Ceramic synthesis

The apparent thermal stabilities of the two families, BaPb1 x BixOg and Ba K BiOg are quite different. Under the normal conditions of ceramic synthesis, the oxidation states desired in BaPb1.x-... 

We have considered ceramic synthesis in an open crucible and closed glass tube. A third possibility is a flow system. Chromium chloride, CrCl3, can be prepared by passing carbon tetrachloride over a sample of chromium oxide maintained at 900°C (Angelici, 1986) ... 

Gas phase ceramic synthesis is the subject of several review papers. The treatment here is analogous to that in Magan [1], Friedlander [2], and Pratsinis and Kodas [3] but instead of using the traditional aerosol nomenclature, this chapter uses the nomenclature developed in Chapter 3 on population balances for educational continuity. Each of the gas phase powder synthesis methods is summarized in Table 7.1. The maximum temperatures are also listed. The adiabatic flame temperature is the maximum possible temperature achieved in flame synthesis and will depend on the concentration of reactants in the feed. Powder synthesis in a furnace uses conduction, convection, and radiation, giving a maximum temperature of 2300 K. A plasma is an ionized gas. High velocity electrons remove other electrons from the neutral gas molecules present in the plasma, thereby producing ions and electrons that sustain the plasma. 

The development of processing ceramics from polymer precursors has attracted great attention. In particular, inorganic polymers containing silicon are important for SiC-based ceramic synthesis. SiC ceramics have the advantage of high-temperature stability in an oxidation atmosphere. SiC is not readily sintered, and thus is difficult to obtain in either fiber or film form by traditional inorganic processes. 

The thermal decomposition of hydrotalcites also is intriguing. They decompose on calcination to nanocrystalline spinel-like phases, and eventually, to crystalline spinels. This pathway initially produces spinels which are hydrated in their large surfaces and poorly ordered in their cation distributions. These materials are very reactive and analogous to precursors sought in ceramic synthesis. The thermochemical study of the evolution of MgAl204 from nitrate precursors (McHale et al. 1998) may in fact have encountered hydrotalcite as an intermediate. Further study of the thermal evolution of hydrotalcite nanomaterials may be applicable to both earth and materials sciences. 

Conventional ceramic synthesis of mixed oxides uses finely divided starting materials, ground up together, and fired at high temperatures to speed up diffusion. An example is the preparation of the high temperature superconductor YBa Og 8 ... 

Historically, the research done on the Ca-Mn-0 system has been performed at high (>1000°) temperatures.1-9 The traditional ceramic synthesis approach to these complex oxides involves repeated high-temperature firing of the component oxides with frequent regrindings. These severe reaction conditions are necessary to obtain a single-phase product because of the diffusional limitations of solid state reactions. Such high-temperature syntheses naturally lead to crystalline, low-surface-area materials and often preclude the preparation of mixed metal oxides that are stable only at relatively low temperatures. 

Table I. Compositions of the Powder Mixtures for Porous SiC Ceramics Synthesis.

Fig. 4i8. Experimental set up for ceramics synthesis in a crucible heated by a DC plasma jet with the arc transferred on the crucible. Reprinted from...

The sol-gel process consists of two steps. First we form a sol. Then we transform this into a gel. In ceramic synthesis, two different sol-gel routes have been identified and depend on the gel structure. 

Multistage process of precursor preparation and the process of ceramics synthesis. 

Ballato J, Serivalsatit K (2011) Sub-micron grained highly transparent sesquioxide ceramics synthesis, processing, and properties. In Laser Technology for Defense and Security Vii. 8039... 

Winterer M. Springer Series in Materials Science NanocrystaUine ceramics-synthesis and structure, 53. Heidelberg, Germany Springer 2002. 

Riedel R, Mera G, Hauser R, Klonczynski A (2006) Silicon-based polymer-derived ceramics synthesis properties and applications a review. J Ceram Soc Jpn 114 425 44... 

Kovalev D, Heckler H, Averboukh B, Ben-Chorin M, Schwartzkopff M, Koch F (1998) Hole burning spectroscopy of porous silicon. Phys Rev B 57(7) 3741-3744 McKeever SWS (1984) Thermoluminescence in quartz and silica. Radiat Prot Dosim 8(l/2) 81-98 Moscovitch M, Horowitz YS (2007) Thermoluminescent materials for medical applications LiF Mg, Ti and LiFiMg, Cu, P. Radiat Meas 41 S71-S77 Pincik E, Bartos P, Jergel M, Falcony C, Bartos J, Kucera M, Kakos J (1999) The metastability of porous silicon/crystalline silicon structure. Thin Solid Films 343-344 277-280 Rivera T (2011) Synthesis and thermoluminescent characterization of ceramics materials. In Sikalidis C (ed) Advances in ceramics - synthesis and characterization, processing and specific applications. InTech, Rijeka, Croatia pp 127-164 Skryshevskii YA, Skryshevskii VA (2001) Thermally stimulated luminescence in porous silicon. J Appl Phys 89(5) 2711-2714... 

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