Structures and Magnetism of La1-xSrxMnO3-(0.5+x)/2 (0.67 <= x <= 1) Phases
Topotactic reduction of La 1-xSr xMnO 3 (0.67 ≤ x ≤1) phases with sodium hydride yields a series of isoelectronic materials of composition La 1-xSr xMnO 3-(0.5+x)/2. Lanthanum rich members of the series (0.67 ≤x ≤0.83) adopt anion deficient perovskite structures with a 6-layer -OTOOT'O- stackin...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2012
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| Summary: | Topotactic reduction of La 1-xSr xMnO 3 (0.67 ≤ x ≤1) phases with sodium hydride yields a series of isoelectronic materials of composition La 1-xSr xMnO 3-(0.5+x)/2. Lanthanum rich members of the series (0.67 ≤x ≤0.83) adopt anion deficient perovskite structures with a 6-layer -OTOOT'O- stacking sequence of sheets of octahedra/square-based pyramids (O) and sheets of tetrahedra (T). The strontium rich members of the series (0.83 ≤x ≤1) incorporate "step defects" into this 6-layer structure in which the OTOOT'O stacking sequence is converted into either OOTOOT' or TOOT'OO at a defect plane which runs perpendicular to the [201] lattice plane. The step defects appear to provide a mechanism to relieve lattice strain and accommodate additional anion deficiency in phases with x > 0.83. Magnetization and neutron diffraction data indicate La 1-xSr xMnO 3-(0.5+x)/2 phases adopt antiferromagnetically ordered states at low-temperature in which the ordered arrangement of magnetic spins is incommensurate with the crystallographic lattice. © 2012 American Chemical Society. |
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