Composition of Superconducting La2CuO4+δ a Superconductor Doped by excess Oxygen Defects

1989 ◽  
Vol 156 ◽  
Author(s):  
B. Dabrowski ◽  
D. G. Hinks ◽  
J. D. Jorgensen ◽  
D. R. Richards
Keyword(s):  
Thermogravimetric Analysis ◽  
Metal Ion ◽  
Neutron Powder Diffraction ◽  
Excess Oxygen ◽  
Rich Phase ◽  
Resistivity Measurements ◽  
Oxygen Defects ◽  
Ion Substitution ◽  
Occurrence Of Superconductivity ◽  
Semiconducting Behavior

ABSTRACTWe have studied mixed-phase samples of bulk LazCuO4 using neutron powder diffraction, thermogravimetric analysis and resistivity measurements. Samples fired at 950°C and slowly cooled form in the K2NiF4 structure with CuO impurities for z<2 and La2O3 impurities for z>2. Neither La-vacancies nor stacking defects were found. The bulk resistivity of the samples show semiconducting behavior which is shorted at 38K by small amounts of superconducting material. The superconductivity is due to the presence of an oxygen-rich phase with stoichiometry La2CuO4.08. The occurrence of superconductivity in pure La2CuO4.08 with the same Tc as observed in the doped La1.85 Sr0.15CuO4 indicates that the excess oxygen provides the same level of doping as metal-ion substitution.

scholarly journals Nb Substitution Effects on Superconducting Properties ofRu1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Maldonado-Mejía ◽  
J. D. Quiz-Celestino ◽  
M. E. Botello-Zubiate ◽  
S. A. Palomares-Sánchez ◽  
J. A. Matutes-Aquino
Keyword(s):  
Solid State Reaction Method ◽  
Substitution Effects ◽  
Superconducting Transition ◽  
Metallic Behavior ◽  
Resistivity Measurements ◽  
Niobium Doping ◽  
Method Substitution ◽  
Insight Into ◽  
Semiconducting Behavior

In order to gain further insight into the role of substitution of Ru by Nb on superconductivity, polycrystalline samples of Ru1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ  (0.0 ≤x≤ 1.0) have been synthesized by solid-state reaction method. Substitution of Nb at the Ru site in the system takes place isostructurally in the tetragonal structure (space groupI4/mmm) with full solubility (x= 1.0). Superconductivity exists for all compositions. Resistivity measurements in function of temperature from 0 to 300 K were done using the four-probe technique. It is found that the substitution of Ru5+for Nb5+depresses the superconductivity of samples fromTc = 29 K forx= 0.0 toTc = 5 K forx= 1.0 (whereTcis the critical temperature, when resistivity becomes equal to zero). In the normal state, the dependence of resistivity with temperature, for compositions withx = 0.0 and 0.2, shows a metallic behavior, while for compositions betweenx= 0.4 andx= 1 it shows a semiconducting behavior. In that way, the density of charge carriers is reduced with niobium doping, leading to the semiconducting behavior. The resistive transition to the superconducting state of all samples is found to be affected by granularity. Samples undergo double superconducting transition.

A novel isotachophoresis of cobalt and copper complexes by metal ion substitution reaction in a continuous moving chelation boundary

The Analyst ◽  
2010 ◽  
Vol 135 (1) ◽  
pp. 140-148 ◽  
Author(s):  
Wei Zhang ◽  
Jian-Feng Chen ◽  
Liu-Yin Fan ◽  
Cheng-Xi Cao ◽  
Ji-Cun Ren ◽  
...  
Keyword(s):  
Substitution Reaction ◽  
Metal Ion ◽  
Copper Complexes ◽  
Ion Substitution

Half-rotation in a kinetically locked [2]catenane induced by transition metal ion substitution

2012 ◽  
Vol 48 (47) ◽  
pp. 5826 ◽  
Author(s):  
David A. Leigh ◽  
Paul J. Lusby ◽  
Alexandra M. Z. Slawin ◽  
D. Barney Walker
Keyword(s):  
Transition Metal ◽  
Metal Ion ◽  
Transition Metal Ion ◽  
Ion Substitution

Metal ion substitution chemistry in the yttrium barium copper oxide system as a probe of the superexchange pathway

1988 ◽  
Vol 110 (20) ◽  
pp. 6716-6720 ◽  
Author(s):  
Ruth. Jones ◽  
Peter P. Edwards ◽  
Martin R. Harrison ◽  
Thitinant. Thanyasiri ◽  
Ekkehard. Sinn
Keyword(s):  
Yttrium Barium Copper Oxide ◽  
Copper Oxide ◽  
Metal Ion ◽  
Barium Copper Oxide ◽  
Oxide System ◽  
Barium Copper ◽  
Substitution Chemistry ◽  
Ion Substitution ◽  
Yttrium Barium

Excess Oxygen in 12CaO·7Al2O3Studied by Thermogravimetric Analysis

2005 ◽  
Vol 34 (4) ◽  
pp. 586-587 ◽  
Author(s):  
Katsuro Hayashi ◽  
Masahiro Hirano ◽  
Hideo Hosono
Keyword(s):  
Thermogravimetric Analysis ◽  
Excess Oxygen

5-Coordinate Compounds of Nickel(II) and Copper(II) With the Triamine Diimine Ligands 13-imino-4,4,6,11,11-pentamethyl-3,7,10-Triazatetradec-6-en-1-amine and 4,6,11-Triethyl-13-imino-4,11-dimethyl-3,7,10-triazapentadec-6-en-1-amine

1988 ◽  
Vol 41 (6) ◽  
pp. 957 ◽  
Author(s):  
NF Curtis
Keyword(s):  
Ground State ◽  
Metal Ion ◽  
Colour Change ◽  
Singlet Ground State ◽  
Diimine Ligands ◽  
Protonation Reaction ◽  
Square Planar ◽  
Ion Substitution ◽  
Secondary Amino ◽  
Coloured Complex

Reaction of nickel(II) with 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate in the presence of ammonia yields a lilac- coloured complex of nickel(II) with 13-imino-4,4,6,11,11-pentamethyl-3,7,10-triazatetradec-6-en-1-amine, a pentadentate ligand with one primary and two secondary amino, plus one primary and one secondary imino , donor groups. The copper(II) complex of the ligand was formed from the nickel(II) compound by metal-ion substitution. The cations have d-d spectra indicative of five-coordination. The complex cations undergo a reversible protonation reaction with a change from five-coordinate to square planar, with a colour change for nickel(II) from lilac (triplet ground state) to yellow (singlet ground state), and for copper(II) from blue to violet. The compounds of the homologous ligand 4,6,11-triethyl-13-imino-4,11- dimethyl-3,7,10-triazapentadec-6-en-1-amine were similarly prepared, and have similar properties.

Selective Catalytic Reduction of NOx: Mechanistic Perspectives on the Role of Base Metal and Noble Metal Ion Substitution

2008 ◽  
Vol 47 (23) ◽  
pp. 9240-9247 ◽  
Author(s):  
Sounak Roy ◽  
A. Marimuthu ◽  
Parag A. Deshpande ◽  
M. S. Hegde ◽  
Giridhar Madras
Keyword(s):  
Selective Catalytic Reduction ◽  
Base Metal ◽  
Noble Metal ◽  
Metal Ion ◽  
Catalytic Reduction ◽  
Ion Substitution ◽  
Reduction Of Nox
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