The properties of optically transparent ceramic materials made of yttrium oxide and yttrium -aluminum garnet were analyzed. The promise of preparing a transparent ceramic that combines both of these compounds was demonstrated. Methods of synthesizing yttrium oxide and yttrium -aluminum garnet were examined. Selection of the method of synthesis was substantiated. The possibility of creating such materials without modifying additives was confirmed.Many domestic and foreign studies on creating transparent ceramic materials are currently underway, which demonstrates the demand for them in modern industry. In contrast to traditional ceramics, these materials have an almost poreless structure and can pass waves in different regions of the spectrum while retaining the other properties characteristic of ceramic materials of similar composition and in some cases, are even superior to them.Yttrium oxide and yttrium aluminum garnet (YAG) materials have high light transmission indexes in the visible region of the spectrum. These ceramics can replace glass in instruments that operate in conditions of night vision, high temperatures, aggressive media, etc.[1].In addition, yttrium aluminum garnet is a promising material due to the high melting point, absence of polymorphous transitions, good electrophysical indexes, stability in alkali metal plasmas, and elevated thermal stability [2]. Luminophores with the structure of garnet activated with cerium began to be used relatively recently for light-emitting diodes with white luminescence (US Patent Application No. 6744196).Light transmission, the almost total absence of porosity, and the possibility of making products with high surface purity due to the absence of vitreous phases significantly expanded the area of application of transparent materials. For example, addition of the ionic activators Nd 3+ (WO Patent Application No. 02/42828), Cr 3+ (US Patent Application No. 6859480), Er 3+ and Yb 3+ added to ceramics [3] allows using it as the working medium for the solid-state laser.A relatively large amount of information has accumulated on yttrium oxide ceramics technology. Data are reported on fabrication of these materials by firing in a vacuum or hydrogen (Japanese Patent Application No. 11189413) at high temperatures, and methods of hot (RF Patent Application No. 2255071) and hot isostatic molding [4]. The method of colloidal casting is promising for creating yttrium oxide and yttrium aluminum garnet stock which is then fired in a vacuum or hydrogen [5]. However, sintering of yttrium oxide ceramics to the dense state with methods that do not require application of external effects without incorporation of ThO 2 , HfO 2 , La 2 O 3 , TiO 2 (US Patent Applications Nos. 3640887, 3545987, 4147744, and 5308809) and other modifiers is almost impossible [2].Diffusion processes on the boundaries and in the bulk of crystals that ensure complete growth of all intracrystalline pores must actively take place to obtain poreless polycrystalline material. The rate of diffusion flows between c...
Methods for producing optically transparent ceramic materials based on Y 2 O 3 using carbonate and alkoxy precursors are considered. It is established that ceramic synthesized from yttrium isopropylate has better optical parameters than ceramics based on yttrium carbonate under equal heat treatment and firing regimes.Progress in science and engineering is closely related to the development of new inorganic materials that have special optical properties. In the past 15 -20 years numerous studies have been carried out in the field of transparent ceramics, which finds wide application in various sectors of engineering. Such ceramics were initially developed on the basis of aluminum and yttrium [1].The upgrade in producing ceramics from pure oxides, the advance in the theory of sintering, and the progress in hightemperature technologies have opened possibilities for synthesizing transparent polycrystalline materials that in some physical properties surpass glass and single clear crystals.While the optical characteristics of transparent ceramic materials are close to those of monocrystals, the advantages of ceramics are a lower production cost, the possibility of producing articles of complex shapes, and higher thermal resistance and strength; at the same time ceramics surpass glass in thermal conductivity, heat resistance, and hardness [2].The purpose of our study is to obtain optically transparent ceramics based on Y 2 O 3 activated by Nd 3+ crystals with a HfO 2 additive facilitating sintering and with carbonate and alkoxy precursors.In order to obtain transparent ceramics, it is necessary to decrease diffusion mass transfer between the crystals in order to lower the probability of capturing pores during their growth, which is usually observed inside strong aggregates [1]. When hafnium oxide is introduced, cation vacancies are formed in the inner parts of the crystal, which facilitates diffusion mass transfer and perfects the structure inside the crystal:The segregation of hafnium oxide at the crystal boundaries leads to the formation of oxygen vacancies in the material (mainly the solid solution of Y 2 O 3 in HfO 2 ), which impedes mass transfer between the crystals and facilitates their rapid growth and the capture of intercrystalline pores:Based on published data [3], the following composition was used in our study (mol.%): 93 Y 2 O 3 , 6 HfO 2 , and 1 Nd 2 O 3 .The main batch components included: industrial yttrium carbonate, whose content of rare-earth oxides and impurities meets standard TU-48-4-191-72; yttrium carbonate synthesized by pulverizing a highly concentrated yttrium chloride solution into a cold solution of ammonium carbonate acting as the precipitator [4]; yttrium isopropylate produced in an exchange reaction of anhydrous yttrium chloride with metallic sodium in the medium of isopropyl alcohol [5].Industrial yttrium carbonate contains particles of size 3 -5 mm; 30% of these particles have a size up to 30 mm. Yttrium carbonate produced by precipitation from highly concentrated solutions contains pa...
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