Structural and magnetic aspects of La₄(Co_1−xNi_x)₃O_10+δ (0 ≤ x ≤ 1)

Abstract

The Ruddlesden–Popper (RP3) type oxides, La₄Co₃O_10+δ and La₄Ni₃O_10+δ, form a complete solid solution. Powder X-ray and neutron diffraction data show that La₄(Co_1−xNi_x)₃O_10+δ is isostructural to the monoclinic La₄Co₃O_10+δ structure (P2₁/a) described for all compositions without any further structural distortions as suggested in the literature. A slight elongation of the Co/Ni–O bonds facing the rock salt interlayer occurs for Ni-rich compositions. The magnetic properties of the solid solution series are mapped in the temperature range from 4 to 300 K, and the results are presented in a magnetic phase diagram. Three regimes with antiferromagnetic order (AF) exist at low temperatures, T_N < 10 − 30 K. For x = 0.00, the AF is ascribed to Co(II), whereas a broader AF regime around x = 0.50 is ascribed mainly to Ni(II). Pauli paramagnetism is observed close to metallic La₄Ni₃O_10+δ, x > 0.80. The possibility to tune the oxidation state of the transition metal atoms is demonstrated for La₄Co₃O_10+δ, and exemplified by weakening of a temperature-induced spin transition at around 480 K.

Keywords:

• crystal structure
• Ruddlesden–Popper
• magnetization
• magnetic susceptibility
• differential scanning calorimetry
• neutron diffraction

Acknowledgements

Henrik Sønsteby is gratefully acknowledged for his assistance with operation of the PPMS instrumentation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Research leading to these results received funding from the Research Council of Norway (FRINATEK project 221905).