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1. Ca ₂ Ga ₄ Ge ₆ and Ca ₃ Ga ₄ Ge ₆ : Synthesis, Structure, and Electronic Properties

   https://doi.org/10.1002/zaac.202100342  

   Hodge, Kelsey L; Davis, H Olivia; Koster, Karl G; Windl, Wolfgang; Moore, Curtis E; Goldberger, Joshua E (August 2022, Zeitschrift für anorganische und allgemeine Chemie)

   Abstract During the search for transition metal‐free alkyne hydrogenation catalysts, two new ternary Ca−Ga−Ge phases, Ca₂Ga₄Ge₆(Cmc2₁, a=4.1600(10) Å, b=23.283(5) Å, c=10.789(3) Å) and Ca₃Ga₄Ge₆(C2/m, a=24.063(2) Å, b=4.1987(4) Å, c=10.9794(9) Å, β=91.409(4)°), were discovered. These compounds are isostructural to the previously established Yb₂Ga₄Ge₆and Yb₃Ga₄Ge₆analogues, and according to Zintl‐Klemm counting rules, consist of anionic [Ga₄Ge₆]⁴⁻and [Ga₄Ge₆]⁶⁻frameworks in which every Ga and Ge atom would have a formal octet with no Ga−Ga or Ga−Ge π‐bonding. These compounds are metallic, based on temperature dependent electrical resistivity and thermopower measurements for Ca₃Ga₄Ge₆, along with density functional theory calculations for both phases. Unlike the highly active 13‐layer trigonal CaGaGe phase, these new compounds exhibit minimal activity in the semi/full alkyne hydrogenation of phenylacetylene, which is consistent with previous observations that the lack of a formal octet for framework atoms is essential for catalysis in these Zintl‐Klemm compounds. 

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2. Solution-based processing of Ge ₂ Sb ₂ Se ₄ Te optical phase change materials

   https://doi.org/10.1364/OME.542387  

   Wiedeman, Daniel; Sharma, Rashi; Bissell, Eric; Banerjee, Parag; Schwarz, Casey; Mills, Brian; Hu, Juejun; Callahan, Dennis; Richardson, Kathleen_A (November 2024, Optical Materials Express)

   Phase change materials (PCMs) are important building blocks in solid-state memory and photonic devices. Solution-based processing promises large-area, cost-effective, conformal coating of optical PCMs (O-PCMs) for photonic applications. In this work, a solution processing route was developed for Ge₂Sb₂Se₄Te₁(GSST), a target PCM of interest due to its large optical contrast, broadband transparency, and improved glass-forming capability. An alkahest solvent mixture of ethanedithiol and ethylenediamine was used as a solvent system to fabricate solution-derived GSST thin films and films from these solutions were prepared and characterized using SEM, XRD, and Raman spectroscopy. 

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3. Understanding and Circumventing Failure Mechanisms in Chalcogenide Optical Phase Change Material Ge ₂ Sb ₂ Se ₄ Te

   https://doi.org/10.1002/adom.202402751  

   Popescu, Cosmin_Constantin; Aryana, Kiumars; Mills, Brian; Lee, Tae_Woo; Martin‐Monier, Louis; Ranno, Luigi; Sia, Jia_Xu_Brian; Dao, Khoi_Phuong; Bae, Hyung‐Bin; Liberman, Vladimir; et al (November 2024, Advanced Optical Materials)

   Abstract Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, optical analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward their practical deployment for these applications. To address this issue, a systematic study elucidating the cycling failure mechanisms of Ge₂Sb₂Se₄Te (GSST) is performed, a common optical PCM tailored for infrared photonic applications, in an electrothermal switching configuration commensurate with their applications in on‐chip photonic devices. Further a set of design rules building on insights into the failure mechanisms is proposed, and successfully implemented them to boost the endurance of the Ge₂Sb₂Se₄Te (GSST) device to over 67 000 cycles. 

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4. Phase Change Dynamics and Two-Dimensional 4-Bit Memory in Ge ₂ Sb ₂ Te ₅ via Telecom-Band Encoding

   https://doi.org/10.1021/acsphotonics.9b01456  

   Sevison, Gary A.; Farzinazar, Shiva; Burrow, Joshua A.; Perez, Christopher; Kwon, Heungdong; Lee, Jaeho; Asheghi, Mehdi; Goodson, Kenneth E.; Sarangan, Andrew; Hendrickson, Joshua R.; et al (January 2020, ACS Photonics)
5. σ‐Aromaticity‐Induced Stabilization of Heterometallic Supertetrahedral Clusters [Zn ₆ Ge ₁₆ ] ⁴⁻ and [Cd ₆ Ge ₁₆ ] ⁴⁻

   https://doi.org/10.1002/anie.202008276  

   Xu, Hong‐Lei; Popov, Ivan A.; Tkachenko, Nikolay V.; Wang, Zi‐Chuan; Muñoz‐Castro, Alvaro; Boldyrev, Alexander I.; Sun, Zhong‐Ming (September 2020, Angewandte Chemie International Edition)

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