Crystal structures of highly hole-doped layered perovskite nickelate Pr2−xSrxNiO4 studied by neutron diffraction

Ryoichi Kajimoto, Kenji Nakajima, Masaki Fujita, Motoyuki Ishikado, Shuki Torii, Yoshihisa Ishikawa, Ping Miao, Takashi Kamiyama

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A high-resolution time-of-flight powder neutron diffraction study of the layered nickel oxide Pr2xSrxNiO4 with x = 0.7 and 0.9 was performed to characterize the crystal structures of these highly hole-doped nickelates. For the sample with x = 0.7, the Ni–O bond lengths decrease uniformly with decreasing temperature, and the atomic displacement parameters are similar to those for x = 1=3. In contrast, for the sample with x = 0.9, the out-of-plane Ni–O bond length shows a sharp thermal contraction in the high-temperature region, which is suggestive of changes in the orbital occupation accompanied by the development of checkerboard-type charge correlations. Furthermore, the x = 0.9 sample is characterized by a large atomic displacement parameter for the apical O atoms along the out-of-plane direction, which is interpreted as the existence of two types of Ni3+ sites with different orbital occupancies. The distinct difference between the x = 0.9 sample and the lower-concentration compounds should be related to the development of checkerboard-type charge ordering in the metallic matrix and possible orbital ordering at the Ni3+ sites at x ∼ 1 in the hole-doped layered nickel oxides.

Original languageEnglish
Article number114602
Journaljournal of the physical society of japan
Issue number11
Publication statusPublished - 2019

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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