Question

Researchers have debated that YBa2Cu3O7 can exist in two different crystal structures, tetragonal and orthorhombic. Predict what the conductivity would look like, to describe the relationship between E and J (in this course, a bold-faced letter represents a vector quantity). How can we use resistivity measurements to prove which of the crystal structures is correct?

Answer 1

The crystal structure and superconductivity properties of sample of YBa2Cu3O7 change with oxygen contents. Old samples where found to have orthorhombic crystal the lattice parameters a and c were observed to monotonically increase while b nearly monotonically decreases with decreasing oxygen content the unit cell volume increases with decreasing oxygen content as well the critical temperature TC and the superconducting volume fraction of the sample decrease with decreasing oxygen

0.21 <r <0.6

And electrical field E in a current the current density J and electrical field E are related by ohm's law
J = 0
the reciprocal of conductivity is electrical resistivity $\rho$ the charge carriers in metals are electrons that are in conduction bands which are partially filled energy bands so they are called conduction electrons the resistance of electrical conduction in metals by collision between electrons and crystal lattices

The crystal structure of YBa2Cu3O7is characterized by arrangement of copper oxygen plains and copper oxygenis char the stacking sequence of YBCO layers along the axis of the crystal is CuO-BaO-CuO2-Y-CuO2-BaO. The structure layers of YBCO are separated by plains of CUO2 with Yttrium atom between copper and oxygen planes planes consists of a square lattice of copper atoms bridged by oxygen atoms chains of see you are parallel to the copper oxygen planes with barium atoms located between the Planes and chains

The resistivity is metallic when
TQ < 500degree
and becomes semiconductor or like when
TQ > 600degree
the data on the letter was interpreted in terms of the three dimensional localisation model