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Creators/Authors contains: "Zuo, Julia L."

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  1. Free, publicly-accessible full text available January 18, 2025
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  4. Abstract

    Vacancy‐ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of RuIVhalides are presented;A2RuCl6andA2RuBr6, whereAis K, NH4, Rb or Cs. We show that the optical properties and spin‐orbit coupling (SOC) behavior can be tuned through changing theAcation and the halide. Within a series, the energy of the ligand‐to‐metal charge transfer increases as the unit cell expands with the largerAcation, and the band gaps are higher for the respective chlorides than for the bromides. The magnetic moments of the systems are temperature dependent due to a non‐magnetic ground state withJeff=0 caused by SOC. Ru‐Xcovalency, and consequently, the delocalization of metald‐electrons, result in systematic trends of the SOC constants due to variations in theAcation and the halide anion.

     
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  5. Abstract

    Vacancy‐ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of RuIVhalides are presented;A2RuCl6andA2RuBr6, whereAis K, NH4, Rb or Cs. We show that the optical properties and spin‐orbit coupling (SOC) behavior can be tuned through changing theAcation and the halide. Within a series, the energy of the ligand‐to‐metal charge transfer increases as the unit cell expands with the largerAcation, and the band gaps are higher for the respective chlorides than for the bromides. The magnetic moments of the systems are temperature dependent due to a non‐magnetic ground state withJeff=0 caused by SOC. Ru‐Xcovalency, and consequently, the delocalization of metald‐electrons, result in systematic trends of the SOC constants due to variations in theAcation and the halide anion.

     
    more » « less
  6. Abstract

    There has been a great deal of recent interest in extended compounds containing Ru3+and Ru4+in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA2RuX6(X=Cl or Br), MA2MRuX6(M=Na, K or Ag;X=Cl or Br) and MA3Ru2X9(X=Br) based upon the use of methylammonium (MA=CH3NH3+) on the perovskite A site. The compounds MA2RuX6with Ru4+crystallize in the trigonal space groupand can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA2MRuX6with M+and Ru3+crystallize in a structure related to BaNiO3with alternatingMX6and RuX6face‐shared octahedra forming linear chains in the trigonalspace group. The compound MA3Ru2Br9crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru2Br9moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models.

     
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  7. Abstract

    There has been a great deal of recent interest in extended compounds containing Ru3+and Ru4+in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA2RuX6(X=Cl or Br), MA2MRuX6(M=Na, K or Ag;X=Cl or Br) and MA3Ru2X9(X=Br) based upon the use of methylammonium (MA=CH3NH3+) on the perovskite A site. The compounds MA2RuX6with Ru4+crystallize in the trigonal space groupand can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA2MRuX6with M+and Ru3+crystallize in a structure related to BaNiO3with alternatingMX6and RuX6face‐shared octahedra forming linear chains in the trigonalspace group. The compound MA3Ru2Br9crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru2Br9moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models.

     
    more » « less