Solid-state physics

Gapless semiconductors, semiconductors with a forbidden-band width Ε g = 0.

Biological crystals are crystals built from biological macromolecules — proteins, nucleic acids or virus particles.

Bloch–Grüneisen formula - a formula describing the temperature dependence of that part of the electrical resistivity ρ of metals which is due to the scattering of conduction electrons by the thermal vibrations of the ato…

Bose liquid , a quantum liquid in which the elementary excitations (quasiparticles) have zero or integer spin and obey Bose—Einstein statistics.

Bolometer , ( from the Greek bole — a throw; a ray, and metreo — I measure), a thermal non-selective detector of optical radiation, based on the change in the electrical resistance of a heat-sensitive element when it is …

Bravais lattices , the fourteen three-dimensional geometrical lattices that characterise the possible types of translational symmetry of a crystal lattice.

The first Brillouin zone — a region of reciprocal space (see Reciprocal lattice ) centred on the origin of coordinates and defined as follows: if planes are drawn through the midpoints of the vectors joining the origin t…

The Bragg-Wulff condition , determines the directions in which maxima of intensity can arise when X-radiation is elastically scattered by a crystal in the diffraction of X-rays.

Vacancy , (from the Latin vacans — standing empty, free), the absence of an atom or an ion at a point of a crystal lattice.

Valence band , the energy region of allowed electron states in a solid; at the absolute zero of temperature it is entirely filled with valence electrons (see Band theory ).

Crystals in which birefringence occurs for all directions of the light ray incident on them except two, each of which is called an optical axis of the crystal.

Ideal crystal: 1) A crystal with a perfect three-dimensionally periodic lattice throughout its volume, free of any structural defects — vacancies, impurity atoms, dislocations and others.

Measuring amplifier , a device for amplifying electrical signals (current, voltage) and also for converting voltage into current and the other way round.

Isomorphism , (from the Greek isos — equal, the same, and morphe — form, shape), the complete similarity in the atomic and crystal structure and in the external faceting of the crystals of substances that have the same c…

Cathodoluminescence , luminescence that arises when a phosphor is excited by an electron beam (cathode rays); one of the forms of radioluminescence.

1) a particular form of interaction between electric currents, between currents and magnets (that is, bodies with a magnetic moment) and between magnets; 2) the branch of physics that studies this interaction and the pro…

Meissner effect , the complete expulsion of a magnetic field from a metallic conductor when the latter becomes superconducting (as the temperature and the magnetic field strength fall below the critical value H k ).

see Elastic moduli .

A characteristic of a material that reflects its strength and plasticity.

Forbidden band (energy gap) , the range of energy values that electrons cannot have in an ideal crystal (see Band theory ).