Spontaneous ferromagnetism at room temperature in oxygen-rich dicalcium cuprate Ca2CuO3+δ

1996 ◽  
Vol 11 (7) ◽  
pp. 1804-1809 ◽  
Author(s):  
Mahjoub A. Abdelgadir ◽  
Richard S. Burrows ◽  
Darl H. McDaniel
Keyword(s):  
Saturation Magnetization ◽  
Elemental Analysis ◽  
Applied Field ◽  
Room Temperature ◽  
Magnetic Impurity ◽  
Oxygen Depletion ◽  
Excess Oxygen ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar

Stoichiometric Ca2CuO3, having square-planar Cu-chains [C. L. Teske and H. Müller-Buschbaum, Z. Anorg. Allg. Chem. 379, 234 (1970); M. Hjorth and J. Hyldtoft, Acta Chem. Scand. 44, 516 (1990)], is expectedly antiferromagnetic due to 1D intrachain superexchange [K. Okuda, S. Noguchi, K. Konishi, H. Deguchi, and K. Takeda, J. Magn. Magn. Mater. 104–107, 817 (1992)]. Nonetheless, we report remarkable spontaneous ferromagnetism at 293 K after sintering, prominently in oxygen. This apparently introduced excess oxygen at vacant quasioctahedral sites, promoting spin-flip and ferromagnetic interchain coupling. Thermogravimetry (TGA) revealed excess oxygen, ≈0.17 O/Cu. X-ray diffraction (XRD) yielded a comparatively smaller unit cell. Ferromagnetism disappeared by oxygen depletion, mimicking reported nonmagnetism of Ca2CuO3−δ [Okuda et al. (1992)]. Elemental analysis showed insignificant magnetic impurity traces. Tc ranged between 680 K and 723 K, depending on freshness and purity. Saturation magnetization varied with processing, optimally 0.30 A · m2/kg at 1.0 T applied field. Coercivity and remanence varied with purity.

scholarly journals Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1023 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Chia-Liang Cheng ◽  
Sheng Yun Wu
Keyword(s):  
Room Temperature ◽  
Excess Oxygen ◽  
Ambient Atmosphere ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Oxygen Ion ◽  
Integrated Intensity ◽  
Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

A three-dimensional cyanide-bridged heterometallic coordination polymer: poly[[diacetonitrilediaqua[μ2-3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine-κ4N1,N6:N3,N4]tetra-μ-cyanido-tetracyanidodimanganese(II)molybdate(IV)] dihydrate]

2014 ◽  
Vol 70 (11) ◽  
pp. 1029-1032 ◽  
Author(s):  
Xiao-Juan Xu
Keyword(s):  
Magnetic Properties ◽  
Ir Spectroscopy ◽  
Coordination Polymer ◽  
Elemental Analysis ◽  
Room Temperature ◽  
Three Dimensional ◽  
Antiferromagnetic Coupling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Investigation

A metal coordination polymer, {[Mn2Mo(CN)8(C12H8N6)(CH3CN)2(H2O)2]·2H2O}n, has been synthesized by the reaction of Mn(ClO4)2·6H2O with 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine (bptz) and (Bu3N)3[Mo(CN)8] at room temperature. The polymer was characterized by IR spectroscopy, elemental analysis and X-ray diffraction, and the magnetic properties were also investigated. The X-ray diffraction analysis reveals that the compound is a new three-dimensional coordination polymer with a PtS-type network. Magnetic investigation shows antiferromagnetic coupling between adjacent Mn2+cations.

The thermal expansion and high temperature transformation of SnS and SnSe*

1979 ◽  
Vol 149 (1-2) ◽  
Author(s):  
Heribert Wiedemeier ◽  
Frank J. Csillag
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Melting Point ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Orthorhombic Modification ◽  
Temperature Transformation ◽  
Increasing Temperature

AbstractThe thermal expansion of SnS and SnSe has been studied above room temperature up to the melting point of 1163 ± 5K and 1135 ± 5K, respectively, by X-ray diffraction techniques using a 190 mm Unicam high temperature camera. The changes of the lattice parameters indicate that the atomic positions in the (010) plane approach a square planar arrangement with increasing temperature. The transformation of SnS and SnSe from orthorhombic to a pseudotetragonal orthorhombic modification with

Effect of Co Doping on the Superconducting Properties of Overdoped (Lu0.8Ca0.2)Ba2Cu3Oz

2006 ◽  
Vol 47 ◽  
pp. 108-112 ◽  
Author(s):  
Ho Keun Lee
Keyword(s):  
Thermoelectric Power ◽  
Room Temperature ◽  
Oxygen Depletion ◽  
Thermal Treatments ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
Heat Treated ◽  
Power Measurements

The effect of Co-doping and thermal treatments on the superconducting properties of the heavily overdoped (Lu0.8Ca0.2)Ba2Cu3Oz has been investigated by X-ray diffraction, resistivity and thermoelectric power measurements. A comparative analysis of the resistivity and thermoelectric power of the (Lu0.8Ca0.2)Ba2(Cu3-xCox)Oz and the heat-treated Co-free (Lu0.8Ca0.2)Ba2Cu3Oz reveals that, in the overdoped region, the hole carriers reduced by the Co doping and by the oxygen depletion play a very similar role in the superconducting properties. As a result, a nearly common inverted parabolic correlation is observed between Tc and the planar carrier concentration determined from the room-temperature thermoelectric power measurements.

Crystal structure of Diaqua(1,10-phenanthroline)copper(II) sulfate

1984 ◽  
Vol 37 (5) ◽  
pp. 1111 ◽  
Author(s):  
PC Healy ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Copper Atom ◽  
Title Compound ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Axial Coordination ◽  
Square Planar

The crystal structure of the title compound, [Cu(OH2)2(phen)] (SO4) (phen = 1,10-phenanthroline), has been determined by single-crystal X-ray diffraction methods at room temperature, being refined by full matrix least-squares methods to a residual of 0.033 for 1445 'observed' reflections. Crystals are monoclinic, C2/c, a 14.883(8), b 13.843(9), c 7.019(4) �, β 108.60(4)�, Z 4. As in a number of other copper(II) and nickel(II) derivatives with (CuL4)(SO4) stoichiometry, the pseudo-square planar copper environments [Cu-N,O: 2.009(2), 1.970(2) � in the present case] are bridged through the two axial coordination positions by sulfate groups: O.SO2.O[Cu(OH2)2(phen)]O.SO2.0, etc. to give a linear polymeric array [Cu-O(SO4), 2.468(3) �]; a crystallographic twofold axis passes through the copper atom.

1,3-Thiazole as Suitable Antenna Ligand for Lanthanide Photoluminescence in [LnCl3(thz)4]·0.5thz, Ln = Sm, Eu, Gd, Tb, Dy

2014 ◽  
Vol 69 (2) ◽  
pp. 255-262 ◽  
Author(s):  
Nicole Dannenbauer ◽  
Ana Kuzmanoski ◽  
Claus Feldmann ◽  
Klaus Müller-Buschbaum
Keyword(s):  
Elemental Analysis ◽  
Room Temperature ◽  
Visible Region ◽  
Lanthanide Ions ◽  
X Ray Diffraction ◽  
Sulphur Atom ◽  
Antenna Effect ◽  
Transfer Energy ◽  
X Ray ◽  
Antenna Ligand

The series of luminescent monomeric lanthanide thiazole complexes [LnCl3(thz)4]⋅0.5thz (Ln = Sm, Eu, Gd, Tb, Dy; thz=1,3-thiazole) has been synthesised and characterised by powder and singlecrystal X-ray diffraction, IR and photoluminescence spectroscopy, DTA/TG as well as elemental analysis. The colourless compounds exhibit photoluminescence in the visible region with varying quantum efficiencies up to QY = 48% for [TbCl3(thz)4]⋅0.5thz. Both, the lanthanide ions as well as the thiazole ligand contribute to the luminescence. Excitation can be achieved via intra-4 f transitions and by exciting the ligand, emission is observed mainly from the lanthanide ions again by 4 f transitions. Thiazole can transfer energy to the lanthanide ions, which further feeds the lanthanide emission by an efficient antenna effect even at room temperature. The lanthanide ions show pentagonalbipyramidal coordination by three chloride anions and four N atoms of 1,3-thiazole, which leads to a strong 5D0 →7F4 transition for europium. Significant differences arise as compared to thiophene complexes because no sulphur atom is involved in the metal coordination, as the thiazole ligand is solely coordinated via its nitrogen function.

The Microdefects, Magnetic Properties and Electron Characters of Fe-Ga Alloys

2017 ◽  
Vol 373 ◽  
pp. 167-170
Author(s):  
Ding Kang Xiong ◽  
H.Q. Wei ◽  
W.T. Liu ◽  
Yu Yang Huang ◽  
Wen Deng
Keyword(s):  
Saturation Magnetization ◽  
Room Temperature ◽  
Positron Lifetime ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Positron Lifetime Spectroscopy ◽  
Diffraction Patterns ◽  
Electron Paramagnetic

The microdefects, magnetic magnetization curves and electric characters of Fe100-xGax (x=16, 17, 18, 19, 20) were investigated by the means of X-ray diffraction, VSM modular on PPMS, positron lifetime spectroscopy and electric paramagnetic resonance spectroscopy. The X – ray diffraction patterns show that the Fe100-xGax alloys is similar to that of α – Fe, but the peaks move to low angle slightly. The result indicates Ga entered the iron lattice and the larger radium lead to the changing of the patterns. Positron lifetime spectra show that the intensity of the defects of the Fe100-xGax alloys varies obviously with different Ga content. The magnetizing curves were measured to check the saturation magnetization at room temperature. The variations of saturation magnetization do not monotonic decrease as expect with the increasing of Ga. When x=18, the magnetization is maximum; the minimum is x=20 because of the lowest iron content. The electron paramagnetic resonance spectrum shows that the peaks become narrower when the x decreases from 20 to 16. These results indicate that the addition of Ga has effect on the 3d electrons of Fe.

FABRICATION OF BaFe12O19 NANOWIRES BY A HYDROTHERMAL PROCESS AND THEIR MAGNETIC PROPERTIES

2006 ◽  
Vol 20 (07) ◽  
pp. 359-364 ◽  
Author(s):  
JUN WANG ◽  
YUEJIN ZHU
Keyword(s):  
Electron Microscopy ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Hydrothermal Process ◽  
Annealing Treatment ◽  
Magnetization Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Magnetic BaFe 12 O 19 nanowires have been prepared by a hydrothermal process. The nanowires with diameters ~ 15 nm and lengths ~ 2 μ m are clearly visible in Transmission Electron Microscopy (TEM) image. The physical properties of the BaFe 12 O 19 nanowires were further characterized by X-ray diffraction (XRD) and magnetization measurement. The results of the magnetization measurement show that the sample displays ferromagnetic properties at room temperature and its saturation magnetization (Ms) reaches 13.36 emu/g. Annealing treatment of the sample in air at 800°C leads to the increasing of the saturation magnetization (Ms: 65.7 emu/g). It is suggested that the oxygen vacancies should be responsible for the low saturation magnetization, which is also supported by the magnetic property (Ms: 21.6 emu/g) of the sample annealed at 800°C in argon shield.

Synthesis, Structure and Photoluminescence of a Potential Luminescent Material of Mn(II) Coordination Polymer

2012 ◽  
Vol 528 ◽  
pp. 206-209 ◽  
Author(s):  
Xiu Ling Zhang ◽  
Kai Cheng ◽  
Yu Lan Song
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Coordination Polymer ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Room Temperature ◽  
Luminescent Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
1D Chain

A new coordination polymer [Mn3(IP)(4,4'-obb)3]n (1) (4,4'-obb = 4,4'-Oxybisbenzoic acid, IP = 1H-imidazo[4,5-f][1,10]-phenanthroline) was synthesized and characterized by IR, elemental analysis and X-ray diffraction. Single-crystal X-ray analyses revealed that the compound demonstrates 1D structure in which the Mn2+ centers are connected via 4,4'-obb anions into 1D chain, the chains are further connected via hydrogen - bonding and π ••• π interactions. In addition, the photoluminescence for compound 1 is also investigated in the solid state at room temperature.

Characterization, luminescent properties, and crystal structure determination of [Pt(Ph2bipy)Cl2]

2016 ◽  
Vol 57 (8) ◽  
pp. 1773
Author(s):  
S. Shamaei ◽  
A. Heidari ◽  
V. Amani
Keyword(s):  
Structure Determination ◽  
Room Temperature ◽  
Diffraction Method ◽  
Luminescent Properties ◽  
Luminescence Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Orange Solution

New complex [Pt(Ph2bipy)Cl2] (1) is obtained from the reaction of H2PtCl6×6H2O and 4,4'-diphenyl-2,2'-bipyridine (Ph2bipy) in a mixture of methanol, chloroform, and dimethyl sulfo­xide. Suitable crystals of 1 for the diffraction experiment are obtained by slow evaporation of the resulted orange solution at room temperature. This complex is characterized by elemental analysis, IR, 1H NMR, UV-Vis, and luminescence spectroscopy and its structure is studied by the single crystal X-ray diffraction method. X-ray structure determination shows that in the structure of this compound, the Pt(II) atom is four-coordinated in a distorted square-planar configuration by two nitrogen atoms from a bidentate 4,4'-diphenyl-2,2'-bipyridine ligand and two terminal chlorine atoms.

Sign in / Sign up

Export Citation Format

Share Document