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Title: Mild hydrothermal synthesis and magnetic properties of the manganates Pr{sub 1-x}Ca{sub x}MnO{sub 3}

Abstract

The calcium-doped manganates, Pr{sub 1-x}Ca{sub x}MnO{sub 3} (x=0.39, 0.46, 0.70, 0.76), were synthesized as cube-shaped crystalline phases under mild hydrothermal conditions for the first time. The crystals could be grown in one step from solutions of metal salts and potassium hydroxide at temperatures {approx}240deg. C, and found to adopt perovskite-like structure (space group Pbnm). Samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis and variable temperature dc/ac magnetic susceptibility. The studies indicate that formation of the materials is dependent on the alkalinity and composition of the initial reaction mixtures. The magnetic properties show spin-glass-like behavior due to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions in Pr{sub 1-x}Ca{sub x}MnO{sub 3} with x=0.39, 0.46.

Authors:
 [1];  [1];  [1];  [1];  [2]
  1. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130023 (China)
  2. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130023 (China), E-mail: shfeng@mail.jlu.edu.cn
Publication Date:
OSTI Identifier:
21015633
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2006.09.029; PII: S0022-4596(06)00521-4; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANTIFERROMAGNETISM; CALCIUM COMPOUNDS; CRYSTALS; DOPED MATERIALS; EXCHANGE INTERACTIONS; HYDROTHERMAL SYNTHESIS; MAGNETIC SUSCEPTIBILITY; MANGANATES; ORTHORHOMBIC LATTICES; PEROVSKITE; SCANNING ELECTRON MICROSCOPY; SOLUTIONS; SPACE GROUPS; SPIN GLASS STATE; TEMPERATURE RANGE 0400-1000 K; X-RAY DIFFRACTION

Citation Formats

Chen Yan, Yuan Hongming, Tian Ge, Zhang Ganghua, and Feng Shouhua. Mild hydrothermal synthesis and magnetic properties of the manganates Pr{sub 1-x}Ca{sub x}MnO{sub 3}. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.09.029.
Chen Yan, Yuan Hongming, Tian Ge, Zhang Ganghua, & Feng Shouhua. Mild hydrothermal synthesis and magnetic properties of the manganates Pr{sub 1-x}Ca{sub x}MnO{sub 3}. United States. doi:10.1016/j.jssc.2006.09.029.
Chen Yan, Yuan Hongming, Tian Ge, Zhang Ganghua, and Feng Shouhua. Mon . "Mild hydrothermal synthesis and magnetic properties of the manganates Pr{sub 1-x}Ca{sub x}MnO{sub 3}". United States. doi:10.1016/j.jssc.2006.09.029.
@article{osti_21015633,
title = {Mild hydrothermal synthesis and magnetic properties of the manganates Pr{sub 1-x}Ca{sub x}MnO{sub 3}},
author = {Chen Yan and Yuan Hongming and Tian Ge and Zhang Ganghua and Feng Shouhua},
abstractNote = {The calcium-doped manganates, Pr{sub 1-x}Ca{sub x}MnO{sub 3} (x=0.39, 0.46, 0.70, 0.76), were synthesized as cube-shaped crystalline phases under mild hydrothermal conditions for the first time. The crystals could be grown in one step from solutions of metal salts and potassium hydroxide at temperatures {approx}240deg. C, and found to adopt perovskite-like structure (space group Pbnm). Samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis and variable temperature dc/ac magnetic susceptibility. The studies indicate that formation of the materials is dependent on the alkalinity and composition of the initial reaction mixtures. The magnetic properties show spin-glass-like behavior due to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions in Pr{sub 1-x}Ca{sub x}MnO{sub 3} with x=0.39, 0.46.},
doi = {10.1016/j.jssc.2006.09.029},
journal = {Journal of Solid State Chemistry},
number = 1,
volume = 180,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • The (NH{sub 4})[Fe(AsO{sub 4}){sub 1-x}(PO{sub 4}){sub x}F] (x=0.3, 0.6, 0.8) series of compounds has been synthesized under mild hydrothermal conditions. The compounds crystallize in the orthorhombic Pna2{sub 1} space group, with the unit-cell parameters a=13.1718(1), b=6.5966(6), c=10.797(1) A for x=0.3; a=13.081(1), b=6.5341(6), c=10.713(1) A for x=0.6 and a=13.0329(9), b=6.4994(4), c=10.6702(6) A for x=0.8, with the volumes 938.6(1), 915.7(1) and 903.8(1) A{sup 3}, respectively, with Z=8. Single crystals of (NH{sub 4})[Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.3}F] heated under air atmosphere at 465 deg. C remain as single crystals, changing the composition to Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.3}. This later phase belongs tomore » the orthorhombic Imam space group, with the unit cell parameters a=13.328(2), b=6.5114(5), c=10.703(1) A, V=928.9(2) A{sup 3} and Z=12. The crystal structure of the ammonium phases consists of a KTP three-dimensional framework constructed by chains formed by alternating Fe(2)O{sub 4}F{sub 2} or Fe(1)O{sub 4}F{sub 2} octahedra and As/P(2)O{sub 4} or As/P(1)O{sub 4} tetrahedra, respectively. These octahedra and tetrahedra are linked by a common oxygen vertex. The chains run along the 'a' and 'b' crystallographic axes. The crystal structure of Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.3} is a three-dimensional skeleton derived from that of the precursor, formed from (100) sheets stacked along the [001] direction, and interconnected by chains of alternating Fe(2)O{sub 6} octahedra and As/P(2)O{sub 4} tetrahedra sharing a vertex in the 'a' direction. Transmission electronic microscopy of this compound indicates the existence of unconnected external cavities with a BET surface area of 3.91(3) m{sup 2} g{sup -1}. The diffuse reflectance spectra in the visible region show the forbidden electronic transitions characteristic of the Fe(III) d{sup 5}-high spin cation in slightly distorted octahedral geometry, for all the compounds. The ESR spectra for all the compounds, carried out from room temperature to 4.2 K, remain isotropic with variation in temperature; the g-value is 1.99(1). Magnetic measurements indicate the predominance of antiferromagnetic interactions, with Neel temperatures near to 70.0 and 50.0 K for the ammonium phases and Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.30}, respectively. At low temperatures a spin canting phenomenon for Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.30} is detected. - Graphical abstract: The relationship between the |100| and |010| chains in (NH{sub 4})[Fe(AsO{sub 4}){sub 1-x}(PO{sub 4}){sub x}F] left and the |100| chains and the (001) sheets in Fe(AsO{sub 4}){sub 0.7}(PO{sub 4}){sub 0.3}.« less
  • The [M{sub x}{sup II}M{sub 2.5-x}{sup III}(H{sub 2}O){sub 2}(HP{sup III}O{sub 3}){sub y}(P{sup V}O{sub 4}){sub 2-y}F; M=Fe (1), x=2.08, y=1.58; M=Co (2), x=2.5, y=2; Ni (3), x=2.5, y=2] compounds have been synthesized using mild hydrothermal conditions at 170 deg. C during five days. Single-crystals of (1) and (2), and polycrystalline sample of (3) were obtained. These isostructural compounds crystallize in the orthorhombic system, space group Aba2, with a=9.9598(2), b=18.8149(4) and c=8.5751(2) A for (1), a=9.9142(7), b=18.570(1) and c=8.4920(5) A for (2) and a=9.8038(2), b=18.2453(2) and c=8.4106(1) A for (3), with Z=8 in the three phases. An X-ray diffraction study reveals that themore » crystal structure is composed of a three-dimensional skeleton formed by [MO{sub 5}F] and [MO{sub 4}F{sub 2}] (M=Fe, Co and Ni) octahedra and [HPO{sub 3}] tetrahedra, partially substituted by [PO{sub 4}] tetrahedra in phase (1). The IR spectra show the vibrational modes of the water molecules and those of the (HPO{sub 3}){sup 2-} tetrahedral oxoanions. The thermal study indicates that the limit of thermal stability of these phases is 195 deg. C for (1) and 315 deg. C for (2) and (3). The electronic absorption spectroscopy shows the characteristic bands of the Fe(II), Co(II) and Ni(II) high-spin cations in slightly distorted octahedral geometry. Magnetic measurements indicate the existence of global antiferromagnetic interactions between the metallic centers with a ferromagnetic transition in the three compounds at 28, 14 and 21 K for (1), (2) and (3), respectively. Compound (1) exhibits a hysteresis loop with remnant magnetization and coercive field values of 0.72 emu/mol and 880 Oe, respectively. - Abstract: Polyhedral view of the crystal structure of the [M{sub x}{sup II}M{sub 2.5-x}{sup III}(H{sub 2}O){sub 2}(HP{sup III}O{sub 3}){sub y}(P{sup IV}O{sub 4}){sub 2-y}F; M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds showing the sheets along the [001] direction.« less
  • We have investigated the role of the stress induced by the presence of the substrate in thin films of colossal magnetoresistive manganites on structural, resistive, and magnetic properties. Because of the strong coupling between the small structural distortions related to the charge ordering (CO) and the resistive properties, the presence of the substrate prevents the full development of the charge ordering in Pr{sub 0.5}Ca{sub 0.5}MnO{sub 3}, especially in the very thin films. For thicker films, the CO state exists, but is not fully developed. Correlatively, the magnetic field which is necessary to suppress the CO is decreased drastically from 25more » T to about 5 T on SrTiO{sub 3} substrates. We have also investigated the influence of the doping level by studying the case of Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3}. {copyright} 2001 American Institute of Physics.« less
  • A detailed study of the properties of Pr{sub 1{minus}{ital x}}Ca{sub {ital x}}MnO{sub 3} shows that for a range of compositions (0.3{le}{ital x}{lt}0.5) there is a first-order magnetic-field-induced insulator-metal transition. For the {ital x}=0.4 composition the magnetic and charge ordering (CO) effects are decoupled with antiferromagnetic (AFM) ordering, {ital T}{sub {ital N}}=170 K, developing at considerably lower temperatures than the CO state, {ital T}{sub CO}=250 K. Below the CO temperature, metamagnetic transitions exist that transform the magnetic correlations from either paramagnetic or AFM to ferromagnetic. Metastable conducting states are formed below 25 K.
  • We report resonant x-ray scattering studies of charge and orbital order in Pr{sub 1-x}Ca {sub x}MnO{sub 3} with x=0.4 and 0.5. Below the ordering temperature, T{sub O}=245 K , the charge and orbital order intensities follow the same temperature dependence, including an increase at the antiferromagnetic ordering temperature, T{sub N} . High resolution measurements reveal, however, that long range orbital order is never achieved. Rather, an orbital domain state is formed. Above T{sub O} , the charge order fluctuations are more highly correlated than the orbital fluctuations. We conclude that the charge order drives the orbital order at the transition.more » (c) 1999 The American Physical Society.« less