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Title: Crystal structure and magnetic properties of Ba-ordered manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd)

Abstract

The structure and magnetic properties of the Ba-ordered state in solid solutions of manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd) with a cation ratio Ln{sup 3+}/Ba{sup 2+} >> 1 are studied experimentally. The samples are obtained by two-stage synthesis. The initial stoichiometric Ba-disordered solid solutions Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3} synthesized in air according to traditional ceramic technology are characterized by the orthorhombic (Imma, Z = 4) perovskite-like unit cell and are ferromagnets with Curie temperatures T{sub C} {approx} 173 and {approx} 143 K for Pr and Nd, respectively. The average size <D> of a crystalline in the initial samples is 5 {mu}m. It is found that annealing of the initial samples in a vacuum of P[O{sub 2}] = 10{sup -4} Pa leads to their separation into three phases: (1) the anion-deficient ordered LnBaMn{sub 2}O{sub 5} phase described by a tetragonal (P4/mmm, Z = 2) perovskite-like unit cell, as well as the phases (2) Ln{sub 2}O{sub 3} (P3-barm1, Z = 1) and (3) MnO (Fm3-barm, Z = 2). Reduction leads to the formation of a nanocomposite with an average crystallite size <D> = 100 nm. Anion-deficient Ba-ordered phases of LnBaMn{sub 2}O{sub 5} exhibit ferrimagnetic properties with Neel temperatures T{submore » N} {approx} 113 and {approx}123 K for Pr and Nd, respectively. Annealing of anion-deficient samples in air at a moderate temperature of T = 800{sup o}C does not change the average size of the nanocrystallite, but noticeably alters their phase composition. Stoichiometric nanocomposites consist of two perovskite-like phases: (1) the Ba-deficient ordered stoichiometric phase LnBaMn{sub 2}O{sub 6}, which is described by a tetragonal (P4/mmm, Z = 2) unit cell and has the Curie temperatures T{sub C} {approx} 313 (Pr) and {approx}303 K (Nd), and (2) the Ba-disordered superstoichiometric phase Ln{sub 0.90}Ba{sub 0.10}MnO{sub 3+{delta}}, which is described by an orthorhombic (Imma, Z = 4) unit cell and has Curie temperatures T{sub C} {approx} 138 (Pr) and {approx}123 K (Nd). The two magnetic phases of the Ba-ordered nanocomposite are exchange-coupled. For the low-temperature magnetic phase, a temperature hysteresis is observed at {delta}T {approx} 22 K in a field of 10 Oe and at {delta}T {approx} 5 K in a field of 1 kOe. It is shown that states with different degrees of ordering of cations in the A sublattice can be obtained employing different technological conditions of treatment. The significant changes in the magnetic properties of Ba-ordered nanocomposites are explained on the basis of chemical phase separation taking into account the effect of compression, which is a consequence of the action of chemical (cation ordering) and external (surface tension) pressures.« less

Authors:
; ; ; ; ; ;  [1]; ;  [2];  [3]; ;  [4]
  1. National Academy of Sciences of Belarus, Joint Institute of Solid-State and Semiconductor Physics (Belarus)
  2. Masherov State University (Belarus)
  3. Polish Academy of Sciences, Institute of Physics (Poland)
  4. University of Texas at El Paso (United States)
Publication Date:
OSTI Identifier:
21067640
Resource Type:
Journal Article
Journal Name:
Journal of Experimental and Theoretical Physics
Additional Journal Information:
Journal Volume: 103; Journal Issue: 3; Other Information: DOI: 10.1134/S1063776106090093; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1063-7761
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANIONS; ANNEALING; BARIUM COMPOUNDS; BARIUM IONS; CATIONS; COMPOSITE MATERIALS; CUBIC LATTICES; CURIE POINT; MAGNETIC PROPERTIES; MANGANESE OXIDES; NANOSTRUCTURES; NEEL TEMPERATURE; NEODYMIUM COMPOUNDS; NEODYMIUM IONS; ORTHORHOMBIC LATTICES; PRASEODYMIUM COMPOUNDS; PRASEODYMIUM IONS; SOLID SOLUTIONS; STOICHIOMETRY; SURFACE TENSION; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0000-0013 K; TEMPERATURE RANGE 0013-0065 K; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0273-0400 K; TETRAGONAL LATTICES; TRIGONAL LATTICES

Citation Formats

Trukhanov, S. V., E-mail: truhanov@ifttp.bas-net.by, Khomchenko, V. A., Lobanovski, L. S., Bushinsky, M. V., Karpinsky, D. V., Fedotova, V. V., Troyanchuk, I. O., Trukhanov, A. V., Stepin, S. G., Szymczak, R., Botez, C. E., and Adair, A. Crystal structure and magnetic properties of Ba-ordered manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd). United States: N. p., 2006. Web. doi:10.1134/S1063776106090093.
Trukhanov, S. V., E-mail: truhanov@ifttp.bas-net.by, Khomchenko, V. A., Lobanovski, L. S., Bushinsky, M. V., Karpinsky, D. V., Fedotova, V. V., Troyanchuk, I. O., Trukhanov, A. V., Stepin, S. G., Szymczak, R., Botez, C. E., & Adair, A. Crystal structure and magnetic properties of Ba-ordered manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd). United States. doi:10.1134/S1063776106090093.
Trukhanov, S. V., E-mail: truhanov@ifttp.bas-net.by, Khomchenko, V. A., Lobanovski, L. S., Bushinsky, M. V., Karpinsky, D. V., Fedotova, V. V., Troyanchuk, I. O., Trukhanov, A. V., Stepin, S. G., Szymczak, R., Botez, C. E., and Adair, A. Fri . "Crystal structure and magnetic properties of Ba-ordered manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd)". United States. doi:10.1134/S1063776106090093.
@article{osti_21067640,
title = {Crystal structure and magnetic properties of Ba-ordered manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd)},
author = {Trukhanov, S. V., E-mail: truhanov@ifttp.bas-net.by and Khomchenko, V. A. and Lobanovski, L. S. and Bushinsky, M. V. and Karpinsky, D. V. and Fedotova, V. V. and Troyanchuk, I. O. and Trukhanov, A. V. and Stepin, S. G. and Szymczak, R. and Botez, C. E. and Adair, A.},
abstractNote = {The structure and magnetic properties of the Ba-ordered state in solid solutions of manganites Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3-{delta}} (Ln = Pr, Nd) with a cation ratio Ln{sup 3+}/Ba{sup 2+} >> 1 are studied experimentally. The samples are obtained by two-stage synthesis. The initial stoichiometric Ba-disordered solid solutions Ln{sub 0.70}Ba{sub 0.30}MnO{sub 3} synthesized in air according to traditional ceramic technology are characterized by the orthorhombic (Imma, Z = 4) perovskite-like unit cell and are ferromagnets with Curie temperatures T{sub C} {approx} 173 and {approx} 143 K for Pr and Nd, respectively. The average size <D> of a crystalline in the initial samples is 5 {mu}m. It is found that annealing of the initial samples in a vacuum of P[O{sub 2}] = 10{sup -4} Pa leads to their separation into three phases: (1) the anion-deficient ordered LnBaMn{sub 2}O{sub 5} phase described by a tetragonal (P4/mmm, Z = 2) perovskite-like unit cell, as well as the phases (2) Ln{sub 2}O{sub 3} (P3-barm1, Z = 1) and (3) MnO (Fm3-barm, Z = 2). Reduction leads to the formation of a nanocomposite with an average crystallite size <D> = 100 nm. Anion-deficient Ba-ordered phases of LnBaMn{sub 2}O{sub 5} exhibit ferrimagnetic properties with Neel temperatures T{sub N} {approx} 113 and {approx}123 K for Pr and Nd, respectively. Annealing of anion-deficient samples in air at a moderate temperature of T = 800{sup o}C does not change the average size of the nanocrystallite, but noticeably alters their phase composition. Stoichiometric nanocomposites consist of two perovskite-like phases: (1) the Ba-deficient ordered stoichiometric phase LnBaMn{sub 2}O{sub 6}, which is described by a tetragonal (P4/mmm, Z = 2) unit cell and has the Curie temperatures T{sub C} {approx} 313 (Pr) and {approx}303 K (Nd), and (2) the Ba-disordered superstoichiometric phase Ln{sub 0.90}Ba{sub 0.10}MnO{sub 3+{delta}}, which is described by an orthorhombic (Imma, Z = 4) unit cell and has Curie temperatures T{sub C} {approx} 138 (Pr) and {approx}123 K (Nd). The two magnetic phases of the Ba-ordered nanocomposite are exchange-coupled. For the low-temperature magnetic phase, a temperature hysteresis is observed at {delta}T {approx} 22 K in a field of 10 Oe and at {delta}T {approx} 5 K in a field of 1 kOe. It is shown that states with different degrees of ordering of cations in the A sublattice can be obtained employing different technological conditions of treatment. The significant changes in the magnetic properties of Ba-ordered nanocomposites are explained on the basis of chemical phase separation taking into account the effect of compression, which is a consequence of the action of chemical (cation ordering) and external (surface tension) pressures.},
doi = {10.1134/S1063776106090093},
journal = {Journal of Experimental and Theoretical Physics},
issn = {1063-7761},
number = 3,
volume = 103,
place = {United States},
year = {2006},
month = {9}
}