Written in English
Thesis (M.A.) -- University of Toronto, 1929.
|The Physical Object|
In the photoelectric effect, light incident on the surface of a metal causes electrons to be ejected. The number of emitted electrons and their kinetic energy can be measured as a function of the Photoelectric Effect - Chemistry LibreTexts. Physica 85B () North-Holland Publishing Company THE EFFECT OF THE SUPERCONDUCTING TRANSITION ON THE ELECTRONIC WORK FUNCTION OF NIOBIUMt D. H. DARLING* and P. B. PIPES** Department of Physics and Astronomy, Dartmouth College, Hanover, N.H., , USA Received 2 December A modified Kelvin method has been employed to measure the temperature Author: D.H. Darling, P.B. Pipes. a persistent current in superconducting lead that held an initial internal zero ux. 1. INTRODUCTION Superconductors are metals or alloys that have been cooled to a temperature below some critical value. When a metal capable of becoming a superconductor does so, it loses all electrical resistance and demonstrates severalFile Size: KB. Superconductivity is a phenomena in certain metals and ceramics where the resistivity of the material drops to zero below a certain critical temperature known as T C. These temperatures are low, with most industrial superconductors below 12 K and higher temperature ceramics .
The type I detectors are characterized by an acceptor doping concentration (N a) in the p +-layer high enough to form an impurity band but still less than the Mott critical value (N c), so the Fermi level (E F) is located in the impurity band at low temperatures. Photoelectric effect 1 Background A photon of frequency ν carries energy hν, where h is Planck’s constant. If such aphoton strikesan electron inside ametallic conductor, itcan knockthe electron out of the metal. Once liberated, the free electron has an energy hν−W, where W is the binding energy which formerly kept it inside the metal File Size: KB. It would be easy to imagine that all superconductors were metals, and that a large number of different metals would superconduct given a sufficiently low temperature. However, this is not the case. Two common low-temperature superconductors are lead and mercury, although an alloy of tin and niobium works at higher temperatures than these. Low Temperature Superconductivity. LTS stands for “low temperature superconductor,” which typically refers to the Nb-based alloy (most commonly Nbwt.%Ti) and A15 (Nb3Sn and Nb3Al) superconductors in use prior to the discovery of “high temperature” oxide superconductors in
Instead in the superconducting state (at low temperature) is necessary that the ions are at a sufficient distance to create and mantain an interaction between two electrons (Cooper's pair). Mercury was the first element observed to display superconducting properties in They generally require extreme cold before they will become superconducting. However, they exhibit a sharp transition as they move into the superconducting state. The table below lists some Type 1 superconductors and their critical temperatures (Tc), i.e. the temperature at which they become superconducting. The electronic specific heat in the superconducting state (designated C es) is smaller than in the normal state (designated C en) at low enough temperatures, but C es becomes larger than C en as the transition temperature T c is approached, at which point it drops abruptly to C en for the classic superconductors, although the curve has a cusp shape near T c for the high-T c superconductors. . Low Temperature Properties of Materials Materials properties affect the performance of cryogenic systems. Properties of materials vary considerably with temperature Thermal Properties: Heat Capacity (internal energy), Thermal Expansion Transport Properties: Thermal conductivity.