Zirconium crystalline

In the case of zirconium, crystalline chloilde-isopropoxide complexes have been obtained according to the reactions illustrated by Eqs (2.277) and (2.278) ... 

Another important class of titanates that can be produced by hydrothermal synthesis processes are those in the lead zirconate—lead titanate (PZT) family. These piezoelectric materials are widely used in manufacture of ultrasonic transducers, sensors, and minia ture actuators. The electrical properties of these materials are derived from the formation of a homogeneous soHd solution of the oxide end members. The process consists of preparing a coprecipitated titanium—zirconium hydroxide gel. The gel reacts with lead oxide in water to form crystalline PZT particles having an average size of about 1 ]lni (Eig. 3b). A process has been developed at BatteUe (Columbus, Ohio) to the pilot-scale level (5-kg/h). 

Sulfates. Sulfate ions strongly complex zirconium, removing hydroxyl groups and forming anionic complexes. With increasing acidity, all hydroxyl groups are replaced zirconium sulfate [7446-31-3] Zr(S04)2-4H20, with an orthorhombic stmcture (206), can be crystallized from a 45% sulfuric acid solution. Zirconium sulfate forms various hydrates, and 13 different crystalline Zr(S0 2 5 2 [14644-61-2] systems are described in Reference 207. 

On the other hand, the provision of vast numbers of minute nuclei assists the phosphate coating reaction to start at a multitude of centres, resulting in a finely crystalline coating. This effect can be obtained chemically by a predip in a solution of sodium phosphate containing minutely dispersed traces of titanium or zirconium salts or in weak solution of oxalic acid. This type of pre-dip entirely eliminates any coarsening effect due to previous treatment in strong alkalis or acids. 

Thenoyltrifluoroacetone(TTA), C4H3S,CO,CH2,COCF3. This is a crystalline solid, m.p. 43 °C it is, of course, a /1-diketone, and the trifluoromethyl group increases the acidity of the enol form so that extractions at low pH values are feasible. The reactivity of TTA is similar to that of acetylacetone it is generally used as a 0.1-0.5 M solution in benzene or toluene. The difference in extraction behaviour of hafnium and zirconium, and also among lanthanides and actinides, is especially noteworthy. 

The only crystalline phase which has been isolated has the formula Pu2(OH)2(SO )3(HaO). The appearance of this phase is quite remarkable because under similar conditions the other actinides which have been examined form phases of different composition (M(OH)2SOit, M=Th,U,Np). Thus, plutonium apparently lies at that point in the actinide series where the actinide contraction influences the chemistry such that elements in identical oxidation states will behave differently. The chemistry of plutonium in this system resembles that of zirconium and hafnium more than that of the lighter tetravalent actinides. Structural studies do reveal a common feature among the various hydroxysulfate compounds, however, i.e., the existence of double hydroxide bridges between metal atoms. This structural feature persists from zirconium through plutonium for compounds of stoichiometry M(OH)2SOit to M2 (OH) 2 (S0O 3 (H20) i,. Spectroscopic studies show similarities between Pu2 (OH) 2 (SOO 3 (H20) i, and the Pu(IV) polymer and suggest that common structural features may be present. 

Selected Average Bond Lengths (A), Angles (deg), and Metrical Parameters Involving Non-Hydrogen Atoms in Crystalline Zirconium Bis(octaethylporphyrazine) (29), Mixed Sandwich (heteroleptic Pz/porphyrin) (30), and Bis(octaethylporphyrin) (Porphyrin Analogue)... 

Suzuki, T. M., Bomani, J. O., Matsunaga, H., Yokoyama T., Preparation of porous resin loaded with crystalline hydrous zirconium oxide and its application to the removal of arsenic. React. Fund. Polym. 2000, 43,165-172. 

Metal alloys can be amorphous, too. LiquidmetaF alloy is an amorphous alloy of zirconium mixed with nickel, titanium, copper, and beryllium. It is used in the heads of some brands of golf clubs. Traditional metal club heads may have microscopic gaps where planes of metallic crystals meet. These tiny gaps are a potential source of weakness. The amorphous alloy is non-crystalline, so the metal structure does not have potential breakage sites. 

Layered metal IV phosphonates are widely used, particularly zirconium phosphonates, because their synthesis is versatile and their structural arrangement may be tailored to applications. Zirconium phosphonates are usually prepared by heating an aqueous solution of a metal IV salt (e.g., ZrOCl2) with a phosphonic acid at 60-80 °C synthesis in the presence of HP permits one to increase significantly the crystallinity of the final products. 

Preparation and characterization of two-dimensional zirconium phosphonate derivatives in either crystalline or amorphous forms have been investigated. Two composite zirconium phosphonates in single crystal phase have also been investigated and characterized by XRD, i c-, and 3ip-MASNMR. The catalytic performance over zirconium phosphonates are evaluated by hydrolysis of ethylacetate in aqueous solution. When the composite zirconium phosphonate is composed with an acidic function and with a hydrophobic function in single crystal phase, the catalytic activity in aqueous medium showed higher activity than that of single acidic zirconium phosphonate. The composite materials become accessible to any reactant molecule and improve hydnq>hobicity. 

Addition of a soluble Zr(IV) salt to phosphoric acid results in the precipitation of a gelatinous amorphous solid. The stoichiometric crystalline zirconium phosphate can be prepared by refluxing zirconium phosphate-gel in concentrated phosphoric acid [5]. The procedures for synthesis of zirconium phosphate have been described in detail elsewhere [6]. 

TABLE 1 Physico-Chemical Properties of Various Crystalline Zirconium Phosphonates... 

Professor von Hevesy and Thai Jantzen separated hafnia from zirconia by repeated recrystallization of the double ammonium or potassium fluorides (20, 26). Metallic hafnium has been isolated and found to have the same crystalline structure as zirconium. A small specimen of the first metallic hafnium ever made is on permanent display at the American Museum of Natural History in New York City. Dr. von Hevesy, who prepared it, presented it to the Museum for the collection of chemical elements (29). A. E. van Arkel and J. H. de Boer prepared hafnium by passing the vapor of the tetraiodide over a heated tungsten filament (26, 30). 

Nanosized crystalline spheres of zirconia (Zr02) ranging from 2.5 to 15 nm in mean diameter with a narrow size distribution have been prepared by a method similar to that for the preparation of the uniform anatase titania (34). In a typical system, zirconium(IV) n-propoxide is mixed with triethanolamine at a molar ratio of 1 3 in a dry box filled with dry air to form a stable compound of Zi against the rapid... 

Cerous iodates and the iodates of the other rare earths form crystalline salts sparingly soluble in water, but readily soluble in cone, nitric acid, and in this respect differ from the ceric, zirconium, and thorium iodates, which are almost insoluble in nitric acid when an excess of a soluble iodate is present. It may also be noted that cerium alone of all the rare earth elements is oxidized to a higher valence by potassium bromate in nitric acid soln. The iodates of the rare earths are precipitated by adding an alkali iodate to the rare earth salts, and the fact that the rare earth iodates are soluble in nitric acid, and the solubility increases as the electro-positive character of the element increases, while thorium iodate is insoluble in nitric acid, allows the method to be used for the separation of these elements. Trihydrated erbium iodate, Er(I03)3.3H20, and trihydrated yttrium iodate, Yt(I03)3.3H20,... 

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