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1.
V Correcher J Garcia-Guinea FJ Valle-Fuentes 《Journal of Thermal Analysis and Calorimetry》2006,83(2):439-444
In
this paper, novel results on the blue thermally stimulated luminescence (TSL)
emission of ulexite (NaCaB5O6(OH)6·5H2O)
have been studied. The four maxima appearing at 60, 110, 200 and 240°C
on the TSL glow curves of this borate could be respectively associated to:
(i) the first dehydration (NaCaB5O6(OH)6·5H2O→NaCaB5O6(OH)6·3H2O),
(ii) the creation-annihilation of the three-hydrated
phase, (iii) the Na-coordinated chains
dehydroxylation and the starting point of the alkali self-diffusion through
the lattice and (iv) the amorphisation
of the lattice. These results are fairly well correlated with the differential
thermal analyses (DTA), in situ thermal observations under environmental scanning
electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques. 相似文献
2.
3.
4.
Polycrystal Li2B4O7 (LBO) doped with Cu and In was prepared and then sintered at different temperatures. X-ray diffraction (XRD) was applied
to get the parameters of the LBO structure, thermoluminescence (TL) and optically stimulated luminescence (OSL) were measured,
and a second-order exponential decay model was fitted to the OSL decay curves. The results indicate that the original number
of OSL traps that have captured electroncs is linearly related with the sum of TL decay during the OSL process. Mean decay
constant of OSL is related to the sintered temperature. The possible reason is that the sintered temperature affects the crystal
sizes of the polycrystal, and consequently affects the stimulating lights’s intensity and the photoionization cross-section
of the electrons, which have been captured by the traps.
__________
Translated from Acta Scientiarum Naturalium Universitatis Sunyatseni, 2005, 44(4) (in Chinese) 相似文献
5.
In the majority of cases, the effects of ion implantation are confined close to the implant zone but, potentially, the resultant distortions and chemical modifications could catalyse relaxations extending into the bulk substrate. Such possibilities are rarely considered but the present data suggest that high dose ion implantation of ZnO has induced bulk changes. Surface implants with Cu and Tb strongly modified the low temperature bulk thermoluminescence properties generated by X-ray irradiation. Suggestions are proposed for the possible mechanisms for bulk relaxations and structural characteristics, which may indicate where such instability may occur in other lattice structures. 相似文献
6.
Abstract In this study, the molecular weights of the polymer from vinyl benzoate has been reported for different dose rates and different temperatures. The mol.wt. remains around 4000. With increasing dose, the molecular weight increases to about 14,000. The degrees of polymerization and the kinetic chain lengths calculated from the experimentally determined G R values have been compared which show that the kinetic chain length is larger than the D ? Pn. From a plot of the (D ? Pn)?1 vs. R p , an intercept is obtained which is equal to 3.25 × 10?2 which is higher than obtained in conventional polymerization. By examining the effect of temperature on mol.wt., the dependence of R p on dose rate and the absence of induction period it has been concluded that chain transfer occurs to impurities that are generated during radiolysis. 相似文献
7.
Synthesis,Persistent Luminescence,and Thermoluminescence Properties of Yellow Sr3SiO5:Eu2+,RE3+ (RE=Ce,Nd, Dy,Ho, Er,Tm, Yb) and Orange‐Red Sr3−xBaxSiO5:Eu2+, Dy3+ Phosphor 下载免费PDF全文
Dr. Ye Li Baohong Li Chenchen Ni Shuxia Yuan Jing Wang Prof. Qiang Tang Prof. Qiang Su 《化学:亚洲杂志》2014,9(2):494-499
Sunlight‐excitable orange or red persistent oxide phosphors with excellent performance are still in great need. Herein, an intense orange‐red Sr3?xBaxSiO5:Eu2+,Dy3+ persistent luminescence phosphor was successfully developed by a two‐step design strategy. The XRD patterns, photoluminescence excitation and emission spectra, and the thermoluminescence spectra were investigated in detail. By adding non‐equivalent trivalent rare earth co‐dopants to introduce foreign trapping centers, the persistent luminescence performance of Eu2+ in Sr3SiO5 was significantly modified. The yellow persistent emission intensity of Eu2+ was greatly enhanced by a factor of 4.5 in Sr3SiO5:Eu2+,Nd3+ compared with the previously reported Sr3SiO5:Eu2+, Dy3+. Furthermore, Sr ions were replaced with equivalent Ba to give Sr3?xBaxSiO5:Eu2+,Dy3+ phosphor, which shows yellow‐to‐orange‐red tunable persistent emissions from λ=570 to 591 nm as x is increased from 0 to 0.6. Additionally, the persistent emission intensity of Eu2+ is significantly improved by a factor of 2.7 in Sr3?xBaxSiO5:Eu2+,Dy3+ (x=0.2) compared with Sr3SiO5:Eu2+,Dy3+. A possible mechanism for enhanced and tunable persistent luminescence behavior of Eu2+ in Sr3?xBaxSiO5:Eu2+,RE3+ (RE=rare earth) is also proposed and discussed. 相似文献
8.
采用微波吸收法,测量了在不同助熔剂条件及不同气氛下烧制的ZnS材料受到超短激光脉冲激发后的光电子衰减过程,并且测量了材料的热释光曲线。样品A采用过量的SrCl作为助熔剂,在1150℃下灼烧制备而成;其热释光曲线显示材料中有浅电子陷阱,电子陷阱密度小,光生电子衰减过程为双指数衰减过程,快过程寿命为45ns,慢过程寿命为312ns。样品B中加入了少量的NaCl作为助熔剂;热释光曲线显示有浅电子陷阱和深电子陷阱,且都有较高的密度,其光电子寿命为1615ns。在NH4Br气氛中烧制样品C,热释光谱显示只有浅电子陷阱形成,光电子寿命为1413ns。结果表明材料的光电子寿命和浅电子陷阱密切相关,浅电子陷阱密度越大,光生电子寿命越长,深电子陷阱对光生电子瞬态过程影响很小。 相似文献
9.
Feldspar thermoluminescence fading phenomena were investigated here by using newly-constructed thermoluminescence spectrometer
on the basis of charge-coupled detector, and thereafter the discussion and explanation on feldspar TL fading mechanism were
presented. The experimental results show that the fading rate of feldspar TL depends on both wavelength and stimulated temperature,
and normally the feldspar TL in every region of wavelength and temperature shows different traits, namely the low temperature
TL (170°–190°) fading at the rate of logarithmic function and furthermore the TL of different wavelengths fading at approximately
the same rate on the condition of 160° preheating. While the medium and high temperature TLs (290°–400°) do not show much
thermal fading, their fading rate at room temperature invariably correlates well with their wavelength, namely the longer
TL wavelength, the slower TL fading rate. The thermal instability of traps and the quantum-mechanical tunneling effects can
explain the above fading phenomena respectively. It is recognized that feldspar TL fading depends on its wavelength, and furthermore
new aspects of the solid thermoluminescence process can be displayed by the combination of three-dimensional TL spectral analysis
and thermal fading or anomalous fading of TL for feldspar.
Supported by the National Natural Science Foundation of China (Grant No. 40534019) and the Knowledge Innovation Program of
the Chinese Academy of Sciences (Grant No. GIGCX3-07-10) 相似文献
10.
The thermoluminescence of x-irradiated CaSO4: Dy phosphors has been studied for diverse activator concentrations. The concentration-dependence of these phosphors on the
increase of glow peak intensities has been found to be remarkable. For higher concentration of dysprosium the concentration
quenching effect has been observed. This has been attributed to the resonant transfer of energy from one activator atom to
another, bringing the possible migration of energy in a solid, which is likely to get dissipated without luminescence, at
the quenching site itself. The effect of irradiation time on the glow peak intensities reveals the initial linearity and a
subsequent decrease indicating the possible radiation damage. The role of Na2SO4 as a charge compensator has been studied in detail. An attempt has been made to unravel the type of kinetics involved in
the process, by calculating the activation energies by different methods. It has been concluded that the type of kinetics
involved in the process is bimolecular. 相似文献