Baddeleyite properties

Baddeleyite has a monocHnic structure with space group Plljc. The Zr + ion has seven-fold coordination, while the idealized ZrOz polyhedron is close to tetrahedral orientation, where one angle in the structure is different significantly from the tetrahedral value. Natural baddeleyite is a raw material for zirconium. In industry ZrOz, named usually zirconia, is important in areas such as surface chemistry, where its activity as a red ox material and its acid-based functions are important. As a ceramic material, zirconia can resist very high temperatures and its stabihzed form, yttrium-stabihzed zirconiiun, shows remarkable mechanical properties. 

At room temperature, pure Zr02 is monoclinic and has a density of 5,7 gcm". When heated it undergoes a quite complex sequence of polymorphic inversions which have not yet been explained to general satisfaction. Ruh and Rockett (1970) attempted to summarize the available data in the phase diagram shown in Fig. 9. Some properties of the modifications are listed in Table 3. The monoclinic modification (baddeleyite) is stable at room temperature and under normal pressures, and is con-... 

Pure Grade ZrO. from Donetsk Plant of Chemical Reagents Properties (acid-washed) baddeleyite, particle size 2-20 pm, BET specific surface area 20 m /g [2182]. 

ZrO2 from INVAP Properties High purity, 1.5 ppmF, baddeleyite, average diameter 0.18 pm, nonporous, nearly spherical, BET specific surface area... 

The new cements and composite based on then can be used in the coating of quartz glass tanks. In contact with glass there are used refractories made of natural baddeleyite without stabilizing oxides. The coating of this material showed good characteristics under thermal shock and quartz glass penetration resistance properties. 

Although the dioxides of zirconium and hafnium crystallize at room temperature in the monoclinic baddeleyite-type structure, this is closely related to fluorite, and they do form fluorite-type solid solutions with rare earth oxides which have important ceramic properties. Compared with Th, U", Ce etc., Zr " and Hf have considerably smaller ionic radii which are close to that of the smallest ion (Sc ), and this fact has an important influence on the phase relationships in these systems, leading to the appearance of intermediate phases not encountered in other MO2-R2O3 systems. They have been studied extensively, particularly in the first instance by Collongues et al. (1965 and references therein). Work published prior to 1964 has been reviewed by Mobius (1964). 

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