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1. Intricate Li–Sn Disorder in Rare-Earth Metal–Lithium Stannides. Crystal Chemistry of RE 3 Li 4–x Sn 4+x (RE = La–Nd, Sm; x 7 Li 8–x Sn 10+x ( x ≈ 2.0)

   https://doi.org/10.1021/acs.inorgchem.8b00583  

   Suen, Nian-Tzu ; Guo, Sheng-Ping ; Hoos, James ; Bobev, Svilen ( April 2018 , Inorganic Chemistry)
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/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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3. 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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4. Li 2 Mg 2 Si 2 S 6 and Li 2 Mg 2 Ge 2 S 6 : Two nonlinear optical sulfides featuring a unique, polar trigonal structure incorporating ethane‐like anions

   https://doi.org/10.1002/zaac.202200071  

   Barton, Ari T. ; Liang, Mingli ; Craig, Andrew J. ; Zhang, Weiguo ; Stoyko, Stanislav S. ; Radzanowski, Anne N. ; Fingerlow, Delenn ; Halasyamani, P. Shiv ; MacNeil, Joseph H. ; Aitken, Jennifer A. ( May 2022 , Zeitschrift für anorganische und allgemeine Chemie)

   The new compounds Li₂Mg₂Si₂S₆and Li₂Mg₂Ge₂S₆have been prepared via traditional high‐temperature, solid‐state synthesis. The title compounds crystallize in the polar, noncentrosymmetric, trigonal space groupP31m(No. 157) and adopt a new structure type featuring staggered, ethane‐like (T₂S₆)⁶⁻units, where T=Si or Ge. These (T₂S₆)⁶⁻units are nestled within the holes of magnesium‐sulfide “layers” that are created through the edge‐sharing of MgS₆octahedra. The holes found in the lithium‐sulfide “layers”, created by LiS₆edge‐sharing octahedra, remain vacant, containing no (T₂S₆)⁶⁻anionic group. Through the face sharing of the respective MgS₆and LiS₆octahedra, the magnesium‐sulfide and lithium‐sulfide “layers” are stitched together resulting in an overall three‐dimensional structure. The optical bandgaps of Li₂Mg₂Si₂S₆and Li₂Mg₂Ge₂S₆are 3.24 and 3.18 eV, respectively, as estimated from optical diffuse reflectance UV‐Vis‐NIR spectroscopy. The compounds exhibit second harmonic generation responses of ∼0.24×KDP and ∼2.92×α‐quartz for Li₂Mg₂Si₂S₆and ∼0.17×KDP and ∼2.08×α‐quartz for Li₂Mg₂Ge₂S₆, using a Nd:YAG laser at 1.064 μm. Electronic structure calculations were performed using density functional theory and the linearized augmented plane‐wave approach within the WIEN2k software package. Examination of the electronic band structures shows that these compounds are indirect bandgap semiconductors.

    

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5. Lithium‐Ion Mobility in Layered Oxide Li 2 (La 0.75 Li 0.25 )(Ta 1.5 Ti 0.5 )O 7 Containing Lithium on both Intra and Inter‐Stack Positions

   https://doi.org/10.1002/ejic.202100950  

   Fanah, Selorm Joy ; Ramezanipour, Farshid ( February 2022 , European Journal of Inorganic Chemistry)

   With the aid of neutron diffraction and electrochemical impedance spectroscopy, we have demonstrated the effect of the increase in lithium concentration and distribution on Li‐ion conductivity. This has been done through the synthesis of a layered oxide Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇, with the so‐called Ruddlesden‐Popper type structure, where bilayer stacks of (Ta/Ti)O₆octahedra are separated by lithium ions, located in inter‐stack spaces. There are also intra‐stack spaces that are occupied by a mixture of La and Li, as confirmed by neutron diffraction. The distribution of lithium over both inter‐ and intra‐stack positions leads to the enhancement of Li‐ion conductivity in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇compared to Li₂La(TaTi)O₇, which has a lower concentration of lithium ions, located only in inter‐stack spaces. The analyses of real and imaginary components of electrochemical impedance data confirm the enhanced mobility of ions in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇. While the Li‐ion conductivity needs further improvement for practical applications, the success of the strategy implemented in this work offers a useful methodology for the design of layered ionic conductors.

    

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