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Oxides zircons

Since discovering and making use of the piezoelectric effect in naturally occurring crystals such as quartz and Rochelle salts, scientists have produced a wide range of piezoelectric materials in the laboratoi y. An early example is barium titanate, used in an electrical component called a capacitor. Currently, most piezoelectric materials are oxide materials based on lead oxide, zirconate oxide, and titanium. These very hard piezoelectric materials are termed piezoceramics. [Pg.951]

A wide array of ferroelectric, piezoelectric and pyroelectric materials have titanium, zirconium and zinc metal cations as part of their elemental composition Many electrical materials based on titanium oxide (titanates) and zirconium oxide (zirconates) are known to have structures based on perovskite-type oxide lattices Barium titanate, BaTiOs and a diverse compositional range of PZT materials (lead zirconate titanates, Pb Zr Tij-yOs) and PLZT materials (lead lanthanum zirconate titanates, PbxLai-xZryTii-yOs) are among these perovskite-type electrical materials. [Pg.155]

The superposition model has also been applied to experimental crystal field parameters obtained for lanthanides [31] substituted into host lattices of oxides, zircons, anhydrous trihalides, oxysulphides, alkaline earth fluorides and some other cubic crystals. The intrinsic parameters obtained from the analysis are given in Table 8.23. The solution spectrum of Er3+ aquo ion is given in Fig. 8.29. [Pg.631]

Furthermore, some experiments with various Bi (III) salts and organometallic derivatives (for example bismuth oxychloride, -acetate, -salicylate, -carbonate oxide, -zirconate, -germanium oxide, triphenylbismuth) have shown that these derivatives are also catalysts for the acylation of anisole by acyl chlorides (ref. 41). [Pg.19]

Zirconium Oxide. Zircon a, zirconium dioxide zirconic anhydride. OjZr mol wt 123.22. Zr 74.03%, O 25.97%. ZrOj. Occurs in nature as the mineral baddeleyite. Prepn Clark, Reynolds, Ind. Eng. Chem. 29, 711 (1937) ... [Pg.1603]

The excitation and emission data of Bi -doped rare-earth oxides, zirconates, stannates, tungstate, niobate, sulfate, phosphate, silicate, germanate, and vanates, etc., are summarized in Table 14.3. Most emissions, some of which are yellow or... [Pg.430]

The heavy mineral sand concentrates are scmbbed to remove any surface coatings, dried, and separated into magnetic and nonmagnetic fractions (see Separation, magnetic). Each of these fractions is further spHt into conducting and nonconducting fractions in an electrostatic separator to yield individual concentrates of ilmenite, leucoxene, monazite, mtile, xenotime, and zircon. Commercially pure zircon sand typically contains 64% zirconium oxide, 34% siUcon oxide, 1.2% hafnium oxide, and 0.8% other oxides including aluminum, iron, titanium, yttrium, lanthanides, uranium, thorium, phosphoms, scandium, and calcium. [Pg.440]

Decomposition of Zircon. Zircon sand is inert and refractory. Therefore the first extractive step is to convert the zirconium and hafnium portions into active forms amenable to the subsequent processing scheme. For the production of hafnium, this is done in the United States by carbochlorination as shown in Figure 1. In the Ukraine, fluorosiUcate fusion is used. Caustic fusion is the usual starting procedure for the production of aqueous zirconium chemicals, which usually does not involve hafnium separation. Other methods of decomposing zircon such as plasma dissociation or lime fusions are used for production of some grades of zirconium oxide. [Pg.440]

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). [Pg.500]

Lead zirconate [12060-01 -4] PbZrO, mol wt 346.41, has two colorless crystal stmctures a cubic perovskite form above 230°C (Curie point) and a pseudotetragonal or orthorhombic form below 230°C. It is insoluble in water and aqueous alkaUes, but soluble in strong mineral acids. Lead zirconate is usually prepared by heating together the oxides of lead and zirconium in the proper proportion. It readily forms soHd solutions with other compounds with the ABO stmcture, such as barium zirconate or lead titanate. Mixed lead titanate-zirconates have particularly high piezoelectric properties. They are used in high power acoustic-radiating transducers, hydrophones, and specialty instmments (146). [Pg.73]

Zirconium occurs naturally as a siUcate in zircon [1490-68-2] the oxide baddeleyite [12036-23-6] and in other oxide compounds. Zircon is an almost ubiquitous mineral, occurring ia granular limestone, gneiss, syenite, granite, sandstone, and many other minerals, albeit in small proportion, so that zircon is widely distributed in the earth s cmst. The average concentration of zirconium ia the earth s cmst is estimated at 220 ppm, about the same abundance as barium (250 ppm) and chromium (200 ppm) (2). [Pg.426]

Baddeleyite, a naturally occurring zirconium oxide, has been found in the Poco de Caldas region of the states of Sao Paulo and Minas Geraes in Brazil, the Kola Peninsula of the former USSR, and the northeastern Transvaal of the Repubflc of South Africa. BraziUan baddeleyite occurs frequently with zircon, and ore shipments are reported to contain 65—85% zirconium oxide, 12—18% siUca, and 0.5% uranium oxide. Veryhttle of this ore is exported now because all radioactive minerals are under close control of the BraziUan government. [Pg.426]

Mixed zircon, coke, iron oxide, and lime reduced together produce zirconium ferrosiUcon [71503-20-3] 15 wt % Zr, which is an alloy agent. Fused zirconia [1314-23-4] has been made from zircon but baddeleyite is now the preferred feed for the production of fused zirconia and fused alumina—zirconia by electric-arc-fumace processing. [Pg.429]

Similarly, fusion of milled zircon with dolomite or lime forms CaSiO and MgZrO [12032-31 -4] CaZrO [12013-47-7] and CaO Ca2SiO or CaSiO and Zr02, and is used to prepare zirconium oxide, usually as calcia-stabiUzed cubic zirconia because of the calcia left in soHd solution in the zirconia (27-29). [Pg.429]

Zirconium oxide is used in the production of ceramic colors or stains for ceramic tile and sanitary wares. Zirconia and siHca are fired together to form zircon in the presence of small amounts of other elements which are trapped in the zircon lattice to form colors such as tin—vanadium yellow, praseodymium—zircon yellow [68187-15-5] vanadium—zircon blue [12067-91 -3] iron—zircon pink [68412-79-3] indium—vanadium orange (105—108). [Pg.432]

Zircon is synthesized by heating a mixture of zirconium oxide and silicon oxide to 1500°C for several hours (163). The corresponding hafnium silicate, hafnon, has been synthesized also. Zircon can be dissociated into the respective oxides by heating above 1540°C and rapidly quenching to prevent recombination. Commercially, this is done bypassing closely sized zircon through a streaming arc plasma (38). [Pg.435]

Oxide Chlorides. Zirconium oxide dichloride, ZrOCl2 -8H2 0 [13520-92-8] commonly called zirconium oxychloride, is really a hydroxyl chloride, [Zr4(OH)g T6H2 0]Clg T2H2O (189). Zirconium oxychloride is produced commercially by caustic fusion of zircon, followed by water washing to remove sodium siUcate and to hydrolyze the sodium zirconate the wet filter pulp is dissolved in hot hydrochloric acid, and ZrOCl2 -8H2 O is recovered from the solution by crystallization. An aqueous solution is also produced by the dissolution and hydrolysis of zirconium tetrachloride in water, or by the addition of hydrochloric acid to zirconium carbonate. [Pg.437]


See other pages where Oxides zircons is mentioned: [Pg.56]    [Pg.22]    [Pg.32]    [Pg.91]    [Pg.224]    [Pg.189]    [Pg.692]    [Pg.684]    [Pg.732]    [Pg.213]    [Pg.25]    [Pg.671]    [Pg.766]    [Pg.738]    [Pg.730]    [Pg.764]    [Pg.684]    [Pg.56]    [Pg.22]    [Pg.32]    [Pg.91]    [Pg.224]    [Pg.189]    [Pg.692]    [Pg.684]    [Pg.732]    [Pg.213]    [Pg.25]    [Pg.671]    [Pg.766]    [Pg.738]    [Pg.730]    [Pg.764]    [Pg.684]    [Pg.358]    [Pg.191]    [Pg.440]    [Pg.440]    [Pg.67]    [Pg.68]    [Pg.227]    [Pg.16]    [Pg.48]    [Pg.128]    [Pg.313]    [Pg.426]    [Pg.426]    [Pg.429]    [Pg.434]    [Pg.435]   


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Barium zirconate oxide

Modern Uses of Zircon and Zirconium Oxide

Zircon

Zirconate

Zirconate pyrochlore oxides

Zirconates

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