排序方式: 共有64条查询结果,搜索用时 15 毫秒
11.
Victor A. Soltamov Ivan V. Ilyin Alexandra A. Soltamova Daniel O. Tolmachev Nikolai G. Romanov Alexandr S. Gurin Vladimir A. Khramtsov Eugene N. Mokhov Yurii N. Makarov Georgy V. Mamin Sergei B. Orlinskii Pavel G. Baranov 《Applied magnetic resonance》2013,44(10):1139-1165
The results of studies of shallow donors and deep-level color centers in bulk AlN crystals are presented. Two shallow donors (presumably oxygen located on the nitrogen site and carbon located on the aluminum site) are suggested to exhibit the DX-relaxation. Third shallow donor (presumably silicon on the Al site) shows the shallow donor behavior up to the room temperature and can be observed without light excitation at temperatures above 200 K. The values of the Bohr radius of the shallow donors are estimated. The structure of deep-level color centers (neutral nitrogen vacancy V N) in bulk AlN crystals is determined and analyzed by electron paramagnetic resonance, electron-nuclear double resonance, optical absorption and thermoluminescence induced by X-ray irradiation. Spin-dependent recombination processes in AlN crystals are studied by means of optically detected magnetic resonance. 相似文献
12.
13.
B. E. Krisyuk A. V. Maiorov E. A. Mamin A. A. Popov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(5):726-733
The UQCISD, UB3LYP, UMP2, and MRMP2 methods in conjunction with the 6-31+G**/6-311+G** and aug-cc-PVDZ basis sets are used
to study the primary reaction of ozone with chlorinated ethylene derivatives: tetrachloroethylene, trichloroethylene, 1,2-trans-dichloroethylene, 1,2-cis-dichloroethylene, 1,1-dichloroethylene, and chloroethylene. The reaction is studied for both concerted and nonconcerted ozone
addition. The UB3LYP DFT method in conjunction with the 6-31+G** basis set is used to examine various modes of addition of
ozone to these chlorinated ethylenes by the Criegee and DeMore mechanisms. The geometry and energy of the transition states,
the enthalpy and entropy, and the rate constants and ratios thereof for all the reactions are calculated. The UB3LYP method
generally satisfactorily describes the two reaction pathways and, largely correctly predicts the rate constants, in agreement
with the available experimental data. At the same time, this method appears to be inapplicable to modeling the interaction
of ozone with 1,1-dichloroethylene. In this case, the single-determinant approximation turns out to be unsuitable, and, therefore,
MCSCF methods should be used. The MRMP2 method yields reasonable values of the rate constants for the DeMore mechanism, whereas
in the case of the Criegee mechanism, the MP2 method does well. The UB3LYP/6-31+G** and UQCISD/aug-cc-PVDZ methods give similar
values of the ratio between the rate constants for the two pathways, a result that demonstrates the versatility of the first
one. 相似文献
14.
A. A. Soltamova I. V. Il’in F. M. Shakhov S. V. Kidalov A. Ya. Vul’ B. V. Yavkin G. V. Mamin S. B. Orlinskii P. G. Baranov 《JETP Letters》2010,92(2):102-106
A giant concentration of nitrogen vacancy defects has been revealed by the electron paramagnetic resonance (EPR) method in
a detonation nanodiamond sintered at high pressure and temperature. A high coherence of the electron spins at room temperature
has been observed and the angular dependences of the EPR spectra indicate the complete orientation of the diamond system. 相似文献
15.
M. R. Gafurov T. B. Biktagirov G. V. Mamin D. V. Shurtakova E. S. Klimashina V. I. Putlyaev S. B. Orlinskii 《Physics of the Solid State》2016,58(3):469-474
The effect of codoping of hydroxyapatite (HAP) nanocrystals with average sizes of 35 ± 15 nm during “wet” synthesis by CO32? carbonate anions and Mn2+ cations on relaxation characteristics (for the times of electron spin–spin relaxation) of the NO32? nitrate radical anion has been studied. By the example of HAP, it has been demonstrated that the electron paramagnetic resonance (EPR) is an efficient method for studying anion–cation (co)doping of nanoscale particles. It has been shown experimentally and by quantummechanical calculations that simultaneous introduction of several ions can be energetically more favorable than their separate inclusion. Possible codoping models have been proposed, and their energy parameters have been calculated. 相似文献
16.
R. F. Mamin 《Physics of the Solid State》2001,43(7):1314-1319
It is shown that the process of charge carrier localization on impurity centers is of importance. Localized carriers produce local electric fields, thereby stimulating the appearance of an induced polarization near the phase transition point. The direction of this polarization is dictated by the spatial distribution of the centers occupied by charge carriers. The temperature dependence of the dielectric constant is determined by the dynamics of the local-center occupation with decreasing temperature. The dispersion of the dielectric constant is determined by the vibrational characteristics of the local states forming near a localized charge. The phase transitions in relaxors are considered in the framework of the thermodynamic approach. 相似文献
17.
R. F. Mamin D. A. Bizyaev A. A. Bukharaev 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(1):5-8
Spatially inhomogeneous states were induced on the surface of single-crystal lanthanum-strontium manganites by the local application of an external electric field. The dynamics of the growth and relaxation of these states were studied by atomic force microscopy. It is shown that the induced states possess a charge and reveal piezoelectric properties. 相似文献
18.
L. K. Aminov I. N. Kurkin S. P. Kurzin I. A. Gromov G. V. Mamin R. M. Rakhmatullin 《Physics of the Solid State》2007,49(11):2086-2090
The electron paramagnetic resonance (EPR) spectra of mixed crystals (BaF2)1 − x
(LaF3)
x
(x = 0, 0.001, 0.002, 0.005, 0.010, 0.020) doped with Ce3+ ions (0.1%) are investigated at a frequency v ≈ 9.5 GHz in magnetic fields up to 1.45 T at temperatures T = 10 and 15 K. The EPR spectrum of “pure” barium fluoride BaF2 (x = 0) is characterized by a single Ce3+-F− center with tetragonal symmetry (i.e., the O center with g
‖ = 2.601 and g
⊥ = 1.555). For a lanthanum trifluoride concentration x ≠ 0, the spectrum exhibits new lines due to the presence of the clusters containing Ce3+ and La3+ ions. The intensity of EPR signals from the O centers decreases rapidly as the lanthanum trifluoride concentration x increases. The lines attributed to a paramagnetic center with tetragonal symmetry and strongly anisotropic g factors (i.e., the K center with g
‖ = 0.725 and g
⊥ = 2.52) are separated in the complex EPR spectrum with the use of the angular dependence of the EPR signal intensity measured
for the samples with x ≥ 0.002. This center is identified as a cubooctahedral cluster of the La6F37 type in which one of the La3+ ions is replaced by the Ce3+ ion.
Original Russian Text ? L.K. Aminov, I.N. Kurkin, S.P. Kurzin, I.A. Gromov, G.V. Mamin, R.M. Rakhmatullin, 2007, published
in Fizika Tverdogo Tela, 2007, Vol. 49, No. 11, pp. 1990–1993. 相似文献
19.
Babunts R. A. Uspenskaya Yu. A. Gurin A. S. Bundakova A. P. Mamin G. V. Anisimov A. N. Mokhov E. N. Baranov P. G. 《JETP Letters》2022,116(7):485-492
JETP Letters - The frequencies of electron–nuclear interactions with 13C and 29Si nuclei on remote coordination spheres are determined in triplet spin centers in the form of neutral... 相似文献
20.
Extremely high values of the relative permittivity up to 107 and the magnetocapacitance up to 105% have been found in La1 − x
Sr
x
MnO3 single crystals (x = 0.1, 0.11). These phenomena are observed even at room temperature. The observed behavior can be a consequence of the strong
interaction among charge, spin, and lattice degrees of freedom, which leads to charge and phase separation in the regime before
the percolation threshold. 相似文献