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DTSTAMP:20260405T191500Z
UID:1695373200@ist.ac.at
DTSTART:20230922T110000
DTEND:20230922T120000
DESCRIPTION:Speaker: Kanishka Biswas\nhosted by Maria Ibáñez\nAbstract: F
 undamental understanding of the nature of chemical bonding and its influen
 ce on the electronic structure is paramount to chemistry\, solid state phy
 sics and materials science. CuBiI4 has a fascinating structure where Cu an
 d Bi are surrounded by a tetrahedral and octahedral halogen framework resp
 ectively. From fundamental inorganic chemistry concepts\, it is expected t
 o have symmetry-allowed d-p overlap in the tetrahedral co-ordination and w
 e see here strong Cu (d)- I (p) strong interaction. This rare interaction 
 generates an antibonding state in the valence band just below the Fermi en
 ergy in the electronic structure. Electrons filling up the antibonding ban
 d  weaken the bond and subsequently the crystal lattice becomes soft and 
 anharmonic giving rise to ultra-low thermal conductivity. In the latter p
 art of my talk\, I will be talking about achieving an ultralow value and u
 nusual glass-like temperature dependence of lattice thermal conductivity 
  in a large single crystal of layered halide perovskite Cs3Bi2I6Cl3. Her
 e\, Bi-Cl interaction also forms a s-p antibonding state below the Fermi l
 evel which renders a soft lattice. While strong anharmonicity originates f
 rom the low energy and localized rattling-like vibration of Cs atoms\, syn
 chrotron X-ray pair-distribution function analysis further evidences the p
 resence of local structural distortions in the Bi-halide octahedra. We pro
 pose that hierarchical chemical bonding\, presence of antibonding states n
 ear Fermi level and low energy vibrations from selective sublattice in cry
 stalline inorganic halide perovskites open an intriguing avenue for therma
 l transport research with their unfathomed lattice dynamics and potential 
 applications.
LOCATION:Office Bldg West / Ground floor / Heinzel Seminar Room\, ISTA
ORGANIZER:
SUMMARY:Kanishka Biswas: Antibonding Electronic States: Not Always a Devil 
URL:https://talks-calendar.ista.ac.at/events/4377
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