SCIENTIFIC RESEARCH AND DEVELOPMENT SINGLE CRYSTALS AND LIGHT-TRANSMITTING BeO-CERAMIC FOR ELECTRONIC TECHNOLOGY

Ceramics and single crystals of beryllium oxide (BeO) are distinguished from other alkali-earth metal oxides by high refractoriness and melting temperature (~2750 K) [1, 2], and they are considered [3] as promising materials for quantum electronics. It is well known that BeO is a good dielectric material with a broad forbidden zone (~10.8 eV), it exhibits high chemical, radiation resistance, and thermal conductivity, that for ceramic BeO specimens is (at room temperature) 250 – 320 W/(m·K) [2, 4]; for BeO single crystals compared with ceramic based on BeO the thermal conductivity is somewhat higher. Currently powerful laser radiation in the ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum is practically realized by means of gas lasers in gases of hydrogen, fluorine, nitrogen, in excimers, and exiplex mixtures [5]. Up until now no quantum generators have been created in the UV and VUV regions of the spectrum based on broad zone high-temperature oxides Al2O3, MgO and BeO. Beryllium oxide is of considerable interest as a working body for quantum electronic instruments, and also reradiators and optical systems of the UV and VUV ranges of the spectrum [2, 3]. Currently powerful coherent radiation in the UV and VUV regions of the spectrum may find practical application in the production of electronic instruments as radiation sources and excitation in photolithography, photoluminescence, photochemistry, biology, in space studies and photonics. With use of beryllium oxide single crystals and lighttransmitting BeO-ceramic as active media for lasers it is necessary to obtain high purity crystals, in order that during radiation there are no discoloration centers and the crystals exhibit photochemical stability. For BeO there is a typical minimum number of crystal lattice defects. In addition, BeO exhibits low isomorphous compatibility (at the level of 10 –3 – 10 –5 wt.%), that makes stepwise ionization of active impurity centers hardly probable. It is well known that BeO-ceramic during excitation with X-radiation and electrons exhibits two peak luminescence peaks in the UV and VUV regions of the spectrum with maxima of 4.9 – 5.0 and 6.7 eV [2], excited the edge of fundamental absorption. All of this makes it possible to consider BeO promising as a material for solid lasers of the UV and VUV regions of the spectrum. In view of this development of technology for preparing optically improved single crystals and ceramics based on BeO with special physicochemical properties, making it possible to provide the required spectral-energy and spatial characteristics, is of particular interest. In this work problems are discussed of preparing and the physicochemical properties of beryllium oxide single crystals and light-transmitting BeO-ceramic as promising materials for electronic technology. Creation of solid active materials based on single crystals and optically transparent ceramic are limited both by the difficulties in growing crystals (slow growth rates), and in the low optical quality of the crystals and ceramics obtained. It is necessary to prepare single crystals, to study their defects carefully at the macrolevel, and to compare the physicochemical properties of single crystals Refractories and Industrial Ceramics Vol. 51, No. 3, 2010