More Like this

1. Multifaceted Sn–Sn bonding in the solid state. Synthesis and structural characterization of four new Ca–Li–Sn compounds

   https://doi.org/10.1039/C9DT02803J  

   Ovchinnikov, Alexander; Bobev, Svilen (October 2019, Dalton Transactions)

   null (Ed.)

   Four novel ternary phases have been prepared in the system Ca–Li–Sn using both the metal flux method and conventional high-temperature synthesis. Each of the obtained compositions represents its own (new) structure type, and the structures feature distinct polyanionic Sn units. Ca 4 LiSn 6 (space group Pbcm , Pearson symbol oP 44) accommodates infinite chains, made up of cyclopentane-like [Sn 5 ]-rings, which are bridged by Sn atoms. The Sn atoms in this structure are two- and three-bonded. The anionic substructure of Ca 9 Li 6+x Sn 13–x ( x ≈ 0.28, space group C 2/ m , Pearson symbol mS 56) displays extensive mixing of Li and Sn and combination of single-bonded and hypervalent interactions between the Sn atoms. Hypervalent bonding is also pronounced in the structure of the third compound, Ca 2 LiSn 3 (space group Pmm 2, Pearson symbol oP 18) with quasi-two-dimensional polyanionic subunits and a variety of coordination environments of the Sn atoms. One-dimensional [Sn 10 ]-chains with an intricate topology of cis - and trans -Sn–Sn bonds exist in the structure of Ca 9–x Li 2 Sn 10 ( x ≈ 0.16, space group C 2/ m , Pearson symbol mS 42), and the Sn–Sn bonding in this case demonstrates the characteristics of an intermediate between single- and double- bond-order. The peculiarities of the bonding are discussed in the context of the Zintl approach, which captures the essence of the main chemical interactions. The electronic structures of all four compounds have also been analyzed in full detail using first-principles calculations. 

   more » « less
2. Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO ₂ (110)

   https://doi.org/10.1021/acs.jpcc.1c03338  

   Beniwal, Sumit; Chai, Wenrui; Metavarayuth, Kamolrat; Maddumapatabandi, Thathsara D.; Shakya, Deependra M.; Henkelman, Graeme; Chen, Donna A. (August 2021, The Journal of Physical Chemistry C)
3. A long-lasting eruption heralds SN 2023ldh, a clone of SN 2009ip

   https://doi.org/10.1051/0004-6361/202554858  

   Pastorello, A; Reguitti, A; Tartaglia, L; Valerin, G; Cai, Y-Z; Charalampopoulos, P; De_Luise, F; Dong, Y; Elias-Rosa, N; Farah, J; et al (September 2025, Astronomy & Astrophysics)

   We discuss the results of the spectroscopic and photometric monitoring of the type IIn supernova (SN) 2023ldh. Survey archive data show that the SN progenitor experienced erratic variability in the years before exploding. Beginning May 2023, the source showed a general slow luminosity rise that lasted for over four months, with some superposed luminosity fluctuations. In analogy toSN 2009ip, we call this brightening ‘Event A’. During Event A,SN 2023ldhreached a maximum absolute magnitude ofM_r = −15.52 ± 0.24 mag. The light curves then decreased by about 1 mag in all filters for about two weeks reaching a relative minimum, which was followed by a steep brightening (Event B) to an absolute peak magnitude ofM_r = −18.53 ± 0.23 mag, replicating the evolution ofSN 2009ipand similar to that of type IIn SNe. The three spectra ofSN 2023ldhobtained during Event A show multi-component P Cygni profiles of H I and Fe II lines. During the rise to the Event B peak, the spectrum shows a blue continuum dominated by Balmer lines in emission with Lorentzian profiles, with a full width at half maximum velocity of about 650 km s⁻¹. Later, in the post-peak phase, the spectrum reddens, and broader wings appear in the Hαline profile. Metal lines with P Cygni profiles and velocities of about 2000 km s⁻¹are clearly visible. Beginning around three months past maximum and until very late phases, the Ca II lines become among the most prominent features, while Hαis dominated by an intermediate-width component with a boxy profile. AlthoughSN 2023ldhmimics the evolution of otherSN 2009ip-like transients, it is slightly more luminous and has a slower photometric evolution. The surprisingly homogeneous observational properties ofSN 2009ip-like events may indicate similar explosion scenarios and similar progenitor parameters. 

   more » « less
4. Stabilization of Sn Anode through Structural Reconstruction of a Cu–Sn Intermetallic Coating Layer

   https://doi.org/10.1002/adma.202003684  

   Wang, Guanzhi; Aubin, Megan; Mehta, Abhishek; Tian, Huajun; Chang, Jinfa; Kushima, Akihiro; Sohn, Yongho; Yang, Yang (August 2020, Advanced Materials)

   Abstract The metallic tin (Sn) anode is a promising candidate for next‐generation lithium‐ion batteries (LIBs) due to its high theoretical capacity and electrical conductivity. However, Sn suffers from severe mechanical degradation caused by large volume changes during lithiation/delithiation, which leads to a rapid capacity decay for LIBs application. Herein, a Cu–Sn (e.g., Cu₃Sn) intermetallic coating layer (ICL) is rationally designed to stabilize Sn through a structural reconstruction mechanism. The low activity of the Cu–Sn ICL against lithiation/delithiation enables the gradual separation of the metallic Cu phase from the Cu–Sn ICL, which provides a regulatable and appropriate distribution of Cu to buffer volume change of Sn anode. Concurrently, the homogeneous distribution of the separated Sn together with Cu promotes uniform lithiation/delithiation, mitigating the internal stress. In addition, the residual rigid Cu–Sn intermetallic shows terrific mechanical integrity that resists the plastic deformation during the lithiation/delithiation. As a result, the Sn anode enhanced by the Cu–Sn ICL shows a significant improvement in cycling stability with a dramatically reduced capacity decay rate of 0.03% per cycle for 1000 cycles. The structural reconstruction mechanism in this work shines a light on new materials and structural design that can stabilize high‐performance and high‐volume‐change electrodes for rechargeable batteries and beyond. 

   more » « less
5. SN 2021foa: the bridge between SN IIn and Ibn

   https://doi.org/10.1093/mnras/staf187  

   Gangopadhyay, Anjasha; Dukiya, Naveen; Moriya, Takashi_J; Tanaka, Masaomi; Maeda, Keiichi; Howell, D_Andrew; Singh, Mridweeka; Singh, Avinash; Sollerman, Jesper; Kawabata, Koji_S; et al (January 2025, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We present the long-term photometric and spectroscopic analysis of a transitioning SN IIn/Ibn from –10.8 d to 150.7 d post V-band maximum. SN 2021foa shows prominent He i lines comparable in strength to the H $$\alpha$$ line around peak, placing SN 2021foa between the SN IIn and SN Ibn populations. The spectral comparison shows that it resembles the SN IIn population at pre-maximum, becomes intermediate between SNe IIn/Ibn, and at post-maximum matches with SN IIn 1996al. The photometric evolution shows a precursor at –50 d and a light curve shoulder around 17 d. The peak luminosity and colour evolution of SN 2021foa are consistent with most SNe IIn and Ibn in our comparison sample. SN 2021foa shows the unique case of an SN IIn where the narrow P-Cygni in H $$\alpha$$ becomes prominent at 7.2 d. The H $$\alpha$$ profile consists of a narrow (500–1200 km s$$^{-1}$$) component, intermediate width (3000–8000 km s$$^{-1}$$) and broad component in absorption. Temporal evolution of the H $$\alpha$$ profile favours a disc-like CSM geometry. Hydrodynamical modelling of the light curve well reproduces a two-component CSM structure with different densities ($$\rho \propto$$ r$$^{-2}$$–$$\rho \propto$$ r$$^{-5}$$), mass-loss rates (10$$^{-3}$$–10$$^{-1}$$ M$$_{\odot }$$ yr$$^{-1}$$) assuming a wind velocity of 1000 km s$$^{-1}$$ and having a CSM mass of 0.18 M$$_{\odot }$$. The overall evolution indicates that SN 2021foa most likely originated from an LBV star transitioning to a WR star with the mass-loss rate increasing in the period from 5 to 0.5 yr before the explosion or it could be due to a binary interaction. 

   more » « less