2014-11-21
due date: 2014-12-02
Solid State Physics (MS613)
Homework #4
Research Paper
Please submit a research paper prepared as follows.
Title: Current status and future of multi-ferroic materials
length: 10 pages of A4 (minimum)
font size ; 10
word-processor s/w : Word
due: Dec 11
1. (a) Given that the atomic polarizabilities of K+ and Cl- ions measured at optical frequencies
are 1.48×10-40 Fm2 and 3.29×10-40 Fm2, respectively, and that the molar volume of KCl is
3.71×10-5m3, use the Clausius-Mossotti formula to determine the optical dielectric constant
εopt for KCl.
(b) Assuming that the atomic polarizabilities are the same in the static case as at optical
frequencies, use the data given in part (a) to determine the amplitude of the displacements of
the ions in KCl when placed in a static electric field of 105Vm-1. (The static dielectric constant
of KCl is 4.84)
2. (a) Estimate the dipole moment of a hydrogen chloride molecule assuming that there is a
complete transfer of the electron from the hydrogen atom to the chlorine atom. (The
separation of the hydrogen and chlorine nuclei is 0.128 nm.)
(b) Given that the measured dipole moment of a hydrogen chloride molecule is 3.3  10-30 Cm,
determine the actual amount of charge transferred from the hydrogen to the chlorine atom.
3. KH2PO4 is a colorless crystalline material which has a relative dielectric constant at low
frequencies of 100. On the assumption that the low-frequency dielectric constant is due
predominantly to the vibration of the H+ ions (of which there are 2×1028 per cubic meter)
about their equilibrium positions, estimate the frequency at which the peak of the dielectric
absorption will occur.
4. The dielectric constant of NaCl is 5.9 at low frequencies, but the effective dielectric constant at
the frequencies of visible light is only 2.25. What are the relative contributions of electronic
and ionic polarization to dc polarization?