Syntheses and magnetic properties of layered LnSrMn[sub 0. 5]Ni[sub 0. 5]O[sub 4] (Ln = La, Pr, Nd, Sm, Gd) compounds

Journal Article · Thu Jul 01 00:00:00 EDT 1999 · Chemistry of Materials

DOI:https://doi.org/10.1021/cm990098k· OSTI ID:6333895

Hong, K; Kwon, Y U; Han, D K ^[1]; Lee, J S ^[2]; Kim, S H ^[3]

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1. Sungkyunkwan Univ., Suwon (Korea, Republic of). Dept. of Chemistry
2. Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)
3. Konkuk Univ., Seoul (Korea, Republic of). Dept. of Chemistry

K[sub 2]NiF[sub 4]-type layered compounds LnSrMn[sub 0.5]Ni[sub 0.5]O[sub 4] (Ln = La, Pr, Nd, Sm, Gd) were synthesized, and their magnetic properties were studied. Both Curie-Weiss fits and X-ray absorption near-edge structure (XANES) of Mn and Ni atoms indicate that the oxidation states of Mn and Ni are +4 and close to +2, respectively. The oxidation state of Ni is assigned primarily at Ni[sup II], although there is increasing contribution from Ni[sup III] as the size of Ln increases. These compounds show overall antiferromagnetic behavior in their magnetic susceptibility vs temperature plots. The data in the paramagnetic regions indicate that there are ferromagnetic contributions by showing positive Weiss temperatures, probably because the Mn[sup IV] and Ni[sup II] atoms are locally ordered to form ferromagnetic regions. The antiferromagnetic behavior of the La compound is attributed to the interactions among these ferromagnetic regions within the MO[sub 2] (M = Mn, Ni) layers. In the Pr and Nd compounds, there are additional local maxima at lower temperatures that are attributed to the interlayer antiferromagnetic ordering between the ferromagnetic regions and the Pr/Nd ions. Low-temperature neutron diffraction data of Pr and Nd samples show a magnetic Bragg peak that is absent in the La sample. The Sm and Gd compounds show still different behaviors from the La-Nd compounds that can be explained with the reduced interlayer interactions due to the small ionic sizes and the different magnetic properties of Sm and Gd ions.

• OSTI ID: 6333895
• Journal Information: Chemistry of Materials, Vol. 11:7; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
FERROMAGNETISM
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OXIDES
RARE EARTH COMPOUNDS
STRONTIUM OXIDES
SYNTHESIS
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ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
MAGNETIC MATERIALS
MAGNETISM
MANGANESE COMPOUNDS
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NICKEL COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STRONTIUM COMPOUNDS
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