Evidence of Hole Self-Doping due to Excess Oxygen Addition in Polycrystal LaMnO3

2021 ◽  
Vol 1023 ◽  
pp. 9-13
Author(s):  
Hiromi Kobori ◽  
Megumi Sogabe ◽  
Akinori Hoshino ◽  
Atsushi Yamasaki ◽  
Toshifumi Taniguchi ◽  
...  
Keyword(s):  
Solid State Reaction Method ◽  
Molar Ratio ◽  
Excess Oxygen ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
Gas Atmosphere ◽  
Electrical Resistivities ◽  
Oxygen Gas ◽  
Oxygen Addition

We have presented the evidence of hole self-doping due to excess oxygen addition in polycrystal LaMnO3 (LMO). The polycrystal LMO samples were prepared by use of a solid-state reaction method. Powder mixtures with a molar ratio of 1:1 between La2O3 and Mn2O3 were pre-annealed at 1100oC for 18 hours in the atmospheres of oxygen gas, helium gas and vacuum. By this heat treatment, non-crystalline LMO samples were produced. After that, the non-crystalline LMO samples were grinded and were pressed into pellets at the pressure of 3t/cm3. The pellets were annealed at 1100oC and 1300oC for 18 hours in the same atmospheres as the pre-annealing. Through these processes, polycrystal LMO samples were finally produced. To investigate crystallographic structure of the LMO samples, X-ray diffraction (XRD) measurements were performed by use of Cu-K radiation. From the experimental results of XRD measurements, we have found that all LMO samples have perovskite structure and are polycrystals. In addition, to investigate surface structure of the LMO samples, scanning electron microscope (SEM) measurements were carried out. Electrical resistivities (ERs) of the polycrystal LMO samples were measured as a function of temperature (4K-300K). The ERs of polycrystal LMO samples produced in an oxygen gas atmosphere show lower values as compared with other LMO ones in He gas and vacuum atmospheres. Especially, the temperature dependence of the ER for a polycrystal LMO sample produced at the annealing temperature of 1100oC in an oxygen atmosphere shows a metallic behavior. Thus, we have considered that this LMO sample has the largest hole self-doping concentration in all LMO ones.

Superconducting Properties of Calcium Substitution in Barium Site of Porous YBa2Cu3O7 Ceramics

2012 ◽  
Vol 501 ◽  
pp. 294-298 ◽  
Author(s):  
A.W. Norazidah ◽  
H. Azhan ◽  
K. Azman ◽  
H.N. Hidayah ◽  
J.S. Hawa
Keyword(s):  
Critical Current ◽  
Solid State Reaction Method ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
X Ray ◽  
Structure Morphology ◽  
Small Change ◽  
Critical Current Density Jc ◽  
Barium Site

The influence of calcium substitution at the barium site of porous Y(Ba1-xCax)2Cu3Oδ (x= 0.00, 0.10, 0.20 and 0.30) samples prepared via solid-state reaction method have been investigated. The structure, morphology, critical temperature and critical current were determined by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and four-point probe method, respectively. Generally, the curves of normalized resistance for all samples displayed normal metallic behavior above Tc onset. The Tc zero was between 84 K and 71 K with increase in Ca concentration corresponding to a small change of carrier concentration. The critical current density, Jc decreases with increase in Ca concentration. The highest Jc of 2.657 A/cm2 at 50 K was obtained in Ca-free porous YBCO which is higher than that of Ca-free non porous YBCO. Further substitution of Ca at Ba site decreased Jc monotonously. The increase of Ca concentration decreased the volume of unit cell but the crystallographic structure remains in the orthorhombic form where a≠b≠c. The grains are highly compacted and randomly distributed while the grain size decreased as the Ca concentration increased.

Performance of B-Doped SrTiO3/ Ni Sheet for Supercapacitor Material Application

2020 ◽  
Vol 851 ◽  
pp. 25-31
Author(s):  
Markus Diantoro ◽  
Ahmad Al Ittikhad ◽  
Thathit Suprayogi ◽  
Nasikhudin ◽  
Joko Utomo
Keyword(s):  
Electrode Materials ◽  
Solid State Reaction Method ◽  
Raw Material ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Energy Storage Devices ◽  
Xrd Pattern ◽  
X Ray ◽  
Storage Devices

The development of energy storage devices encourages the sustainability of research on basic materials of supercapacitor technology. SrTiO3 is one of metal oxide called as titanate alkali metal ATiO3 (A = Ba, Sr, Ca). This material shows an excellent dielectric constant, thus expected to be potential as raw material of supercapacitor. In this work, boron was used as a dopant on the SrTiO3 system to modify its local structure and enhance the electrical properties. Synthesis SrTi1-xBxO3 was carried out using a solid-state reaction method followed by the sintering process in various molar ratio. The microstructure of SrTi1-xBxO3 compound was identified by X-ray Diffraction with Cu-Kα. XRD pattern identified the presence of SrTi1-xBxO3 phase with a slight change in the lattice parameters. I-V measurement confirmed that the electrical conductivity increased gradually up to 16.04 Ω-1cm-1. For investigating their application for electrode materials, CV was employed and it presents that the specific capacitance and energy density of x = 0.08 were 5.488 Fg-1 and 0.110 Jg-1.

Effect of Antimony (Sb) Substitution on Ba-Site of Porous Structured YBA2Cu3Oδ Superconductor

2018 ◽  
Vol 7 (3.28) ◽  
pp. 106
Author(s):  
Fariesha Farha Ramli ◽  
Azhan Hashim
Keyword(s):  
Resistivity Measurement ◽  
Crystallographic Structure ◽  
Ybco Superconductor ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Metallic Behavior ◽  
Sb Doping ◽  
Sem Micrograph ◽  
High Level

The effect of antimony (Sb) substitution on Ba-site of porous structure YBa2Cu3Oδ (YBCO) superconductor was investigated. Polycrystalline sucrose was used to create the open pores in the structure. A series of sample with a nominal composition of YBa2-xSbxCu3Oδ where x = 0.05, 0.10, 0.15, 0.20, 0.30, 0.40 and 0.50 were synthesized and characterized using X-ray diffraction (XRD) method, resistivity measurement technique and Scanning Electron Microscopic (SEM) equipment. For porous Sb-doped sample with x ≤ 0.30, the samples showed metallic behavior above onset critical temperature (TC onset) while semiconducting behavior was shown for x ³ 0.40. The optimum Sb concentration was achieved at x = 0.15, where TC zero is 85 K and critical current (JC) value measured at 70 K is 2.75 A/cm2. TC onset and TC zero of the sample were suppressed towards higher Sb concentration. High level of Sb concentration resulted in the non-superconducting sample and Sb was not incorporated properly into YBCO system. Generally, the crystallographic structure with 123 phase remains as orthorhombic. But, for Sb doping at x = 0.30, the sample exhibits tetragonal structure before the presence of 211 phase with the higher Sb concentration. SEM micrograph for porous sample showed the less dense packing with irregular grain shape compared to the standard sample where the small rounded particles grains that can be clearly seen. It can be summarized that the superconducting properties were attributed mainly by the dopants compared to the porous characteristic. 

Synthesis and Characterization of Low Density Bi-2223 Cuprates Superconductor Doped Eu2O3 Nanoparticles

2021 ◽  
Vol 317 ◽  
pp. 131-137
Author(s):  
Suhaimi Nurbaisyatul Ermiza ◽  
Azhan Hashim ◽  
Azman Kasim ◽  
Norazila Ibrahim ◽  
Siti Fatimah Saipuddin
Keyword(s):  
Solid State Reaction Method ◽  
Synthesis And Characterization ◽  
Crystallographic Structure ◽  
Low Density ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Resistivity Measurements

Bi1.6Pb0.4Sr2Ca2-xEuxCu3Oδ cuprates superconductor doped with Eu nanoparticles (x = 0.0000, 0.0025, 0.0200 and 0.0500) were synthesized through conventional solid state reaction method. Crystalline sucrose was added during pelletization and burn at 400°C for two hours to create low density sample. The effect of doping Eu2O3 nanoparticles on the structural and superconducting properties by means of critical temperature (Tc), critical current density (Jc), X-ray diffraction (XRD) together with Field Emission Scanning Electron Microscopy (FESEM) and Alternating Current Susceptibility (ACS) were studied. Based on XRD analyses, the crystallographic structure has shown slightly changed from tetragonal to orthorhombic. The amount of 2223 phase gradually decreased with the increment of Eu concentration which indicates that Eu nanoparticles substitution favours the growth of 2212 phases. The resistivity measurements show that the highest Tcvalue for doped samples found at 90 K for x = 0.0025. The FESEM images showed that the plate-like grains become smaller and distributed randomly without specific alignment due to the increment of Eu concentration.

Decreased Thermal Conductivity of CaMnO3 by Added-CNTs

2013 ◽  
Vol 770 ◽  
pp. 327-330
Author(s):  
Prapawan Thongsri ◽  
Tosawat Seetawan
Keyword(s):  
Thermal Conductivity ◽  
Manganese Oxide ◽  
Figure Of Merit ◽  
Solid State Reaction Method ◽  
Precursor Powder ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensionless Figure Of Merit

The CaMnO3compound is synthesized by solid state reaction method. The precursor powder of calcium carbonate (CaCO3) and manganese oxide (MnO2) are mixed by ball milling then calcined at 850°C for 10 h and sintering at 1,150 °C for 36 h to obtain the calcium manganese oxide (CaMnO3) compound. The compound was doped the carbon nanotubes (CNTs) 2%, 4%, 6%, 8% and 10% by molar ratio following the calcinations and sintering process. The morphology and crystallography of the samples are analyzed by the X-ray diffraction (XRD) technique and scanning electron microscope (SEM). The Seebeck coefficient (S), electrical resistivity (ρ), thermal conductivity (κ) and dimensionless figure of merit were anlyzed. It results shown in a good thermoelectric properties after doping CNTs.

scholarly journals Superconducting Properties of Bi2-xPb0.3WxSr2Ca2Cu3O10+ Compounds

2021 ◽  
pp. 490-495
Author(s):  
Mohammed J. Tuama ◽  
Lamia K. Abbas
Keyword(s):  
Volume Fraction ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Crystallographic Structure ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Two Phases ◽  
Parameter Values

The conventional solid-state reaction method was utilized to prepare a series of superconducting samples of the nominal composition Bi2-xPb0.3WxSr2Ca2Cu3O10+d with 0≤x≤0.5 of 50 nm particle size of tungsten sintered at 8500C for 140h in air . The influence of substitution with W NPs at bismuth (Bi) sites was characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and dc electrical resistivity. Room temperature X-ray diffraction analysis revealed that there exists two phases, i.e. Bi-(2223) and Bi-(2212), in addition to the impurity phases of (SrCa) 2Cu2O3, Sr2Ca2Cu7Oδ, Ca2PbO4, CaO, and WO. It was found that the crystallographic structure of all samples was orthorhombic. Lattice parameter values and the volume fraction of the (2223)-phase of the prepared samples were also calculated. The superconductivity transition temperature (Tc) for samples subjected to substitution with W NPs was found to be higher than that for the pure sample. The optimal value of W NPs content in (Bi, Pb)-2223 system was found to be at x=0.3. 

The Effects of Nanoparticle Addition in Bi-2212 Superconductors

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
M. A. Suazlina ◽  
S. Y. S. Yusainee ◽  
H. Azhan ◽  
R. Abd-Shukor ◽  
R. M. Mustaqim
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Density Measurement ◽  
Solid State Reaction Method ◽  
Crystallographic Structure ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Oxide Powders ◽  
Critical Current Density Jc

The effect of Y2O3 nanoparticle addition on the superconducting properties of Bi1.6Pb0.4Sr 2CaCu 2Oy have been investigated. The samples were prepared using high purity oxide powders via solid state reaction method. Y2O3 nanoparticle with 0.0-1.0 wt. % was systematically added to the well balanced Bi1.6Pb0.4 Sr2CaCu2Oy before sinter in order to trace the existense of nanoparticle addition in the system. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and critical current density, Jc. The current density measurement was done via four-point probe method under zero magnetic fields. The critical current density, Jc and superconductivity transition temperature, Tc for sample with addition of Y2O3 nanoparticle were found to be higher than the pure sample. The optimal addition of Y2O3 nanoparticle to the sample Bi-2212 system was found at 0.7 wt. %. The crystallographic structure of all samples was evidenced to be orthorhombic where a ≠ b ≠ c. Changes in superconducting properties of Y2O3 nanoparticle added Bi-2212 system were discussed.

Electrical and Structural Properties of Ca Substitution in High and Low Density Y(Ba1-xCax)2Cu3O7-δ Superconductor

2016 ◽  
Vol 846 ◽  
pp. 586-590
Author(s):  
Azhan Hashim ◽  
Abd Wahab Norazidah ◽  
Azman Kasim ◽  
A. Nazree ◽  
S. Akmal Syamsyir ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Structural Properties ◽  
Structural Identification ◽  
Solid State Reaction Method ◽  
High Density ◽  
Crystallographic Structure ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ca Substitution

The effect of Ca substitution on the electrical and structural properties in high and low density Y(Ba1-xCax)2Cu3Oδ where x = 0.00, 0.10, 0.20 and 0.30 via solid state reaction method has been investigated. The electrical properties, elemental analysis, and structural identification were measured by the four-point probe technique, energy dispersive x-ray (EDX) and X-ray diffraction (XRD) respectively. The electrical properties such as critical temperature (Tc) and critical current density (Jc) were found to be strongly dependent in both high and low densities Y(Ba1-xCax)2Cu3O7-δ. These parameters were decreased monotonously with the increasing of Ca substitution. An obvious results of the Ca-doped samples can be seen in x = 0.20 where Tc zero of high density sample is 77 K, which is higher than that of the low density sample that occurred at 73 K. Meanwhile, Jc at 60 K for high density is 1.842 A/cm2 compared to 1.410 A/cm2 in low density sample. EDX analysis confirmed the existence of Ca in all doped samples. The crystallographic structure remained orthorhombic and the volume of unit cell increased towards further increased of Ca concentration.

On the Properties of an Ion Conductive System Incorporated in Hybrid Films

2000 ◽  
Vol 628 ◽  
Author(s):  
G. González ◽  
P. J. Retuert ◽  
S. Fuentes
Keyword(s):  
Electrochemical Impedance ◽  
Ternary Phase Diagram ◽  
Lithium Perchlorate ◽  
Molar Ratio ◽  
Ionic Conductors ◽  
X Ray Diffraction ◽  
Poly Ethylene Oxide ◽  
Ion Conducting ◽  
Poly Ethylene ◽  
High Degree

ABSTRACTBlending the biopolymer chitosan (CHI) with poly (aminopropilsiloxane) oligomers (pAPS), and poly (ethylene oxide) (PEO) in the presence of lithium perchlorate lead to ion conducting products whose conductivity depends on the composition of the mixture. A ternary phase diagram for mixtures containing 0.2 M LiClO4 shows a zone in which the physical properties of the products - transparent, flexible, mechanically robust films - indicate a high degree of molecular compatibilization of the components. Comparison of these films with binary CHI-pAPS nanocomposites as well as the microscopic aspect, thermal behavior, and X-ray diffraction pattern of the product with the composition PEO/CHI/pAPS/LiClO4 1:0.5:0.6:0.2 molar ratio indicates that these films may be described as a layered nanocomposite. In this composite, lithium species coordinated by PEO and pAPS should be inserted into chitosan layers. Electrochemical impedance spectroscopy measurements indicate the films are pure ionic conductors with a maximal bulk conductivity of 1.7*10-5 Scm-1 at 40 °C and a sample-electrode interface capacitance of about 1.2*10-9 F.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

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