Aluminate variants

Variants of preparation have been proposed [135, 248] including sintering [391] or co-electrodeposition of the precursors [138, 407], and aluminization of the surface of Ni at high temperature whose nature has a definite effect on the resulting electrocatalytic activity [408]. The main features of Raney Ni have been evaluated, including the pore size distribution and the real surface area [93, 135]. It has been found that the composition of the precursor alloys and their particle size have important influence on the adsorption properties of the resulting Raney metal, hence on its electrocatalytic properties [409]. 

Al + x(Mj jt. 2 Li 2)Oi7- Without these dopants, the ferrites are charge-compensated by Fe (giving rise to electronic conductivity), and sodium gallates, by sodium substitution for gallium. For aluminates, these variants are impossible. As a result. 

In processes with conventional quench rates of 10 K/s, the inviscid liquid (melt) or resulting jet is carefully under- or supercooled to its narrow fiber forming range (log 2.5 to log 3.0 poise). Three types of fibers have been made by variants of this process continuous optical yttrium aluminum garnet (YAG) glass fibers, continuous aluminate glass fibers and steel fibers. 

The preparation of LDHs has been the subject of over 50 patents. The claims are specific variants of the general methods previously described, including coprecipitation (148), anion exchange (149), preparation from oxides and hydroxides (150-152), reaction of metal oxides or hydroxides with a salt (152-154), and precipitation via aluminate (115-118,120,155). The principal material described is Mg/Al LDH carbonate however, other anions, such as those composed of heavy metal complexes (120,149), alcoholates (156), anionic surfactants (148), phosphates (148,157), and halides (115,158a), have also been claimed. LDH can also be produced by controlled addition of Ca(OH)2 and AICI3 to seawater (158b). 

Other, but not all, ceramic crystal structures may be treated in a similar manner included are the zinc blende and perovskite structures. The spinel structure is one of the A B Xp types, which is foimd for magnesium aluminate or spinel (MgAl204). With this structure, the ions form an FCC lattice, whereas Mg ions fill tetrahedral sites and ions reside in octahedral positions. Magnetic ceramics, or ferrites, have a crystal structure that is a slight variant of this spinel structure, and the magnetic characteristics are affected by the occupancy of tetrahedral and octahedral positions (see Section 20.5). 

---