Pressure-Induced Collapse Transition in BaTi2Pn2O (Pn = As, Sb) with an Unusual Pn-Pn Bond Elongation

Takafumi Yamamoto, Takeshi Yajima, Zhi Li, Takateru Kawakami, Kousuke Nakano, Takami Tohyama, Takehiko Yagi, Yoji Kobayashi, Hiroshi Kageyama

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Making and breaking bonds in a solid-state compound greatly influences physical properties. A well-known playground for such bonding manipulation is the ThCr2Si2-type structure AT2X2, allowing a collapse transition where a X-X dimer forms by a chemical substitution or external stimuli. Here, we report a pressure-induced collapse transition in the structurally related BaTi2Pn2O (Pn = As, Sb) at a transition pressure Pc of ∼15 GPa. The Pn-Pn bond formation is related with Pn-p band filling, which is controlled by charge transfer from the Ti-3d band. At Pc, the Sb-Sb distance in BaTi2Sb2O shrinks due to bond formation, but interestingly, the Sb-Sb expands with increasing pressure above Pc. This expansion, which was not reported in ThCr2Si2-type compounds, may arise from heteroleptic coordination geometry around titanium, where a compression of the Ti-O bond plays a role. Electrical resistivity measurements of BaTi2Sb2O up to 55 GPa revealed an increasing trend of the superconducting transition temperature with pressure. This study presents structure motifs that allow flexible bonding manipulation and property control with heteroleptic coordination geometry.
Original languageEnglish (US)
Pages (from-to)2228-2233
Number of pages6
JournalInorganic Chemistry
Issue number4
StatePublished - Feb 15 2021
Externally publishedYes

Bibliographical note

Generated from Scopus record by KAUST IRTS on 2022-09-13

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry


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