Twinning microstructure and charge ordering in the colossal magnetoresistive manganite Nd{sub 1/2}Sr{sub 1/2}MnO{sub 3}
Charge ordering (C.O.) in the colossal magnetoresistive (CMR) manganites gives rise to an insulating, high-resistance state. This charge ordered state can be melted into a low-resistance metallic-like state by the application of magnetic field. Thus, the potential to attain high values of magnetoresistance with the application of small magnetic fields may be aided by a better understanding of the charge-ordering phenomenon. This study focused on microstructural characterization in Nd{sub 1/2}Sr{sub 1/2}MnO{sub 3}. In Nd{sub 1/2}Sr{sub 1/2}MnO{sub 3}, the nominal valence of Mn is 3.5+. On cooling, charge can localize and lead to a charge ordering between Mn 3+ and Mn 4+. The ordering of charge results in a superlattice structure and a reduction in symmetry. Thin foil specimens were prepared from bulk samples by conventional thinning and ion milling (at LiqN{sub 2} temperature) methods. The room temperature TEM observation of Nd{sub 1/2}Sr{sub 1/2}MnO{sub 3} reveals that it contains a highly twinned microstructure, together with a small number of stacking faults (SFS). A figure shows the same area of the specimen at different zone axes obtained by tilting around two perpendicular directions as indicated. Three grains A, B and C are labeled for each of the zone axes. The room temperature EDPs from the matrix and twins shows an approximate 90{degree} rotation suggesting a 90{degree} twin orientation. These results are further confirmed by C.O. at low temperatures. The twinning planes can be determined by tilting with large angles.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 755874
- Report Number(s):
- ANL/MSD/CP-101864; TRN: US0003633
- Resource Relation:
- Conference: Microscopy & Microanalysis 2000, Philadelphia, PA (US), 08/13/2000--08/17/2000; Other Information: PBD: 10 May 2000
- Country of Publication:
- United States
- Language:
- English
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