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Sarychev M. N. Bondarevskaya A. S. Zhevstovskikh I. V. Ulanov V. A. Shakurov G. S. Egranov A. V. Surikov V. T. Averkiev N. S. Gudkov V. V. 《JETP Letters》2021,113(1):47-51
JETP Letters - The temperature dependences of attenuation and the velocity of ultrasonic waves at frequencies of 26–158 MHz in a CaF2 fluorite crystal at the substitution of... 相似文献
2.
This paper reports on a study of cross-luminescence in barium fluoride crystals doped by a variety of impurities (K+, Cd2+, Y3+, Yb3+, La3+). It is shown that doping of the crystal with a trivalent impurity gives rise to the formation of an additional cross-luminescence
band peaking at 7.5 eV, the intensity of this band increasing with increasing impurity concentration.
Original Russian Text ? A.S. Myasnikova, E.A. Radzhabov, A.V. Egranov, 2008, published in Fizika Tverdogo Tela, 2008, Vol.
50, No. 9, pp. 1582–1584. 相似文献
3.
A. V. Egranov T. Yu. Sizova V. A. Kozlovskiy 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(9):1069-1074
The ground state of monovalent ions of transitional metals in alkaline-earth fluorides is localized in the conduction band. It is shown by the example of monovalent Co and Ni ions in CaF2 and SrF2 crystals that this is responsible for the unstable state of these ions in cubic environments. A stable state is achieved by the monovalent ions shifting to off-center positions. 相似文献
4.
The mechanism of coloration of alkaline-earth fluoride crystals CaF2, SrF2, and BaF2 in calcium vapors in an autoclave with a cold zone is studied. It was found that the pressure in the autoclave upon constant evacuation by a vacuum pump within the temperature range of 500–800°C increases due to evaporation of metal calcium. In addition to the optical-absorption bands of color centers in the additively colored undoped crystals or to the bands of divalent ions in the crystals doped with rare-earth Sm, Yb, and Tm elements, there appear intense bands in the vacuum ultraviolet region at 7.7, 7.0, and 6.025 eV in CaF2, SrF2, and BaF2, respectively. These bands belong to the Ha - hydrogen centers. The formation of hydrogen centers is also confirmed by the appearance of the EPR signal of interstitial hydrogen atoms after X-ray irradiation of the additively colored crystals. Grinding of the outer edges of the colored crystals leads to a decrease in the hydrogen absorption-band intensity with depth to complete disappearance. The rate of hydrogen penetration inside the crystal is lower than the corresponding rate of color centers (anion vacancies) by a factor of tens. The visible color density of the outer regions of the hydrogen-containing crystals is several times lower than that of the inner region due to the competition between the color centers and hydrogen centers. 相似文献
5.
T. Yu. Sizova V. Yu. Veslopolova R. Yu. Shendrik A. V. Egranov E. A. Radzhapov A. A. Shalaev 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(9):1090-1093
The absorption spectra of radiation-colored CaF2, SrF2, and BaF2 crystals activated by trivalent Pr, Sm, Нo, Er, Tm, and Yb (rare-earth, RE) ions are studied. It is shown that ionizing radiation reduces the impurity ions to the divalent state. The temperature resistance of divalent RE ions of radiation-colored CaF2 crystals correlates with the chemical stability of the compounds with divalent RE ions. The photochromic centers are produced in CaF2-Pr crystal colored by radiation at room temperature and heated to 200°C. 相似文献
6.
R. Yu. Shendrik A. S. Myasnikova A. V. Egranov E. A. Radzhabov 《Optics and Spectroscopy》2014,116(5):777-782
We have studied the absorption spectra of radiation-induced divalent cerium and praseodymium ions in crystals of alkaline-earth fluorides. Using ab initio quantum-mechanical methods, we have calculated absorption spectra of divalent praseodymium ions in CaF2 crystals for the first time. The theoretical spectrum agrees rather well with the experimentally registered spectra. 相似文献
7.
A. I. Nepomnyashchikh E. A. Radzhabov A. V. Egranov V. F. Ivashechkin A. S. Istomin 《辐射效应与固体损伤》2013,168(6-12):715-719
Nominally pure BaF 2 single crystals were investigated at 77 v K with optical absorption and electron paramagnetic resonance to understand the mechanism of radiation damage. We find that X-irradiation at 77 v K of undoped BaF 2 produces V k - and F -centres having absorption bands at 3.4 and 2.3 v eV respectively. 相似文献
8.
Optics and Spectroscopy - Photoluminescence spectra of impurity centers containing anion vacancy Cd+ $${{{v}}_{a}}$$ or Zn+ $${{{v}}_{a}}$$ in alkali-earth fluorides have been studied. A comparison... 相似文献
9.
A. V. Egranov E. A. Radzhabov A. I. Nepomnyashchikh V. F. Ivashechkin I. E. Vasil’eva 《Physics of the Solid State》2008,50(9):1740-1746
Ionization radiation is shown to reduce impurity ions to the univalent state in strontium and calcium fluoride crystals doped by divalent cadmium and zinc ions. In this case, a univalent ion is surrounded by eight equivalent fluorine ions and exhibits cubic symmetry O h . At room temperature, the symmetry of the center is revealed to be sequentially lowered to C 3v and then to C 2v owing to the addition to the nearest environment of the impurity univalent ion of one or two anion vacancies, respectively, which are intrinsic defects not forming in undoped strontium and calcium fluoride crystals. Stable intrinsic defects are assumed to form through the separation of anion vacancy-interstitial fluorine ion pairs in the electric field induced by the reduced impurity ions. This electric field lowers the energy barrier to thermal separation of charged intrinsic defects. 相似文献
10.
Sarychev M. N. Bondarevskaya A. S. Zhevstovskikh I. V. Ulanov V. A. Shakurov G. S. Egranov A. V. Surikov V. T. Averkiev N. S. Gudkov V. V. 《Journal of Experimental and Theoretical Physics》2021,132(5):790-799
Journal of Experimental and Theoretical Physics - The results of the study of the temperature dependence of attenuation and velocity of ultrasonic waves are presented for CaF2:Cr and CaF2:Ni... 相似文献
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