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1.
Fabrication and properties of highly transparent Er:YAG ceramics 总被引:1,自引:0,他引:1
Xianpeng Qin Hao YangGuohong Zhou Dewei LuoYan Yang Jian Zhang Shiwei Wang Jan MaDingyuan Tang 《Optical Materials》2012,34(6):973-976
Highly transparent Er:YAG ceramics with different Er doping concentrations were fabricated by a reactive sintering method under vacuum. The optical properties and the microstructures of the Er:YAG ceramics were investigated. For 3 mm thickness samples, the in-line transmittances of the as-fabricated Er:YAG ceramics at the wavelength of 1100 nm and 400 nm were about 84% and 82%, respectively. The micrograph of the Er:YAG transparent ceramics exhibited a pore-free structure and the average grain size was about 10 μm. The grain boundary of the ceramics was clean and no secondary phase was detected. The absorption and emission spectra, the fluorescence decay traces of the Er:YAG ceramics were measured and discussed. The ceramics obtained may have potential use for eye-safe solid-state lasers partly replacing Er:YAG single crystals. 相似文献
2.
测量了30%(原子分数)Er:YSGG晶体的晶胞参数:a=b=c=(1.24640±0.00065)nm,α=β=γ=90°.用Rietveld方法对X射线衍射谱进行了精修,给出了处于96h位置的O原子分数坐标(x, y, z)=(-0.031433±0.000780、0.058253±0.000792、0.155358±0.000776),并计算了氧配位多面体中的阴阳离子间距和夹角,结果表明Er3 /Y3 处于畸变十二面体的中心.另外还研究了该晶体在室温下的吸收光谱和荧光光谱的性质.在200~1700nm波段内,Er:YSGG晶体吸收谱带主要为Er3 离子的特征吸收,计算了Er3 在966、790nm处的吸收截面;测量了966、790和488nm为激发波长时的室温发射光谱, 当激发波长为966nm时发射谱带强度较大.另外,以1534nm为监测波长得到室温下的激发光谱,研究结果表明Er:YSGG激光晶体适合于InGaAs二极管激光器的泵浦. 相似文献
3.
Beatriz?Togoro?Ferreira?da?Silva Paulo?Francisco?Cesar Patrícia?Moreira?de?Freitas Regina?Guenka?Palma-Dibb Adriana?Bona?Matos
This study evaluated the effects of different Er:YAG laser pulse width protocols on surface roughness, loss of volume of the material, and the step height formed of pre-sintered yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) by three-dimensional profilometric assessment. Blocks of pre-sintered Y-TZP were cut providing 63 standard 5-mm-thick samples which were divided by surface treatment, as follows (n = 9): G50 (100 mJ/10 Hz/1 W-50 μs); G100 (?100 μs); G300 (?300 μs); G600 (?600 μs); G1000 (?1000 μs); GTC (tribochemical silica coating); and GNC (untreated). After treated or not, samples were sintered according to the manufacturer’s recommendations. Roughness, volume loss and step height were analyzed by 3D profilometric assessment with confocal laser microscopy. ANOVA and Tukey’s test (p < 0.05) detected that irradiated groups showed increased roughness in the groups G50, G100, G300, and G600 when compared to GTC and GNC groups. The G1000 group showed a completely flat and unfavorable surface for retention. The groups G50, G100, and G300 showed great loss of volume and the step height formed, which can lead to a gap on the crowns. In G600 was observed satisfactory roughness with little loss of volume and the step height formed similar to GTC. Irrespective of laser protocol, any of the specimens showed the presence of cracks. It is suggested that the pulse width 600 μs (G600) is the most suitable pulse width protocol as an alternative surface treatment, promoting micro-retention, with little loss of volume of material, comparable to silica coating treatment. 相似文献
4.
Laser-induced breakdown spectroscopy (LIBS) is widely dependent on the conditions of its implementation in terms of laser characteristics (wavelength, energy, and pulse duration), focusing conditions, and surrounding gas. In this study two wavelengths, 1.06 and 2.94 microm, obtained with Nd:YAG and Er:YAG lasers, respectively, were used for LIBS analysis of aluminum alloy samples in two conditions of surrounding gas. The influence of the laser wavelength on the laser-produced plasma was studied for the same irradiance by use of air or helium as a buffer gas at atmospheric pressure. We used measurements of light emission to determine the temporally resolved space-averaged electron density and plasma temperature in the laser-induced plasma. We also examined the effect of laser wavelength in two different ambient conditions in terms of spectrochemical analysis by LIBS. The results indicate that the effect of the surrounding gas depends on the laser wavelength and the use of an Er:YAG laser could increase linearity by limiting the leveling in the calibration curve for some elements in aluminum alloys. There is also a significant difference between the plasma induced by the two lasers in terms of electron density and plasma temperature. 相似文献
5.
Randles AB Esashi M Tanaka S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2010,57(11):2372-2380
This paper presents the etch rate of lithium niobate (LiNbO(3)) as a function of crystal orientation. Etching is a fundamental technology needed for the fabrication of new sensors, actuators, and other new devices. In this study, LiNbO(3) spheres 30 mm in diameter were etched in hydrofluoric acid and a mixture of hydrofluoric and nitric acids at different temperatures and different times. The measured data of the etched sphere shape were processed and plotted, giving etch rate diagrams over the entire spheres. Based on the etch rate data obtained, the Wulff-Jaccodine method was used to predict the etched shape of 128° Y-cut and 155° Y-cut LiNbO(3). The predicted etching profiles were compared with those obtained by experiments. A least-square polynomial fit for the data was also developed and was found to be useful in removing some of the variation in the measurements. 相似文献
6.
The Er:YAG laser-induced damage (LID) threshold and modal properties of single-crystal sapphire fibers grown by the laser-heated pedestal-growth method have been measured. The lowest loss (~0.4-dB/m) sapphire fibers produce little mode mixing and therefore deliver a near-single-mode output profile if the Er:YAG laser input beam profile is also nearly Gaussian. Normally, however, Er:YAG laser output beam profiles are multimode with numerous high-energy spikes. This leads not only to a multimode output from the fiber but also increased fiber loss that is due to higher-order mode coupling. The results of LID testing give a damage fluence of ~1.4 kJ/cm(2) for 300-mum core-only sapphire fibers at 2.94 mum. 相似文献
7.
Lin S Pan D Lin Q Yin S Chen D Liu Q Yu L Lin Z 《Journal of nanoscience and nanotechnology》2011,11(3):2421-2426
This study aims to evaluate the composition, micro-structure and inorganic phase alternations of human dentine irradiated by Er,Cr:YSGG laser with water cooling spray system. X-ray diffraction (XRD) analysis indicated that the main inorganic phase of dentine before and after laser irradiation were all Hydroxyapatite (HA) structure, approximately 30 nm in size. No significant changes occurred in the average particle size after irradiation in four energy densities (6.18 J/cm2, 8.04 J/cm2, 9.89 J/cm2, 11.1 J/cm2). Atomic force microscope (AFM) phase image and the energy-dispersive spectroscope (EDS) analysis, however, demonstrated that the thermal effects of Er,Cr:YSGG laser with water-cooling spray system on the dentin surface was intense enough to induce notable decrease of the organic matter. Both scanning electron microscopy (SEM) and AFM analysis showed that the irradiated dentine presented rough surface morphology. The surface is clean and dentinal tubules are completely open. The ablation rate of both peri- and intertubular dentine increased at higher energy densities but no significant changes of gross appearance took place. Chemical analysis reveals that laser photothermal effect would decrease significantly the organic content of superficial dentinal layer. We conclude that the Er,Cr:YSGG laser, as a new type clinic laser, would not significantly influence the inorganic phase structure of the surface dentine layer, however, thermal ablation was occurred in organic component. Moreover, the rough ablated surface as well as the opened dentinal tubules induced by irradiation, might be advantageous to the infiltration of the adhesive materials, thus the adhesion of dental restoration could be enhanced. Further studies should focus on the correlation between bond strength and Er,Cr:YSGG lased dentine. 相似文献
8.
A 3-mum laser-generation delivery instrument that uses chalcogenide fibers with a unique damage threshold and conical radiation input has been developed for medical applications. A new purification and synthesis scheme has been elaborated that yields fibers with a heterophase inclusion content of less than 10(4) cm(-3). In such fibers the damage threshold is 350 J/cm(2) at an average power density of 0.5 kW/cm(2) in a YAG:Er laser operating in the repetitive pulse free-running regime with a pulse duration of 350 ms. 1-3 x 10(4) laser pulses were transmitted at a repetition rate of 3 Hz and an average output power of 1 W under the condition of a 15% decrease in the output power. 相似文献
9.
Seyyed Hossein Asadpour H. Rahimpour Soleimani 《Journal of Materials Science: Materials in Electronics》2014,25(8):3578-3585
The effect of Er3+ doped ion concentration on optical properties of two type three-level schemes in 35 nm Er3+:YAG (yttrium aluminum garnet) crystal is studied. It is found that intensity threshold of optical bistability and multistability can be changed by Er3+ doped ion concentration. Moreover, switching from optical multistability to optical bistability can be done differently by Er3+ concentration in two types of three-level schemes. The steady-state and transient behaviors of absorption, dispersion and group index of weak probe field in two schemes are also discussed. In this study, we will report an initial study on optical properties in Er3+:YAG crystal and propose a basis for selecting the suitable concentration to carry out experimental investigations in the future. 相似文献
10.
11.
Varghese Mathew Jochan Joseph Sabu Jacob K. E. Abraham 《Bulletin of Materials Science》2010,33(4):433-437
The preparation of manganese malonate crystals by gel method and its spectroscopic studies are reported. X-ray diffraction (XRD) pattern reveals the crystalline nature. The FTIR and FT Raman spectra of the crystals are recorded and the vibrational assignments are given with possible explanations. Diffuse reflectance spectroscopy (DRS) is used to measure the bandgap (E g) of the material. 相似文献
12.
N.E. Alekseevskii A.P. Dodokin C. Bazan Kh.S. Bagdasarov E.A. Fedorov L.M. Belyaev 《低温学》1981,21(10):598-600
The paramagnetic salts, eg alums, usually employed in adiabatic demagnetization experiments are inconvenient because of their tendency to dehydration, etc. The refractive oxides with magnetic impurities seem to be more favourable. The authors describe the results obtained with Er3+ and Nd3+ substituted yttrium aluminium garnets (YAG). Final temperatures reached after adiabatic demagnetization are comparable to those obtained with cerium magnesium nitrate. The paper illustrates the possible use of Er3+ and Nd3+ substitued in YAG for creating a very simple device for obtaining low temperatures in the mK region by adiabatic demagnetization. 相似文献
13.
L.C. Nistor V.S. Teodorescu M. Dinescu N. Frangis C. Liutas 《Materials Research Bulletin》2004,39(13):2089-2101
Hydroxyapatite (HA) thin films has been successfully deposited by Nd:YAG laser ablation at λ = 532 nm. The morphology and microstructure of the deposited layers was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Polycrystalline HA films were directly obtained with the substrate at 300 °C and without introducing water vapors in the deposition chamber. Electron paramagnetic resonance (EPR) measurements show that the oxygen stoichiometry in the HA films is also maintained. Depositions performed at λ = 335 nm laser wavelength and 300 °C substrate temperature resulted in polycrystalline layers of mixed composition of HA and tricalciumphosphate (TCP). 相似文献
14.
Yan MaJian Lin Jingjing ChenZhaobin Feng Hengyong WeiJingyu Mao 《Materials Letters》2011,65(2):282-284
Solid-state field-assisted diffusion was used to prepare Ag nano-composite silicate glass. After positive diffusion process, small Ag atoms clusters were formed in the slides. The Ag atom clusters could aggregate into Ag nanoparticles (NPs) with bigger size after subsequent reverse diffusion process. YAG: Yb, Er nanopowders were screen-printed on the glass slides after positive and reverse diffusion, respectively, for up-conversion luminescence measurement. Almost no luminescence enhancement was observed for the slide after positive diffusion. Whereas, obvious enhancement was obtained for the slide after reverse diffusion, and the enhancement factor could reach about 26. The strong enhancement was due to the larger size of Ag NPs. The present work suggested a new promising method to enhance the luminescence of YAG: Yb, Er nanopowders. 相似文献
15.
A. H. Eldarrat A. S. High G. M. Kale 《Journal of materials science. Materials in medicine》2010,21(1):45-51
One of the age-related changes occurring in dentine structure is the formation of peritubular dentine on the inner walls of
dentinal tubules leading to complete closure of tubules. Ac-impedance is safe, fast and non-invasive technique. In the last
decade, the popularity of the technique has increased in dental research. Several investigators have used the technique to
detect tooth cracks and caries. The results of in vitro studies showed that ac-impedance technique was more advanced for caries
detection than visual and radiographic methods. However, other studies demonstrated that the accuracy of impedance measurements
can be affected by many factors such as remineralization after tooth eruption. A study has been published on effect of age
on impedance measurements by the authors for two age groups by employing ac-impedance spectroscopy. Therefore, the aim of
this study was to demonstrate the importance of this technique by conducting further investigations on dentine samples of
wider age groups. Dentine samples were prepared from extracted sound third molars of known patient age. The ac-impedance measurements
were carried out over a wide range of frequency. After performing all electrical measurements, dentine samples were examined
under SEM to correlate the electrical measurements with their structure. Impedance measurements showed that there were differences
in impedance between young and old dentine. One-way ANOVA of the means of resistance and capacitance for all age groups (20,
25, 30, 40 and 50 years old dentine) revealed a significant difference (ANOVA, P < 0.0001) as a function of age. Applying Tukey’s post hoc test, to the same data showed that this difference was due to the
50 years old dentine for resistance and was due to the 40 and 50 years old dentine for capacitance which were statistically
different to all other groups. SEM investigation of dentine samples showed that young dentine is characterized by open dentinal
tubules distributed all over the sample while in old dentine most dentinal tubules were occluded by peritubular dentine. It
is believed that this peritubular deposition is responsible for differences in impedance measurements. In spite of increasing
use of electrical techniques to understand electrical properties of teeth, it is clear from this study that local structural
variations have a marked influence. 相似文献
16.
The electromagnetically induced left-handedness with zero absorption and large negative refractive index was investigated in a solid Er3+:YAG crystal with a four-level system proposed for an atomic medium. It was found that the frequency region with simultaneous negative permittivity and negative permeability, the zero absorption intervals, and the maximum values of the negative refractive index can be adjusted by changing the signal field, the coherent field, as well as the concentration of Er3+ ion in crystal. It is shown that wider zero absorption intervals with a higher index of refraction can be easily obtained when the signal field is only off resonance. The slab fabricated by the left-handed solid medium Er3+:YAG crystal with zero absorption may be a practical candidate for designing perfect lenses. 相似文献
17.
High field electrical switching studies on x Ag2O − (50−x) P2O5 −50V2O5 glasses have been carried out as a function of sample thickness, composition and temperature. The I–V characteristic show
that switching in these glasses is memory type. The switch voltages are found to decrease with increase of temperature, on
the other hand, the voltages increase with the thickness of the sample. The experimental findings clearly reveal that switching
in these glasses is a thermally assisted bulk effect. The results obtained are explained on the basis of formation of crystalline
conducting channels. Another notable observation is that the glass with 15 mol% Ag2O concentration only exhibits the switching property at room temperature. This aspect is examined in view of various structural
groups present in these glasses with the help of spectroscopic studies; IR and MAS–NMR measurements have been carried out.
IR studies of these glasses show characteristic absorption peaks corresponding phosphate and vanadium vibrations in the network.
31P MAS–NMR chemical shift show presence of [POO3/2]0 and [POO2/2O]− groups. 相似文献
18.
19.
Mochalov IV Petrovskii GT Sandulenko AV Sandulenko VA Cervantes M Terpugov VS 《Applied optics》1997,36(18):4090-4093
It has been established that Tm(3+) ions do not prevent multiple-wavelength oscillation in Cr:Tm:Er:YAG laser crystals inserted inside of the completely nonselective mirror resonator. The output mirror spectral selectivity needed for single-wavelength oscillation at 2.697 mum for a considerable excess of pumping energy over the threshold has been determined experimentally. It has been shown that Tm(3+) optimum concentration in the crystals could be determined correctly in the described resonator scheme. 相似文献
20.
Eldarrat AH Wood DJ Kale GM High AS 《Journal of materials science. Materials in medicine》2007,18(6):1203-1210
Non-destructive methods, such as the ac-impedance technique, have recently been applied to early caries detection and to identify
micro-leakage between tooth structure and filling materials. However, in vitro impedance measurements are affected by a number
of external factors. The purpose of present study was to investigate the effect of the age of teeth on impedance measurements
of human dentine by employing electrical impedance spectroscopy (EIS). Fully hydrated dentine samples were prepared from extracted
third molars of 20 and 50 year old patients. Ac-impedance measurements were carried out over a wide frequency range. Impedance
measurements showed that there were differences in impedance between young and older dentine. In their circuit models, both
resistance and capacitance were found to be significantly different (p < 0.05) for the two age groups. One of the age-related changes in dentine is the formation of peritubular dentine on the
inner walls of dentinal tubules and we propose that this is responsible for the differences in impedance. Sample or patient
age therefore must be considered when making impedance measurements on any tooth. 相似文献