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1.
Results of investigations of the spectroscopic properties of manganese-activated single crystals of Sr 3Ga 2Ge 4O 14 by the methods of optical and EPR spectroscopy are reported. It is shown that magnagese activator ions form substitutional
centers Mn 3+ and Mn 2+ in 1a-octahedral positions of the Sr 3Ga 2Ge 4O 14 lattice. Changes in the opticla properties of Sr 3Ga 2Ge 4O 14: Mn after vacuum thermal annealing are attributed to charge transfer of some of the manganese ions (Mn 3+→Mn 2+). The relationship between the spectroscopical properties of Mn 2+ ions and the crystallochemical structure of the system are discussed.
I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 6, pp. 779–783, November–December, 1997. 相似文献
2.
High optical quality Tm:La 3Ga 5SiO 14 single crystals with dopant concentration of 1 at. % Tm 3+ ions were grown by the Czochralski method. The structure was studied by the X-ray powder diffraction method. The absorption spectrum and fluorescence spectrum of Tm 3+:La 3Ga 5SiO 14 crystals were measured at room temperature. PACS 42.70.-a; 42.70.Hj; 61.10.Nz; 61.66.Fn; 78.20.-e; 78.90.+t; 81.10.-h 相似文献
3.
We measured the dispersion of light in thin Y 2O 3 films in the visible and near UV regions of the spectrum. The spectrum of edge absorption is investigated. We found the parameters
of a single-oscillator approximation and determined the dispersion energy and the ionicity of bonding.
I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 5, pp. 651–654, September–October, 1997. 相似文献
4.
Luminescence spectra for isostructural Y 2SiO 5 and Y 2GeO 5 are investigated. The spectra are resolved into elementary components by the Alentsev—Fock method. Bands with maxima in regions
of 2.6, 2.3, and 2.05 eV in the spectra of Y 2SiO 5 luminescence and in regions of 2.55, 2.25, and 2.0 eV in the spectra of Y 2GeO 5 luminescence are considered as radiative recombination of excited associative donor-acceptor Y 3+−O 2− pairs. The indicated bands are related to certain distances between yttrium (the donor) and oxygen (the acceptor). A band
with a maximum of 2.95 eV in Y 2SiO 5 and 3.0 eV in Y 2GeO 5 occurs in recombination of electrons with holes trapped by an anionic sublattice.
I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 65, No. 4, pp. 528–531, July–August, 1998. 相似文献
5.
The Er-single-doped and Er/Ce-codoped La 3Ga 5SiO 14 polycrystalline powders are synthesized by the solid-phase synthesis method. The room-temperature luminescence spectra of the samples are investigated. The Near-infrared-region spectroscopic properties of Er 3+ ions in the La 3Ga 5SiO 14 systems are analysed with Judd-Ofelt theory and rate equations. The effective deactivating effect of Ce 3+ ions on Er 3+ ions is confirmed. 相似文献
6.
The IR reflection spectra are investigated for the systems “thin film of PbWO 4 or Bi 2WO 6-molten quartz v-SiO 2 substrate” within the region of 400–1600 cm −1 at T=295 K. Interference in the thin films is considered. Interpretation of the bands belonging to the PbWO 4 and Bi 2WO 6 films is carried out.
I. Franko L’vov State University, 50, Dragomanova St., 290005, L’vov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 65, No. 3, pp. 459–461, May–June, 1998. 相似文献
7.
We investigate the spectra of the x-ray radiation-induced absorption of SrCl 2−Ce crystals over the spectral range 345–830 nm and their temperature transformations in the interval from 77 to 450 K. We
found that radiative color centers are characterized by a complex spectrum of induced absorption that contains wide bands
of photochromic PC (750, 519, 378 nm) and PC + (620, 446, 340 nm) centers and quasi-linear bands of Ce 2+ centers. The most significant thermal transformations of radiative color centers occur in the vicinity of the thermostimulated
luminescence peak of 394 K, at which the holes of the PC + centers recombine with the electrons of the Ce 2+ centers.
Ivan Franko L’vov State University, 8, Kirilla i Mefodiya St., L’vov 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 4, pp. 545–547, July–August, 1997. 相似文献
8.
Ferrobielastic switching is observed by measuring the change in the frequency of a compound acoustic cavity made from a langasite
(La 3Ga 5SiO 14) single crystal, under uniaxial pressure. The effect is detected from the jump in the cavity frequency at the point of switching.
In quartz the measured value of the pressure at the point of switching is found to be much higher, 740 MPa.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 338–340 (10 September 1997) 相似文献
9.
Sc 2O 3 luminescence spectra are studied. The spectra are separated into elementary bands by the Alentsev–Fock method. It is established
that the luminescence spectra consist of a number of overlapping bands with maxima at 3.5; 3.05; 2.65; 2.35, and 2.05 eV.
The band at 3.5 eV is interpreted as emission of self-localized excitons, and the other bands, as defect-center recombination.
L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
64, No. 6, pp. 776–778, November–December, 1997. 相似文献
10.
Experimental evidence that nuclear magnetic resonance (NMR) can detect structural changes of piezoelectric La 3Ga 5SiO 14 induced by dilute paramagnetic ions is presented. Gd 3+ and Eu 3+ cations have been incorporated into La 3Ga 5SiO 14 monocrystals. As expected, the line-width of the tetrahedral 29Si magic angle spinning (MAS) NMR spectra as well as the inverse of the T2 relaxation time of 71Ga increases with the concentration of the paramagnetic ions. A surprising result is shown by 71Ga multiple quantum (MQ) MAS NMR spectrum, which changes with the concentration of paramagnetic ions. The changes in the 71Ga MQMAS spectra can be explained by a more ordonated distribution of Ga ions inside the oxygen tetrahedra. The 71Ga MQMAS NMR spectra allow identification of the one octahedral and two tetrahedral Ga sites. 相似文献
11.
Based on the phenomenon of coherent spin Raman scattering a magnetooptical method of measuring the characteristics of the
reservoir of electronic spin-spin interactions in paramagnets was implemented. A formula relating the intensity of the inelastically
scattered light to the temperature of the spin-spin reservoirs under conditions of saturation of the EPR of paramagnetic ions
has been derived. For the Ce 3+ ions in the (Ce xLa 1−x) 2Mg 3(NO 3) 12·24H 2O crystal values of the time of spin-lattice relaxation of the spin-spin reservoir and the local magnetic field have been
measured, and a relation between the spin-spin reservoir temperature and the external magnetic field strength under conditions
of stationary saturation of the EPR of the Ce 3+ ions has been obtained.
V. I. Ul’yanov-Lenin Kazan State University, 18, Lenin St., Kazan, 420008, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 76–81, January–February,
1997. 相似文献
12.
The polarization rotating coefficient and the laser-damage threshold of La 3Ga 5SiO 14 crystal at 1064 nm are measured, which are 1.1 deg/mm and , respectively. The working principle and the design method of electrooptic Q-switch based on La 3Ga 5SiO 14 crystal, which has the optical activity, are reported. The performance of Nd:YLF laser with the electrooptic Q-switch of La 3Ga 5SiO 14 crystal was studied. The output pulses with an energy of 379 mJ, a duration of 8.7 ns and repetition of 10 Hz are achieved. 相似文献
13.
The variation of the resonance frequency of piezoelectric resonators subjected to a constant electric field is demonstrated
with longitudinal vibrations in La 3Ga 5SiO 14 (langasite) crystal rods at temperatures between −60 and +80°C. For the rods whose longtudinal axis makes angle α with the
crystal axis
in the plane of the axes
and [0001], the change in the frequency is proportional to the field strength and depends on α. For a field of ±1.5 × 10 6 V/m and α = 15°, the relative change in the frequency is ±120 × 10 −6. It is shown that La 3Ga 5SiO 14 crystals offer a set of physical parameters that makes them promising for electrically controlled acoustoelectronic devices
and for devices based on nonlinear interaction between acoustic waves. 相似文献
14.
Based on the data from optical-spectral studies of (NH 2(CH 3) 2) 2CoCl 4 crystals, the existence of high-temperature phase transitions at 419, 380, 352, and 313 K is confirmed. It was shown that
with the exception of the first transition, they are related to a considerable extent to rearrangement of the network of hydrogen
bonds and are not accompanied by, considerable deformation of the lattice. In this connection the character of the electron-phonon
interaction remains unchanged in the entire temperature range of the measurements. The (NH 2(CH 3) 2) 2CoCl 4 structure at room temperature is close to that of the ordered low-temperature phases of such isomorphous crystals as β-K 2SO 4.
I. Franko State University, L’vov, Ukraine, 8, Kirill and Mefodii St., UA-290005, L’vov. Translated from Zhurnal Prikladnoi
Spektroskopii, Vol. 65, No. 3, pp. 412–418, May–June, 1998. 相似文献
15.
The morphology and phase composition of the surface of La3Ga5SiO14 (langasite) crystals at annealing in a temperature range 1000–1200°C have been studied using electron and atomic force microscopy. It has been shown that trigonal lanthanum oxide (La2O3) crystals with sizes to 3–4 μm, as well as a microstructure with sizes to 50 μm with gallium excess, with the approximate composition of 15 mol % La2O3, 65 mol % Ga2O3, and 20 mol % SiO2 are formed on the surface of langasite crystals annealed in air at temperatures above 1100°C. Possible reasons for thermal destruction of the compound can be a significant rearrangement of the disordered crystal structure of langasite caused by the interaction with air oxygen and under the intense surface diffusion of atoms of the crystal, as well as the incongruent character of melting of the La3Ga5SiO14 compound. The revealed thermal destruction of the surface of langasite crystals should be taken into account when using this material to fabricate piezoelectric elements for operation at high temperatures. 相似文献
16.
The electronic structure of La 1–x
Ga
x
MnO 3+δ. solid solutions is studied by X-ray photoelectron spectroscopy (XPS). The valence state of the manganese is estimated by
various methods: by analyzing the difference in the binding energies of the Mn2p 3/2 and O1s electronic levels, analyzing exchange splitting in the spectrum of Mn3s, and from the dependence of the binding energy
of the XPS spectrum of Mn2p 3/2 on the calcium concentration. The state of oxidation of the manganese in the compositions containing calcium lies between
Mn 3+ and Mn 4+. The efficacies of these methods are compared. A correlation is found between the type of crystalline structure of La 1–x
Ga
x
MnO 3+δ. (0 ≤ x < 1) and the binding energy of the Mn2p 3/2 peak.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 419–427, May–June, 2009. 相似文献
17.
Results of investigations of spectroscopic properties of Ca 3Ga 2Ge 4O 14 single crystals activated with Sm 3+ ions are reported. It is shown that Sm 3+ ions in Ca 3Ga 2Ge 4O 14 form a type of activator quasicenter whose nature is associated with disordering of the matrix.
I. Franko Lvov State University, 50, Dragomanov St., Lvov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 2, pp. 296–298, March–April, 1998. 相似文献
18.
The dynamic and static Jahn-Teller effects are observed in ESR on rare-earth ions, specifically, on Sm 3+ ions in the fluctuating-valence material SmB 6.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 10, 645–648 (25 November 1997) 相似文献
19.
Investigations of the sputtering of Al xGa 1−x
As semiconductor solid solutions by Ar + ions with energies of 2–14 keV are performed. The dependence of the sputtering yield on the energy and angle of incidence
of the ions are determined and the character of the surface relief formed during the sputtering is investigated. A comparison
with theory shows that the best agreement between theory and experiment is achieved when the Haff-Switkowski formula is used
together with Yudin’s stopping cross section. It is shown that the surface binding energies obtained differ from the atomization
energies by an amount approximately equal to the amorphization energy.
Zh. Tekh. Fiz. 67, 113–117 (June 1997) 相似文献
20.
The recent interest in the (Sr, Mg) doped LaGaO 3 family compounds as electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs) has suggested the study of
the system α-Al 2O 3/La 0.8Sr 0.2Ga 0.8Mg 0.2O 3–δ as a possible new ionic conductor composite. The studies concerning the electrical and microstructural characterization of
the system α-Al 2O 3/La 0.8Sr 0.2Ga 0.8Mg 0.2O 3–δ, in a wide compositions range, are reported and discussed.
Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 – 18, 2004. 相似文献
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