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high pressure, perovskite oxide, PbCoO3, spin state transition, Intermetallic charge transfer, inelastic X-ray scattering
NSRRC Researcher Jin-Ming Chen’s Collaborative Research Selected as the Cover Image of JACS
2020/11/25
NSRRC Researcher Dr. Jin-Ming Chen’s high pressure research on PbCoO3 was selected as the cover image of JACS.
An international team coordinated by the researcher of National Synchrotron Radiation Research Center (NSRRC), Dr. Jin-Ming Chen, explored the physical phenomena of a specific material under high pressure. The research results were published in the Journal of the American Chemical Society (JACS) and were selected as the cover story for Volume 142 Number 12.

Spin state transitions and intermetallic charge transfers can essentially change material structural and physical properties, but these two effects have rarely been found to occur sequentially in a specific material. Dr. Chen’s research team shows the realization of these two phenomena in a perovskite oxide PbCoO3 under high pressure by using the inelastic X-ray scattering technique of NSRRC’s SP12U1 beamline, a Taiwan Contract Beamline at SPring-8, Japan. The material they use, PbCoO3, possesses a peculiar A- and B-site ordered charge distribution with insulating behavior at ambient conditions. The high spin Co2+ gradually changes to low spin with increasing pressure up to about 15 GPa, leading to an anomalous increase of resistance magnitude. Between 15 and 30 GPa, the intermetallic charge transfer occurs between Pb4+ and Co2+ cations. The accumulated charge-transfer effect triggers a metal–insulator transition as well as a first-order structural phase transition at the onset of ∼20 GPa near room temperature. On further compression over 30 GPa, the charge transfer completes, giving rise to another first-order structural transformation and returning to electrical insulating behavior. The significant research was selected as the cover photo of JACS.