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1. Sr(Ag 1−x Li x ) 2 Se 2 and [Sr 3 Se 2 ][(Ag 1−x Li x ) 2 Se 2 ] Tunable Direct Band Gap Semiconductors

   https://doi.org/10.1002/ange.202301191  

   Zhou, Xiuquan ; Wilfong, Brandon ; Chen, Xinglong ; Laing, Craig ; Pandey, Indra R. ; Chen, Ying‐Pin ; Chen, Yu‐Sheng ; Chung, Duck‐Young ; Kanatzidis, Mercouri G. ( February 2023 , Angewandte Chemie)

   Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag_1−xLi_x)₂Se₂layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag_1−xLi_x)₂Se₂withxup to 0.45. In addition, a new type of intergrowth compound [Sr₃Se₂][(Ag_1−xLi_x)₂Se₂] was synthesized upon further reaction of Sr(Ag_1−xLi_x)₂Se₂with SrSe. Both Sr(Ag_1−xLi_x)₂Se₂and [Sr₃Se₂][(Ag_1−xLi_x)₂Se₂] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag_1−xLi_x)₂Se₂can be precisely tuned via fine‐tuningxthat is controlled by only the flux ratio and temperature.

    

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2. Sr(Ag 1−x Li x ) 2 Se 2 and [Sr 3 Se 2 ][(Ag 1−x Li x ) 2 Se 2 ] Tunable Direct Band Gap Semiconductors

   https://doi.org/10.1002/anie.202301191  

   Zhou, Xiuquan ; Wilfong, Brandon ; Chen, Xinglong ; Laing, Craig ; Pandey, Indra R. ; Chen, Ying‐Pin ; Chen, Yu‐Sheng ; Chung, Duck‐Young ; Kanatzidis, Mercouri G. ( February 2023 , Angewandte Chemie International Edition)

   Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag_1−xLi_x)₂Se₂layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag_1−xLi_x)₂Se₂withxup to 0.45. In addition, a new type of intergrowth compound [Sr₃Se₂][(Ag_1−xLi_x)₂Se₂] was synthesized upon further reaction of Sr(Ag_1−xLi_x)₂Se₂with SrSe. Both Sr(Ag_1−xLi_x)₂Se₂and [Sr₃Se₂][(Ag_1−xLi_x)₂Se₂] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag_1−xLi_x)₂Se₂can be precisely tuned via fine‐tuningxthat is controlled by only the flux ratio and temperature.

    

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3. 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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4. Electrical Detection and Magnetic Imaging of Stabilized Magnetic Skyrmions in Fe 1− x Co x Ge ( x < 0.1) Microplates

   https://doi.org/10.1002/adfm.201805418  

   Stolt, Matthew J. ; Schneider, Sebastian ; Mathur, Nitish ; Shearer, Melinda J. ; Rellinghaus, Bernd ; Nielsch, Kornelius ; Jin, Song ( February 2019 , Advanced Functional Materials)

   Magnetic skyrmions are topologically protected spin textures that are being investigated for their potential use in next generation magnetic storage devices. Here, magnetic skyrmions and other magnetic phases in Fe_1−xCo_xGe (x< 0.1) microplates (MPLs) newly synthesized via chemical vapor deposition are studied using both magnetic imaging and transport measurements. Lorentz transmission electron microscopy reveals a stabilized magnetic skyrmion phase near room temperature (≈280 K) and a quenched metastable skyrmion lattice via field cooling. Magnetoresistance (MR) measurements in three different configurations reveal a unique anomalous MR signal at temperatures below 200 K and two distinct field dependent magnetic transitions. The topological Hall effect (THE), known as the electronic signature of magnetic skyrmion phase, is detected for the first time in a Fe_1−xCo_xGe nanostructure, with a large and positive peak THE resistivity of ≈32 nΩ cm at 260 K. This large magnitude is attributed to both nanostructuring and decreased carrier concentrations due to Co alloying of the Fe_1−xCo_xGe MPL. A consistent magnetic phase diagram summarized from both the magnetic imaging and transport measurements shows that the magnetic skyrmions are stabilized in Fe_1−xCo_xGe MPLs compared to bulk materials. This study lays the foundation for future skyrmion‐based nanodevices in information storage technologies.

    

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5. A Dual Plating Battery with the Iodine/[ZnI x (OH 2 ) 4−x ] 2−x Cathode

   https://doi.org/10.1002/anie.201909324  

   Hong, Jessica J. ; Zhu, Liangdong ; Chen, Cheng ; Tang, Longteng ; Jiang, Heng ; Jin, Bei ; Gallagher, Trenton C. ; Guo, Qiubo ; Fang, Chong ; Ji, Xiulei ( September 2019 , Angewandte Chemie International Edition)

   Plating battery electrodes typically deliver higher specific capacity values than insertion or conversion electrodes because the ion charge carriers represent the sole electrode active mass, and a host electrode is unnecessary. However, reversible plating electrodes are rare for electronically insulating nonmetals. Now, a highly reversible iodine plating cathode is presented that operates on the redox couples of I₂/[ZnI_x(OH₂)_4−x]^2−xin a water‐in‐salt electrolyte. The iodine plating cathode with the theoretical capacity of 211 mAh g⁻¹plates on carbon fiber paper as the current collector, delivering a large areal capacity of 4 mAh cm⁻². Tunable femtosecond stimulated Raman spectroscopy coupled with DFT calculations elucidate a series of [ZnI_x(OH₂)_4−x]^2−xsuperhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode‐plated iodine as triiodides.

    

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