摘要
High oxygen pressure floating zone growth and crystal structure of the metallic nickelates R4Ni3O10 ( R = La, Pr )
材料
本批次暂无数据。
方法
本批次暂无数据。
关键词
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亮点
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结论
本批次暂无数据。
主要论断
- The room-temperature thermodynamic phase of R4Ni3O10 (R=La, Pr) is monoclinic P21/a (Z=2); a metastable orthorhombic Bmab phase can be trapped by rapid cooling.
- 证据: Synchrotron single-crystal XRD unambiguously solves both structures,Annealing biphasic samples converts Bmab to P21/a,Different MMT temperatures correspond to the two phases
- The metal-to-metal transition (MMT) is accompanied by a weak lattice response and differs by ≈10 K between the two La4Ni3O10 phases.
- 证据: Temperature-dependent XRD shows anomalies in lattice parameters at the MMT,Resistivity, susceptibility, and heat capacity all show sharp anomalies at the respective T_MMT
研究流程
- high_o2_crystal_growth — High-quality single crystals of R4Ni3O10 grown.
- 材料: Polycrystalline R4Ni3O10 rods (R=La, Pr)
- 方法: High-pressure optical-image floating zone (SciDre HKZ); O2 pressures: 20 bar (La), 140 bar (Pr); Xe arc lamp (3-5 kW)
- 观察: La4Ni3O10 boule with shiny facets; single crystals up to 4.5 mm; Synchrotron XRD confirms large single crystal region; Oxygen content 9.98(1) for La, 10.05(1) for Pr
- structure_determination — Crystal structures established: P21/a (Z=2) is the thermodynamic phase.
- 材料: R4Ni3O10 single crystals
- 方法: Synchrotron and lab single-crystal XRD; Neutron powder diffraction; Rietveld refinement
- 观察: La4Ni3O10: Bmab (fast cooling) and P21/a (slow cooling) identified; Pr4Ni3O10: onlyP21/a; Lattice anomalies at MMT
- physical_property_measurements — Physical properties confirm metal-to-metal transitions.
- 材料: Oriented single crystals
- 方法: Resistivity (four/six-terminal); Magnetic susceptibility (SQUID); Heat capacity (PPMS)
- 观察: MMT at 138.6 K (P21/a La4Ni3O10), 147.5 K (Bmab La4Ni3O10), 157.6 K (Pr4Ni3O10); Anisotropic resistivity and susceptibility; γ ≈13-14.5 mJ/(mol K2)