Phosphates ternary, structure

Structures of ternary condensed phosphates The structures of alkali rare earth condensed phosphates can be divided into fourteen different types (table 1). The formation of a particular structure depends on the crystallization conditions as well as on the alkali and rare earth metals concerned (fig. 21). Characteristic of all alkali rare earth ternary polyphosphates is that the structural framework consists of a helical chain of (P03) , formed by corner sharing of PO4 tetrahedra along some axis. Besides the polyphosphates, there are cyclic condensed phosphates containing the cyclic P40 2 group. 

The synthesis of the title compositions has been selected as representative of compounds that can readily be prepared by the flux-reaction technique. In this technique, a halide melt serves both as a flux and as a constituent component of the basic reaction. The procedure has been described in the literature1 and has served for the preparation of a variety of ternary oxides, usually in the form of small, well-defined, single crystals. The halide phosphates and vanadates of strontium represent the apatite and spodiosite structures, both interesting compositions from a biochemical and solid-state point of view. 

BL Stoddard, AM Dean, DE Koshland Jr. Structure of isocitrate dehydrogenase with isocitrate, nicotinamide adenine dinucleotide phosphate, and calcium at 2.5-A resolution a pseudo-Michaelis ternary complex. Biochemistry 32 9310-9316, 1993. 

A number of spectacular applications in structural studies of glasses were reported employing the INADEQUATE experiment.174 175 The basic sequence and different modifications were discussed in Section 2.2.2. Smith and coworkers176 used 31P refocused INADEQUATE MAS NMR experiment for searching the length of phosphate chain and quantification of crystalline phases in ternary sodium calcium phosphate ceramic of composition (CaO)0.4(Na20)0.i(P205)o.5. 

Simple binary interactions were not enough to achieve a long-term stability [24, 25]. Table 6 presents relative stabilities of binary and quaternary complex structures. This table qualitatively illustrates the concept that multiple interactions are necessary in order to stabilize the final product. Both binary and some ternary interactions in Table 7 showed instability throughout the matrix. This behavior was very common. Matrix stability was normally evaluated in 0.9 % NaCl or PBS (phosphate-buffered saline), fluids of physiologic significance. The introduction of more ingredients into the nanoparticulate formulation also increased... 

The zircon structure-type (ZrSi04) [49] is also adopted occasionally by so-called ternary compositions (Table 3) [38], Zircon is isostructural with the xenotime series of phosphates, typified by xenotime-(Y), YPO4 [50, 51], In this structure-type, the eight-coordinate polyhedra (snub disphenoids) share edges to form a framework composed of cross-linked chains that extend along the [100] and [010] directions. The framework of polyhedra exhibits prominent voids along the [111] direction these are occupied by tetrahedra. The tetrahedra share edges with the polyhedra and thus serve to further connect the chains (Fig. 7). 

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