Jing He Liu

Growth and Absorption Spectrum of Tm,Ho:BaY2F8 Crystal

The Tm,Ho:BaY2F8 single crystal was successfully grown by the Cz method. The optimal technical parameters obtained are as follows: the pulling rate is 0.5—0.6mm/h; the rotation speed is 5—7rpm; the cooling rate is 10°C/h. The result of XRD curve shows that as-grown Tm,Ho:BaY2F8 laser crystal belongs to the monoclynicsystem and space group I41/a, the cell parameters calculated are: a = 0.69829 nm, b = 1.0519 nm, c = 0.42644 nm, β=99.676°, Z=2. Absorption spectra of Tm,Ho:BaY2F8 laser crystal at room temperature were measured and analysed, the absorption cross-section at 781nm calculated are 7.66×10-21cm-2.

Synthesis of Ytterbium-Doped Yttrium Aluminum Garnet Laser Ceramic Nano-Powders by Carbonate Altogether Precipitation Method

Yb:YAG laser ceramic nanopowders were synthesized by the carbonate altogether precipitation method, and the thermal properties with structure and morphology characterized and analyzed by the measurements of TG-DTA, XRD, IRS, SEM. The results show that well-crystallized Yb:YAG nanopowders calcined at 900°C are obtained with higher sintering performance and purity, and the average diameter is in the range of 100 nm. The crystalline size grew with the increase of the heat treatment temperature. The size of powder calcined at 1100°C is about 70-150 nm with higher purity, regular shape and even particle size distribution, which is favorable for good sinterability of Yb:YAG ceramics.Key words: Yb; YAG laser ceramic powders; nanopowders synthesis; carbonate altogether precipitation method;

Synthesis of Nd:GGG Powder by Liquid Phase Co-Precipitation or Solid State Method and Preparation of its Transparent Ceramic

Neodymium-doped gadolinium gallium garnet (Nd:GGG) precursor and ceramic were prepared by liquid phase co-precipitation or solid-state methods, and the properties were studied. The results indicate that the precursor prepared with the liquid phase co-precipitation method has a small particle size. The sub-transparent ceramic was obtained after the body sintered for 2-3h at 1650°C at 1100Pa using liquid-phase co-precipitation method. When the body was sintered at 1750°C for 2-3h, a sintered body with non-transparency was obtained. The absorption spectrum and fluorescence spectrum of the sub-transparent ceramic were measured with the cross section at 807nm was calculated as1×10-20cm2 and the strongest emission peak located at 1061nm.

Preparation of Nd:YAG Nanopowders by the Urea Co-Precipitation

Nd:YAG nanopowder was prepared by urea co-precipitation method. XRD, TG-DTA, SEM and spectra analysis were utilized to study the properties of the powder. Results indicated that fine Nd:YAG nanopowder can be acquired at 1000°C for 10h. The fluorescence spectra shown that the strongest peak was located at 1061nm, corresponding to the 4F3/24I11/2 energy level transition of Nd3+ ion.

Growth and Spectrum Properties of Ho:BaY2F8 Crystal

Ho3+:BaY2F8(Ho:BYF) single crystal was grown by the Czochralski method. The optimal technical parameters obtained are as follows: the pulling rate is 0.5mm/h, the rotation rate is 5rad/min, the cooling speed is 10°C/h.The result of XRD curve shows that as-grown Tm:BYF crystal belongs to the monoclinic system and space group C12/m1. The cell parameters calculated are a=0.642nm,b=1.03293nm,c=0.42621nm,β= 99.62o.The absorption and fluorescence spectra of the Ho:BYF crystal were measured.FWHM is 8 nm on 884 nm wavelength,absorption coefficient and absorption cross-section calculated are 1.21cm-1 and 1.21×10-21cm2.

Nd,Yb:YAG Laser Crystal Production and its Property

To produce Nd, of Yb: YAG laser crystal by use of medium frequency induction heating Czochralski method.Taking advantage of the XRD, absorption spectra and fluorescence spectra on the crystal of the phase structure of and spectral to analyze the performance of structureshows that: Nd, Yb: YAG crystals belong to the cubic crystal system with the lattice parameters a = 1.2021 nm. There is a strong absorption in the 808nm but under the common temperature Nd, Yb: YAG crystal fluorescence spectra of the strongest fluorescence emission peak at 1030nm, attributable to the Yb3 + ion 2F5/22F7/2 level transition

1.03μmYb: YAG Laser Crystal Production and its Property

In this paper, the crystal growth, ceramic preparation and performance of Yb: YAG was studied systematically. The new technics that is filling protective atmosphere in the lower vacuum has been presented firstly. The Yb: YAG laser with a dimension of Φ27mm×100mm was grown by Czochralski method to medium frequency induction heating. The performance of Yb: YAG crystal was investigated by using several measurements, such as absorption spectrum, fluorescence spectrum and so on.

Growth and Spectral Properties of Ho3+,Tm3+ Codoped BaY2F8 Laser Crystal

Ho3+:Tm3+:BaY2F8(Ho:Tm:BYF) laser crystal was grown by Czochralski method. The technical parameters as follows: the seeding temperature is 955°C; the pulling rate is 0.5mm/h; the rotation rate is 5rad/min; the cooling rate is 15°C/h; the period of growth is 6d. According to the spectra of crystal sample, the strongest absorption peak exists at 781nm, and the absorption cross section is 6.16×10-21cm2. While the strongest emission peak exists at 2056nm with the FWHM of 38nm, and the emission cross section is 4.05×10-21cm2, and the emission mechanism at 2056nm was analyzed based on energy level diagram of Ho3+ and Tm3+ ions.

Study on Growth and Crack of Yb:YAG Laser Crystal

The 5at.% Yb3+-doped YAG crystal was grown by the Czochraski method, and the crystal growth process was investigated. the optimal process parameters were determined as follows: The crystal growing rate for Shoulder growth and equal-diameter growth were 0.8mm/h and 1mm/h, respectively. The optimal Rotation speed of this crystal was 15rad/min, and the axial temperature gradient was 0.01−0.05°C/mm. The impact factors to crystal growth were analyzed theoretically, such as growth rate, rotation speed, thermal effect and crystal size.

Effect of Different Fillers on Microstructure and Mechanical Properties of Ultrahigh Molecular Weight Polyethylene Composite

Three fillers i.e. micro glass bead, nano-montmorillonite and graphite at 8wt% were respectively filled into ultrahigh molecular weight polyethylene (UHMWPE). The microstructure, mechanical properties were investigated. The results indicated that: The performances of three kinds of composites, such as morphology, tensile strength, impact strength, elongation at break and fraction wear, were in great difference. The bonding of interface between glass bead and UHMWPE was not firm, but nano-montmorillonite and graphite as filler dispersed in matrix evenly and coupling tight. Due to filling the filler, the tensile strength, impact strength and elongation at break decreased in varying degree compared with that of simple UHMWPE, but impact strengths reduced only a few; however the wear resistance of composite filled by graphite was improved obviously.