Developments in Ceramic Materials Research

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66 T. T. Basiev, V. A. Demidenko, K. V. Dykel’skii et al. Figure 11. Transmission spectra of the CaF 2 single crystal (#3) and CaF 2 artificial optical ceramics (# 1, 2) in the UV and IR ranges. Shoot at λ – 900 (Perkin – Elmer) spectrophotometer and Brucker IFS – 113v Fourier spectrometer. Besides, a comparison of the optical properties of single crystals and optically transparent ceramics made for the same samples by thermo-stimulated depolarization method of laser radiation [29] is provided. As a result the absorption coefficients α < 4.5 10 -4 cm -1 for the single crystal and α < 1.33 10 -3 cm -1 for the ceramics are estimated. ABSORPTION AND FLUORESCENCE PROPERTIES OF THE CAF2 OPTICAL CERAMICS DOPED WITH ER 3+ Cheap and eye – safe lasers with 1.5 µm wavelength are attractive as an optical range - finder, for environment monitoring, telecommunication, etc. due to good atmosphere transparency and transparency of fused silica optical fibers and availability of sensitive detectors at this wavelength. As a result preparation of transparent fluoride ceramics doped with Er 3+ is of practical interest. Besides, this material can be used for laser generation in the 3 µm mid - IR spectral range. The CaF2:Er 3+ ceramic samples with 1 and 5 mol.% of ErF3 are prepared by hot - pressing assisted sintering method. The CaF2:5% ErF3 (Ca0,95Er0,05F2,05) ceramic sample (В(2)39-05) is prepared by pressing of two powders (CaF2 and ErF3). The CaF2:1% ErF3 (В(2)2-06) and CaF2:5% ErF3 (В(1)3-06) ceramic samples are prepared from chemically homogeneous precursors. The absorption of the ceramic samples must be studied for its use as a laser medium. The absorption spectra at the 4 I15/2 → 4 I13/2, 4 I15/2 → 4 I11/2, 4 I15/2 → 4 I9/2 and 4 I15/2 → 2 G(1)9/2
Optical Fluoride and Oxysulfide Ceramics: Preparation and Characterization 67 transitions are measured in three ceramic samples at T=300 K using Shimadzu UV – 3101 PC UV – VIS – NIR spectrometer (Figure 12). Figure 12. Absorption spectra of the CaF 2: Er 3+ ceramic samples with different concentrations of the Er 3+ ion measured at room temperature: CaF 2: Er 3+ (1%) – dark grey curve (В(2)2-06 sample) - 1, CaF 2: Er 3+ (5%) – black curve (B(2)39-05 sample) - 2, CaF 2: Er 3+ (5%) – grey curve (В(1)3-06 sample) - 3. As seen from the measured spectra the transitions in the samples with 5% concentration of the Er 3+ ions is ∼ five – fold more intensive in comparison with the sample with 1% concentration. But for the same mean concentration of Er 3+ (5%) in two samples the absorption spectra are different. Thus, for the measured transitions in the B(2)39-05 ceramic sample the absorption is larger than that in the В(1)3-06 one. It seems, the absorption spectrum for the B(2)39-05 ceramic sample is measured in the range where mean concentration of the Er 3+ ions is higher than in precursors (Figure 6). The ratio of the areas for the 4 I15/2 → 4 I13/2 transition for the В(1)3-06 and В(2)2-06 ceramic samples with the 5% and 1% concentration of the Er 3+ ions is 5.76 that is more or less in an agreement with the concentration of ErF3 in raw materials. Thus, preliminary chemical homogenization of raw materials is required to obtain fluoride ceramics with uniform distribution of activator impurities. Fluorescence spectra at the 4 I11/2 → 4 I15/2 transition are measured under 810 nm CW laser excitation in the CaF2:Er 3+ (5 mol. %) ceramic sample and the powdered ceramic sample of the same composition at T=300 K (Figure 13). Comparison of the fluorescence spectra in the ceramics and in the CaF2:Er 3+ (5 %) crystal shows small spectral shift to the shorter wavelengths in the former and some modification in spectral shape in the CaF2: Er 3+ (5 mol. %) ceramic sample, but the difference is not significant.
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DEVELOPMENTS IN CERAMIC MATERIALS R
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Copyright © 2007 by Nova Science P
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PREFACE Ceramics are refractory, in
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Preface ix crystals is discussed. A
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Preface xi spectra and the directio
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2 Leslie G. Cecil comprehensive dat
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4 Leslie G. Cecil Ringle et al. (19
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6 Leslie G. Cecil The main architec
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8 Leslie G. Cecil can study “the
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10 Leslie G. Cecil Middleton et al.
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12 Leslie G. Cecil The laser ablate
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14 Leslie G. Cecil There are two ge
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Page 68 and 69: 54 T. T. Basiev, V. A. Demidenko, K
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Sm (J/Kmol) Sm (J/Kmol) 15 10 5 Syn
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The Use of Ceramic Pots in Old Wors
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IACC ( τ ) = t2 ∫ The Use of Cer
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where σ res is the scattering cros
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D50 0.8 0.7 0.6 0.5 0.4 0.3 The Use
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Definition (D50) 1 0.95 0.9 0.85 0.
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Modeling of Thermal Transport in Ce
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q x = Modeling of Thermal Transport
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212 R. Ramesh, H. Kara, Ron Stevens
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220 ε S 33 R. Ramesh, H. Kara, Ron
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242 Development of Display Technolo
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244 Li Chen technology moved to the
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246 Li Chen The continuing evolutio
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248 Li Chen the back contact cathod
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250 Li Chen Figure 3. Vertical side
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252 Li Chen Figure 6. Molybdenum mi
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254 Li Chen Figure 8(a). I-V curve
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256 Li Chen Figure 9. Life time tes
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258 Figure 11(a). Plasma generated
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260 Li Chen [13] C.A. Spindt, K.R.
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262 S. Ardizzone, C. L. Bianchi, G.
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A absorption spectra, 66, 67, 77, 7
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correlation function, 156 corrosion
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group membership, 13, 20, 21, 22, 2
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microstructure(s), x, xi, 73, 74, 2
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Developments in Ceramic Materials Research

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