The cscl melting point is the temperature at which an ionic solid transforms into gaseous ions. It depends on lattice energy and the ionic or covalent nature of the compound.
Lattice energy is the amount of energy needed to separate one mole of an ionic solid into its gaseous ions. Hence, the higher the value of the lattice energy of an ionic solid, the lower its melting point is.
Alkali metal chlorides consist of a halogen atom and an alkali metal cation which are linked together to form an interpenetrating primitive cubic lattice. Lithium chloride has the lowest melting point among all alkali metal halides as it is covalent.
Despite its low melting point, it has numerous practical applications in a wide range of fields, including the preparation of electrically conducting glasses, screens for cathode ray tubes, and activated electrodes in welding. It is also used in conjunction with rare gases to produce excimer lamps and lasers.
CsCl crystallizes in a primitive cubic lattice and therefore is more stable than NaCl. In addition, its Bravais lattice has peaks for all values of h2+ k2+l2 which allows an independent determination of the lattice parameter a that determines pressure.
It is twice as compressible as NaCl and more than ten times as compressible as MgO, so it is extremely sensitive to small changes in pressure. It has a broad pressure range, from about 1 GPa to 70 GPa, which is more extensive than that of NaCl and MgO. Moreover, it is more stable than both of those compounds, which are much less compressible. This makes it a good choice as the primary standard in many high P-T studies.