Microstructure evolution and magnetoresistance of the A-site ordered Ba-doped manganites

Journal Article · Tue May 15 00:00:00 EDT 2007 · Semiconductors

DOI:https://doi.org/10.1134/S1063782607050041· OSTI ID:21088070

Lobanovski, L S; Bushinsky, M V; Khomchenko, V A; Fedotova, V V; Troyanchuk, I O ^[1]; Szymczak, H ^[2]

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1. National Academy of Sciences of Belarus, Joint Institute of Solids and Semiconductor Physics (Belarus)
2. Polish Academy of Sciences, Institute of Physics (Poland)

The microstructure, crystal structure, and magnetotransport properties of microsized and nanosized Badoped manganites have been investigated. A 'two-step' reduction-reoxidation procedure has been used to obtain nanosized ceramic manganite Nd{sub 0.70}Ba{sub 0.30}MnO{sub 3} (II). The parent microsized manganite Nd{sub 0.70}Ba{sub 0.30}MnO{sub 3} (I) was prepared by usual ceramic technology in air. Then the sample was annealed in vacuum. The grain size of the reduced sample, determined by scanning electron microscopy, decreased from {approx}5 {mu}m down to {approx}100 nm. To obtain the oxygen stoichiometry nanosized sample, the Nd{sub 0.70}Ba{sub 0.30}MnO{sub 2.60} was again annealed in air. It is established that the (I) sample is a pseudocubic perovskite, whereas (II) is tetrahedral as a consequence of Nd{sup 3+} and Ba{sup 2+} ions as well as the ordering of oxygen vacancies. The (I) sample is a ferromagnet with T{sub C} {approx} 140 K. It has metal-insulator transition at T{sub MI} {approx} 135 K and a peak of magnetoresistance {approx}50% in a field of 9 kOe. For the (II) sample, the critical points of phase transitions move to higher temperatures, T{sub C} {approx} 320 K and T{sub MI} {approx} 310 K. The magnetoresistance of the (II) sample at room temperature (T {approx} 293 K) is about 7% in a field of 9 kOe. The magnetotransport properties are interpreted in the framework of the nanosized effect.

• OSTI ID: 21088070
• Journal Information: Semiconductors, Vol. 41, Issue 5; Other Information: DOI: 10.1134/S1063782607050041; Copyright (c) 2007 Nauka/Interperiodica; Article Copyright (c) 2007 Pleiades Publishing, Ltd; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7826
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
BARIUM COMPOUNDS
BARIUM IONS
CERAMICS
DOPED MATERIALS
GRAIN SIZE
MAGNETORESISTANCE
MANGANESE COMPOUNDS
NANOSTRUCTURES
NEODYMIUM COMPOUNDS
NEODYMIUM IONS
OXIDES
PEROVSKITE
PHASE TRANSFORMATIONS
SCANNING ELECTRON MICROSCOPY
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
VACANCIES