A recent theoretical study [Phys. Rev. B 85, 121411(R) (2012)] predicted a thickness limit below which ideal polar cuprates turn nonpolar driven by the associated electrostatic instability. Here we demonstrate this possibility by inducing a structural transformation from the bulk planar to chainlike structure upon reducing the SrCuO2 repeat thickness in SrCuO2/SrTiO3 superlattices with unit-cell precision. Our results, based on structural investigation by x-ray diffraction and high resolution scanning transmission electron microscopy, demonstrate that the oxygen sublattice can essentially be built by design. In addition, the electronic structure of the chainlike structure, as studied by x-ray absorption spectroscopy, shows the signature for preferential hole occupation in the Cu 3d(3z2-r2) orbital, which is different from the planar case.
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http://dx.doi.org/10.1103/PhysRevLett.111.096102 | DOI Listing |
ACS Nano
December 2024
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, China.
Anionic redox has emerged as a transformative paradigm for high-energy layered transition-metal (TM) oxide cathodes, but it is usually accompanied by the formation of anionic redox-mediated oxygen vacancies (OVs) due to irreversible oxygen release. Additionally, external factor-induced OVs (defined as intrinsic OVs) also play a pivotal role in the physicochemical properties of layered TM oxides. However, an in-depth understanding of the interplay between intrinsic and anionic redox-mediated OVs and the corresponding regulation mechanism of the dynamic evolution of OVs is still missing.
View Article and Find Full Text PDFRSC Adv
November 2024
Institute of Applied Physics, Henan Academy of Sciences Zhengzhou Henan 450008 China.
Perovskite-type solid electrolytes exhibit a diverse range of conductive properties due to the competition and coupling of multiple degrees of freedom. In perovskite structures, B-site and X-site ions form topological octahedral sublattices, which are instrumental in regulating transport properties for various charge carriers. However, research focused on the relationship between octahedral distortion and conductive properties in perovskite-type proton conductors remains limited.
View Article and Find Full Text PDFAdv Mater
December 2024
Nanoionics and Fuel Cells group, Catalonia Institute for Energy Research, Jardins de Les Dones de Negre 1, Sant Adrià de Besòs, Barcelona, 08930, Spain.
Perovskite oxides form a large family of materials with applications across various fields, owing to their structural and chemical flexibility. Efficient exploration of this extensive compositional space is now achievable through automated high-throughput experimentation combined with machine learning. In this study, we investigate the composition-structure-performance relationships of high-entropy LaSrMnCoFeO perovskite oxides (0 < x, y, z <1; x+y+z≈1) for application as oxygen electrodes in Solid Oxide Cells.
View Article and Find Full Text PDFInorg Chem
November 2024
College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 401331, China.
The hexagonal perovskite derivatives BaM'M″O featuring a hybrid structure composed of 9R hexagonal perovskite and palmierite structure motifs exhibit significant oxide ionic conductivity due to the highly disordered oxide-ion and M-cation sublattices. Herein, we report the structure and electrical properties of the perovskite BaTiWO. Three-dimensional (3D) electron diffraction (ED), neutron powder diffraction (NPD), and neutron pair distribution functions (nPDF) revealed a 9R hexagonal perovskite structure for BaTiWO with fully occupied central M2 sites, partially occupied outer M1 sites, and oxygen-deficient cubic c-BaO sublayers.
View Article and Find Full Text PDFPhys Chem Chem Phys
November 2024
School of Physics, East China University of Science and Technology, Shanghai, 200237, China.
Crystal materials can exhibit novel properties under high pressure, which are completely different from properties under ambient conditions. Water ice has an exceptionally rich phase diagram with at least 20 known crystalline ice phases from experiments, where the high-pressure ice X and ice XVIII behave as an ionic state and a superionic state, respectively. Thus, the ice structures stabilized under high pressure are very likely to possess other novel properties.
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