question archive X-ray crystallography was used to examine a sample of CaO at room temperature
X-ray crystallography was used to examine a sample of CaO at room temperature
Subject:PhysicsPrice: Bought3
X-ray crystallography was used to examine a sample of CaO at room temperature. It was found to have a face-centred cubic (FCC) crystal structure with an interaction constant r* of 57 pm, a Madelung constant of 1.748 and an average internuclear separation ro of 207 pm. a) Calculate the lattice enthalpy for CaO at room temperature. You will need to multiply the Madelung constant by a factor of 4 due to the ions (Ca2+ and 02-) being doubly charged. MnO also has a FCC crystal structure and exhibits antiferromagnetic properties with a Neel temperature of 122 K. b) Describe the differences between ferromagnetism and antiferromagnetism. c) Define the term Neel temperature. d) Sketch a diagram of a typical hysteresis loop showing the magnetisation of a typical ferromagnet. Include in your diagram the approximate orientation of the domains at each end of the loop and at the points where magnetisation is equal to zero (M = 0). e) List two spectroscopic techniques that utilise magnetic fields. Briefly describe/explain the use or purpose of the magnetic field in each technique..
