Rus Articles Journal

Whether the modern information field without crystal chemistry is possible?

Are impossible. Fighters against chemistry, be consecutive - throw out the TVs, computers and mobile phones! Because superpure silicon for chips is a crystal chemistry product.

The crystal chemistry studies laws of an arrangement of atoms and types of symmetry in crystalline solids, and also defects in their structure. The crystal chemistry is closely connected with a crystallography.

The central concept of a crystal chemistry - crystal structure (an arrangement of atoms, ions, molecules in a crystal). Over 150000 crystal structures (~ 70000 inorganic, more than 80000 organic), from simple substances to proteins and viruses are defined.

Diffraction methods of research are source of data on structures: X-ray diffraction analysis, elektronografiya, neytronografiya, messbauerografiya. The reasons of formation of this or that crystal structure are defined by the general principle of thermodynamics: the structure which with this pressure and temperature has the minimum free energy is steadiest.

On type of a chemical bond crystals are divided into four main groups - ionic crystals (for example, NaCl), covalent (for example, diamond, silicon), metal (metals and intermetallic connections) and molecular crystals (molecules are connected by of van - der - vaalsovy forces , for example, naphthalene).

In many crystals communication has intermediate character. For example, in crystals of silicates it it is ionic - covalent , at semiconductors communication generally of covalent , but with impurity ionic and metal . Special kristallokhimichesky regularities come to light in structure of polymeric crystals (chained structures), of liquid crystals, biological crystals . In some crystals (for example, ice, organic crystals) there is a hydrogen communication . Now of 9 structural modifications of ice knows , they have various crystal lattices, various density and temperatures of melting.

(1890) 230 spatial groups of symmetry of crystals determined by E. S. Fedorov are the natural law the nature which does not have mathematical expression (along with Periodic system of D. I. Mendeleyev). In 1926-27 systems of kristallokhimichesky ionic and nuclear radiuses (V. Goldshmidt, L. Poling) were created.

Semiconductors - a crystal chemistry product. U. Shokli offered methods of creation of the diffusive basic transistor. Together with J. It could measure by Haynes directly mobility and time of life of carriers of a charge in Germany (Haynes`s experience - Shokli, 1949), with G. Sul established influence of a magnetic field on concentration of carriers. Shokli constructed the theory of p - n - transition, received the equation for density of a total current in it (Shokli`s equation, 1949) and on the basis of it offered p - n - p - the transistor. In 1951 he predicted the saturation phenomenon in semiconductors and developed a method of determination of effective mass of carriers of a charge. In 1956 “for researches of semiconductors and discovery of transistor effect“ U. Shokli together with D. Bardin and U. Bratteyn was conferred the Nobel Prize on physics.

Cultivation of crystals of superpure silicon - too a problem of kristallokhimik. Consumption of polycrystalline silicon electronic industry makes several thousands of tons per year.

The Institute of a crystallography of the Russian Academy of Sciences (Moscow) works. There is a Kristallografiya magazine. It is possible to esteem: Urusov V. S., Theoretical crystal chemistry (M.: 1987).