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Bulk acoustic wave (BAW) filters have been proven to be of high demand in today's low power RF front-ends for mobile communication devices. Within the launch of 5G applications worldwide, especially in the region of new radio (nr-1) up to 6 GHz, defined frequency bands require filters of wide bandwidths, while simultaneously featuring steep edges and high out-of-band rejection. Due to the coexistence with 4G LTE (long term evolution) wireless standards as well as advanced data transfer concepts such as carrier aggregation, the increasing complexity of antenna systems forces the implementation of highly selective acoustic filters. In contrast to the widely used surface acoustic wave (SAW) technology, BAW filters appear with superior performance for frequencies above 1 GHz. This work describes the fabrication of a BAW-solidly mounted resonator (BAW-SMR) with a tailored material system of a-SiOCN:H as a low impedance (low-Z) material integrated within its acoustic Bragg mirror. A direct comparison to the widely used low-Z material of SiO2 with an acoustic impedance of around 13 MRayl is demonstrated by two equal resonator stacks by replacing only the uppermost low-Z thin film of the acoustic reflector. A single-mask design was chosen with platinum as a bottom electrode to ensure the most equal growth conditions for the piezoelectric aluminum nitride (AlN) layers on both reflectors' surfaces featuring either the tailored a-SiOCN:H or standard SiO2. The a-SiOCN:H thin films were deposited by plasma-enhanced chemical vapor deposition and the according acoustic impedance was priorly depicted to 7.1 MRayl, which could be exploited to achieve an increase in the effective coupling coefficient beyond 7% as well as a resonator bandwidth of more than 60 MHz. [ABSTRACT FROM AUTHOR]

When chloroaluminate ( A l C l 4 − ) serves as the electrolyte, aluminum nitride (AlN) has shown promise as a cathode material in aluminum ion batteries. However, there is currently a lack of research on the mechanisms of charge transfer and cluster intercalation between AlCl4 and AlN cathode materials. Herein, first-principles calculations are employed to investigate the intercalation mechanism of AlCl4 within the AlN cathode. By calculating the formation energies of stage-1–5 AlN–AlCl4 intercalation compounds with the insertion of individual AlCl4 cluster, we found that the structure of the stage-4 intercalation compounds exhibits the highest stability, suggesting that when the clusters begin to intercalate, it is important to start with the formation of the stage-4 intercalation compounds. In the subsequent phases of the charging process (stages 1 and 2), the stabilized structure with four inserted clusters demonstrates two characteristics: the coexistence of standing and lying clusters and the insertion of two standing clusters in an upside-down doubly stacked configuration, which further improve the spatial utilization while maintaining the structural stability. In addition, we infer that a phenomenon of coexisting intercalation compounds with mixed stages will occur in the course of the charging and discharging processes. More importantly, the diffusion barrier of AlCl4 in AlN–AlCl4 intercalation compounds decreases with the reduction of stage number, ensuring the rate performance of batteries. Therefore, we expect that our work will contribute to comprehend the intercalation mechanism of AlCl4 into the AlN cathode materials of aluminum ion batteries, providing guidance for related experimental work. [ABSTRACT FROM AUTHOR]

Nonlinear-optical microscopy and spectroscopy provide detailed spatial and spectroscopic contrast, specifically sensitive to structural symmetry and order. Ferroics, in particular, have been widely studied using second harmonic generation imaging, which provides detailed information on domain structures but typically lacks spectroscopic detail. In contrast, infrared-visible sum-frequency generation (SFG) spectroscopy reveals details of the atomic structure and bonding via vibrational resonances, but conventionally lacks spatial information. In this work, we combine the benefits of nonlinear optical imaging and SFG spectroscopy by employing SFG spectro-microscopy using an infrared free-electron laser. In particular, we demonstrate the feasibility of SFG spectro-microscopy for spectroscopy using in-plane anisotropic wurtzite-type aluminum nitride as a model system. We find the experimental spectra to agree well with our theoretical calculations, and we show the potential of our microscope to provide spatially resolved spectroscopic information in inhomogeneous systems such as ferroics and their domains in the near future. [ABSTRACT FROM AUTHOR]

Face-to-face annealed and sputter-deposited aluminum nitride (FFA Sp-AlN) has potential in deep-ultraviolet light-emitting devices. Herein, the effects of the substrate off-cut angle (θsub) from an r-plane sapphire toward the c-axis projection direction and sputtering temperature (Tsp) on the crystallinity and surface morphology of a-plane AlN films are investigated. Increasing θsub in the minus-off direction, which occurs when the substrate surface approaches the sapphire c-plane, and lowering Tsp suppress the mixing of anomalous non-a-direction oriented domains. This reduced mixing enhances the surface flatness and crystallinity of a-plane FFA Sp-AlN. Moreover, the c-axis direction of the a-plane AlN film is inverted depending on the substrate off-cut angle. Ab initio calculations indicate that the interface stability between the r-plane sapphire substrate and the a-plane AlN film can explain the dependence of the crystallinity and c-axis orientation of FFA Sp-AlN on the surface off-cut of the r-plane sapphire. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) and aluminum nitride (AlN), as examples of third-generation semiconductors, have attracted significant interest due to their remarkable physical attributes, including a wide bandgap, high breakdown voltage, exceptional chemical stability, and high thermal conductivity. These characteristics render GaN and AlN highly promising for use in power and (opto)-electronic devices. Consequently, there is a growing demand for high-quality GaN and AlN crystals on the centimeter scale. As the dislocation density in these materials decreases, the need for a reliable method of dislocation characterization becomes more pressing. Synchrotron radiation x-ray topography (SR-XRT) has emerged as a superior, nondestructive technique for the precise characterization of crystal defects. This review briefly introduced the principle of XRT, and its application in the analysis of dislocations in GaN and AlN crystals is summarized. By examining the relationship between the SR-XRT image contrast and the Burgers vectors of dislocations, it is possible to categorize wafer dislocations and determine the magnitude and direction of Burgers vectors. Additionally, SR-XRT facilitates the analysis of interactions between dislocations in GaN and AlN crystals. These analyses are instrumental in advancing the development of superior crystals. This review concludes with a discussion of the current challenges faced by SR-XRT and a projection of its future applications in characterizing third-generation semiconductor crystal materials. This review offers significant guidance for the characterization of nitride crystal defects using SR-XRT. [ABSTRACT FROM AUTHOR]

This study demonstrates the fabrication of dense AlN-based ceramics through the flash sintering technique for the first time. Flash sintering was performed at a furnace temperature of 1500 °C with 10 wt% Y 2 O 3 as a sintering aid in a nitrogen atmosphere. The effects of the current density and holding time on the microstructure evolution and mechanical properties were investigated. The results show that the relative density, grain size, and Vickers hardness of specimens increase with increasing current density and holding time. The specimen showed the highest relative density of 98.6 % and a Vickers hardness of 12.68 GPa when a current density of 100 mA/mm2 and a holding time of 60 min were used. Additionally, the grain sizes at the positive side of the electrodes were found to be larger than those at the negative side. These findings suggest that dense AlN-based ceramics can be fabricated in a rapid and efficient way through the flash sintering technique. [ABSTRACT FROM AUTHOR]

Telecommunication of the next generation demands filters that can operate in the 10 GHz range with sufficient bandwidths. For surface-acoustic-wave (SAW) devices this prerequisite translates into high sound velocities and high piezoelectric couplings. Wurtzite AlN on diamond, which exploits the strong piezoelectricity of AlN with the very high SAW velocity of diamond, has been considered a promising platform. A significant boost (up to a factor of 4) of the piezoelectric response can be obtained by alloying AlN with Sc. Here, the main challenge lies in the synthesis of highly-oriented thin (Sc,Al)N films on diamond. In this work, we aim at establishing a platform for SAW devices using plasma-assisted molecular beam epitaxy for the deposition of Sc0.2Al0.8N on diamond. We investigate the structural properties related to SAW generation gearing towards applications at high frequencies. To this end, we prepare (Sc,Al)N thin films on polished polycrystalline diamond wafers and demonstrate the efficient generation of SAW modes with frequencies up to 8 GHz. Systematic studies of the dependence of the SAW velocity and electromechanical coupling coefficient on the Sc0.2Al0.8N film thickness is presented for various SAW modes. Our result demonstrates the potential of this material combination for future application that requires large bandwidth in the ultra-high frequency range. [ABSTRACT FROM AUTHOR]

The metal-doped aluminum nitrides have attracted special attention as new technology-related materials owing to their combination of fullerene-like and metallic properties. The structure, electronic and magnetic properties of the TM@Al 1 2 N 1 2 clusters have been investigated by using first principles. The results indicate that the V@Al 1 2 N 1 2 , Ni@Al 1 2 N 1 2 , Zr@Al 1 2 N 1 2 , Rh@Al 1 2 N 1 2 , Ta@Al 1 2 N 1 2 and Pt@Al 1 2 N 1 2 clusters display more structural stability than their neighbors. The Sc@Al 1 2 N 1 2 , V@Al 1 2 N 1 2 , Mn@Al 1 2 N 1 2 , Zn@Al 1 2 N 1 2 , Y@Al 1 2 N 1 2 , Nb@Al 1 2 N 1 2 , Tc@Al 1 2 N 1 2 , Ag@Al 1 2 N 1 2 , Lu@Al 1 2 N 1 2 , W@Al 1 2 N 1 2 and Hg@Al 1 2 N 1 2 clusters are more dynamically stable than their neighbors. The amount of charge transfer between the TM (TM=Ti, Y and Os) atoms and Al 1 2 N 1 2 clusters is the most. The maximum spin densities (3.025 | e | , 2.779 | e | and 3.231 | e |) of the TM@Al 1 2 N 1 2 clusters occur at the subgroup VIIB TM@Al 1 2 N 1 2 clusters. [ABSTRACT FROM AUTHOR]

Bismuth (Bi)‐doped glass fibers are being developed into next‐generation broadband amplifiers and tunable lasers. Yet, the well‐developed Bi‐doped fiber devices only realize silica‐based optical fibers prepared by the modified chemical vapor deposition method, which faces challenges such as low doping concentration, high cost, intricate device structure, and high preparation difficulty. Here, a novel highly Bi‐doped multicomponent phosphate glass was developed. The high ion solubility of this phosphate glass facilitates achieving a Bi doping concentration of 8 mol%. The introduction of aluminum nitride (a new reducing agent) can create a local reducing environment, further increasing the concentration of low‐valence near‐infrared (NIR) active Bi ions. Furthermore, the resulting enhanced highly Bi‐doped multicomponent phosphate glass with efficient 900–1600 nm NIR emission can be drawn into corresponding optical fibers by a rod‐in‐tube method. Broadband NIR amplified spontaneous emission with a 3 dB bandwidth of 275 nm was achieved in this new fiber. As far as we know, this is the first successful preparation of Bi‐doped multicomponent phosphate glass fiber. Our results indicate that this fiber will be a powerful alternative to Bi‐doped silica‐based fibers for the preparation of related Bi‐doped fiber devices. [ABSTRACT FROM AUTHOR]

The recent realization of ferroelectricity in scandium‐ and boron‐substituted AlN thin films has spurred tremendous research interests. Here we established a molecular dynamics simulation framework to model the ferroelectricity of AlN thin films. Through reparameterization of Vashishta potential for AlN, the coercive field strength and the AlN polarization were found to be close to experimental values. Furthermore, we examined the effects of film thickness, temperature, in‐plane strain on polarization‐electric field hysteresis loop, and the thickness‐dependent Curie temperature. Lastly, we incorporated electrodes towards atomic‐level modeling of ferroelectric device, by considering the induced charge at the interface between electrodes and ferroelectric film. We found that low dielectric contrast significantly lowers the coercive field for switching AlN. [ABSTRACT FROM AUTHOR]

Wireless local area network (WLAN) has gained widespread application as a convenient network access method, demanding higher network efficiency, stability, and responsiveness. High-performance filters are crucial components to meet these needs. Film bulk acoustic resonators (FBARs) are ideal for constructing these filters due to their high-quality factor (Q) and low loss. In conventional air-gap type FBAR, aluminum nitride (AlN) is deposited on the sacrificial layer with poor crystallinity. Additionally, FBARs with single-crystal AlN have high internal stress and complicated fabrication process. These limit the development of FBARs to higher frequencies above 5 GHz. This paper presents the design and fabrication of FBARs and filters for WLAN applications, combining the high electromechanical coupling coefficient ( K t 2 ) of Al0.8Sc0.2N film with the advantages of the thin film transfer process. An AlN seed layer and 280 nm-thick Al0.8Sc0.2N are deposited on a Si substrate via physical vapor deposition (PVD), achieving a full width at half maximum (FWHM) of 2.1°. The ultra-thin film is then transferred to another Si substrate by wafer bonding, flipping, and Si removal. Integrating conventional manufacturing processes, an FBAR with a resonant frequency reaching 5.5 GHz is fabricated, demonstrating a large effective electromechanical coupling coefficient ( k eff 2 ) of 13.8% and an excellent figure of merit (FOM) of 85. A lattice-type filter based on these FBARs is then developed for the Wi-Fi UNII-2 band, featuring a center frequency of 5.5 GHz and a −3 dB bandwidth of 306 MHz, supporting high data rates and large throughputs in WLAN applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Considering the impact of metamaterials on the magnetic coupling effect and electromagnetic response characteristics in wireless power transfer systems for implantable cardiac pacemakers, this paper proposes a wireless power transfer system operating at the 300‐kHz frequency band, enhanced by spiral ring mu‐negative materials (SR‐MNG) to improve magnetic coupling efficiency. First, based on the resonance principle, the SR‐MNG is designed, and the system's mutual inductance coupling is analyzed using the magnetic dipole coupling model theory. Second, the impact of metamaterial thickness and loss on the system's coupling strength is investigated, and the performance of the system is analyzed when using FR4, polyimide, and aluminum nitride as dielectric substrate. The system's tolerance to misalignment is discussed bearing in mind the special implantation environment of the peacemaker. The experimental results indicate that, at a transmission distance of 20 mm, the system achieves optimal magnetic coupling strength with a thickness of 1.6 mm, resulting in a minimum power transmission efficiency of 71%. Increasing the thickness to 2 mm disrupts the trend of increasing efficiency, causing it to drop by at least 23.3%. The SR‐MNG with polyimide as the dielectric plate performs exceptionally well, maintaining an efficiency range of 17.3%–73.1% for lateral displacements between 0 and 30 mm and achieving a minimum efficiency of 39.2% for angular misalignment of 15°. [ABSTRACT FROM AUTHOR]

Piezoelectric thick-film (10–100 μm) sensors are mainly manufactured using lead zirconate titanate (PZT) materials, however, their performance is limited in high-temperature environments. Therefore, this paper proposes a high-temperature aluminum nitride (AlN) thick-film accelerometer. The AlN film with a thickness of 10 μm was directly deposited on the stainless steel substrate using the reactive RF magnetron sputtering technique. Compared with the silicon-based piezoelectric accelerometer, the preparation method can improve the energy transfer efficiency of the piezoelectric layer and the fracture toughness of the cantilever beam under vibration deformation and eliminate the need for complicated photolithography, etching, and thinning while being compatible with microelectromechanical systems (MEMS) technology. The experimental results indicated that the sensitivity, resonant frequency, resolution, and thermal noise (T = 300 K) of the accelerometer were 6.73 mV/g, 1193 Hz, 0.45 mg, and 39.76 nV/ Hz , respectively. Further, the designed accelerometer had long-term (6 h) and stable sensitivity at a temperature of 600 °C, indicating its broad potential for application in high-temperature environments. [ABSTRACT FROM AUTHOR]

This study proposes a sandwich structure 1-3 piezoelectric composite, incorporating flexible silicone rubber to enhance the thickness vibration mode of piezoelectric ceramics. Rigid aluminum nitride (AlN) is employed to bolster the mechanical stability of the composite. Utilizing equivalent parameter theory, we establish a mathematical model for the sandwich structure composite material. The impact of the piezoelectric phase size and the volume fraction of AlN on several performance parameters of the material are analyzed, including the thickness electromechanical coupling coefficient, density, sound velocity, and characteristic impedance. The sandwich structure piezoelectric composite was fabricated using the "cutting and filling" technique. Experimental outcomes reveal that this material demonstrates concentrated thickness vibration modes, with a thickness electromechanical coupling coefficient reaching as high as 0.72, a 16.6 % increase compared to traditional 1-3 piezoelectric composites. Results from thermal shock tests and tensile tests suggest that the sandwich structure 1-3 piezoelectric composite has considerable potential for use in highly reliable low-frequency receiving transducers. [ABSTRACT FROM AUTHOR]

The necessity for efficient heat dissipation compels AlN packaging materials towards a thinner profile. In response to the ensuing concerns regarding the reliability of strength, the effects of the grain edge phases and grain size on flexural strength are investigated in this study. Different preparation processes, including (hot-pressed sintering, pressureless sintering, and annealing) are employed to prepare AlN ceramics with different grain edge phases and grain sizes. After classifying the morphology of the grain edge phases and fitting the Hall-Petch relationship, it is found that the grain edge phases had a more significant influence on the flexural strength. Depending on the morphology, the negative effects can be divided into three degrees. While the finer grain size proves advantageous for the flexural strength. Consequently, in the non-additive system, the flexural strength of AlN ceramic is 422 MPa, with an average grain size of 8.47 μm. For the additive-doped system, the maximum flexural strength can reach 532 MPa, which can be attributed to the limited average grain size resulting from the hot-pressed sintering process, approximately 1.32 μm. These results could potentially be employed in the microstructural design of high-strength AlN ceramics. [ABSTRACT FROM AUTHOR]

Scandium‐doped aluminium nitride (ScxAl1‐xN)has made extensive progress in its applicationfor non‐volatile ferroelectric field effect transistors (FeFETs). However, ScAlN FeFET studies have mainly focused on memory devices based on n‐ and p‐type channel. Photodetectors based on ScAlN ferroelectric gatehave rarely been reported. Here, a FeFET device consisting of a metallic channel material, SnSe, and a ferroelectric gate material, Sc0.25Al0.75N is presented. Due to the different energy levels of Sc0.25Al0.75N and SnSe, a potential barrier is formed at the interface between them, which regulates the dark current and photoresponsivity of the heterostructure; meanwhile, the interfacial potential barrier is changed under three polarization states of Sc0.25Al0.75N. As a result, dark current of the device with Sc0.25Al0.75N gate is reduced by 104, on/off ratio is increased by 40 times, and the photoresponsivity is enhanced to 1 × 104 A W−1 compared with that of SiO2 gate; Moreover, on/off ratio of the devicesunder the positively polarized state is increased by nearly 103 underillumination; under the negatively polarized state, photoresponsivity reaches 5.4 × 105 and 3.1 × 104 A W−1 under illumination. This work demonstrates the feasibility of Sc0.25Al0.75N applied in FeFET photodetectors and opens up the possibility of developing ScAlN‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

To address metallurgical waste residue pollution, this study utilized copper slag tailings (CST) and waste glass (WG) as primary raw materials, with secondary aluminum dross (SAD) as a pore-forming agent, to produce lightweight spontaneous foam glass-ceramics. The effects of raw material ratios, sintering temperature (1120–1160 °C), and sintering time (0–40 min) on foam glass-ceramics properties were investigated, elucidating the correlations between various properties. Under optimal preparation conditions (CST: WG: SAD = 7:11:2, sintered at 1150 °C for 20 min), the foam glass-ceramics exhibited a bulk density of 0.41 g/m³, compressive strength of 2.32 MPa, open porosity of 61.02 %, 2-h water absorption of 83.76 %, and mean pore size of 3.12 mm. The sintering process transformed raw materials into substances like diopside subsilic ferrian, which enhanced the strength of lightweight foam glass-ceramics. Harmful substances in the raw materials can be immobilized within the internal structure of foam glass-ceramics, ensuring excellent environmental safety. Additionally, comprehensive characterization was conducted on the foam glass-ceramics, elucidating their composition, structure, and pore-forming mechanisms. [ABSTRACT FROM AUTHOR]

In this study, we employed radio frequency magnetron sputtering technology with pure gallium to deposit high-quality GaN thin films onto glass substrates. The deposition process was fine-tuned to optimize the GaN crystal quality. To further enhance the crystal quality of the GaN films grown on glass substrates, we introduced an AlN buffer layer which was also sputter deposited in the same chamber. For the reactive sputtering process, we utilized pure 6 N nitrogen as the working gas, and the thin-film deposition temperature was maintained at 600 °C. Comprehensive investigations were conducted on the GaN thin films to assess their chemical composition, structural properties, optoelectronic characteristics, and morphology. X-ray diffraction measurements of the GaN thin films revealed a crystalline phase of GaN (002) with a 2θ angle of approximately 34.2° and a full width at half maximum of 0.85°. Low-temperature photoluminescence spectroscopy unveiled a band-edge emission at 3.36 eV (369 nm) in the low-temperature photoluminescence spectrum. Our research findings conclusively demonstrate the suitability of radio-frequency magnetron sputtering for depositing high-quality GaN thin films on glass substrates. These GaN films exhibit significant potential for applications in several optoelectronic devices. [ABSTRACT FROM AUTHOR]

Gate dielectrics for gallium nitride (GaN) high electron mobility transistor (HEMT) technology have always been challenging because of the nonideal semiconductor–dielectric interface, which leads to electronic traps. Plasma‐enhanced chemical vapor deposition and atomic layer deposition are standard techniques, but they require surface treatment and post‐annealing to control these traps. This article explores metal organic chemical vapor deposition‐grown in situ aluminum nitride (AlN) as a gate dielectric. The interface is expected to be pristine as there is no change in the chamber environment. A thin (10 nm) AlN layer is deposited at a low temperature to minimize strain and prevent the formation of an unwanted conductive channel within the device. The electrical and structural properties of this AlN‐capped HEMT are compared to a standard GaN‐capped HEMT, including temperature‐dependent studies. The results show that the AlN‐capped HEMT retains a higher charge in the channel while having an order of magnitude lower gate leakage than the GaN‐capped sample. Furthermore, the AlN‐capped HEMT performs similarly to the GaN‐capped HEMT in terms of temperature‐dependent leakage, dynamic on‐resistance, and temperature coefficient of resistance. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) possesses a high critical electric field, allowing for thinner drift regions and lower resistances compared with current materials used for power semiconductor devices. However, high activation energies of impurity dopants like magnesium or silicon and high contact resistances impede the application of AlN for typical device concepts such as TrenchFET. This article aims to develop and investigate novel vertical device structures using an AlN drift region. To evade the aforementioned issues, polarization‐induced doping is applied to generate an effective charge concentration and to accomplish less resistive ohmic contacts. [ABSTRACT FROM AUTHOR]

This article presents the effect of aluminium nitride (AlN) epilayer (EPL) growth rate on the growth of semipolar (11–22) InGaN/GaN light emitting diode (LED). Three samples are grown with different AlN EPL growth rates, which are low (L1, 1.0 nm s−1), intermediate (L2, 1.3 nm s−1), and high (L3, 1.6 nm s−1) growth rate. The root‐mean‐square (RMS) and peak‐to‐valley roughness show an increasing trend with the increasing AlN EPL growth rate which is attributed to an increment in indium composition as justified by the photoluminescence results. The sample with AlN EPL growth rate of 1.3 nm s−1 (L2) exhibits an outstanding crystal quality in terms of defect densities reduction, with a minimum basal stacking fault density of 1.60 × 104 cm−1 as calculated. Besides that, the obvious fringes of InGaN/GaN peaks observed in 2θ−ω scan proves that a high abruptness multi‐quantum well is attained. Sample L2 also shows a single peak profile in both photoluminescence and electroluminescence spectra with green wavelength emission of 506 and 537 nm, respectively, indicating a homogeneous indium composition. As the injection current is swept from 5 to 40 mA for sample L2, a weak blueshift of ≈6 nm is observed which indicates a reduction in quantum‐confined Stark effect (QCSE). [ABSTRACT FROM AUTHOR]

Large‐diameter, single‐crystalline aluminum nitride (AlN) substrates are sought for growth of AlGaN‐based devices. A combination of high crystalline perfection and optical transparency is desired for UV‐C emitter applications. A mapping analysis of 2‐in. AlN substrates grown by physical vapor transport is performed to study the within‐wafer uniformity of structural and optical properties. Substrates with spatially uniform crystalline perfection and UV‐C absorption coefficients, as determined by typical X‐ray rocking curve widths below 15 arcsec and 4.68 eV absorption coefficients below 20 cm−1, are shown. These findings demonstrate a robust mass production process for high‐quality, 2 in. AlN substrates possessing uniform structural and UV optical properties, making them highly suited for growth of next‐generation, AlGaN‐based devices. [ABSTRACT FROM AUTHOR]

It is expected that two-dimensional (2D) metal nitrides (MNs) consisting of the 13th group elements of the periodic table and nitrogen, namely aluminium nitride (AlN), gallium nitride (GaN), indium nitride (InN) and thallium nitride (TlN), have enhanced physical and mechanical properties due to the honeycomb, graphene-like atomic arrangement characteristic of these compounds. The basis for the correct design and improved performance of nanodevices and complex structures based on 2D MNs from the 13th group is an understanding of the mechanical response of their components. In this context, a comparative study to determine the elastic properties of metal nitride nanosheets was carried out making use of the nanoscale continuum modelling (or molecular structural mechanics) method. The differences in the elastic properties (surface shear and Young's moduli and Poisson's ratio) found for the 2D 13th group MNs are attributed to the bond length of the respective hexagonal lattice of their diatomic nanostructure. The outcomes obtained contribute to a benchmark in the evaluation of the mechanical properties of AlN, GaN, InN and TlN monolayers using analytical and numerical approaches. [ABSTRACT FROM AUTHOR]

High‐resolution, low‐excitation photoluminescence (PL) spectroscopy is performed for unintentionally doped, silicon‐doped, and magnesium‐doped homoepitaxial aluminum nitride (AlN) films, using a wavelength‐tunable high‐repetition‐rate laser. The wavelength‐tunable laser is used to distinguish between the luminescence and scattering signals from AlN. Providing the high‐resolution, low‐excitation PL spectra, the current understanding of the deep‐ultraviolet luminescence properties of AlN is reviewed and potential assignments for the unknown luminescence lines and bands are discussed. Although previous studies have led to a consensus on the origins of some emission peaks and bands such as the neutral silicon donor‐bound exciton transition and free exciton transitions involving longitudinal optical phonons, it is shown that many of the emission peaks are still unidentified. The origins of all the emission peaks should be elucidated to enable control of the electronic and optoelectronic properties of AlN. [ABSTRACT FROM AUTHOR]

This study presents an innovative method for the synthesis of indium aluminum nitride (InAlN) layers by direct current (DC) co-sputtering at room temperature, with the aim of reducing production costs of optoelectronic devices. Indium and aluminum targets are used, varying the power applied to the aluminum target. The results show that increasing the target power favors the formation of aluminum nitride (AlN), which modifies the chemical composition of the material. The layers obtained present smooth surfaces with a roughness of less than 3 nm, which is beneficial for applications requiring interfaces with low defect density. Regarding the optical properties, it is observed that the optical bandgap varies between 1.8 eV and 2.0 eV, increasing with the target power. Hall effect measurements indicate a decrease in the free carrier concentration and an increase in the resistivity with increasing power. This approach allows for the synthesis of InAlN with properties suitable for optoelectronic applications, solar cells, photocatalysis, and photoelectrocatalysis at low cost. [ABSTRACT FROM AUTHOR]

High‐aluminum advanced high‐strength steels have received increasing interest due to their excellent combination of strength and ductility. The control of nonmetallic inclusions in steel is among the most important issue for the production of high‐aluminum steel. This study proposes a model for the evolution of size distributions of AlN inclusions during solidification of steel based on the Kampmann–Wagner numerical model and microsegregation calculation. Both homogeneous (pure AlN) and heterogeneous precipitations (AlN+oxide or MnS) are described using homogeneous nucleation and free growth models of Greer et al. respectively. The model is applied to calculate the size distributions of AlN in high‐Al (up to 5%) Fe–Cr–Al steels and high‐ and medium‐manganese steels and validated by the experimental data in the literature. The model correctly describes the influence of cooling rates on the precipitation of AlN in Fe–Cr–Al steels and high‐manganese steels, and the sizes of AlN are reduced and the number densities of AlN inclusions are increased by increasing the cooling rate. The effects of nitrogen and aluminum concentration in medium‐manganese steel on inclusion precipitation are investigated by the model calculation. The increases in nitrogen and aluminum concentration facilitate the homogeneous precipitation of AlN inclusions. [ABSTRACT FROM AUTHOR]

Purpose: The present paper aims to study the influence of the substrate system on the thermomechanical response of various lead-free die attach materials used in power electronics using nonlinear finite element simulations. Design/methodology/approach: Particularly, three ceramic substrate systems, including direct copper bonded (DCB) and aluminum nitride (AlN) – as well as silicon nitride (Si3N4) –based insulated metal substrate (IMS) configurations are examined in this study. Additionally, three die attach systems, namely, silver-tin transient liquid phase (TLP), sintered silver (Ag) and sintered copper (Cu) are included in the analysis. ANSYS software is employed to build the finite element models of the power modules and to conduct the nonlinear thermomechanical investigations. Findings: The simulation results revealed that the IMS, Si3N4 and DCB-based power modules end up with significantly lower interconnect inelastic strains and inelastic strain energies suggesting better fatigue life performance. Additionally, the bonding layer stresses and expected failure mechanism are not influenced by the substrate configuration rather than the bond material. For instance, the silver-tin TLP joints develop high stresses and hence brittle failures are expected. Nonetheless, the sintered Ag and sintered Cu have significantly lower stresses which could lead to fatigue-induced failures. Originality/value: Power electronics use various ceramic-based substrate systems because of their improved thermal conductivity, electrical insulation and heat resistance properties. The proper selection of the substrate structure could highly enhance the thermal fatigue of the power modules. Markedly, the findings of this research are useful for designing highly reliable and effective power modules continuously subjected to thermomechanical loadings. [ABSTRACT FROM AUTHOR]

The major purpose of this study is to analyze the resistance of honeycomb ceramic matrix composites to penetration and to explore the effect of the performance characteristics of the filler materials on this capability. We used alumina ceramics, polyurea, quartz sand powder, and boron carbide powder to manufacture composite materials, and conducted impact tests and numerical simulations on them. The simulation results of Abaqus were found to be very consistent with the test results. The results demonstrate that the polyurea coating and filler materials may effectively improve the anti-penetration penetration performance of the composites, and different filler materials have varying energy absorption effects. Extended research on composites was carried out utilizing experimentally validated numerical models with filler materials comprising silicon carbide, aluminum nitride, and silicon nitride. After a comparative analysis of the simulation results of different composites, compared to quartz sand composites, the energy absorption efficiency of boron carbide composites increased by 12.03 %, silicon carbide composites increased by 14.63 %, aluminum nitride composites increased by 15.16 %, and silicon nitride composites increased by 18.29 %. Among the relevant materials in this study, there exists an optimal value of the stress wave impedance difference between the matrix material and the filler material. Honeycomb ceramic matrix composites with an ideal combination of stress wave impedance differences can considerably increase the anti-penetration efficiency of the composites. [ABSTRACT FROM AUTHOR]

A demand of power module devices has been increasing for highly energy efficient social system. The insulated heat sink printed circuit board is the key component of power module devices, which is composed of copper and aluminum nitride (AlN) due to high thermal conductivity. The conventional method of the joining between copper and AlN is active metal brazing method, but there is an issue that the high heat treatment of this method generates thermal residual stress on the board and decrease the reliability. For that reason, the development of a direct bonding process between copper and AlN has been demanded. Therefore, we focused on the laser metal deposition (LMD) method, which is a selective heating and microfabrication process. The LMD method is a method in which a powder material is supplied to the processing point and irradiated with a laser to melt the powder and form layer on the surface of the substrate. Then, a blue diode laser with a wavelength of 450 nm, which has a high absorptivity of 60% for copper, is used as a heat source. In addition, the multibeam type LMD system has been installed for the uniform heating of powder. In this study, the laser power density, laser scanning speed, and powder feeding rate were changed to explore the conditions for forming a copper layer on the AlN substrate. [ABSTRACT FROM AUTHOR]

The rapid development of lithium battery technology is leading to the increasing miniaturization of electronic devices, thereby elevating the demand for dielectric materials with exceptionally high thermal conductivity and dielectric properties. In this study, the composites were fabricated by integrating multilayer core‐shell hybrid structure particles into silicone rubber (SR). These particles were created by attaching the conductive polymer polypyrrole (PPy) and the silane coupling agent (KH570) onto the surface of highly thermally conductive ceramic particles aluminum nitride (AlN). The combination of PPy and KH570 serves to enhance the interfacial compatibility between AlN and SR, thereby concurrently enhancing the thermal conductivity and dielectric properties of the composites. The experimental results demonstrated that the thermal conductivity of the 50 phr AlN‐PPy‐KH570/SR composite was 0.37 W/(m · K), 1.65 times higher than that of pure SR (0.23 W/(m · K)). Additionally, the dielectric constant of the composite increased to 4.59, 1.32 times that of pure SR (3.48). Moreover, the thermal decomposition temperature of the composite was elevated to 475°C. The synthesized SR composites hold promise for widespread use in miniaturized electronic devices operating in high‐frequency and high‐temperature environments. [ABSTRACT FROM AUTHOR]

Piezoelectric micromachined ultrasonic transducers (PMUTs) have been widely applied in distance sensing applications. However, the rapid movement of miniature robots in complex environments necessitates higher ranging capabilities from sensors, making the enhancement of PMUT sensing distance critically important. In this paper, a scandium-doped aluminum nitride (ScAlN) PMUT based on a flexurally suspended membrane is proposed. Unlike the traditional fully clamped design, the PMUT incorporates a partially clamped membrane, thereby extending the vibration displacement and enhancing the output sound pressure. Experimental results demonstrate that at a resonant frequency of 78 kHz, a single PMUT generates a sound pressure level (SPL) of 112.2 dB at a distance of 10 mm and achieves a high receiving sensitivity of 12.3 mV/Pa. Distance testing reveals that a single PMUT equipped with a horn can achieve a record-breaking distance sensing range of 11.2 m when used alongside a device capable of simultaneously transmitting and receiving ultrasound signals. This achievement is significant for miniaturized and integrated applications that utilize ultrasound for long-range target detection. [ABSTRACT FROM AUTHOR]

In recent years, the exponential growth of the machining industry and its needs has driven the development of new manufacturing technologies, more advanced cutting tool types, and new types of coatings to extend tool lifespan. New coating solutions have been studied and implemented for machining tools, which provide a low friction coefficient and lubrication, thus increasing tool lifespan. Following this line of reasoning, it is relevant to develop scientific work aimed at studying the behavior of cutting tools coated with thin films that promote low friction and high lubrication, as is the case with DLC (diamond-like carbon) coatings. These coatings promote good resistance to oxidation and allow high machining speeds, properties also exhibited by TiAlN (titanium aluminum nitride) coatings. In fact, there is a gap in the literature studying the performance of cemented carbide tools provided with multilayered coatings in milling operations of Cu–Be alloys, commonly used in inserts of plastic injection molds. This study's objective was to investigate the effect of a multilayer coating (TiAlN/DLC) on end-milling tools to analyze their cutting performance when milling a Cu–Be alloy known commercially as AMPCOLOY®83. The quality of the machined surface was evaluated, and the wear of the cutting tool was studied. A comparative analysis of milling parameters with respect to their effect on the condition of the surface after machining and the resulting wear on the tools, using coated and uncoated tools and different machining parameters, allowed us to verify a better quality of the machined surface and wear quantified in approximately half when used coated tools. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN)‐based semiconductor laser diodes (LDs) have garnered significant attention due to their promising applications. However, high‐power LDs face serious degradation issues that limit their practical use. This study investigates the degradation factors of 437 nm and 6.3 W LDs by comparing light–current–voltage (L–I–V) characteristics, transmission electron microscopy (TEM), cathodoluminescence (CL), and secondary ion mass spectroscopy (SIMS) before and after 1000‐h aging. The diffusion of mirror coating from the resonant cavity surface is identified as a key factor contributing to high‐power LD degradation, which has not been reported in milliwatt‐level LDs. Meanwhile, the mechanisms behind the LD degradation are profiled and summarized together with the diffusion and other factors. On basis of the mechanism exploration, an anti‐aging technology for high‐power GaN‐based LDs is developed by using aluminum nitride for passivation layer and sapphire materials for mirror film. This anti‐aging technology has been verified, and a nearly ten‐time degradation suppression is achieved from 1000 h. This study elucidates the degradation mechanisms of high‐power GaN LDs and provides an effective technology to extend their lifespan, thereby prompting the practical applications of high‐power LDs. [ABSTRACT FROM AUTHOR]

Thermal shock resistance and mechanical reliability of aluminum nitride (AlN) ceramic substrates are essential in electronic device modules. In this study, the thermal shock behavior of AlN doped with aluminum - yttrium oxide (Al - Y 2 O 3) was explored. The results indicate that adding Al to AlN ceramics increases its flexural strength, thermal conductivity, and thermal expansion coefficient. The microcracks caused by thermal mismatch between the AlN matrix and the secondary phases relieved internal stress, thereby improving thermal shock resistance of AlN ceramics. Furthermore, the addition of Al isolates and homogenizes the secondary phases, resulting in a more uniform microstructure and strengthened grain boundaries, which enhance the flexural strength, Weibull modulus, and thermal shock resistance. After introducing 0.5 wt% Al, the Weibull modulus of AlN ceramics increased by 73.37 %, and their critical thermal shock temperature difference exceeded 800 °C, with a maximum residual strength of 488.01 ± 48.26 MPa at 600 °C. Overall, an appropriate amount of Al improves the reliability and thermal shock resistance of AlN ceramics. [ABSTRACT FROM AUTHOR]

AbstractThe single source precursor tris(N,N,N’,N’-tetramethylethylenediamine)Al(III)Cl3 has been synthesized by the reaction of N,N,N’,N’-tetramethylethylenediamine (TMEDA) with AlCl3 in 3:1 molar ratio in ethanol. The precursor is stable for long periods of time and cleanly generated aluminum nitride upon pyrolysis. The pyrolysis process was optimized by varying parameters such as temperature, pressure, and the flow rate of gases (N2 and Ar). Thin films of AlN were prepared by spin coating the precursor onto Si(100) and quartz substrates followed by pyrolysis under optimized CVD conditions obtained from bulk pyrolysis. Pyrolyzed powders and films were characterized with a variety of techniques. X-ray diffraction (XRD) showed 8.5 nm grain size with a dominant 220 orientation. UV-Vis spectroscopy indicated a band gap for the AlN films of ∼5.7 eV, which is close to bulk AlN (6.1 eV). FESEM showed a smooth and homogeneous film surface and EDAX showed a 1.4:1 ratio of Al:N, respectively. [ABSTRACT FROM AUTHOR]

Conventional aluminum nitride (AlN) ceramics exhibited insufficient mechanical properties expected from their potential applications in the presence of dynamic loads and intensive stresses caused by thermal shock. In this study, the mechanical properties of AlN ceramics were enhanced by toughening them using AlN whiskers (AlNw) via gel casting followed by low‐temperature sintering at 1650°C. The addition of AlNw simultaneously increased the bending strength, toughness and thermal conductivity of the AlN ceramics. The maximum values of the bending strength, toughness, and thermal conductivity of 9.0 wt% AlNw/AlN were 303.92 MPa, 3.92 MPa·m1/2 and 186.53 W·m−1·K−1, respectively, which were higher than those of the AlN ceramics by 39.93%, 61.31% and, 15.61%, respectively. The AlNw in AlNw/AlN ceramics tightly bonded with the ceramic matrix, leading to two characteristic toughening mechanisms in the ceramics: crack pinning and deflection at irregular grain boundaries caused by doped whiskers, as well as bridging and stress relaxation caused by whiskers incorporated with the grains. Moreover, the one‐dimensional morphology of AlNw can provide a channel for quick photon transport, thereby enhancing the thermal conductivity of AlNw/AlN. [ABSTRACT FROM AUTHOR]

Physical unclonable function (PUF) has emerged as a unique physical'fingerprint' that is inherently difficult to replicate. It shows tremendous application value in various hardware security areas such as identity authentication, chip anticounterfeiting, communication encryption, blockchain, etc. However, with the rapid development of 3D nanoprinting, classical PUFs constructed with disordered micro‐nanostructures face tremendous threats from physical cloning attacks. Herein, this study proposes and demonstrates the utilization of room‐temperature single‐photon emitters derived from atomic defects in randomly distributed pyramidal aluminum nitride (AlN) nanocrystals as a novel quantum PUF to resist physical cloning attacks. The fabrication of this quantum PUF on silicon (Si) wafers enables seamless integration with silicon photonic integrated circuits. The multidimensional fingerprint features of the single‐photon emitters are highly sensitive to the lattice parameters of the uneven AlN nanocrystals. Furthermore, each single photon emitter can work as a quantum random number generator to ensure the fundamental unpredictability of PUFs. The subatomic precision requirement coupled with unpredictable quantum emission behavior makes it practically impossible to attack the proposed quantum PUF, providing a promising solution for information security in the post‐quantum era. [ABSTRACT FROM AUTHOR]

Over the past few years, more studies have been conducted on the use of photonic crystals (PCs) in the detection field. Particularly fascinating for use as gas sensors are these materials’ outstanding spectrum sensitivity and small design. Using one-dimensional PCs as the theoretical foundation, this work aims to develop and analyze a nanoscale system that can identify the concentration of gases in ambient air and differentiate it from contaminated air. The intended structure is composed of layers of gallium nitride (GaN) and aluminum nitride (AlN) that alternate. In between these layers is a defective layer cavity that is filled with polluted air, which has a refractive index that is quite similar to pure air. The transfer matrix method (TMM) was used to perform numerical results for the proposed sensor. This sensor achieves average sensitivity of 1791 nm/RIU, average quality factor and figure of merit (FoM) of 1833 and 2287, respectively. We therefore think that the suggested detector’s design offers a strong candidate for accurate and efficient detection. [ABSTRACT FROM AUTHOR]

The electronic, optical, and photocatalytic features of a newly proposed 2D material-based van der Waals heterobilayer, formed by vertically stacking monolayered SiS and AlN, have been investigated. The feasibility of utilizing this heterojunction as a potential photocatalyst for spontaneous water decomposition has been predicted by using the ab initio calculations. The findings reveal that the SiS@AlN heterobilayer can be stacked in four different patterns, resulting in a direct band gap ranging from 2.11 to 2.70 eV, as determined by HSE-06 calculations. The SiS@AlN composites exhibit appropriate band-edge locations for the oxidation and reduction reactions of water splitting. Moreover, the photocatalytic activity of SiS@AlN composites is significantly influenced by the electrolyte's pH. At equilibrium, the composite displays a direct Z-scheme band alignment, which facilitates the effective spatial separation of photo-excited charges and extends their lifetimes. Additionally, a significant built-in electric field is generated at the composite interface, further preventing the recombination of photo-excited electron-hole pairs. Furthermore, the hetero-bilayers exhibit better absorption of sunlight in both the visible and ultraviolet regions compared to individual 2D-SiS and 2D-AlN. These findings highlight the potential of the SiS@AlN hetero-bilayer for applications in solar water decomposition and optical device technologies. [Display omitted] • The SiS@AlN vdW heterostructures possess a direct bandgaps. • The SiS@AlN heterojunction equipped with direct Z-scheme type. • Exhibiting outstanding optical absorption ability in the visible and UV regions. • The SiS@AlN vdW heterostructures show overall water-splitting capability. • The photocatalytic performance of SiS@AlN heterobilayer is affected by the pH of water. [ABSTRACT FROM AUTHOR]

Transition metal nitride (TMN) films hold great promise in temperature sensing due to their excellent stability, but the decreased sensitivity with increasing temperature has limited their adaptability to various temperature scenarios. In this paper, a method for regulating the high-sensitivity temperature range (HSTR) of the temperature sensors based on the zirconium aluminum nitride (Zr1−xAlxN) films by adjusting the Al content is proposed. According to the resistance–temperature (R–T) curves from 4.2 to 300 K, the metal-to-semiconductor transition was observed when Al atoms were doped in ZrN. Moreover, the semiconductor R–T curve gradually shifts to 300 K and then backs to cryogenics by continuously increasing the Al content in Zr1−xAlxN. Interestingly, the phase transition from cubic (c)-ZrN to cubic (c)-Zr1−xAlxN, then to the mixed phases of c-Zr1−xAlxN and wurtzite aluminum nitride (w-AlN), and, finally, to the hexagonal close packed-zirconium (α-Zr) precipitation was observed with increasing Al content, which shows high consistency with R–T characteristics. Moreover, the bandgap energy initially increases and then decreases, which matches well with the phase and electrical transitions. Based on the experimental results, we build a physical model that can clarify the above phase and electrical transition when the Al content in Zr1−xAlxN films changes, proposing that the effect of Al content on the phase and electrical characteristics can realize the control of the HSTR of Zr1−xAlxN films. These findings suggest ideas for developing temperature sensors based on TMN films with high sensitivity across a wide temperature range. [ABSTRACT FROM AUTHOR]

Due to the characteristics of hard brittleness and strengthening inertia, the high-efficiency and ultra-precision machining of the third generation semiconductor materials has become an urgent problem, with low processing efficiency and poor surface quality. The aggregate fixed-abrasive (FA) lapping pad was used to lap polycrystalline aluminum nitride (AlN) substrates, which provided practical experience for efficient precision machining of hard and brittle semiconductor substrates. The results indicated that: the effect of aggregate particle initial size and applied load on MRR and Ra during rough lapping and fine lapping were most significant. In the rough and fine lapping stage, W5-7 and W3-5 Al-Si binder aggregate diamond lapping pads were adopted, respectively, with an applied load of 2.0 psi. The optimized process can reduce the Ra value of the AlN blank to <70 nm within 1 h. [ABSTRACT FROM AUTHOR]

Recently, optical simulation has attracted more attention in different thin film applications. Each layer's thickness and refractive index are the most essential simulation parameters. This paper discusses and fits the refractive index of aluminum nitride at different geometrical and physical conditions over a wide wavelength range for optical simulations. This study simplifies the use of aluminum nitride in thin film-simulated applications and devices. Plotted curves and fitted equations with MATLAB scripts for aluminum nitride refractive indices at different conditions will be provided to minimize modeling errors. [ABSTRACT FROM AUTHOR]

The natural fiber nanocomposite materials employed in this study, which included sappanwood (SW), polyvinyl alcohol (PVA), polyethylene (PE), aluminum nitride (AlN), and epoxy resin (EP), were made by hand lay-up processes. Acryl Silane Coupling Agent (ASCA) was employed in the deep-dip coating method to enhance the tribology and microstructure of the natural fiber nano composite materials. For composite materials made of sappanwood and polyethylene, the resin microstructure was largely responsible for the observed homogeneous phase and hexagonal structure. The solid outer and secondary phases of the outer and inner surface layers of the EP-PE-SW-AlN composite materials were created using the silane coating process. Tensile properties of EP-PVA-SW-PE-AlN samples were reached at 42.8 MPa, and three-point bending tests were reached at 47.6 MPa. Furthermore, 597 °C was obtained for EP-PVA-SW-PE-AlN composite materials on TGA results. The average hardness value of (60) EP combined (10%) PVA, (10%) SW, (10%) PE, and (10%) AlN nano particle was highly present 98 (shore-D) throughout the silane coating process. Wear resistance and friction tests were performed on EP-PVA-SW-AlN, EP-PE-SW-AlN, and EP-PVA-SW-PE-AlN composite materials in order to improve the outer surface layers and interior composite structure. Dimples, micro voids, microscopic holes, and basket voids were seen on the fracture surfaces of each composite sample. [ABSTRACT FROM AUTHOR]

Metasurfaces have the capability to boost the generation of distinct colors by improving the interaction between surface materials and photons. We present a straightforward and polarization-tunable aluminum nitride metasurface. This metasurface enables the display and concealment of the composition pattern and exhibits color switching by modifying the polarization state of the incident light. We further explore the impact of different substrates on metasurface performance. The results indicate that the full width at half maximum of the reflectance curves increases with the increase of the refractive index between the nanostructures and the substrate material, which leads to a broader dispersion of the structural colors in the spectrum. Moreover, the sizes of the nanostructures can be gradually reduced for the substrate with a high refractive index. These findings not only offer polarization-tunable structural color metasurfaces but also provide essential insights in selecting nanostructure and substrate materials, which will help in the design of nanostructures for such metasurfaces. [ABSTRACT FROM AUTHOR]

This review explores the processes involved in enhancing AlN film quality through various magnetron sputtering techniques, crucial for optimizing performance and expanding their application scope. It presents recent advancements in growing AlN thin films via magnetron sputtering, elucidating the mechanisms of AlN growth and navigating the complexities of thin-film fabrication. Emphasis is placed on different sputtering methods such as DC, RF, pulsed DC, and high-power impulse DC, highlighting how tailored sputtering conditions enhance film characteristics in each method. Additionally, the review discusses recent research findings showcasing the dynamic potential of these techniques. The practical applications of AlN thin films, including wave resonators, energy harvesting devices, and thermal management solutions, are outlined, demonstrating their relevance in addressing real-world engineering challenges. [ABSTRACT FROM AUTHOR]

This research proposes a complete analysis of the use of physical vapour deposition coated dies in the sheet metal forming process for high‐strength‐steel sheets. The goal of the proposed approach is to investigate how PVD coatings affect die performance and how that affects the formability and quality of the high‐strength‐steel‐sheets that are made. The finite element analyses are used to simulate and evaluate the mechanical behaviour and deformation characteristics during the forming process. Studies to enhance the forming characteristics of these materials, typically denoted by limiting draw ratio and maximum punch force are required. A reduction in punch force required and improved limiting draw ratio is observed that is attributed to the enhanced contact with friction‐conditions in the die‐sheet interfaces. The experimental results are compared with simulation results from DD3IMP, a code used for deep drawing simulations, and it is evident that the experimental outcomes are analysed well with the simulation results. [ABSTRACT FROM AUTHOR]

A comprehensive review of the application of different ceramics for MEMS devices is presented. Main ceramics materials used for MEMS systems and devices including alumina, zirconia, aluminum Nitride, Silicon Nitride, and LTCC are introduced. Conventional and new methods of fabricating each material are explained based on the literature, along with the advantages of the new approaches, mainly additive manufacturing, i.e., 3D-printing technologies. Various manufacturing processes with relevant sub-techniques are detailed and the ones that are more suitable to have an application for MEMS devices are highlighted with their properties. In the main body of this paper, each material with its application for MEMS is categorized and explained. The majority of works are within three main classifications, including the following: (i) using ceramics as a substrate for MEMS devices to be mounted or fabricated on top of it; (ii) ceramics are a part of the materials used for an MEMS device or a monolithic fabrication of MEMS and ceramics; and finally, (iii) using ceramics as packaging solution for MEMS devices. We elaborate on how ceramics may be superior substitutes over other materials when delicate MEMS-based systems need to be assembled or packaged by a simpler fabrication process as well as their advantages when they need to operate in harsh environments. [ABSTRACT FROM AUTHOR]

14C, a radionuclide, which is widely used in all works of life, such as medical research and determination of PM2.5, has been realized autonomous production in China. It relied on imports, which was expensive and unstable supply in the past time. At present, Qinshan Nuclear Power has started 14C production to completely solve the problem of the serious shortage of 14C independent supply in China. Aluminum nitride powder is the main raw material for the preparation of 14C, whose elemental aluminum directly affects the safety and quality of 14C isotopic targets in nuclear reactors. Aluminum nitride is very stable in an inert high temperature environment. But a lot of elemental aluminum will react with water producing hydrogen in a high temperature environment which can result in the expansion of component rods or it will react with cladding tubes producing hydrogen embrittling effect, and these can affect the quality of 14C isotopic target. According to the characteristic of aluminum nitride insoluble in acid, this study researched different dissolution effect of elemental aluminum in aluminum nitride nano-powder by nitric acid, hydrochloric acid and sulfuric acid. It was found that the above mentioned acid can only dissolve a small amount of aluminum nitride powder, and there was a small amount of aluminum nitride powder suspending in solution, which would seriously interfere the determination of elemental aluminum. At present, microwave digestion, laser ablation, X-ray fluorescence and other methods are used to dissolve or determinate aluminum nitride, but they are not suitable for the determination of elemental aluminum. The determination of elemental aluminum is generally used in pharmaceutical, soil, tea and other samples, but most of the aluminum in the above samples exists as an impurity element, or aluminum is combined with organic matter, which is easy to separate from elemental aluminum. However, it is difficult to achieve complete separation of elemental aluminum(unbound elemental aluminum) and the aluminum nitride matrix in the aluminum nitride powder. This study used replacement reaction to selectively dissolve elemental aluminum. Then the suspended aluminum nitride powder was separated by filter membrane filter. By this method, it could solve the determination interference to elemental aluminum. This study established the determination of elemental aluminum in aluminum nitride nanoparticles by inductively coupled plasma mass spectrometer(ICP-MS), which has the advantages of low determination limit, high accuracy, fast determination speed and small matrix effect. This method’s linear range is 10-100 μg/g and the relative standard deviation is 3.8%(n=6). Using high purity alumina powder to verify the established determination method, the dissolution efficiency can reach 96%-98%.