A-site disorder driven sharp field-induced transition and collapse of charge ordering in Sm1/2Ca1/2-xSrxMnO3

In this study, nanosized La1-xCaxFeO3 (0.00≤x≤0.40) compounds prepared via sol-gel method followed by heat treatment at 1100oC for 24 hours are studied. Crystal structure, microstructure, surface morphology and temperature-dependent resistivity of the samples are investigated. TEM investigation reveals nanoparticles with an average size of 35nm produced from the sol-gel process. The crystal structure of the compounds belongs to an orthorhombically distorted perovskite structure with Pbnm space group. Lattice distortion and cation size mismatch increase with an increase in Ca and particle and grain growth are suppressed by Ca doping. Electrical conduction is explained via thermally activated hopping of small polarons. Unit cell volume, charge ordering temperature, and activation energy for small polarons decrease linearly with an increase in cation size mismatch. Room temperature resistivity decreases with Ca doping and gets its minimum value for 30% Ca at which the orthorhombic distortion is maximum.

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A-site and B-site Charge Ordering of Perovskite Oxide PbCoO3 Realized by s-d Level Controlling

Nihon Kessho Gakkaishi ◽

10.5940/jcrsj.60.227 ◽

2018 ◽

Vol 60 (5-6) ◽

pp. 227-228

Author(s):

Yuki SAKAI ◽

Masaki AZUMA

Keyword(s):

Charge Ordering ◽

Perovskite Oxide ◽

A Site

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Study of A-Site Disorder Dependent Structural, Magnetic, and Magnetocaloric Properties in La0.7-xSmxCa0.3MnO3Manganites

Japanese Journal of Applied Physics ◽

10.7567/jjap.52.10mc12 ◽

2013 ◽

Vol 52 (10S) ◽

pp. 10MC12 ◽

Cited By ~ 20

Author(s):

Mohammad Shafique Anwar ◽

Faheem Ahmed ◽

Seung Rok Lee ◽

Rehan Danish ◽

Bon Heun Koo

Keyword(s):

Site Disorder ◽

Magnetocaloric Properties ◽

A Site

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A-Site Cational Size Disorder Effects in La0.55Ca0.45MnO3

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.351 ◽

2007 ◽

Vol 336-338 ◽

pp. 351-355

Author(s):

K.F. Wang ◽

X.P. Liu ◽

Q.C. Li ◽

Y. Wang ◽

L.F. Wang ◽

...

Keyword(s):

Ground State ◽

Curie Point ◽

Atomic Fraction ◽

Ionic Radii ◽

Disorder Effects ◽

Radial Distortion ◽

Site Disorder ◽

Glass Insulator ◽

A Site ◽

Cation Size

The effects of A-site cation size disorder in ABO3 type ferromagnetic metallic La0.55Ca0.45MnO3 system have been studied by substituting La3+ and Ca2+ by other ions, while keeping the valency of Mn ions and the A-site cation mean radius <rA> constant in the substituted compounds with different A-site ionic radii variance σ2 = Σi (xiri 2 − <rA>2), where xi and ri are the atomic fraction and ionic radii of i-type ions at A-site, respectively. It is revealed that the A-site disorder induces the decreasing of the magnetization and the increasing of the resistivity. The ferromagnetic Curie point TC decreases with the increasing of the A-site ionic radii variance, too. Moreover, the ground state of the system transits from ferromagnetic metal to glass insulator upon increasing variance of the A-site ionic radii from 0.0003 for La0.55Ca0.45MnO3 to 0.009 for Gd0.55Sr0.45MnO3. It is argued that the suppression of the ferromagnetism is ascribed to the enhanced radial distortion of the MnO6 octahedra due to the increasing A-site disorder.

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