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991.
Pure and WO3 doped CeO2-PbO-B2O3 glasses are prepared by the melt-quench technique. The structural and optical analyses of glasses are carried out by XRD, FTIR, density and UV-vis spectroscopic measurement techniques. FTIR analysis indicates the transformation of structural units of BO3 into BO4 with W-O-W vibration and the presence of WO4 and WO6 units observed with increase in WO3 contents. Decrease in band gap for CeO2-PbO-B2O3 glasses from 2.89 to 2.30 eV and for WO3 doped glasses from 2.89 to 1.95 eV has been observed and discussed. This decrease in band gap with WO3 doping approaches to semiconductor behavior. It shows that the presence of WO3 in the glass samples causes more compaction of the borate network due to the formation of BO4 groups and the presence of WO4 and WO6 groups, which result in a decrease in the optical band gap energy and increase in the density. 相似文献
992.
In the present paper, self‐focusing of laser beams in relativistic plasmas is studied by the moment theory approach. The equilibrium beam radius of the self‐trapped laser beams is also derived. Results are compared with the paraxial ray theory. It is observed from the analysis that at higher intensities, the equilibrium beam radius increases in case of the paraxial ray theory, whereas it becomes independent of the beam intensity in case of the moment theory. Analysis also confirms the role of relativistic electrons travelling with the light pulse in (3D PIC) simulation studies (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
993.
Gurinder Pal SinghParvinder Kaur Simranpreet KaurD.P. Singh 《Physica B: Condensed Matter》2011,406(24):4652-4656
Glass samples of composition xAl2O3-20PbO-(80−x)B2O3 and xWO3-xAl2O3-20PbO-(80−2x)B2O3 with x varying from 0% to 10% mole fraction are prepared by melt quench technique. The optical band gap decreases (from 3.21 to 2.37 eV) more for WO3-Al2O3-PbO-B2O3 glasses with an addition of WO3 content. The FTIR spectral studies have pointed out the conversion of structural units of BO3 to BO4 and WO4 to WO6 in these glasses. The increase in density from 4.51 to 5.80 g cm−3 for WO3-Al2O3-PbO-B2O3 glasses is observed with an increase in WO3 content. This is observed that the atomic structure changes more with the incorporation of WO3. This is due to the formation of WO6, WO4 and BO4 units. 相似文献
994.
V. Singh S. Watanabe T. K. Gundu Rao I.-J. Lee 《Applied physics. B, Lasers and optics》2011,104(4):1019-1027
Tricalcium aluminate doped with Eu3+ was prepared at furnace temperatures as low as 500°C by using the convenient combustion route and examined using powder X-ray
diffraction, scanning electron microscope and photoluminescence techniques. A room-temperature photoluminescence study showed
that the phosphors can be efficiently excited by UV/Visible region, emitting a red light with a peak wavelength of 616 nm
corresponding to the 5D0–7F2 transition of Eu3+ ions. The phosphor exhibits three thermoluminescence (TL) peaks at 195°C, 325°C and 390°C. Electron Spin Resonance (ESR)
studies were carried out to study the defect centres induced in the phosphor by gamma irradiation and also to identify the
defect centres responsible for the TL process. Room-temperature ESR spectrum of irradiated phosphor appears to be a superposition
of three distinct centres. One of the centres (centre I) with principal g-value 2.0130 is identified as O− ion while centre II with an axially symmetric principal values g
∥=2.0030 and g
⊥=2.0072 is assigned to an F+ centre (singly ionized oxygen vacancy). O− ion (hole centre) correlates with the TL peak at 195°C and the F+ centre (electron centre), which acts as a recombination centre, is also correlated to the 195°C TL peak. F+ centre further appears to be related to the high temperature peak at 390°C. Centre III is also assigned to an F+ centre and seems to be the recombination centre for the TL peak at 325°C. 相似文献
995.
Single-phase Bi(0.80)La(0.20)FeO(3) (BLFO) and Bi(0.80)La(0.20)Fe(1-x)Nb(x)O(3) (BLFNO) samples were prepared in order to study the dielectric, magnetic and magnetoelectric properties of La and Nb codoped BiFeO3. Rietveld refinement of x-ray diffraction patterns of La and Nb codoped samples has been performed using the R3c space group. Magnetic hysteresis loops revealed that codoping can effectively increase the spontaneous magnetization due to change in the bond angle of Fe-O-Fe as a result of distortion created by the Nb5+ doping. Magnetic field-induced relative change of the dielectric constant for BLFO and BLFNO samples is a signature of magnetoelectric coupling. 相似文献
996.
Zhongkui Tan Vijay Patel Konstantin K. Likharev Dong Su Yimei Zhu 《Applied Physics A: Materials Science & Processing》2011,103(2):293-300
We have studied resistive bistability (memory) effects in junctions based on metal oxides, with a focus on sample-to-sample
reproducibility, which is necessary for the use of such junctions as crosspoint devices of hybrid CMOS/nanoelectronic circuits.
Few-nm-thick layers of NbO
x
, CuO
x
and TiO
x
have been formed by thermal and plasma oxidation, at various deposition and oxidation conditions, both with and without rapid
thermal post-annealing. The resistive bistability effect has been observed for all these materials, with particularly high
endurance (over 103 switching cycles) obtained for single-layer TiO2 junctions, and the best reproducibility reached for multi-layer junctions of the same material. Fabrication optimization
has allowed us to improve the OFF/ON resistance ratio to about 103, but the sample-to-sample reproducibility is so far lower than that required for large-scale integration. 相似文献
997.
Surinder Singh Jatinder SinghSandeep Singh Gill 《Optics and Lasers in Engineering》2011,49(1):152-158
Employing a Mach-Zehnder Interferometer (MZI), this paper describes simulation demonstration of an all-optical scheme for data format conversion between non-return-to-zero (NRZ) and return-to-zero (RZ). Data format conversion between NRZ and RZ at 120 Gb/s has been simulated for the first time using an MZI. In addition, we have proposed for the first time data format conversion from NRZ to RZ by using a single SOA in an MZI. 相似文献
998.
S. Ganguly Aparajita Dey P. Banerjee S. Bhattacharya R. P. Singh S. Muralithar R. Kumar R. K. Bhowmik 《Brazilian Journal of Physics》2011,41(2-3):135-139
Excited states of 83Kr, populated in the 76Ge(11B, 3npγ) reaction at a beam energy of 50 MeV, have been studied. The ΔI?=?1 band, built upon the 2,510.0 keV state, has been observed up to 5,639.4 keV with spin (27/2???). Mean lifetimes have been measured up to spin 23/2?? in ΔI?=?1 band using the Doppler shift attenuation method. The B(M1) rates derived from the measured lifetimes decrease smoothly with spin indicating that the angular momentum belonging to this band are generated by the shears mechanism. 相似文献
999.
We present a label-free, nondestructive and high sensitivity biosensor by using the phase information of a gold nanoparticles enhanced ellipsometry signal. The refractive index (RI) resolution from ellipsometric phase information is of the order of 1.6×10(-6) RI units. Furthermore, spectroscopic and dynamic measurements show substantial change in the phase signal when biomolecules are coated on gold nanoparticles. The detection limit of our proposed technique is up to ~18?pM concentration of the target biomolecules. 相似文献
1000.
Structural and optical properties of RF magnetron sputtered aluminum nitride films without external substrate heating 总被引:1,自引:0,他引:1
Atul Vir Singh Sudhir ChandraA.K. Srivastava B.R. ChakrobortyG. Sehgal M.K. DalaiG. Bose 《Applied Surface Science》2011,257(22):9568-9573
We report structural and optical properties of aluminum nitride (AlN) thin films prepared by RF magnetron sputtering. A ceramic AlN target was used to sputter deposit AlN films without external substrate heating in Ar-N2 (1:1) ambient. The X-ray diffraction and high resolution transmission electron microscopy results revealed that the films were preferentially oriented along c-axis. Cross-sectional imaging revealed columnar growth perpendicular to the substrate. The secondary ion mass spectroscopy analysis confirmed that aluminum and nitrogen distribution was uniform within the thickness of the film. The optical band gap of 5.3 eV was evaluated by UV-vis spectroscopy. Photo-luminescence broad band was observed in the range of 420-600 nm with two maxima, centered at 433 nm and 466 nm wavelengths related to the energy states originated during the film growth. A structural property correlation has been carried out to explore the possible application of such important well oriented nano-structured two-dimensional semiconducting objects. 相似文献