Crystal Growth and Spectral Properties of Yb^3＋ ：KY（WO4 ）2

Laser crystal Yb:KYW was grown by the Kyropoulos method. A grown crystal was identified as β-Yb:KYW by XRD. By TG-DTA the melting point and transition point of the crystal are 1045 and 1010 °C, respectively. Infrared spectrum and Raman spectrum were measured, and the vibrational frequencies of infrared and Raman active modes for Yb:KYW crystal were assigned. Absorption spectrum of Yb:KYW shows that there are two intensive absorption peaks at 940 and 980 nm, respectively, and the absorption cross section is 1.34 × 10⁻¹⁹ cm² at chief peak of 980 nm. There exist three intensive emission peaks in Yb:KYW at 990, 1010 and 1030 nm, respectively, and the emission line width of the chief peak 1030 nm runs up to 16 nm. It was calculated that the peak emission cross section is 3.1 × 10⁻²⁰ cm² at 1030 nm.     

Crystal Growth and Laser Characteristics of Nd3+ :KGd(WO4)2

The Nd3 3.2% (atom fraction):KGd(WO4)2 crystal was grown by Kyropoulos method. The absorption spectrum and fluorescence spectrum of Nd3 :KGW crystal were measured. The absorption cross sections at 808 nm(0.6799 ×10-20 cm2) were calculated, and the output wavelength of fluorescence is 1064 and 1351 nm. The diode-pumped laser was operated both in the free-running and passively Q-switched operating modes. The maximum laser output( 1064 nm) is 326mW with 62.7 % slope efficiency when input energy is 900 mW. The beam quality factor M2 ≈ 1.1. The green light of 532 nm is obtained in frequency doubling operation. The laser is passively Q-switched by using Cr4 :LuAG as saturable absorber. The pulse width is 170 ns at repetitive frequency of 15 kHZ.     

Study on Growth and Spectra Properties of Nd: GGG Crystal

The laser crystal Nd GGG was grown by Cz method. The optimum processing parameter is that the pulling rate is 2~4mm·h-1, the rotation rate is 20~40 r·min-1 and the cooling rate is 20℃. The absorption and fluorescence spectra of Nd GGG were measured. The main absorption peak of Nd GGG is at 808 nm and the fluorescence emission peak is at 9430cm-1, corresponding to 4F3/2-4I11/2 emission band of Nd3 ions.     

Growth and Spectral Properties of Crystal Er3+:Y0.5Gd0.5VO4

Er3 :Y0.5Gd0.5VO4 crystal with good optical quality was grown by Czochraski method. The structure of the crystal was determined by X-ray powder diffraction method. The segregation coefficient of Er3 ions in the crystal was measured by the ICP method. The absorption and emission spectra were also measured. On the basis of the spectra, the absorption cross-sections, emission spectrum FWHM and fluorescence lifetime of the crystal were calculated. From the properties mentioned above.     

Growth, Thermal and Optical Properties of Dyx Y1 - x Al3 （ BO3 ） 4 Crystal

Recently ,solid statelasersoperatingintheyel lowregionhavegainedmuchattentionbecauseoftheirimportantapplicationinmilitaryandtelecommunica tion .SomeresearcheshavedemonstratedthatDy3 canobtainyellowlaseremissionusingthe 4 F9/2 →6 H13/2 channel[1～ 3] .RareearthionsdopedYAl3(BO3) 4(YAB)crystalwasreportedtobepromisingmaterialsforlaserapplications .TheYABcrystalhashigh hardness ,isnonhygroscopicandchemicallysta ble,andonlycanbegrownbythefluxmethodbe causeofmeltingincongruently .TheYABcryst…     

Paramagnetic Anisotropy of CdGd2(WO4)4-δ Single Crystal

CdGd2(WO4)4-δ single crystal was grown using the Czochralski's method. The crystal structure was tetragonal scheelite with lattice parameters a=b=0.5203 nm and c=1.1359 nm. There were vacancies of (WO4)2-, therefore, there were some Gd2+ ions. Langevin paramagnetism and anisotropy were observed from the σ-T curves at room temperature. The susceptibility χ// was 3.5018×10-3, and χ⊥ was 3.4403×10-2. The anisotropy was also observed in the electron spin resonance (ESR) experiments. The anisotropic Landé factors were g//=2.1333 and g⊥=2.8411. The direction of easy magnetization was in the a-b plane. Anisotropic paramagnetic Curie constants C// and C⊥ were not only related to macroscopic σ that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd2+ and Gd3+ ions. Based on the detailed analyses, the proportion of 36.8% of Gd3+ ions to 63.2% of Gd2+ ions in the Gd ions of the CdGd2(WO4)4-δ crystal was calculated, and δ was 0.638 in the single crystal.     

Growth and Characteristic of YbAl3(BO3)4 Crystal

YbAl3(BO3)4 crystal of good optical quality was grown by the flux method. The structure of YbAl3(BO3)4 crystal was determined by single-crystal X-ray diffraction. The experiment shows that YbAl3(BO3)4 belongs to the double borates with a trigonal structure. The space group is R32 and its unit cell constants were measured to be a=0.92965 nm, c=0.72129 nm, V=0.53673 nm3, Z=3. The transmittance spectra were measured. The cut-off of YbAl3(BO3)4 crystal is 216 nm, and there are two absorption peaks located at 940 and 975 nm from 190 nm to 2600 nm. The thermal properties of YbAl3(BO3)4 crystal were studied for the first time. The average thermal expansion coefficients were determined to be 2×10-6/℃, 9.5×10-6/℃ along a- and c- direction. The specific heat of YbAl3(BO3)4 crystal was measured to be 0.6695 J·(g·℃)-1 at room temperature. All results indicate that the YbAl3(BO3)4 crystal is an excellent stoichioimetric laser material.     

Spectral and Lasing Properties of Er~(3 0/Yb~(3 ) Co-Doped Phosphate Glasses Pumped by LD

Spectral and Lasing Properties of Er~(3 0/Yb~(3 ) Co-Doped Phosphate Glasses Pumped by LD     

Spectral Properties and Upconversion Luminescence of Er^3＋, yb^3＋： BaWO4 Crystal

The optical quality of Er^3＋, yb^3＋： BaWO4 crystal was gown by Czochralski method. Absorption spectra were measured and energy levels were assigned. According to Judd-Ofelt theory, the spectral strength parameters of Er^3＋ ion were fitted to beΩ2 =0.3926 x 10^-20 cm^2, Ω4 =0.0721×10^-20 cm^2, Ω6 =0.0028 ×10.20 cm^2. Emission peaks centered at around 523,544 and 670 nm were observed under 334 nm He-Cd laser excitation and emission peaks centered at 1001 and 1534 nm were detected under 976 nm laser excitation. Strong green emission was also observed when the crystal was pumped with 808 nm and 976 nm laser. The mechanisms of frequency upconversion and sensitization were analyzed.     

Upconversion Luminescent Properties of YVO4:Yb3+, Er3+ Nano-Powder by Sol-Gel Method

YVO4:Yb3 , Er3 nano-sized upconversion luminescent powder was prepared by sol-gel method in the presence of citric acid. It was characterized by XRD, TEM and emission spectrum. The results show that the grain size of YVO4:Yb3 , Er3 is under 100 nm, and its grain size and upconversion luminescent intensity all increase with roasting temperature raises. Under 980 nm laser diode(LD) excitation, two strong green emissions that centered around 523 and 551 nm were observed with naked eyes at room temperature, corresponding to the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions of Er3 , respectively. According to the dependence of green upconversion emission intensity on excitation power, it can be concluded that these two kinds of green emissions all belong to two-photon process.     

Synthesis and properties of Yb:Sc_2O_3 transparent ceramics

Yb:Sc2O3 transparent ceramics were fabricated by solid-state reaction and vacuum sintering method.CaO was added as sinteringaids by a high energy ball milling.Transparent nearly-fully dense samples were obtained after 1840 oC sintering.Using transmitted-light microscopewe get the grain sizes are more than 100 μm.Using spectrophotometer we get the absorption coefficient centered at 975 nm was 2.65 cm-1.The phosphorescence spectra showed that the line-widths(FWHM) at 975 and 1041 nm were about 4 and 10 nm and the lifetime of Yb ionsin Sc2O3 transparent ceramics was about 883 μs.According to the absorption and fluorescence band centers of Yb:Sc2O3 transparent ceramics,the level scheme of Yb3+ ions in Sc2O3 ceramics could be gotten.     

Spectral Parameters of Nd~(3+)∶Sr_6YSc(BO_3)_6

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Synthesis, Characterization and Crystal Structure of Neutral Homoleptic Lanthanide Amide Yb（NPh2）3（THF）2

A neutral homoleptic lanthanide amide Yb(NPh2)3(THF)2 was obtained by reaction of anhydrous YbCl3 with LiNPh2 in THF. The product was characterized by elemental analysis, infrared spectrum and X-ray crystallographic analysis. The crystal data are monoclinic, P21/n space group, a=1.2052(2) nm, b=1.9369(3) nm, c=1.6523(2) nm, β=92.79(1)°, V=3.8524(9) nm3, Z=4, Dc=1.417 g*cm-3, μ=24.67 cm-1 (Mo Kα), F(000)=1668, R=0.036, Rw=0.039. The central metal ytterbium is coordinated by three terminal NPh2 groups and two THF molecules to form a five-coordinate distorted trigonal bipyramid. The mean Yb-N bond length is 0.2219(6) nm.     

Synthesis, Characterization and Crystal Structure of Neutral Homoleptic Lanthanide Amide Yb(NPh_2)_3(THF)

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Investigation on Preparation and Fluorescence Properties of Oxy-Fluoride Glass Co-Doped with Er^3＋ and Yb^3＋

The glass sample based on the composition of 45PbF2-45GeO2-10WO3 co-doped with Yb^3 /Er^3 was prepared by the fusion method in two steps : melted at 950℃ for 20～25min then annealed at 380℃ for 4 h. Through the V-prism it is found that the refractive index of host glass and the sample are 1.517 and 1.65 respectively. The transmittance was observed by using the ultraviolet-visible-infrared spectrometer in the wavelength range from 0.35 to 2.5μm. The transmittance of the host glass is beyond 73%. That of the sample is beyond 50% and there are characteristic absorption peaks of rare-earth ions. The emission spectrum was measured by using the Hitachi F-4500 fluorescent spectrometer pumped by 980nm semiconductor laser. There are a strong emission peak at 530 nm and a weak peak at 650 nm.     

Photoluminescent properties of Ca2Gd8(SiO4)6O2: Dy3+ phosphor films prepared by sol-gel process

There are growing interests on phosphor thin films owing to their potential application in high-resolution devices such as cathode ray tubes and flat panel display devices. The solution-based sol-gel method is one of the most important techniques for the synthesis of vari-ous functional coating films. Compounds with the apatite structure are very suitable host lattices for various luminescent ions. Ca2RE8(SiO4)6O2 ( RE=Y, Gd, La ) is a kind of ternary rare-earth-metal silicate with oxyapatite structure, which has been used as host mate-rial for the luminescence of various rare earth and mercury-like ions. In this article, Ca2Gd8(SiO4)6O2:Dy3 phosphor films were dip-coated on quartz glass substrates through the sol-gel process. X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectra, as well as lifetimes were used to characterize the resulting films. AFM study revealed that the phosphor films consisted of homoge-neous particles. The Dy3 showed its characteristic emission in crystalline phosphor films, i.e., 4F9/2–6H15/2 and 4F9/2–6H13/2.     

Research of Three-Dimensional Fluorescence Spectra of RE3+ (RE=Eu, Tb) and Na2WO4 Co-doped Silica Luminescence Materials

In the preparation of this precursor tetraethlortho silicate (TEOS), sodium tungstate, ethyl alcohol, HCl and RECl3 (RE=Eu, Tb) were mixed and then heated at 800℃ for 2h, leading to a luminescent compound. The structure of the materials was characterized by TG-DTA and IR analysis, and the results indicate that the materials were in SiO2 network structure. Three-dimensional fluorescence spectra was used to characterize the luminescent properties of the materials. The luminescence property of doped and un-doped Eu3 or Tb3 and Na2WO4 in silica materials were prepared and measured. The results show that good energy transfer from WO2-4 to Eu3 ion, sensitized the luminescence intensify of Eu3 remarkably. Tb3 ion incorporated silica materials expressed the inverse energy transition from Tb3 to WO2-4, however, we got the materials with homogeneous green blue fluorescent light. Finally, the energy transfer of WO2-4 and Eu3 , WO2-4 and Tb3 were expained by energy levels diagram.     

Synthesis of Long Afterglow Phosphor CaAl2Si2O8:Eu2+, Dy3+ via Sol-Gel Technique and Its Optical Properties

The long afterglow phosphor CaAl2Si2O8:Eu2 , Dy3 was prepared by a sol-gel method. The sol-gel process and the structure of the phosphor were investigated by means of X-ray diffraction analysis (XRD). It is found that the single anorthite phase formed at about 1000 ℃, which is 300 ℃ lower than that required for the conventional solid state reaction. The obtained phosphor powders are easier to grind than those of solid state method and the partical size of phosphor has a relative narrow distribution of 200 to 500 nm. The photoluminescence and afterglow properties of the phosphor were also characterized. An obvious blue shift occurs in the excitation and emission spectra of phosphors obtained by sol-gel and solid state reaction methods. The change of the fluorescence spectra can be attributed to the sharp decrease of the crystalline grain size of the phosphor resulted from the sol-gel technique.     

Up-Conversion Properties of Oxy-Fluoride Glasses Co-Doped with Ho3+ and Yb3+

Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540 and 650 nm. The up-conversion mechanism and processes were analyzed. The relationship between pumping power and relative intensity of emissions was discussed. From the dependence, it is known that the emissions centered at 540 and 650 nm are both attributed to two-photon process.