density n_m at the optimum collector potential can be much greater than the plasma density when the collector is at ground or at floating potential. The nonmonotonic dependence n(φ) is found to be caused by the contribution of secondary electrons from the collector to plasma generation.

Fe₆₅Co₃₅ thin films have been deposited on SiO₂ substrates using sputtering technique with different choices of seed layer; Ru, Ni_82.5Fe_17.5, Rh, Y and Zr. Best soft magnetic properties were observed with seed layers of Ru, Ni_82.5Fe_17.5 and Rh. Adding these seed layers, the coercivity of the Fe₆₅Co₃₅ films decreased to values of around 1.5 mT, which can be compared to the value of 12.5 mT obtained for films deposited without seed layer. Further investigations were performed on samples with these three seed layers in terms of dynamic magnetic properties, both on as prepared and annealed samples, using constant frequency cavity and broadband ferromagnetic resonance measurements. Damping parameters of around 8.0 10⁻³ and 4.5 10⁻³ were obtained from in-plane and out-of-plane measurements, respectively, for the as prepared samples, values that were reduced to about 6.5 10⁻³ and 4.0 10⁻³ for annealed samples.

Detailed magnetic studies of polycrystalline GdCrO₃ show a spectrum of interesting features, such as temperature induced magnetization reversal, spin flipping and spin reorientation, etc, which arise due to the competing magnetic interactions within and between Cr and Gd-sublattices. It also exhibits a giant magnetocaloric effect (MCE) with a maximum entropy change of 36.97 J kg⁻¹ K⁻¹, an adiabatic temperature change of 19.12 K and a refrigeration capacity of 542 J kg⁻¹ for a field change of 7 T at low temperatures. Such an exceptionally large MCE arises from the suppression of the spin entropy associated with the suppression of spin reorientation transition, in addition to the Gd-ordering, which makes it one of the best candidates for magnetic refrigeration among all known potential low temperature magnetic refrigerants.

The dynamical properties of saturated spherical shells are investigated in the exchange-dominated regime when assuming that surface anisotropy is present at both the inner and outer boundaries. It is found that surface anisotropy plays an important role in determining the dependence of lower-order eigenvalues on shell thickness. The mode frequency can increase with decreasing shell thickness, or is driven rapidly towards the ferromagnetic resonance frequency depending on the choice of the surface anisotropy constant at each boundary. The presence of surface anisotropy significantly modifies the size dependence of the modes which can be suppressed or amplified based on the coupling between boundaries. When surface anisotropy is present only on the outer boundary, similar behaviour to the solid sphere is observed for lower-order eigenvalues up to a thickness of after which large deviations begin to occur, where and are the inner and outer radius, respectively. Moreover, surface anisotropy introduces a dependence of the zeroth mode on shell thickness, removing the degeneracy with the ferromagnetic resonance and leading to a pronounced size dependence of this mode for thin shells.

The mechanism for electromagnetic (EM) mode transition and filtering in an asymptotically single-HE₁₁-mode hollow THz Bragg fibre is investigated. We designed, fabricated, and measured Bragg fibres with an asymptotically single-mode pattern, achieving measured signal propagation loss of better than 3 dB m⁻¹ at 0.265 THz and with an operating frequency range from 0.246 to 0.276 THz. Mode transition and filtering effects are both verified by 3D full-wave simulations using measured material properties, with geometrical parameters extracted from the fabricated Bragg fibre prototypes. By optimizing the coupling efficiency between the free-space Gaussian beam and the guided Bessel function mode, the optimum distance of mode transition from the Gaussian-beam excitation into the guided mode is calculated to be ~13.7 free-space wavelengths in our fibre, to ensure fast EM-field convergence to the desired asymptotically single-mode mode pattern in the Bragg fibre. After this mode transition region, the electric field amplitude ratio between the desired HE₁₁ mode and the main competing HE₁₂ mode is approximately 7 times, with the HE₁₂ mode attenuation being more than 10 dB m⁻¹ larger than the fundamental HE₁₁ mode; the results indicate that our fibre is one of the best candidates for low-loss asymptotically single-mode terahertz signal interconnections.

Considering the electron dynamics in a deeper area from the surface is important to improve the efficiency of optoelectronic devices. Potential variations due to InAs quantum dot (QD) growth in the GaAs crystal are investigated via measurements of terahertz electromagnetic waves emitted from the surface. In the pump-energy dependence of the time-domain signal, a phase inversion was observed in the QD sample. In addition, while the signal intensity from the InAs QD sample is maintained in the lower pump energy region, the intensity profile does not show this specific change related to the phase inversion. These results demonstrate that the potential change around QDs caused by lattice-mismatched strain can be examined using observations of the time-domain terahertz signal, which can be used to improve the device performance.

We theoretically presented the generation of optically induced spin photocurrents as well as an optically induced magnetoresistance (MR) in a spin-photovoltaic device based on chevron-type graphene nanoribbons, sandwiched between asymmetric ferromagnetic contacts. The designed spin photodetector showed that spin photocurrents could be generated under circularly and even linearly polarized radiations at room temperature. However, applying a circularly polarized radiation resulted in an improved sensitivity of the device to the switching of the magnetization arrangement of ferromagnetic contacts. Interestingly, the spin photovoltaic response generated a spin photocurrent ranging from terahertz to visible light with a considerable spin-dependent quantum efficiency more than and a high spin polarization () and an optically induced MR (). The novel properties could be promising for developing graphene-based spin-photovoltaic applications such as spin filtering and helicity detection, especially in terahertz and visible regions.

A high sensitivity refractive index sensor based on D-shaped photonic crystal fiber with surface plasmon resonance (SPR) is designed and analyzed by a full-vector finite element method. The side-polished fiber has two micro-openings of the same size, and the gold film is deposited on the polished surface between them. The D-shaped fiber is completely immersed in the analyte whose different refractive indices vary from 1.31 to 1.37. In the proposed sensor, the coating of the gold film and the filling of the analyte can be achieved on the outer surface of the fiber. Numerical simulation results show that the maximum sensitivity can reach 11 750 nm/RIU, corresponding to a resolution of 8.51  ×  10⁻⁶ RIU in this sensor. Due to the simple structure, convenient detection and ultrahigh sensitivity, the proposed SPR sensor can be widely used in environmental, biological and biochemical sensing fields.

Photo-induced changes of capacitance–voltage curves for amorphous Ni-doped HfO₂ films are probed under different visible light illumination conditions. The illumination-induced minority carriers injection effect enhances the negative shift of flat band voltage, and results in a significant enlargement of memory window. This enlargement exhibits negligible dependence on light wavelength but strong dependence on light intensity in the visible light region. A large memory window width of 6.12 V is obtained under illumination using 650 nm red light with an intensity of 5 mW cm⁻². Acceptable endurance and retention properties show potential applications on new-type photosensitive nano-floating-gate nonvolatile memory devices.

Ag nanoparticles (NPs) and a CdSe nanocrystal were successively deposited on the surface of a TiO₂ nanotube array film (CdSe/Ag/TiO₂ NTs) via microwave assisted chemical reduction and in situ fabrication methods. The nanotubular structure of TiO₂ preserves well after loading Ag and CdSe, as the ternary composite not only exhibits an excellent visible light harvesting ability but also has the smallest charge transfer resistance according to electrochemical impedance measurement. The most positive flat band potential of CdSe/Ag/TiO₂ NTs facilitates charge carrier transfer at the semiconductor-electrolyte interface. Notably, the introduction of Ag nanoparticles forms a unique carrier-transfer-channel in the CdSe/Ag/TiO₂ NTs system, in which the Ag nanoparticles can take advantage of its high carriers transfer rate as a linker. In addition, Ag serving as a surface plasmon resonance source further improves photoelectric catalytic activities of the sample. It is noteworthy that CdSe/Ag/TiO₂ NTs exhibits the desired photoelectrochemical performance with the highest H₂ production rate of 413.99 µmol cm⁻² after 2.5 h irradiation.

The effective lifetime of ozone in a cylindrical cell filled with oxygen was measured in a wide range of gas pressures and temperatures by the HgI photoabsorption method. The observed effective lifetime of ozone increased with the gas pressure from 20 to 500 Torr, reached a maximum at approximately atmospheric pressure and then decreased in inverse proportion to the gas pressure. These characteristics were investigated at temperatures of 293–423 K and good agreement was observed with theoretical results derived by diffusion equation analysis of the ozone concentration in the photoabsorption cell. From the gas pressure and temperature dependencies of the effective lifetime of ozone, the diffusion coefficient of ozone in oxygen was determined together with the reflection coefficient of ozone at the surface, which was used to derive the loss rate of ozone at the surface of the cell at low gas pressures below 200 Torr. Moreover, we also simultaneously determined the rate coefficients for the decomposition of ozone by collisions with oxygen molecules and atoms which were used to derive the loss rate of ozone in the gas phase at high gas pressures of above 200 Torr. We have revealed that the Arrhenius plots, expressing the observed rate coefficients, comprised two linear portions with different slopes that transitioned from one to the other at around 353 K. Considering that the two trends reflected the decomposition of ozone by interactions with molecular and atomic oxygen, we obtained coefficients k(O₂) and k(O) taking into account the diffusion effect of ozone molecules. We derived the rate coefficient k(O₂)  =  7.28  ×  10⁻¹⁴exp(−9300/T) (cm³ s⁻¹) as a re-evaluated value in the present paper and k(O)  =  9.52  ×  10⁻¹²exp(−2080/T) (cm³ s⁻¹) which was consistent with data compiled in the original databases.

A transferred arc system consisting of a crucible type anode and hollow cathode with gas injection is being considered for melting and evaporation of materials to improve the heat transfer efficiency. Knowledge of arc behavior inside the crucible and the effect of gas injection through the cathode on the characteristics of the arc are required to optimize the process parameters for better process efficiency. The available literature on this is very limited. A 2D steady-state axi-symmetrical mathematical model of a DC transferred arc is developed and the plasma arc created between a hollow cathode with gas injection and a crucible anode is simulated. The effects of cathode geometry and gas flow through the cathode on the arc characteristics are studied for different electrode gaps and arc currents. The effect of gas flow through the cathode on the arc voltage is clarified for various electrode gaps and arc currents. The gas flow through the cathode is strong enough to push the arc root attachment from the center of the anode and the plasma covers the entire surface of the crucible bottom at higher gas flow rates. Irrespective of the gas flow rate, arc current, and arc length, the higher arc heating efficiency is achieved when the arc root attachment starts to move away from the center of the anode/arc voltage is minimal. The characteristics of the arc inside the crucible and open arc are compared for different flow rates of the gas injected through the cathode. The present model is validated by comparing the predicted results with previously published results.

The acoustic source amplitude of low-frequency modulated spark discharges is determined experimentally. Burst and pulse-density modulation are utilized in order to generate source components at frequencies much lower than the pulse repetition frequency. Pulse sequences consist of high-voltage pulses with 10 ns duration, 9–12 kV amplitude, and pulse repetition frequencies up to 30 kHz. The source amplitude is experimentally determined by microphone measurements in an impedance tube. Spurious components in the measured pressure signals, associated with electromagnetic noise from the high-voltage discharges, are removed by appropriate data processing. The Fourier component of the electric power at the modulation frequency is determined by phase-averaged pulse energy measurements, and the relation between electric power and sound source amplitude is revealed. The effect of pulse energy, electrode gap distance, and the number of pulses per modulation period on the initialization phase, during which HV-pulses do not generate sparks, is determined. An analytical model based on sound generation by unsteady heating is employed to estimate the acoustic source amplitude from the electrical power input; good overall agreement with the measured source amplitudes is observed. The sound generated by low-frequency modulated NRP discharges in the present work, with modulation frequencies in the range of 50–1000 Hz, can be predicted well by assuming that the entire electrical power acts as unsteady heating over the relevant timescales.

All-carbon heterostructures consisting of carbon allotropes have attracted considerable attention because of their intriguing properties. However, understanding is still lacking of the interactions at the interface, as well as the connection between such interactions and their performance. Herein, we systematically explore the interfacial interaction in all-carbon penta-graphene (PG)/C₂₀ (C₆₀) heterostructures, and its effect on structural and electronic properties. Based on first-principles calculations, we report that the all-carbon PG/C₂₀ (C₆₀) heterostructures show two types of interfacial interactions: dispersive and covalent. The PG/C₂₀ van der Waals (vdWs) heterostructure is less stable than its covalent one. By contrast, the PG/C₆₀ vdWs heterostructure is the more stable. In the covalent heterostructures, either two or four C–C bonds can be formed between PG and C₂₀, whereas only two can be formed between PG and C₆₀. The near-gap electronic structures depend on the interfacial interactions, and the levels near the Fermi level are mainly composed of C₂₀ (C₆₀) states, giving rise to a small band gap of heterostructure, making them promising for visible light absorption. All the differences in these PG/C₂₀ (C₆₀) heterostructures can be well understood in terms of the different topology of fullerene. This finding indicates that all-carbon PG/fullerene heterostructures are promising candidates for photocatalysis, photodetectors, and solar energy harvesting and conversion.

We have prepared Eu²⁺ (1%) doped BaCl₂ nanopowders by using a hybrid sol-gel/thermal decomposition route using barium acetate and trichloracetic acid as in situ chlorination agent. Structural and thermal analysis data have shown that orthorhombic BaCl₂ phase crystallization occurs at 260 °C. BaCl₂:Eu²⁺ nanocrystals of about 100–200 nm in size were produced after annealing (in air) at 500 °C and they displayed Eu²⁺ d  →  f type luminescence at 396 nm. X-ray photoelectron spectroscopy indicated the presence of both Eu²⁺, Eu³⁺ ions species and a BaO passivating layer at the surface of the nanocrystals.

A polymer nanocomposite (PVP@BaCl₂:Eu²⁺) was also processed and its optical response under x-ray irradiation was found to be similar to that of the nanopowder. X-ray excited luminescence showed Eu²⁺ luminescence at 396 nm, whereas the thermoluminescence peak at 130 °C was assigned to the F(Cl)-center recombination with Eu²⁺ related hole centers.

Silicon heterojunction (SHJ) solar cells with hydrogenated microcrystalline silicon oxide (µc-SiOx:H) emitters are fabricated and studied using the open circuit voltage (V_oc) transient. The built-in electric field (E_in), minority carrier lifetime, hole mobility, and a-Si:H/c-Si heterointerface valance band offset (ΔE_v) of the solar cells can be excavated by the V_oc transient. The rising rate of the V_oc transient curve, which has not been studied in previous research, is found to be dependent on E_in in SHJ cells. The measurements of the V_oc transient curves at different excitation intensities are used as a powerful approach for analysis of the ΔE_v difference between SHJ cells with different µc-SiOx:H emitters. Based on this analysis, it is demonstrated that the origin of the S-shaped J–V characteristics of SHJ cells lies in an inferior E_in and/or severe interface ΔE_v, and the role of ΔE_v is more dominant.

Noise is a common occurrence in many structural and functional materials during plastic deformation processes. The acoustic signal is hard to obtain for traditional materials due to the one-off nature of the deformation. But for shape memory alloys, this phenomenon can be analyzed systematically during cyclic tensile experiments, owing to the shape memory effect. Acoustic emission (AE) is studied in Ni₄₆Mn₂₈Ga₂₀Co₃Cu₃ shape memory microwires with various diameters during stress-induced martensitic transformation. The microwires exhibit fully reversible strain larger than 10% and obvious serration behavior at room temperature. The AE waves obtained during tensile processing reflect the phonon softening and lattice vibration during stress-induced phase transformation. Analysis of the spectra shows that AE frequency concentrates in certain selected frequency ranges, and this result reveals the characteristic nature of collective atom movement. The correlations between the amplitude, cut-off frequency and size effect of the microwires were also analyzed, respectively. Focusing on the relationship between the acoustic properties and deformation behavior of shape memory alloys may provide a new perspective for materials science.