Optical properties and photocatalytic activity of Nd-doped ZnO powders

To improve the photocatalytic activity of zinc oxides, ZnO powders doped with different neodymium （Nd） concentrations were prepared via hydrothermal method. X-ray diffraction （XRD） together with X-ray photoelectron spectroscopy （XPS） patterns revealed that Nd atoms were successfully incorporated into the ZnO lattice. XRD pattern also showed some anisotropy of the powders. The photoluminescence （PL） spectrum demonstrated a strong and broad peak in the visible light region, and the intensity of visible light emission was enhanced by Nd-doping. The photocatalytic activity was evaluated by the degradation of methyl orange solution. It is shown that doping of Nd into ZnO induces an increase of the photocatalytic activity and it attains to optimum at 3% （mole fraction） doping concentration. The intense visible light emission and the enhanced photocatalytic activity were explained by the increase in electron hole pairs and induced defects like antisite oxygen Ozn and interstitial oxygen Oi, due to the doping of Nd.

Effects of Technical Conditions on Structure, Morphology and Crystalline Size of Nanocrystalline Nd-Doped Ceria Powders

Nanocrystalline solid solution CeO2-Nd2O3 powders were prepared by low temperature combustion process.Special attention was paid to the influence of the glycine/metal ratio and calcination temperature on the powders phase structure, morphology and particle size.TG-DSC curves and XRD peaks of different glycine/metal ratio show that smaller particle size can be obtained with a slightly fuel-deficient ratio.XRD results indicate that the as-prepared powders are crystallized in a single fluorite structure.The crystalline size ranges from 9 to 24 nm, which increases with the increase of calcination temperature.The lower SEM images were characterized by the spongy and form-like microstructure of the powders.Organic agent may be gradually eliminated by high temperature calcination process.

Enhanced photocatalytic activities of Nd-doped TiO2 under visible light using a facile sol-gel method

Titanium dioxide nanoparticles modified with neodymium in the range of 1 mol% to 5 mol% were prepared with template-free sol-gel method.The structures of obtained samples were characterized by X-ray powder diffraction analysis.X-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy and diffuse reflectance spectroscopy.The photocatalytic activity of the obtained samples was evaluated by photodegradation of methyl orange in aqueous solution under ultraviolet-visible(λ> 350 nm) and visible(λ> 420 nm) irradiation.The experimental results show that the 1 mol% Nd-doped TiO2 exhibits the highest photocatalytic activity,of which the degradation can reach to 96.5% under visible irradiation.According to the XRD results,the pristine samples are combined with anatase TiO2 and rutile TiO2.while the Nd-doped TiO2 samples are anatase TiO2 only.This transformation has made an obvious promotion of photocatalyst activity after modification.

Effect of copper impurity on the optical loss and Nd^(3+) nonradiative energy loss of Nd-doped phosphate laser glass

N31-type phosphate laser glasses doped with different concentrations of Cu were prepared. Their optical loss coefficient at 1053 nm wavelength and nonradiative transition rate from the Nd3＋ 4F3/2 state were determined and analyzed in detail. The optical loss coefficient per unit of Cu2＋ （cm–1/ppmw） and the fluorescence decay rate （Hz/ppmw） caused by Cu2＋ and Nd3＋ interaction were 0.0024 and 7.9, respectively. Cu impurity affected both optical loss at 1053 nm and fluorescent emission of Nd3＋ 4F3/2 state seriously in N31 laser glass.

Monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped high-power laser glass

This paper investigates the monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped phosphate laser glass,which will be utilized under liquid cooling conditions for high-power laser systems.The thermal stress,interface bubbles and residual refiectivity,which are due to high-temperature casting and bonding during the monolithic edge-cladding process,are simulated and determined.The applied mould is optimized to a rectangular cavity mould,and the casting temperature is optimized to 1000℃.The resulting lower bubble density makes the mean residual refiectivity as low as 6.75×10^(-5),which is enough to suppress the amplified spontaneous emission generated in the Nd-glass disk,and the resulting maximum optical retardation is converged to 10.2–13.3 nm/cm,which is a favourable base for fine annealing to achieve the stress specification of less than or equal to 5 nm/cm.After fine annealing at the optimized 520℃,the maximum optical retardation is as low as 4.8 nm/cm,and the minimum transmitted wavefront peak-to-valley value is 0.222 wavelength(632.8 nm).An N31 elliptical disk with the size of 194 mm×102 mm×40 mm can be successfully cladded by the optimized monolithic edge-cladding process,whose edge-cladded disk with the size of 200 mm×108 mm×40 mm can achieve laser gain one-third higher than that of an N21-type disk of the same size.

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase.The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.

Nd-doped SnO_2:characterization and its gas sensing property

Nd-doped(2%,5%,10% in mass ratio) SnO2 powders were prepared via a facile hydrothermal procedure.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the Nd-doped SnO2 samples had more uniform and smaller primary particles compared with the pure sample,the particle size of the doped SnO2 decreased gradually with the increase of Nd,and the specific surface area also increased with the increase of the doped Nd.When used as gas sensing materials,the 5% and 10% Nd-doped sample showed high sensitivity and selectivity to ethanol.Furthermore,the Nd-doped sample showed fast response and recovery time to ethanol gas.This could be attributed to their small diameter,large surface area and Nd element doping.

Generation of 12th order harmonic mode-locking in a Nd-doped single-mode all-fiber laser operating at 0.9μm

Based on the Nd-doped single-mode fiber as the gain medium,an all-fiber 12th harmonic mode-locked(HML)laser operating at the 0.9μm waveband was obtained for the first time,to the best of our knowledge.A mandrel with a diameter of 10 mm was employed to introduce bending losses to suppress mode competition at 1.06μm,which resulted in a suppression ratio of up to 54 dB.The 1st–12th order HML pulses with the tunable repetition rate of 494.62 kHz–5.94 MHz were obtained in the mode-locked laser with a center wavelength of∼904 nm.In addition,the laser has an extremely low threshold pump power of 88 mW.To the best of our knowledge,this is the first time that an HML pulse has been achieved in a 0.9μm Nd-doped single-mode all-fiber mode-locked laser with the advantages of low cost,simple structure,and compactness,which could be an ideal light source for two-photon microscopy.

CHARACTERISTICS OF Nd-DOPED FIBER LASER PUMPED BY Ar ION LASER

Nd-doped fiber laser pumped by Ar ion 514.5 nm laser has been reported previously. Our recent experiment demonstrates that 1060 nm CW operation can also be achieved when pumped by other wavelength components of Ar ion laser, i. e. 476.5 nm, 488.0 nm

Nd-doped ZnO as a multifunctional nanomaterial

Chemically synthesised ZnO and Nd-doped ZnO nanoparticles were investigated for structural, optical, magnetic properties along with photocatalytic activity. Transmission electron microscopy measurement was performed on the undoped and doped ZnO nanoparticles. Compared to the undoped ZnO, Nd-doped ZnO nanoparticles showed enhanced photoluminescent and ferromagnetic properties. The Nd- doped ZnO nanoparticles also showed improved photocatalytic properties compared with the undoped ZnO nanoparticles. Furthermore, the effect of UV light irradiation was studied with thermoluminescence （TL） and photoluminescence （PL） measurement techniques. It was found that in case ofNd-doped ZnO nanoparticles TL intensity increased while the green emission in PL spectra decreased with UV-light irradiation. This was attributed to the production of more surface defects on UV irradiation on Nd-doping.