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1. Unlocking High Capacity and Fast Na ⁺ Diffusion of H _x CrS ₂ by Proton‐Exchange Pretreatment

   https://doi.org/10.1002/adma.202209811  

   Stiles, Joseph_W; Soltys, Anna_L; Song, Xiaoyu; Lapidus, Saul_H; Arnold, Craig_B; Schoop, Leslie_M (January 2023, Advanced Materials)

   Abstract This study presents a new material, “H_xCrS₂” (denotes approximate composition) formed by proton‐exchange of NaCrS₂which has a measured capacity of 728 mAh g⁻¹with significant improvements to capacity retention, sustaining over 700 mAh g⁻¹during cycling experiments. This is the highest reported capacity for a transition metal sulfide electrode and outperforms the most promising proposed sodium anodes to date. H_xCrS₂exhibits a biphasic structure featuring alternating crystalline and amorphous lamella on the scale of a few nanometers. This unique structural motif enables reversible access to Cr redox in the material resulting in higher capacities than seen in the parent structure which features only S redox. Pretreatment by proton‐exchange offers a route to materials such as H_xCrS₂which provide fast diffusion and high capacities for sodium‐ion batteries. 

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2. Oxygen Incorporation in the Molecular Beam Epitaxy Growth of Sc _x Ga _1−x N and Sc _x Al _1−x N

   https://doi.org/10.1002/pssb.201900612  

   Casamento, Joseph; Xing, Huili Grace; Jena, Debdeep (January 2020, physica status solidi (b))

   Secondary‐ion mass spectrometry (SIMS) is used to determine impurity concentrations of carbon and oxygen in two scandium‐containing nitride semiconductor multilayer heterostructures: Sc_xGa_1−xN/GaN and Sc_xAl_1−xN/AlN grown by molecular beam epitaxy (MBE). In the Sc_xGa_1−xN/GaN heterostructure grown in metal‐rich conditions on GaN–SiC template substrates with Sc contents up to 28 at%, the oxygen concentration is found to be below 1 × 10¹⁹ cm⁻³, with an increase directly correlated with the scandium content. In the Sc_xAl_1−xN–AlN heterostructure grown in nitrogen‐rich conditions on AlN–Al₂O₃template substrates with Sc contents up to 26 at%, the oxygen concentration is found to be between 10¹⁹and 10²¹ cm⁻³, again directly correlated with the Sc content. The increase in oxygen and carbon takes place during the deposition of scandium‐alloyed layers. 

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3. Rationally Engineered Vertically Aligned β ‐Ga _{2− x} W _x O ₃ Nanocomposites for Self‐Biased Solar‐Blind Ultraviolet Photodetectors with Ultrafast Response

   https://doi.org/10.1002/admt.202300014  

   Das, Debabrata; Sanchez, Francelia; Barton, Dallin_J; Tan, Susheng; Shutthanandan, Vaithiyalingam; Devaraj, Arun; Ramana, Chintalapalle_V (May 2023, Advanced Materials Technologies)

   Abstract With the astonishing advancement of present technology and increasing energy consumption, there is an ever‐increasing demand for energy‐efficient multifunctional sensors or transducers based on low‐cost, eco‐friendly material systems. In this context, self‐assembled vertically alignedβ‐Ga_2−xW_xO₃nanocomposite (GWO‐VAN) architecture‐assisted self‐biased solar‐blind UV photodetection on a silicon platform, which is the heart of traditional electronics is presented. Utilizing precisely controlled growth parameters, the formation of W‐enriched verticalβ‐Ga_2−xW_xO₃nanocolumns embedded into the W‐deficientβ‐Ga_2−xW_xO₃matrix is reached. Detailed structural and morphological analyses evidently confirm the presence ofβ‐Ga_2−xW_xO₃nanocomposite with a high structural and chemical quality. Furthermore, absorption and photoluminescence spectroscopy explains photo‐absorption dynamics and the recombination through possible donor–acceptor energy states. The proposed GWO‐VAN framework facilitates evenly dispersed nanoregions with asymmetric donor energy state distribution and thus forms build‐in potential at the verticalβ‐Ga_2−xW_xO₃interfaces. As a result, the overall heterostructure evinces photovoltaic nature under the UV irradiation. A responsivity of ≈30 A/W is observed with an ultrafast response time (≈350 µs) under transient triggering conditions. Corresponding detectivity and external quantum efficiency are 7.9 × 10¹²Jones and 1.4 × 10⁴%, respectively. It is believed that, while this is the first report exploiting GWO‐VAN architecture to manifest self‐biased solar‐blind UV photodetection, the implication of the approach is enormous in designing electronics for extreme environment functionality and has immense potential to demonstrate drastic improvement in low‐cost UV photodetector technology. 

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4. Machine learning–guided optimization of coercive field in Al _{1− x} Sc _x N thin films for nonvolatile memory

   https://doi.org/10.1111/jace.20347  

   Das, Shaon; Garg, Prachi; Mazumder, Baishakhi (December 2024, Journal of the American Ceramic Society)

   Abstract This study employs a data‐driven machine learning approach to investigate specific ferroelectric properties of Al_1−xSc_xN thin films, targeting their application in next‐generation nonvolatile memory (NVM) devices. This approach analyzes a vast design space, encompassing over a million data points, to predict a wide range of coercive field values that are crucial for optimizing Al_1−xSc_xN‐based NVM devices. We evaluated seven machine learning models to predict the coercive field across a range of conditions, identifying the random forest algorithm as the most accurate, with a testR²value of 0.88. The model utilized five key features: film thickness, measurement frequency, operating temperature, scandium concentration, and growth temperature to predict the design space. Our analysis spans 13 distinct scandium concentrations and 13 growth temperatures, encompassing thicknesses from 9–1000 nm, frequencies from 1 to 100 kHz, and operating temperatures from 273 to 700 K. The predictions revealed dominant coercive field values between 3.0 and 4.5 MV/cm, offering valuable insights for the precise engineering of Al_1−xSc_xN‐based NVM devices. This work underscores the potential of machine learning in guiding the development of advanced ferroelectric materials with tailored properties for enhanced device performance. 

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5. Reinvestigation of the ν ₃ – ν ₆ Coriolis interaction in trifluoroiodomethane

   https://doi.org/10.1039/D4CP02640C  

   Bhujel, Arun; Akter, Salma; Ali, Muhammad Qasim; Park, G Barratt (November 2024, Physical Chemistry Chemical Physics)

   An updated fit to the interacting levelsν₃andν₆of CF₃I has been evaluated in this work. 

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