When temperatures are lowered steadily, below water’s freezing point, (0 ºC), nitrogen, which is the major element of air, becomes liquid. Lowering the temperature further, at about -269 ºC, helium, which is the most resistant gas to cold, liquefies. As learnt during our Physics tuition class, by lowering the temperature further to -273.15 ºC, the absolute zero point is reached. At this point, no heat can exist inside a body. This leads to some quite outstanding variations in the behavior of both inorganic and organic matter. The cryogenics science involves the study of these effects developed by incredibly minimal temperature.
The cryogenic temperature range can be defined as the temperature between -150 ºC and the absolute zero (-273.15 ºC). Cryogenicists are accountable for studying as well as observing the behavior of different materials and matter within this range of temperature. Cryogenic temperatures are normally measured in Kelvin scale, in which 0 K represents the absolute zero.
Process of Cryogenic Freezing
The extremely minimal temperatures necessary for cryogenic freezing hardly occur in nature, and as a result, have to be developed artificially. These minimal temperatures can be conveniently developed by the means of magnetism. Some materials warm up when magnetized, and then cool down when demagnetized. A specifically controlled magnetic freezer is used in freezing of substances to incredibly minimal temperatures. It is possible to cool gases to minimal temperatures, by foremost compressing them, getting rid of their heat by means of regular refrigeration, and finally letting them expand.
The natural properties of different materials, at standard temperatures, have a tendency of altering substantially when exposed to cryogenic temperatures. The molecules’ movement inside the materials is accountable for the heat production. By steadily cooling a body, the internal molecular movement slows down steadily, until it stops completely at absolute zero. This explains why there is no heat generated at absolute zero.
Molecules are almost static, when cooled to cryogenic temperatures, attaining an almost flawlessly well-ordered state. This brings about the inorganic materials’ internal properties, like; ductility, thermal conductivity, strength, electrical conductance, malleability, and so on, which are wholly dependent on the molecular action, to be modified in techniques which prove to be of commercial as well as scientific significance.
Cryogenic cooling also ceases all biological activities. Both decomposition and growth/development of living matter substantially slows down and may even stop completely. Through this, it’s possible to preserve different organic substances prolonged duration by making use of cryogenic freezing.