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

scholarly journals Enhanced Magnetic Properties of Co-Doped BiFeO3 Thin Films via Structural Progression

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1798
Author(s):  
Liang Bai ◽  
Mingjie Sun ◽  
Wenjing Ma ◽  
Jinghai Yang ◽  
Junkai Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Sol Gel ◽  
Sem Images ◽  
Size Mismatch ◽  
Structural Progression ◽  
Gel Technique ◽  
Average Size ◽  
Perovskite Lattice ◽  
Co Doped

Co3+ doping in BiFeO3 is expected to be an effective method for improving its magnetic properties. In this work, pristine BiFeO3 (BFO) and doped BiFe1-xCoxO3 (BFCxO, x = 0.01, 0.03, 0.05, 0.07 and 0.10) composite thin films were successfully synthesized by a sol–gel technique. XRD and Raman spectra indicate that the Co3+ ions are substituted for the Fe3+ ion sites in the BFO rhombohedral lattice. Raman vibration of oxygen octahedron is obviously weakened due to the lattice distortion induced by the size mismatch between two B-site cations (Fe3+ and Co3+ ions), which has an impact on the magnetic properties of BFCxO. SEM images reveal a denser agglomeration in Co-doped samples. TEM results indicate that the average size of grains is reduced due to the Co3+ substitution. XPS measurements illustrate that the replacement of Fe3+ with Co3+ effectively suppresses the generation of oxygen defects and increases the concentration of Fe3+ ions at the B-site of perovskite lattice. Vibrating sample magnetometer (VSM) measurements show that the remanent magnetization (Mr) of BFC0.07O (3.6 emu/cm3) and the saturation magnetization (Ms) of BFC0.10O (48.84 emu/cm3) thin film both increase by approximately two times at room temperature, compared with that of the pure BFO counterpart.

Synthesis and Electrochemical Characteristics of Li3V2(PO4)3/C Cathode Materials for Li-Ion Batteries

2014 ◽  
Vol 912-914 ◽  
pp. 356-361
Author(s):  
Lu Zheng ◽  
Hony Yuan Peng ◽  
Jian Hua Wang ◽  
Yu Zhong Guo
Keyword(s):  
Crystal Structure ◽  
Sol Gel ◽  
Carbon Sources ◽  
Particle Aggregation ◽  
High Rate ◽  
Electrochemical Performances ◽  
Electrochemical Characteristics ◽  
Preparation Conditions ◽  
Average Size ◽  
Charge Discharge

Li3V2(PO4)3/C composites were synthesized by sol-gel routine with citric acid as chelates and carbon sources at different preparation conditions , meanwhile saccharose has been used to separate the Li3V2(PO4)3/C particles When it dissolve out in the process of solvent volatilizing. The effects of different preparation conditions and the existence of saccharose on crystal structure and electrochemical performance were characterized by XRD, SEM and electrochemical workstation. The results shows that all the Li3 V2 (PO4)3 samples are pure monoclinic phase; The crystal structure and the lattice parameters remain unchanged in different conditions, but it has effects on their average size of particles. The existence of saccharose suppress the growth of particle size and particle aggregation, and then affect electrochemical performances indirectly. In addition , the cycling performances of all samples displayed well at 3.0~4.2V on low rate charge/discharge, but the rate performance become worse with the increasing of average size of particle and particle aggregation and the capacity reduces seriously on high rate charge/discharge.

The role of A-site cation size mismatch in tune the catalytic activity and durability of double perovskite oxides

2020 ◽  
Vol 270 ◽  
pp. 118868 ◽  
Author(s):  
Shengli Pang ◽  
Jie Xu ◽  
Yanjing Su ◽  
Gongmei Yang ◽  
Meng Zhu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Double Perovskite ◽  
Perovskite Oxides ◽  
Size Mismatch ◽  
A Site ◽  
Cation Size

scholarly journals Influence of crystal structure on the electrochemical performance of A-site-deficient Sr1−sNb0.1Co0.9O3−δ perovskite cathodes

RSC Advances ◽  
2014 ◽  
Vol 4 (77) ◽  
pp. 40865-40872 ◽  
Author(s):  
Yinlong Zhu ◽  
Ye Lin ◽  
Xuan Shen ◽  
Jaka Sunarso ◽  
Wei Zhou ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Electrochemical Performance ◽  
Charge Ordering ◽  
Orr Activity ◽  
A Site

Sr0.95Nb0.1Co0.9O3−δ (P4/mmm crystal structure), displaying a large JT distortion combined with charge-ordering of cobalt, shows improved ORR activity at low temperature, whereas Sr0.98Nb0.1Co0.9O3−δ (P4mm crystal structure), with a slight JT distortion, shows diminished performance.

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

Structural Transition and Magnetic Properties of (Sr2-3xLa2xBax)FeMoO6

2010 ◽  
Vol 663-665 ◽  
pp. 1036-1040
Author(s):  
Zhen Feng Xu ◽  
Jun Liang ◽  
Juan Pei ◽  
Yan Yan Yin ◽  
Chang Li
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Structural Transition ◽  
Double Perovskite ◽  
Perovskite Oxides ◽  
Cubic Phase ◽  
X Ray ◽  
Lattice Constants ◽  
Average Size ◽  
A Site

Ordered double perovskite oxides (Sr2-3xLa2xBax)FeMoO6 (0≤x≤0.3) have been investigated in this work. X-ray powder diffraction reveals that the crystal structure of the compounds changes from a tetragonal I4/m lattice to a cubic Fm 3m lattice around x=0.2. Though the nominal average size of the A site cation of (Sr2-3xLa2xBax)FeMoO6 is designed to be almost independent of x, the refinements of the crystal structure show that the lattice constants increase with x in both the tetragonal and the cubic phase regions due to electron doping. As the x increases, the degree of cationic ordering on the B site is decreased pronouncedly, while the Curie temperature of the compounds is nearly unchanged.

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