Effect of A-site cation size on magnetic and charge-ordering properties of Ln0.5Sr0.5Mn0.9Cu0.1O3 (Ln=La, Pr, Nd, or Ho)

2012 ◽  
Vol 177 (14) ◽  
pp. 1225-1231 ◽  
Author(s):  
Kamlesh Yadav ◽  
M.P. Singh ◽  
F.S. Razavi ◽  
G.D. Varma
Keyword(s):  
Charge Ordering ◽  
A Site ◽  
Cation Size

scholarly journals Structural and Electrical Properties of Ca2+ Doped LaFeO3: The Effect of A-site Cation Size Mismatch

2020 ◽  
Vol 10 (2) ◽  
pp. 5538-5546
Author(s):  
A. E. Irmak
Keyword(s):  
Crystal Structure ◽  
Sol Gel ◽  
Charge Ordering ◽  
Room Temperature Resistivity ◽  
Size Mismatch ◽  
Ca Doping ◽  
Average Size ◽  
A Site ◽  
Cation Size ◽  
Small Polarons

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.

Effect of A-site cation size mismatch on charge ordering behavior in (La1−xYx)0.5(Ca1−ySry)0.5MnO3

2001 ◽  
Vol 90 (1) ◽  
pp. 488-492 ◽  
Author(s):  
Y. Q. Wang ◽  
Ian Maclaren ◽  
X. F. Duan ◽  
Z. H. Wang ◽  
B. G. Shen
Keyword(s):  
Charge Ordering ◽  
Size Mismatch ◽  
A Site ◽  
Cation Size

Hydrothermal synthesis of ABi2Ta2O9Aurivillius phase: A comparative study of A-site cation size on structure, dielectric, optical properties

2021 ◽  
Author(s):  
Ilona Bella ◽  
Tio Putra Wendari ◽  
Novesar Jamarun ◽  
Nandang Mufti ◽  
Zulhadjri
Keyword(s):  
Xrd Analysis ◽  
Aurivillius Phase ◽  
Hydrothermal Route ◽  
Orthorhombic Crystal ◽  
Ionic Radii ◽  
Aurivillius Phases ◽  
Orthorhombic Crystal Structure ◽  
A Site ◽  
Cation Size ◽  
Ferroelectric Transition Temperature

In this study, the double-layered Aurivillius phases CaBi2Ta2O9 (CBT) and PbBi2Ta2O9 (PBT) were prepared through a hydrothermal route with NaOH as a mineralizer. XRD analysis confirmed that the CBT and PBT compounds were successfully formed and adopted an orthorhombic crystal structure with an [Formula: see text]21am symmetry. Le Bail refinements of XRD data indicated that the unit cell volume of CBT was smaller than PBT and is associated with the smaller ionic radius of Ca[Formula: see text] compared to Pb[Formula: see text]. The surface morphology of both samples, as determined using SEM, demonstrated plate-like grains with anisotropic grain growth. It was found that the different ionic radii of [Formula: see text]-site cations (Ca[Formula: see text] and Pb[Formula: see text] strongly affected the structural, optical and electrical properties of the Aurivillius phase. The occupation of smaller Ca[Formula: see text] cations induced a higher structural distortion, which resulted in higher bandgap ([Formula: see text] energy and ferroelectric transition temperature ([Formula: see text] of CBT, compared to those of PBT.

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

2012 ◽  
Vol 112 (7) ◽  
pp. 073905 ◽  
Author(s):  
Sk. Sabyasachi ◽  
A. Karmakar ◽  
S. Majumdar ◽  
S. Giri ◽  
S. Das ◽  
...  
Keyword(s):  
Charge Ordering ◽  
Site Disorder ◽  
A Site

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

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.

Cation Size and Disorder Effects in Conducting Perovskite Oxides

1998 ◽  
Vol 547 ◽  
Author(s):  
J. Paul Attifield ◽  
Andrei L. Kharlanov ◽  
Judith A. McAllister ◽  
Lide M. Rodriguez-Martinez
Keyword(s):  
Transition Temperature ◽  
Colossal Magnetoresistance ◽  
Linear Increase ◽  
Doping Effects ◽  
Cation Radius ◽  
Mean Size ◽  
The Mean ◽  
A Site ◽  
First Moment ◽  
Cation Size

AbstractThe electronic and magnetic properties of ATO3 and related perovskites (A is a mixture of lanthanide Ln3+ and alkaline earth M2+ cations; T is a transition metal) are very sensitive to the A site composition. The importance of doping effects controlled by the Ln3+/M2+ ratio is well-known, but the other lattice effects controlled by the sizes of these cations are less well understood. A simple approach making use of the mean (first moment) and the variance (second moment) in the A cation distribution has been applied to the metal-insulator transition temperature in colossal magnetoresistance AMnO3 perovskites and to the critical temperature in A2CuO4 and LnBa2Cu3O7-δ superconductors. Series of compositions prepared with a constant doping level and mean A cation radius show a linear decrease of the transition temperature Tt with the A cation size variance σ2. The rate of decrease -dTt/dσ2 is found to lie in the range 1,000-30,000 KÅ-2. The orthorhombic-tetra onal structural transition in the A2CuO4 materials is found to show a linear increase with σ2. A pair of quadratic relationships for the mean size and size variance effects are proposed to be the result of changing strain energies that give rise to these effects.

Role of the A-site size and oxygen stoichiometry in charge ordering commensurability of Ln0.50Ca0.50MnO3 manganites

1998 ◽  
Vol 84 (10) ◽  
pp. 5506-5514 ◽  
Author(s):  
A. Barnabé ◽  
M. Hervieu ◽  
C. Martin ◽  
A. Maignan ◽  
B. Raveau
Keyword(s):  
Charge Ordering ◽  
Oxygen Stoichiometry ◽  
A Site
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