i wrote this for an assignment. idk how accurate it is or if its any help but whatever
1. DESCRIBE THE OCCURRENCE OF SUPERCONDUCTIVITY.
Superconductivity is the occurrence of no electron flow resistance in a material as a result of the materials temperature being decreased below a certain point called the critical point. Lattice structures of conductors made up of atoms that are formed into what is known as crystal lattices where the atoms that form it can be imagined as a sea of atoms . These atoms have a loose electron on the valence shell that allows for conductivity. When electrons flow through a lattice (current), they experience resistance by colliding with vibrating atoms. The vibration of the lattice structure and the atoms is a result of the temperature of the conductor, hence higher the temperature, the more the atoms vibrate and therefore greater resistance. Resistance is also caused by the imperfections of the lattice structure, again forcing collisions between atoms and electrons.
Superconductivity occurs when the temperature of the conductor decreases to a critical point where there is a sudden drop from minimal resistance to none (diagram 1). In order for this to happen (according to BCS theory), cooper pairs must form. Cooper pairs form when the first electron of the current passes through a lattice creating a positive region of temporary excess charge (phonon). Consequently there is an attraction from ions in the atoms to the electron. This causes a distortion in the lattice structure as the atoms move closer to the electron forming the phonon and allowing the second electron to join with the first. They then help each other to pass through the lattice. When the lattice is below its critical temperature, the atoms lack the energy to respond and cause the distortion to the moving cooper pair, which in turn results in a free path for the electrons to move hence no resistance. This process of cooper pairs moving through the superconductor repeats constantly. However, it must be noted that this can only occur in a single direction making it a direct current only because the cooper pairs need the direction.
Another important factor to note is that critical point varies between different materials as lattice structures differ and have different critical temperatures. Also, not all materials or metals have this ability as they cannot reach a critical temperature.
