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The groundbreaking discovery of unconventional ferroelectricity in HfO2 opens exciting prospects for next‐generation memory devices. However, the practical implementation, particularly its epitaxial stabilization and a clearer understanding of its intrinsic ferroelectricity has been a significant challenge. The study arouses the potential importance of atomic layer deposition (ALD) for mass production in modern industries, demonstrating its proficiency in achieving epitaxial growth of ferroelectric Hf0.5Zr0.5O2 (HZO) thin films on Yttria‐stabilized zirconia (YSZ) substrates. Moreover, with distinct ferroelectric switching currents, the work reveals the ferroelectric characteristics of epitaxial HZO thin films deposited through ALD on YSZ‐buffered Si substrates, which aligns well with CMOS technology. Overall, the results pave the way for a scalable synthesis system for ferroelectric HfO2‐based materials, hinting at a bright future for low‐temperature epitaxial nanoelectronics. [ABSTRACT FROM AUTHOR]

Ferroelectric materials are promising candidates for neuromorphic computing synaptic devices due to the nonvolatile multiplicity of spontaneous polarization. To ensure a sufficient memory window, ferroelectric materials with a large coercivity are urgently required for practical applications in highly scaled multi‐bit memory devices. Herein, a remarkable reliability of intermediate ferroelectric polarization states is demonstrated in a textured Al0.66Sc0.34N thin film with a coercive field of 2.4 MV cm−1. Al0.66Sc0.34N thin films are prepared at 300 °C on Pt (111)/Ti/SiO2/Si substrates using a radio frequency reactive sputtering method. Al0.66Sc0.34N thin films exhibit viable ferroelectricity with a large remanent polarization value of >100 µC cm−2. Through the conventional current–voltage characteristics, polarization switching kinetics, and temperature dependence of coercivity, the reproducibility of multiple polarization states with apparent accuracy is attributed to a small critical volume (3.7 × 10−28 m3) and a large activation energy (3.3 × 1027 eV m−3) for nucleation of the ferroelectric domain. This study demonstrates the potential of ferroelectric Al1‐xScxN for synaptic weight elements in neural network hardware. [ABSTRACT FROM AUTHOR]

This study aimed to estimate impact loads delivered to vibro-ripper housing through link modules, together with loads transmitted in various directions. Housing vibration resulting from impact loads generated during the operating condition and frequency response functions were assessed by vibration and modal experiments, respectively. Vibration data and transfer functions were applied in a transfer path analysis (TPA) model to analyze the quantified impact loads transmitted through the key components of the vibro-ripper to its housing. Impact loads derived by TPA for different housing parts were compared with those in the tooth derived from load-cell measurements, validating the TPA method. As a result of the verification, the impact load calculated by the TPA method was 193.7 kN, whereas that from the striking force measured by the load cell was 220 kN, a difference of 12.3%. The results of this study may be important input values for numerical analysis in equipment design and can be used as key data for structural safety evaluation and optimization. In summary, this paper introduces the vibration-based TPA method and considers its applicability to construction machinery exposed to impact vibration and loads. [ABSTRACT FROM AUTHOR]

We report the effect of 60Co gamma-ray irradiation on the ferroelectric properties of metal–ferroelectric Hf0.5Zr0.5O2–metal thin film structures. The pristine Hf0.5Zr0.5O2 films showed strong radiation tolerance against gamma-rays with stable remanant polarization values. When Hf0.5Zr0.5O2 films were exposed to electric field cycling, or "wake-up" process, prior to irradiation, however, their ferroelectricity demonstrated a clear degradation of remanant polarization and coercive voltage shift of the hysteresis curves. The analysis of ferroelectric switching dynamics revealed faster polarization switching with broadening of Lorentzian distribution of characteristic switching time for higher radiation doses, which is contrary to the wake-up behavior. The relationship between the wake-up process and gamma-ray irradiation on the stability of ferroelectric Hf0.5Zr0.5O2 films was discussed in light of domain alignment and defect mechanisms, considering both the redistribution and trapping of defect charges. [ABSTRACT FROM AUTHOR]

This study suggests a method for quantitatively estimating the drilling performance of the down-the-hole (DTH) hammer during percussive drilling of rock surfaces. A pneumatic dynamic model of the DTH hammer was developed that considers the mass flow rate relations representing the orifice opening areas of the air tube, the piston, and bit flushing channels. A drill bit motion model was developed to represent the dynamics of a drill bit impacted by a dropped piston and explain the impact stress propagation and rock-crushing mechanism. The rock-crushing effect of the drill button bit was measured through a piston drop test. The pneumatic hammer model and drill bit motion model were then combined in a prediction model to determine the impact efficiency according to different rock types (i.e., soft, medium-hard, and very hard). The drilling efficiency was defined as the input value of the prediction model, which was used to simulate the drilling performance of DTH hammers considering the rock type and dynamic effect of the drill bit. Finally, the simulation results were compared with the results of in situ drilling tests for verification. [ABSTRACT FROM AUTHOR]

This paper presents a simulation model to predict the percussive drilling performance of a down-the-hole (DTH) hammer. First, the pneumatic dynamic model of the DTH hammer is developed considering mass flow rate relations representing orifice opening areas of the air tube, the piston, and the bit flushing channels. Next, the performance of the DTH hammer is numerically simulated and evaluated by considering fluctuations of the upper and lower chamber pressure, impact frequency, and force. The simulation model is validated through a series of laboratory tests. Finally, design factors influencing the hammers impact performance are selected via screening design, and the progressive quadratic response surface method then optimizes the set of design factors to propose a design modification to increasing the impact performance of the DTH hammer. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal button arrangement of a percussion drill bit and its operating condition to improve drilling efficiency. A new evaluation method is introduced for the button arrangement that utilizes the superimposed impact area, blank area, and drilling deviation moment as the quantitative indices to evaluate the impact of buttons on the rock surface. To determine the optimal button arrangement and its operating conditions, a progressive metamodel-based design optimization was conducted using the new evaluation indices as the analysis response, and then the optimal solution was determined through iteration. Consequently, all the button evaluation indices were reduced significantly and the impact areas were distributed uniformly under a specific operating condition. Additionally, the drilling performances of the optimal button arrangement were investigated according to the operating conditions to obtain the maximum drilling performance in terms of the drilling machine operation. [ABSTRACT FROM AUTHOR]