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1.
Thermally stimulated luminescence (TSL) of Bi2Ge3O9, Bi4Ge3O12, and Bi12GeO20 and the primary components Bi2O3 and GeO2 was studied under x-ray excitation. Thermal activation energies and frequency factors of trapping centers in the studied
ceramics were determined. The relationships of TSL bands of the studied ceramics with maxima at 141–145 and 166–170 K and
damage to the Ge sublattice and of TSL bands with maxima at 104–110 and 180–190 K and recombination processes in the Bi sublattice
were demonstrated. Recombination processes causing luminescence upon nonequilibrium charge carrier release from trapping centers
occur in structural complexes of similar configuration that contain the Bi ion in a nearest environment of O atoms.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 359–364, May–June, 2008. 相似文献
2.
Thermally stimulated luminescence (TSL) of ceramics having the structure of eulytine Bi4X3O12 (X = Si, Ge, Zr) on exposure to x-ray irradiation in the temperature region 80–400 K is studied. An analysis of the forms of the TSL curves implies that the recombination processes in the TSL peaks at 149 and 212 K in Bi4Si3O12 ceramics and at 143 and 230 K in Bi4Ge3O12 ceramics can be described by the linear kinetics. The spectral composition of TSL of the ceramics obtained is investigated, and the activation energy and frequency factors which correspond to the TSL maxima are determined by various methods. Based on common spectral and energy characteristics of TSL, a conclusion concerning the connection of TSL with recombination processes in common structural complexes of BiO6
9– is drawn. 相似文献
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O. M. Bordun 《Journal of Applied Spectroscopy》2001,68(6):974-978
Luminescence spectra of thin Bi4Ge3O12 films annealed in air and in vacuum have been investigated. It has been established that the luminescence spectra for different forms of excitation consist of three bands with maxima at 2.70, 2.40, and 2.05 eV. The relation of the bands with maxima at 2.40 and 2.05 eV to the centers that incorporate an oxygen vacancy has been shown. The separated emission bands have been interpreted. 相似文献
4.
The spectra of IR reflection of the systems thin Bi4Ge3O12 film–substrate made of molten -SiO2 quartz in the region 10–1600 cm–1 at 295 K are investigatedterpretation of fundamental vibrations in the region 10–800 cm–1 and two phonon processes in the region 800–1600 cm–1 are considered. 相似文献
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本文报道室温下Cd3Al2Ge3O12:Mn2+(简称CAGG:Mn2+)锗酸盐石榴石的漫反射光谱、激发和发射光谱.在UV光激发下,在CAGG中Mn2+离子发射强黄光,这是基质到Mn2+离子无辐射能量传递的结果.Mn2+的黄发射带是由一个弱的红带和一个强的绿带所组成.讨论了这两个Mn2+发射带的起因. 相似文献
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Time-domain spectroscopy of coherent optical phonons in bismuth germinate (Bi4Ge3O12) is presented. Utilizing both impulsive stimulated Raman scattering and time-domain terahertz spectroscopy, more than 12 unique vibrational states ranging in frequency from 2 to 11 THz are identified, each with coherent lifetimes ranging from 1 to 20 ps. These modes are highly sensitive to crystal orientation and demonstrate frequency shifts on picosecond timescales consistent with an anharmonic lattice potential. 相似文献
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V. G. Orlov E. A. Kravchenko Tetsuo Asaji G. S. Sergeev Yu. F. Kargin O. S. Volkova A. N. Vasil’ev 《Hyperfine Interactions》2010,197(1-3):65-70
The quadrupole 209Bi spin–spin and spin–lattice relaxation were studied within 4.2–300 K for pure and doped Bi4Ge3O12 single crystals which exhibit, as was previously found, anomalous magnetic properties. The results revealed an unexpectedly strong influence of minor amounts of paramagnetic dopants (0.015–0.5 mol.%) on the relaxation processes. Various mechanisms (quadrupole, crystal electric field, electron spin fluctuations) govern the spin–lattice relaxation time T 1 in pure and doped samples. Unlike T 1, the spin–spin relaxation time T 2 for pure and Nd-doped samples was weakly dependent on temperature within 4.2–300 K. Doping Bi4Ge3O12 with paramagnetic atoms strongly elongated T 2. The elongation, although not so strong, was also observed for pure and doped crystals under the influence of weak (~30 Oe) external magnetic fields. To confirm the conclusion about strong influence of crystal field effects on the temperature dependence of T 1 in the temperature range 4.2–77 K, the magnetization vs. temperature and magnetic field was measured for Nd- and Gd-doped Bi4Ge3O12 crystals using a SQUID magnetometer. The temperature behavior of magnetic susceptibility for the Nd-doped crystal was consistent with the presence of the crystal electric field effects. For the Gd-doped crystal, the Brillouin formula perfectly fitted the curve of magnetization vs. magnetic field, which pointed to the absence of the crystal electric field contribution into the spin–lattice relaxation process in this sample. 相似文献
14.
The structure of Bi4?x La x Ti3O12 (BLaTx) as a function of La content from x = 0.00 to 1.25 was studied by Raman spectroscopy and X-ray diffraction (XRD). It was observed that the Raman modes evolve discontinuously at about x = 1.00, which indicates a structural phase transition. Specifically, the B 2g and B 3g Raman modes shown evidences to coalesce into E g modes with increasing La content. The evolution of Raman modes corresponds to the weakening of ferroelectric orthorhombic lattice distortion with increasing La substitution when x ≤ 1.00 and the final transition into the paraelectric tetragonal structure at higher La content. XRD and electrical measurement results confirm this phase transition by the observation that diffraction peaks from (200) and (020) planes of BLaT0.75 coalesce into one peak in BLaT1.25 and by the corresponding disappearance of remanent polarisation. The impact of La substitution on electrical properties of BLaTx is discussed briefly. 相似文献
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O. M. Bordun 《Journal of Applied Spectroscopy》1997,64(2):246-250
The fundamental absorption edge of thin films of Bi4Si3O12 is investigated. On the basis of its temperature dependence, exciton-phonon interaction is investigated, which made it possible
to interpret the absorption edge as the absorption of autolocalized excitons. The temperature dependence of the forbidden
band width is given.
I. Franko Lvov State University, 50, Dragomanov St., Lvov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 2, pp. 232–235, March–April, 1997. 相似文献
16.
L. Kovács E. Moya K. Polgár F. J. López C. Zaldo 《Applied Physics A: Materials Science & Processing》1991,52(5):307-312
The changes induced by ultraviolet (UV) illumination on the optical absorption and electron paramagnetic resonance (EPR) spectra of Bi4Ge3O12 single crystals, doped either with Fe (and Gd) or Mn, have been followed at room temperature (RT). In both crystals several overlapping optical absorption bands develop under UV illumination, covering from 0.7 eV up to the band edge of the matrix. The optical damage can be bleached by heating the samples above RT or by illumination with visible light. Although these optical changes temporarily correlate with the variation of the Gd3+ and Mn2+ concentrations, it has been concluded that other defects are present and partially responsible for the optical damage. 相似文献
17.
The luminescence spectra of thin Bi2W2O9 films have been investigated. The spectra were separated into elementary components by the Alentsev–Fock method. The radiation band with a maximum at 2.43 eV in the luminescence spectrum of Bi2W2O9 has been assigned to the Frenkel autolocalized excitons. The luminescence bands with maxima at 2.10 and 1.90 eV have been assigned to the emission of the centers whose energy levels are located in the forbidden band. The luminescence of the Bi2W2O9 films is due to the emission of the WO6 complex. 相似文献
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V. A. Pustovarov A. V. Kruzhalov A. L. Krymov B. V. Shul'gin 《Journal of Applied Spectroscopy》1990,52(3):260-263
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 3, pp. 400–405, March, 1990. 相似文献
20.
J. Manam 《辐射效应与固体损伤》2013,168(12):955-965
Thermally stimulated luminescence (TSL) of undoped and doped CaSO4 with activators such as Cu and Mn has been investigated. The polycrystalline samples of undoped and doped CaSO4 are prepared by the melting method. The formation of CaSO4 compound is confirmed by X-ray diffraction and Fourier transform infrared studies. Scanning electron microscopic studies of CaSO4 are also carried out. The TSL glow curves of undoped CaSO4, Cu- and Mn-doped CaSO4 are studied. Comparison of the thermoluminescence (TL) intensity of the most intensive glow peak of Cu-doped CaSO4 compound with that of undoped CaSO4 shows that addition of Cu impurity in CaSO4 compound enhances the TL intensity by about four times. However, the addition of Mn impurity to undoped CaSO4 increases the TL intensity by about three times when compared with that of undoped CaSO4. The TL-dose dependence of all three samples was studied and was observed to be almost linear in the studied range of irradiation time. Among the samples studied, namely undoped CaSO4 and Cu- and Mn-doped CaSO4, Cu-doped CaSO4 is found to be the most sensitive. The trap parameters, namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the most intensive glow peaks of CaSO4:Mn, CaSO4:Cu and CaSO4 phosphors were determined using the glow curve shape (Chen's) method. 相似文献