Developments in Ceramic Materials Research

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90 T. T. Basiev, V. A. Demidenko, K. V. Dykel’skii et al. CONCLUSION Thus, the possibility of preparation of transparent fluoride ceramics with low optical losses at the level of 10 -2 - 10 -3 cm -1 is demonstrated. Such a loss factor achieved indicates that the prepared materials are appropriate to use for the development of the photonics elements. The measurements are carried out for the ceramics at 1 μm wavelength. At this wavelength the transparency of the ceramics is much worse than that for the single crystal (optical absorption of the single crystal is lower than 10 -4 cm -1 ). The difference increases in passing from IR to UV range. The CaF2 single crystal has more far absorption edge in the UV range than the optical ceramics. However, in passing from near to mid IR range the difference between the single crystal and the optical ceramics goes down and practically disappears. Elucidation of the nature of such behavior requires additional studies. Evidently, this is not concerned with the cation contamination. The results show that right now fluoride optical ceramics is a material for the near and mid IR ranges (1 – 8 μm). Like an oxide laser ceramics the fluoride optical ceramics reveals improved mechanical properties comparing to single crystals. The fluoride ceramics keeps very important property of single crystals – high thermal conductivity that makes it attractive for high power laser systems. The spectroscopic properties of fluoride ceramics are not differ strongly from the single crystals of similar composition. It is demonstrated for Gd and La oxysulfide optical ceramics that in spite of anisotropy of raw materials preparation of optically transparent material by hot pressing assisted method is possible. High emission rate A about 10 4 s −1 is measured for the 4 F3/2 laser level in Gd2O2S:Nd 3+ due to the large refractive index (n=2.2) of this oxysulfide. That is together with narrow fluorescence spectral lines provides high emission cross- section at 1.08 μm wavelength, which is one of the most IR shifted among neodymium doped laser media. Rather short depletion time of the order of hundred nanoseconds for the 4 I11/2 low laser level is estimated as well. For the 4 F3/2 laser level in the Gd2O2S:Nd 3+ and La2O2S: Nd 3+ ceramic samples the detailed fluorescence kinetics decay measurements and analysis are provided. Analysis of the kinetics decay and concentration behavior for the Gd2O2S:Nd 3+ (0.1; 0.5 wt%) ceramic samples in the temperature range from T = 77 to 300 K leads to the conclusion that the transfer of energy from the 4 F3/2 excited state of the Nd 3+ ion occurs directly to the acceptors (unexcited Nd 3+ ions) in accordance with the dipole–dipole mechanism (s=6). A high value of the quenching microparameter CDA, i.e. 3.8×10 −39 cm 6 /s, because of large emission and absorption cross-sections of electronic transitions is found. In the La2O2S:Nd 3+ (1 w%) ceramic sample at T=300 K together with direct energy transfer (DET) with CDA=2.2×10 −39 cm 6 /s a stationary migration-controlled stage is observed starting from tbound2=54.6 μs with microefficiency of donor–donor Nd–Nd interaction CDD=6.2×10 −38 cm 6 /s calculated in hopping model of energy migration. It can be concluded that moderate and small concentrations of Nd 3+ ions should be used for synthesis of effective oxysulfide transparent optical ceramics for 1 μm lasing.
Optical Fluoride and Oxysulfide Ceramics: Preparation and Characterization 91 ACKNOWLEDGMENTS This work was partially support by Russian Government, Contract #02.435.11.2011 from July 15, 2005 -2006 and CRDF #RUP2-1517-MO-06. Authors are very grateful for their help to M.Sh. Akchurin, O.K. Alimov, G.V. Anan’eva, L.S. Bolyasnikova, I.V. Khristich, O.A. Khristich, M.V. Kocherova, S.V. Kuznetsov, S.V. Lavrishchev, E.O. Orlovskaya, O.P. Ovsyannikova, O.V. Palashov, P.A. Popov, V.G. Plotnichenko, V.G. Rygikov, A.A. Sobol, V.V. Voronov, E.V. Yarotzkaya. REFERENCES [1] Lu, J.; Prabhu, M.; Song, J.; Li, C.; Xu, J.; Ueda, K.; Kaminskii, A.; Yagi, H.; Yanagitani, T. Optical properties and highly efficient laser oscillation of Nd:YAG ceramics. J. of Appl. Phys. B. 2000, 71, 469-474. [2] Kaminskii, A.; Akchuryn, M.; Alshits, V.I., et. al. New results on investigation of physical properties of monocrystalline laser ceramic on the base of Y3Al5O12. Crystallography Reports. 2003, 48, 515-519. [3] Yanagitani, T.; Yagi, H.; Ishikawa, T. Japanese Patent 10-101333, 1998. [4] Volynets, F.K. Methods of preparation, structure, and physico-chemical properties of optical ceramics. Opt.-mekh. prom-st. 1973, N 9, 48-60 (in Russian). [5] Vydrik, G.A.; Solov’eva, T.V.; Kharitonov, F.V. Prozrachnaya keramika (Transparent ceramics). Moscow, Energiya, 1980, 96. (in Russian) [6] Tonkaya tekhnicheskaya keramika (Fine technical ceramics). Ed. Yanagita, H. Moscow, Metallurgiya, 1986 (Russian translation from Japanease) [7] Ryzhikov, E.N. Itogi i perspektivy razvitiya polikristallicheskikh opticheskikh materialov (Results and prospects of development of polycrystalline optical materials). Trudy GOI, Leningrad. 1985, P.21. (in Russian) [8] Geguzin, Ya.E. Fizika spekaniya (Physics of sintering). Moscow: Nauka. 1967, 360 (in Russian). [9] Geguzin, Ya.E. Pochemu i kak ischezaet pustota (Why and how void dissapears). Moscow: Nauka. 1976, 360 (in Russian). [10] Tret’yakov Yu.D.; Lepis Kh. Khimiya i tekhnologiya tverdofaznykh materialov (Chemistry and technology of solid state materials). Moscow: MGU. 1985 (in Russian). [11] German, R.M. Sintering theory and practice. John Wiley and Sons, INC., New York. 1996, 550. [12] Mortier, M.; Monteville, A.; Patriarche, G.; Maze, G.; Auzel, F. New progresses in transparent rare-earth doped glass-ceramics. Opt. Mat. 2001, 16, 255-267. [13] Kouznetzov, S.V.; Osiko, V.V.; Tkatchenko, E.A.; Fedorov, P.P. Inorganic nanofluorides and related nanocomposites, Russian Chemical Rev. (Uspekhi Khimii). 2006, 75, 1065-1082. [14] Greskovich, С.; Chernoch, J.P. Polycrystalline ceramic lasers. J. of Appl. Phys. 1973, 44, 4599-4606. [15] Greskovich, С.; Chernoch, J.P. Improved polycrystalline ceramic lasers. J. of Appl. Phys. 1974, 45, 4495-4502.
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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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16 Leslie G. Cecil distinct recipes
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18 Leslie G. Cecil second group (Fi
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22 Leslie G. Cecil Table 3. Mahalan
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24 Leslie G. Cecil Ixlú and Ch’i
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34 Leslie G. Cecil Schele, L., Grub
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36 Z. C. Li, Z. J. Pei and C. Tread
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38 Z. C. Li, Z. J. Pei and C. Tread
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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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D50 0.8 0.7 0.6 0.5 0.4 0.3 The Use
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212 R. Ramesh, H. Kara, Ron Stevens
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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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