Basic crystal structure

The basic crystal structure consists of P04 (or As04 ) tetrahedra alternating with the K" " (or NH4 ) ions along the c-axis. The P04 units are connected by 0-H...0 hydrogen bonds in the ab plane, forming a three-dimensional hydrogen-bonded lattice [2]. In the ferroelectric phases, the H atoms are localized such that the two close protons are both on the top of the oxygen ions of the XO4 units, as depicted in Fig. 4b. In the antiferroelectric... 

Two types of diffraction measurements are typically made on cosmochemical samples. Powder diffraction, where a sample powder is mounted on the end of a fiber and placed in the X-ray beam, is most commonly used. The term powder in this usage means that the crystal lattice domains are randomly oriented. Powder diffraction is used to identify unknown materials and to determine their basic crystal structure. Single-crystal X-ray diffraction is used to solve the complete structure of crystalline materials. For more details, see Cullity (1978). 

FIGURE 2.1 Basic crystal structure for ice Ih. (Reproduced from Durrant, P.J., Durrant.B., Introduction to Advanced Inorganic Chemistry, John Wiley Sons, Inc., New York (1962). With permission.)... 

The compounds [M(bipy)2(N03)2] guest have also been studied extensively by us and, interestingly, we have only observed three basic crystal structure types (Figure 15). 

The rational design of novel stmctures possessing predetermined physical properties thus remains an extremely daunting task. From the perspective of the synthetic chemist, it is often fruitful to take a compound with a known stable- (thermodynamically or kineti-caUy) crystal structure and alloy one of more of the sublattices to form a stable solid solution in which the product phase retains the same basic crystal structure of the parent phase. In this way, the properties of the parent phase can be tuned to meet the... 

Fig. 6. Basic crystal structure of RE-TM compounds near the 1-5 stoichiometry (CaCu5 type).

Fig. 7. Basic crystal structures of RE-TM compounds near the 2-17 stoichiometry rhombohedral Th2Zn17 (left) and hexagonal Th2Ni17 type (right).

The general formula of magnetic garnets,is P3Q2R3O12 or 3Mc203 5Fe203, where Me is typically yttrium but can also be other rare earth ions. The basic crystal structure is cubic with an octahedron, a tetrahedron. 

Fig. 7.2 The basic crystal structure of the transition-metal ferrocyanides.

Staab, H.A., Kirsch, A., Barth, T. et al. (2000) New proton sponges , 14. Isomeric tetrakis (dimethylamino)naphthalenes syntheses, structure-dependence of basicities, crystal structures and physical properties. European Journal of Organic Chemistry, 1617-1622. 

We start our discussion with the magnetic ordering in the electron-type R2CUO4 (2-1-4) materials. The basic crystal structure is tetragonal I4/mmm (T phase) in which the Cu... 

Let s consider the possibilities of compactness for basic crystal structures. 

Basic crystal structure Octahedral B, 12-coordinate A, cubic unit cell ideally... 

Table 2.6 A selection of materials with the perovskite structure illustrating the enormous range of properties found in different materials with the same basic crystal structure...

A number of modern pigments are sometimes referred to as rutile pigments this is because they share the same basic crystal structure (that is, they are isostructural) rather than because they share a close compositional similarity. For more information, see the entry for rutile pigments. 

A detailed classification scheme for oxides is given in Table 5, but oxides that have never or only rarely been observed in soils are omitted for simplicity. Some naturally occurring oxides, which have been described since Rostov [1956] developed his classification scheme, have been added in the various groups, and the system in which the minerals crystallize has also been included the basic crystal structures of the oxides are, in some ways, more complex than those of the silicates and are not considered in detail here. The scheme is self-explanatory and requires little comment except upon a few specific aspects. 

---