Magnetic Properties of Microcrystalline Poly(Phenyl- Diacetylenes) Carrying Radical or Carbene Centers on the Side Chains

1989 ◽  
Vol 173 ◽  
Author(s):  
Noboru Koga ◽  
Katsuya Inoue ◽  
Noriko Sasagawa ◽  
Hiizu Iwamura
Keyword(s):  
Cryogenic Temperature ◽  
Room Temperature ◽  
X Ray ◽  
Spontaneous Polymerization ◽  
Weakly Coupled ◽  
Two Samples ◽  
Phenyl Rings ◽  
Insoluble Polymer ◽  
Polymeric Samples ◽  
Triplet Carbene

ABSTRACT1-Phenyl-l,3-butadiyne derivatives (3 and 4) carrying stable t-butylnitroxide and diazomethyl groups, respectively, have been prepared. Mixed crystals of 3 and the corresponding hydroxylamine 2 (x003c:1:1) polymerized in the solid state at 100°C to give black-violet microcrystals with a metallic luster. A microcrystalline sample of 4 underwent spontaneous polymerization at room temperature when crystallized to give an insoluble polymer which was then photolyzed at cryogenic temperature to generate triplet carbene centers attached to the phenyl rings of the poly(phenyldiacetylene). Some of these microcrystalline polymeric samples were responsive to a magnet at room temperature. Magnetic susceptibility measurements on the two samples revealed only weakly coupled independent spins Hydrogen bonding between the polydiacetylene chains as estimated by X-ray crystal structure of 2 is expected to be effective for increasing the dimension of the spin alignment.

ROOM TEMPERATURE MAGNETIC ANOMALIES IN BENZENE TREATED Bi–Pb–Sr–Ca–Cu–O POWDER

1991 ◽  
Vol 05 (21) ◽  
pp. 1447-1456 ◽  
Author(s):  
A. R. HARUTUNYAN ◽  
L. S. GRIGORYAN ◽  
A. S. KUZANYAN ◽  
A. A. KUZNETSOV ◽  
A. A. TERENTIEV ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chemical Composition ◽  
Room Temperature ◽  
Microprobe Analysis ◽  
Magnetic Anomalies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Samples ◽  
Field Dependent ◽  
History Of

Two samples of benzene-treated Bi–Pb–Sr–Ca–Cu–O powder exhibited at 300 K magnetic field dependent diamagnetism and magnetization irreversibility. The treatment with benzene resulted also in the appearance of microwave absorption at low magnetic fields, while is sensitive to magnetic history of the sample. From X-ray diffraction data one can see that upon benzene treatment the reflections of 85 K and 110 K phases do not change practically, but a series of new reflections appeared, indicating a lattice modulation with 4.9 nm periodicity. A microprobe analysis revealed substantial inhomogeneity of chemical composition across the samples. The room temperature anomalies were weakened in one sample and vanished in the second upon thermal cycling.

scholarly journals NMR and X-ray Studies Concerning Structure of 6,6’-(Oxybis(4,1-phenylene))bis-(2-allylpyridazin- 3(2H)-one)

2014 ◽  
Vol 22 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Vasilichia Antoci ◽  
Mircea Apostu ◽  
Catalina Ciobanu ◽  
Dorina Mantu
Keyword(s):  
Phenyl Ring ◽  
Room Temperature ◽  
Heterocyclic System ◽  
Crystal Packing ◽  
Diphenyl Ether ◽  
The Novel ◽  
X Ray ◽  
Pyridazine Ring ◽  
Phenyl Rings ◽  
C Nmr

Abstract The structural NMR and X-ray studies of 6,6’-(Oxybis(4,1- phenylene))bis-(2-allylpyridazin-3(2H)-one), a bis-pyridazine derivative heterocycle, are reported in this study. Both 1H- and 13C- NMR confirm the proposed structure of compound. In order to establish unequivocally the structure of compound, the X-ray data analysis was performed. The compound crystallizes in the triclinic P-1(2) space group with a = 10.3699(7) Å, b = 10.6972(6) Å, c = 11.0449(4) Å, α = 87.941(5)°, β = 75.564(5)°, γ = 72.055(5)°, V= 1127.68 (12) Å3 and Z = 2. Molecular and crystal packing parameters for the novel heterocyclic system were obtained from intensity data collected at room temperature. The two phenyl rings (from the diphenyl ether moiety) are perpendicular one to each other and, on its turn, each phenyl ring is almost coplanar with the pyridazine ring

Room Temperature Ferromagnetism and its "Switch" Behaviour in some Dilute Magnetic Oxides: an Electronic Structure and Magnetization Study

2011 ◽  
Vol 171 ◽  
pp. 19-38 ◽  
Author(s):  
R.K. Singhal
Keyword(s):  
Electronic Structure ◽  
Quantum Interference ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Diluted Magnetic Semiconductor ◽  
Room Temperature Ferromagnetism ◽  
Secondary Phase ◽  
X Ray ◽  
Two Samples ◽  
Doped Zno

ZnO doped with a few per cent of magnetic ions such as Ni, Fe, Co exhibits room temperature ferromagnetism (RTFM), transforming it into a very promising candidate for future spintronic applications. Two samples i.e. ZnO doped with Ni and Cr (5% each) have been investigated in the present work. The samples were characterized by Rietveld refinement of X-ray diffraction (XRD) patterns and the superconducting quantum interference device (SQUID) magnetometry. Rietveld analysis confirms that both the polycrystalline samples possess wurtzite structure with no evidence of any secondary phase. The SQUID measurements exhibit a diamagnetic state for the pristine ZnO and a paramagnetic state for the as-synthesized (Cr and Ni)-doped ZnO samples. However, the post annealing in H2 and vacuum drive them to a remarkable ferromagnetic state at room temperature. No element specific signature for ferromagnetism was seen. Then the X-ray photoelectron spectroscopic (XPS) measurements were performed to investigate their electronic structure and exploring the origin of ferromagnetism in these diluted magnetic semiconductor materials. The XPS results confirm the creation of oxygen vacancies upon Hydrogen/ vacuum annealing, owned to the (Ni/Cr) 3d¬−O 2p hybridization. The findings suggest oxygen vacancies as the intrinsic origin for ferromagnetism in doped ZnO. The important feature of this work is that the ferromagnetism and the consequent electronic property changes are found to be reversible with regard to re-heating the samples in air, showing a switch “on” and “off” ferromagnetic ordering in the ZnO matrix.

scholarly journals Synthesis and structure of the donor-free potassium silanide K[SiPh3]

2019 ◽  
Vol 74 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Edith Alig ◽  
Isabelle Georg ◽  
Inge Sänger ◽  
Lothar Fink ◽  
Matthias Wagner ◽  
...  
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
State Structure ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Solid State Structure ◽  
X Ray ◽  
Phenyl Rings ◽  
Short Contacts

AbstractThe donor-free potassium silanide K[SiPh3] was prepared by the reaction of hexaphenyldisilane, Ph3Si–SiPh3, with potassium metal in benzene at room temperature. The solid-state structure, determined by powder X-ray diffraction consists of {K[SiPh3]}2 units, which interact with adjacent dimers to form an infinite chain along the crystallographic c axis (orthorhombic, space group Cmc21, Z=4). The structure features short contacts between the π system of the phenyl rings and the potassium atoms of neighbouring K[SiPh3] units.

scholarly journals Laser system design for table-top X-ray light source

2018 ◽  
Vol 6 ◽  
Author(s):  
Anne-Laure Calendron ◽  
Joachim Meier ◽  
Michael Hemmer ◽  
Luis E. Zapata ◽  
Fabian Reichert ◽  
...  
Keyword(s):  
System Design ◽  
Light Source ◽  
Free Electron ◽  
Cryogenic Temperature ◽  
Room Temperature ◽  
Laser System ◽  
Free Electron Lasers ◽  
X Ray ◽  
Laser Amplifiers ◽  
Laser Media

We present possible conceptual designs of a laser system for driving table-top free-electron lasers based on terahertz acceleration. After discussing the achievable performances of laser amplifiers with Yb:YAG at cryogenic and room temperature and Yb:YLF at cryogenic temperature, we present amplification modules with available results and concepts of amplifier chains based on these laser media. Their performances are discussed in light of the specifications for the tasks within the table-top light source. Technical and engineering challenges, such as cooling, control, synchronization and diagnostics, are outlined. Three concepts for the laser layout feeding the accelerator are eventually derived and presented.

Structures of two newly synthesized A0.50SbFe(PO4)3 (A=Mn, Cd) Nasicon phases

2005 ◽  
Vol 20 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Abderrahim Aatiq ◽  
Rabia Hassine ◽  
My Rachid Tigha ◽  
Ismael Saadoune
Keyword(s):  
Solid State ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
Cation Distribution ◽  
Room Temperature ◽  
Rietveld Method ◽  
Hexagonal Cell ◽  
X Ray ◽  
Cell Parameters ◽  
Two Samples

Crystal structures of A0.50SbFe(PO4)3(A=Mn, Cd) phases, obtained by solid state reaction at 920 °C, were determined at room temperature from X-ray powder diffraction (XRD) using the Rietveld method. The structures of the two samples are of the Nasicon-type with the R3 space group. Hexagonal cell parameters for A=Mn and Cd are: a=8.375(1) Å, c=21.597(2) Å and a=8.313(1) Å, c=21.996(2) Å, respectively. From XRD data, it is difficult to unambiguously distinguish between Cd2+ and Sb5+ ions in Cd0.50SbFe(PO4)3 and between Mn2+ and Fe3+ cations in Mn0.50SbFe(PO4)3. Nevertheless the overall set of cation–anion distances within the Nasicon framework clearly shows that the cation distribution can be illustrated by the {[A0.50]3a[◻0.50]3b}M1SbFe(PO4)3 (A=Mn, Cd) crystallographic formula. The divalent A2+ cations and vacancies are ordered within the two positions, 3a and 3b, of the M1 sites. Structure refinements show also a quasi-ordered distribution of Sb5+ and Fe3+ ions within the Nasicon framework. Thus, each A(3a)O6(A=Mn, Cd) octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (◻(3b)O6) site is located between two Sb5+O6 octahedra.

scholarly journals Formation of anorthite containing cordierite materials through reaction sintering kaolin, MgO and CaO precursors

2020 ◽  
Vol 52 (2) ◽  
pp. 135-147
Author(s):  
Smail Lamara ◽  
Djaida Redaoui ◽  
Foudil Sahnoune ◽  
Menad Heraiz ◽  
Nouari Saheb
Keyword(s):  
Room Temperature ◽  
Diffraction Method ◽  
Nucleation And Growth ◽  
The Other ◽  
Formation Temperature ◽  
Reaction Sintering ◽  
Heating Rates ◽  
Powder Mixtures ◽  
X Ray ◽  
Two Samples

The effect of CaO on cordierite formation from kaolin-MgO-CaO powder mixtures, milled for 5 h and reaction sintered for 2 h in the temperature range 900-1400?C, was investigated. Phases formed in the developed materials were characterized by x-ray powder diffraction method (XRD) and Raman spectroscopy. Non-isothermal differential thermal analysis (DTA) and thermogravimetric (TG) experiments were performed from room temperature to 1400?C, at heating rates from 20 to 40?C/min. Activation energies were determined using Kissinger method. It was found that sintering the stoichiometric kaolin-magnesia mixture led to the nucleation and growth of monolithic cordierite; while cordierite along with anorthite were present in the other two samples where 4 or 8 wt% of CaO was added. The increase in CaO decreased cordierite formation temperature and increased the activation energy, which ranged from 445 to 619 kJ/mol for ?-cordierite and from 604 to 1335 kJ/mol for ?-cordierite.

Differential anomalous wide-angle X-ray scattering and X-ray absorption experiments to investigate the formation of glass ceramics in the CaO–SiO2–ZrO2system

1999 ◽  
Vol 32 (6) ◽  
pp. 1090-1099 ◽  
Author(s):  
Carlo Meneghini ◽  
Alessandro F. Gualtieri ◽  
Cristina Siligardi
Keyword(s):  
Glass Ceramic ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Anomalous Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Two Samples ◽  
Devitrification Process ◽  
X Ray Absorption

The structure of a CaO–SiO2–ZrO2-based glass ceramic has been investigated by X-ray diffraction, X-ray absorption spectroscopy and differential anomalous scattering techniques as a function of the thermal treatment of the sample. The microstructure of the glass has been investigated at room temperature, before the recrystallization of the glass ceramic, and on two samples annealed at 1073 and 1273 K for 1 h to follow the early stages of nucleation of the quartz and wollastonite crystalline phases. Indications on the roles of Ca, Si and Zr during the devitrification process are given.

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