Physics Of Solids Flashcards
(13 cards)
Name the 5 types of bonding and separate then into strong and weak groups
Weak: van der Waals, hydrogen
Strong: metallic, covalent, ionic
Describe the general characteristics of the force between atoms, and why there is in condensed matter an equilibrium spacing and a binding energy.
Atomic forces involve a balance between short-range repulsion and long-range attraction. At equilibrium spacing, the potential energy is minimized, giving rise to a stable configuration and a binding energy.
Describe the main features of ionic, covalent, metallic, hydrogen, and Van der Waals bonding.
Ionic: electrons transferred, strong electrostatic attraction. Covalent: electrons shared, directional bonds. Metallic: delocalized electrons, good conductivity. Hydrogen: partial charges due to polar covalent bonds. Van der Waals: weak dipole interactions.
Explain the concept of a crystal structure being composed of a lattice plus a basis of atoms.
A crystal structure = lattice (repeating points in space) + basis (group of atoms associated with each point).
Describe the concept of crystal planes and define the Miller indices for a set of planes.
Crystal planes are sets of parallel atomic layers described by Miller indices (hkl), derived from the reciprocals of axis intercepts, reduced to integers.
Explain how the distribution of scattering angles from a polycrystalline sample or powder crystal gives information about the lattice spacing.
X-ray diffraction patterns show rings or spots at angles where Bragg’s law is satisfied, allowing calculation of lattice spacing from the angles.
Describe how electrons may be used to image thin samples.
Electrons with small de Broglie wavelengths can be used in TEM to image atomic-scale structures in thin samples via diffraction patterns.
Explain the principal features of the free electron gas model of a metal.
In this model, electrons move freely in a potential well formed by positive ions, leading to properties like high conductivity and thermal transfer.
Explain what is meant by the Fermi energy.
The Fermi energy is the highest occupied energy level of electrons in a metal at absolute zero; it characterizes the energy distribution.
Explain the concept energy bands and show how it leads to the basic properties of semiconductors
In solids, atomic orbitals overlap to form energy bands. In semiconductors, a small gap exists between valence and conduction bands, enabling controllable conductivity.
Describe the Hall effect and be able to calculate parameters associated with this.
The Hall effect arises when a magnetic field causes a voltage across a conductor perpendicular to current flow. It’s used to find carrier type and density. ( V_H = -IB/nq y_0 ).
Explain different types of magnetic order, such as ferromagnetism and antiferromagnetism.
Ferromagnetism: spins align parallel. Antiferromagnetism: spins align antiparallel, canceling out net magnetization.
Explain why neutron scattering is useful in the study of magnetic crystals.
Neutrons interact with atomic nuclei and magnetic moments, making them ideal for probing both atomic and magnetic structures in crystals.
