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Lithium titanate (Li4Ti5O12) is a commercial anode material used for high-power and long-lifespan lithium batteries. The key drawback of this material is its low electronic conductivity. Although doping is commonly used to solve this problem, the introduction of dopants also diminished lattice stability. In this work, we studied fast and slow laser-induced degradation processes of single Mn-doped lithium titanate particles and proposed a physicochemical model of their degradation mechanism. We suppose that the preferable route of LTO alteration is the formation of amorphous phases rather than crystalline decomposition products. Our results may be useful for not only developing a nondestructive characterization tool utilizing Raman spectroscopy but also for understanding other degradation processes, including thermal alteration and structural changes caused by the intercalation/deintercalation cycles of lithium ions.

Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment. Inspired by nature, researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate. Among many fabrication methods for stimulus-responsive structures, femtosecond laser direct writing (FsLDW) has received increasing attention because of its high precision, simplicity, true three-dimensional machining ability, and wide applicability to almost all materials. This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW. Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies, different stimulating factors that can trigger structural responses of prepared intelligent structures, such as magnetic field, light, temperature, pH, and humidity, are emphatically summarized. Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW, as well as the present obstacles and forthcoming development opportunities, are discussed. Fundamentals of femtosecond laser–matter interaction are presented. Fabrication strategies based on femtosecond laser direct writing are reviewed. Diverse stimulus-responsive structures by femtosecond laser direct writing are summarized. Functional applications of these stimulus-responsive structures are discussed.

Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict the optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. These results open the way for a better optimization of the ion energy in future laser-solid experiments.

Accurate knowledge of nonlinear optical parameters is essential for optimizing energy deposition in ultrafast laser 3D printing, yet these values remain undetermined for many commonly used materials. In this study, we address this gap by experimentally determining the two-photon absorption (TPA) and non-linear refraction coefficients ( and ) of the widely used SZ2080 resist with the photo-initiators (PI) IRG369 and BIS (Irgacure 369 and 4,4′ bis(diethylamino)-benzophenone or Michler’s ketone). Using the Z-scan method at 515 nm with a low repetition rate (1 kHz) to avoid thermal accumulation, we found that the nonlinear response of the host polymer has a considerable contribution to energy deposition despite the addition of the PI, as the host polymer makes up the majority of 99 % in the solution. The TPA cross section were 5.7 ± 0.4 GM (1 GM = 10  cm  s photon ) for pure SZ2080 ,  GM for IRG and  GM for BIS at 515 nm. The nonlinear refractive index for pure polymer was (85.3 ± 6) × 10  cm /TW, favoring a self-focusing, and was larger than that for PIs:  cm /TW (IRG369) and  cm /TW (BIS). Hence, the properties of the host material govern non-linear light propagation, although, in high numerical aperture focusing, self-focusing has a minor contribution to the variation of refractive index. Crucially, the determined TPA coefficients for pure SZ2080 provide experimental evidence that it can initiate polymerization without PIs, enabling a more sustainable and environmentally friendly fabrication route by avoiding the use of toxic additive compounds. These findings will allow for the estimation of exact energy deposition in 3D laser printing using ultrashort laser pulses and support the development of an initiator-free additive manufacturing approach.

This review proposes to summarize the development of laser shock applications in a confined regime, mainly laser shock peening, over the past 50 years since its discovery. We especially focus on the relative importance of the source term, which is directly linked to plasma pressure. Discussions are conducted regarding the experimental setups, experimental results, models and numerical simulations. Confined plasmas are described and their specific properties are compared with those of well-known plasmas. Some comprehensive keys are provided to help understand the behavior of these confined plasmas during their interaction with laser light to reach very high pressures that are fundamental for laser shock applications. Breakdown phenomena, which limit pressure generation, are also presented and discussed. A historical review was conducted on experimental data, such as pressure, temperature, and density. Available experimental setups used to characterize the plasma pressure are also discussed, and improvements in metrology developed in recent years are presented. Furthermore, analytical and numerical models based on these experiments and their improvements, are also reviewed, and the case of aluminum alloys is studied through multiple works. Finally, this review outlines necessary future improvements that expected by the laser shock community to improve the estimation of the source term.

We investigate damage inside the bulk of borosilicate glass by a single shot of IR picosecond laser pulse both experimentally and numerically. In our experiments, bulk damage of borosilicate glass with aspect ratio of about 1:10 is generated. The shape and size of the damage site are shown to correspond to an electron cloud with density of about 1020 cm−3. The underlying mechanism of electron generation by multiphoton ionization and avalanche ionization is numerically investigated. The multiphoton ionization rate and avalanche ionization rate are determined by fitting experimental results. The relative role of multiphoton ionization and avalanche ionization are numerically studied and the percentage of electron contribution from each ionization channel is determined.

We present a finite-difference integration algorithm for solution of a system of differential equations containing a diffusion equation with nonlinear terms. The approach is based on Crank–Nicolson method with predictor–corrector algorithm and provides high stability and precision. Using a specific example of short-pulse laser interaction with semiconductors, we give a detailed description of the method and apply it to the solution of the corresponding system of differential equations, one of which is a nonlinear diffusion equation. The calculated dynamics of the energy density and the number density of photoexcited free carriers upon the absorption of laser energy are presented for the irradiated thin silicon film. The energy conservation within 0.2 % has been achieved for the time step 10 8 times larger than that in case of the explicit scheme, for the chosen numerical setup. The implemented Fortran source code is available in the Supplementary Materials. We also present a few examples of successful application of the method demonstrating its benefits for the theoretical studies of laser–matter interaction problems. Finally, possible extension to 2 and 3 dimensions is discussed.

A theoretical investigation of the underlying ultrafast processes upon irradiation of rutile TiO2 of (001) and (100) surface orientation with femtosecond (fs) double pulsed lasers was performed in ablation conditions, for which, apart from mass removal, phase transformation and surface modification of the heated solid were induced. A parametric study was followed to correlate the transient carrier density and the produced lattice temperature with the laser fluence, pulse separation and the induced damage. The simulations showed that both temporal separation and crystal orientation influence the surface pattern, while both the carrier density and temperature drop gradually to a minimum value at temporal separation equal to twice the pulse separation that remain constant at long delays. Carrier dynamics, interference of the laser beam with the excited surface waves, thermal response and fluid transport at various pulse delays explained the formation of either subwavelength or suprawavelength structures. The significant role of the crystalline anisotropy is illustrated through the presentation of representative experimental results correlated with the theoretical predictions.

In the present study, we used low-field nuclear magnetic resonance (LF-NMR) measurements and mercury intrusion porosimetry (MIP) to evaluate the influence of the water–binder ( w / b ) ratio, fly ash (FA) replacement and curing regimes on the pore structure of concrete. The main advantage of LF-NMR is that it is nondestructive and suitable for large concrete samples compared with other traditional methods, such as MIP, adsorption methods and scanning electron microscopy methods. Hence, the LF-NMR relaxometry method measures the pore structures that are closer to reality. The LF-NMR relaxation time, T 2 , represents the change in the pore structure during the hydration and hardening processes of concrete. The results showed that the T 2 spectrum of the concrete sample was mainly composed of 3–5 signal peaks. Additionally, the w / b ratio, FA replacement and the curing regimes have significant effects on the T 2 spectrum, porosity, and pore size distribution of concrete. In addition, the compressive strength of concrete has a close relationship with its pore structure. Based on the LF-NMR test results, the relationship between the compressive strength and the porosity, pore size distribution of concrete was established.

When high-energy and high-power lasers interact with matter, a significant part of the incoming laser energy is transformed into transient electromagnetic pulses (EMPs) in the range of radiofrequencies and microwaves. These fields can reach high intensities and can potentially represent a significative danger for the electronic devices placed near the interaction point. Thus, the comprehension of the origin of these electromagnetic fields and of their distribution is of primary importance for the safe operation of high-power and high-energy laser facilities, but also for the possible use of these high fields in several promising applications. A recognized main source of EMPs is the target positive charging caused by the fast-electron emission due to laser–plasma interactions. The fast charging induces high neutralization currents from the conductive walls of the vacuum chamber through the target holder. However, other mechanisms related to the laser–target interaction are also capable of generating intense electromagnetic fields. Several possible sources of EMPs are discussed here and compared for high-energy and high-intensity laser–matter interactions, typical for inertial confinement fusion and laser–plasma acceleration. The possible effects on the electromagnetic field distribution within the experimental chamber, due to particle beams and plasma emitted from the target, are also described. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.