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Diamond structure

Diamond structure is divided into: equiaxed tetrahedral cubic and hexagonal diamond.

In diamond crystal, carbon atoms are interconnected by tetrahedral bonds, forming an infinite three-dimensional skeleton, which is a typical atomic crystal. Each carbon atom forms a valence bond with the other four carbon atoms through SP3 hybrid orbitals, forming a regular tetrahedron.

Because the C-C bond in diamond is very strong, all valence electrons participate in the formation of valence bond, and there are no free electrons, so diamond is not only hard, but also has a very high melting point and is not conductive. In industry, diamonds are mainly used to make probes and abrasives for drilling, and also used to make high-grade decorations such as hand ornaments with complete shapes, which are very expensive.

The Mohs hardness of diamond is10; Because the hardness of natural substances is the highest, diamond powder must be used in diamond cutting. The density of diamond is 3.52g/ cm3, the refractive index is 2.4 17, and the dispersion rate is 0.044.

Extended data

Diamond has stable chemical properties, acid resistance and alkali resistance.

Diamond also has non-magnetism, poor conductivity, oleophilic hydrophobicity and triboelectricity. Only Ⅱ B diamond has good semiconductor properties. According to the difference of nitrogen impurity content and thermal, electrical and optical properties of diamonds, diamonds can be divided into two categories: type I and type II, and further subdivided into four subcategories: 1a, 1b, 2a and 2b.

Type Ⅰ diamond, especially subtype Ⅰ A, is a common common diamond, accounting for about 98% of the total natural diamonds. Type I diamonds contain a certain amount of nitrogen, which has good thermal conductivity, poor electrical conductivity and good crystal shape.

Type ⅱ diamond is extremely rare, with little or no nitrogen content, and has the characteristics of good thermal conductivity and crystal bending. Diamonds of type Ⅱ b are semiconductors. Second-class diamonds are mostly used in aerospace technology and cutting-edge industries because of their excellent properties.

Baidu Encyclopedia-Diamonds (minerals made of pure carbon)