scholarly journals Magnetic characterization of microcrystalline Na3Ln0.99–xEr0.01Crx(PO4)2 orthophosphates synthesized by Pechini method (Ln = La, Gd)

2018 ◽  
Vol 35 (4) ◽  
pp. 733-745 ◽  
Author(s):  
S.M. Kaczmarek ◽  
G. Leniec ◽  
H. Fuks ◽  
T. Skibiński ◽  
A. Pelczarska ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Susceptibility ◽  
Low Temperature ◽  
Pechini Method ◽  
Epr Spectra ◽  
Magnetic Characterization ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
Co Doped

Abstract Na3Ln(PO4)2 orthophosphates (Ln = La, Gd) doped with Er3+ and co-doped with Cr3+ ions were synthesized by Pechini method and characterized by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. Low temperature EPR spectra were detected and analyzed in terms of temperature dependence and the structure of the obtained materials. They show that erbium and chromium ions substitute Ln3+ and also Na+ ions or Na+ channels forming complex EPR spectra. Both kinds of ions reveal ferromagnetic type of interaction which shows some anomaly at the temperature between 10 K and 15 K. Magnetic susceptibility reveals a weak antiferromagnetic kind of interaction dominating in the whole temperature range, from 3.5 to 300 K.

Characterization of titanium dopants in sodium alanate by electron paramagnetic resonance spectroscopy

2005 ◽  
Vol 20 (12) ◽  
pp. 3265-3269 ◽  
Author(s):  
Meredith T. Kuba ◽  
Sandra S. Eaton ◽  
Christine Morales ◽  
Craig M. Jensen
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Epr Spectra ◽  
Minor Amount ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Dehydrogenation Kinetics ◽  
Electron Paramagnetic ◽  
Kinetics Of

Electron paramagnetic resonance (EPR) spectra were obtained for samples of Ti-doped NaAlH4 subjected to different numbers of cycles of dehydrogenation/re-hydrogenation. Ti is observed to evolve from its initial Ti(III) state through a series of Ti(0) species during the first 5 cycles. Although the conversion of Ti(III) to Ti(0) occurs much more readily for TiCl3-doped samples than those prepared with TiF3, in both cases the evolution of Ti follows the same sequence that involves 3 distinguishable Ti(0) species and ends in the predominance of the same single Ti(0) species. The spectrum of a sample of NaAlH4 containing 2 mol% of cubic Al3Ti is distinctly different than any of those observed for the Ti(0) species that arise during the hydrogen cycling of the hydride. The major changes in the nature of the predominant Ti species have little if any effect on the dehydrogenation kinetics, which strongly suggests that the profoundly enhanced hydrogen cycling kinetics of Ti-doped NaAlH4 are due to a Ti species present in only a relatively minor amount.

LOCAL STRUCTURE CHARACTERIZATION OF GADOLINIUM DOPED AMORPHOUS AND CRYSTALLINE ALUMINA

2001 ◽  
Vol 15 (12n13) ◽  
pp. 375-384 ◽  
Author(s):  
S. SIMON
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Local Structure ◽  
Sol Gel ◽  
Structure Characterization ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Amorphous Alumina ◽  
Electron Paramagnetic ◽  
Crystalline Alumina

The evolution of local structure during the transition from amorphous to crystalline states of gadolinium doped alumina is characterized by electron paramagnetic resonance (EPR). The EPR spectra of samples belonging to the (1 - x) Al 2 O 3x Gd 2 O 3 system, where x = 0.002, 0.01, 0.05 and 0.1, show that the gadolinium ions are relatively uniformly distributed in amorphous alumina granules prepared by sol–gel methods. First, gadolinium doped α-alumina appears on the surface of the γ-alumina granules where there are low coordinated (N < 6) gadolinium species. The transition from γ- to α-alumina is postponed by the presence of high coordinated gadolinium (N < 6) ions inside of γ-alumina granules.

Quand la résonance paramagnétique électronique de l'uranium(IV) est-elle observable?

1980 ◽  
Vol 58 (22) ◽  
pp. 2377-2379 ◽  
Author(s):  
Edgar Soulié ◽  
Gérard Folcher ◽  
Basil Kanellakopulos
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Susceptibility ◽  
Ground State ◽  
Excited Level ◽  
Electronic Ground State ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Electron Paramagnetic ◽  
Electronic Ground

For non-Kramers ions, the electronic ground state may be nondegenerate. Then, if the first electronic excited level lies more than 0.3 cm−1 above the ground state, no electron paramagnetic resonance can occur between them in the X band. This is the case whenever a temperature-independent paramagnetism is observed in the magnetic susceptibility of the powder. An example of this situation, conflicting with published epr spectra, is provided by U(cupferron)4.

Electron Paramagnetic Resonance Characterization of Mn- and Co-Doped ZnO Nanowires

2007 ◽  
Author(s):  
A. O. Ankiewicz ◽  
W. Gehlhoff ◽  
E. M. Kaidashev ◽  
A. Rahm ◽  
M. Lorenz ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Zno Nanowires ◽  
Paramagnetic Resonance ◽  
Doped Zno ◽  
Electron Paramagnetic ◽  
Co Doped

The Microscopic Structure Of Shallow Donors In Silicon Carbide

1996 ◽  
Vol 442 ◽  
Author(s):  
J.-M. Spaeth ◽  
S. Greulich-Weber ◽  
M. März ◽  
E. N. Kalabukhova ◽  
S. N. Lukin
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Double Resonance ◽  
Epr Spectra ◽  
Electron Nuclear Double Resonance ◽  
Paramagnetic Resonance ◽  
Vacancy Pair ◽  
Temperature Spectra ◽  
Electron Paramagnetic

AbstractThe electronic structure of nitrogen donors in 6H-, 4H- and 3C-SiC is investigated by measuring the nitrogen hyperfine (hf) interactions with electron nuclear double resonance (ENDOR) and the temperature dependence of the hf split electron paramagnetic resonance (EPR) spectra. Superhyperfine (shf) interactions with many shells of 13C and 29Si were measured in 6H-SiC. The hf and shf interactions are discussed in the framework of effective mass theory. The temperature dependence is explained with the thermal occupation of the lowest valley-orbit split A1 and E states. It is proposed that the EPR spectra of P donors observed previously in neutron transmuted 6H-SiC at low temperature (<10K) and high temperature (>60K) are all due to substitutional P donors on the two quasi-cubic and hexagonal Si sites, whereby at low temperature the E state is occupied and at high temperature the A1 state. The low temperature spectra are thus thought not to be due to P-vacancy pair defects as proposed previously.

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