The phenomenon of superconductivity, in which the electrical resistance of certain materials completely vanishes at low temperatures, is one of the most interesting and sophisticated in condensed matter physics. It was first discovered by the Dutch physicist Heike Kamerlingh Onnes, who was the first to liquefy helium (which boils at 4.2 Kelvin at standard pressure). In 1911 Kamerlingh Onnes and one of his assistants discovered the phenomenon of superconductivity while studying the resistance of metals at low temperatures. They studied mercury because very pure samples could easily be prepared by distillation. The historic measurement of superconductivity in mercury is shown in Figure 1. As in many other metals, the electrical resistance of mercury decreased steadily upon cooling, but dropped suddenly at 4.2 K, and became undetectably small. Soon after this discovery, many other elemental metals were found to exhibit zero resistance when their temperatures were lowered below a certain characteristic temperature of the material, called the critical temperature, Tc, some of which are given in Figure 2.…
Superconductivity is an electrical resistance[->0] of exactly zero which occurs in certain materials[->1]below a characteristic temperature[->2]. It was discovered by Heike Kamerlingh Onnes[->3] in 1911. Likeferromagnetism[->4] and atomic spectral lines[->5], superconductivity is a quantum mechanical[->6]phenomenon. It is also characterized by a phenomenon called the Meissner effect[->7], the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity[->8] in classical physics[->9].…
Abstract: Superconductivity is the phenomena of a material to have an electrical resistance of zero when cooled to a certain temperature known as the critical temperature. The phenomenon of superconductivity was first observed in 1911 by Heike Kamerlingh Onnes when cooling mercury down to a temperature of 4.2 K. Since then, many advances in the field of superconductivity have been made. In 1986, superconductivity was observed at temperatures well above 30 K, which was thought to be forbidden by BCS theory. This discovery led to the classification of Type I and Type II superconductors. The former are superconducting at low temperatures and have a very shallow London penetration depth and sharp critical magnetic field. The critical magnetic field is the external field at which the superconductor no longer repels the external field. Type II superconductors have high critical temperatures and contain flux tubes, which allow for a higher critical magnetic field. The discovery of type II superconductors has had many applications in the field of science, including MRIs and particle accelerators. In lab YBa2Cu3O7, a type II superconductor, was fabricated. A powder x-ray diffraction was carried out on the sample to verify the chemical makeup and identify any impurities. Two thin rods of the sample were also used to measure the resistivity verses temperature and the Meissner effect.…
Superconductive wire can be made from an alloy of niobium and titanium which can then be used to make superconductive magnets. Other alloys of niobium, such as those with tin and aluminum, are superconductive as well. Pure niobium is itself a superconductor when it is cooled below 9.25 K (-442.75°F). Superconductive niobium cavities are at the heart of a machine built at the Thomas Jefferson National Accelerator Facility. This machine, called an electron accelerator, is used by scientists to study the quark structure of matter. The accelerator's 338 niobium cavities are bathed in liquid helium and accelerateelectrons to nearly the speed of…
What is so super about superconductors? Perhaps the fact that superconductors are materials that have no resistance to the flow of electricity. So they basically will conduct electricity without resistance when the material is at a very cool temperature. Resistance becomes undesirable because it produces losses in the energy flowing through the material. Resistance creates heat which is why, when the material is cooled, the resistance will no longer be an included factor in the flow of electricity. Due to there being no resistance that means there is no loss in energy. Superconductivity creates much more energy than a normal conductor. If a current can be superconducting its flow of electricity will remain continuous.…
. Bismuth is a solid like most metals in room temperature; it has a high Malleability and a high-density (9.78 g·cm−3) rate. Except from Mercury, Bismuth has lowest thermal conductivity of all metals!…
* While in an unstressed state the QTC Material is a near-perfect insulator; with any form of deformation the material starts to conduct and with sufficient pressure metallic conductivity levels can be achieved.…
Conductivity- measure of ability to conduct electricity. Bismuth has a high resistance to electricity, which is unusual for a metal. Ductility- When a solid material stretches or breaks under tensile stress. Natural occurring and man made Bismuth have a very low ductility. The hardness of Bismuth is 2-2.5.…
In this essay we will explore some brief historical information about Giant Magnetoresistance (GMR), its basic principle of operation and some of its current and potential applications. To begin with, the idea of GMR is based on the change in the resistance of very thin (scale of nanometers) ferromagnetic materials when an external magnetic field is applied. The term “Giant” is to describe the size of the change in the resistivity in the order of 10% to 20%, considered to be enormous compared to the response of other magnetic sensors in the presence of an external magnetic field.…
A thermistor is a piece of semiconductor made from metal oxides, pressed into a small bead, disk, wafer, or other shape, sintered at high temperatures, and finally coated with epoxy or glass. The resulting device exhibits an electrical resistance that varies with temperature. There are two types of thermistors – negative temperature coefficient (NTC) thermistors, whose resistance decreases with increasing temperature, and positive temperature coefficient (PTC) thermistors, whose resistance increases with increasing temperature. NTC thermistors are much more commonly used than PTC thermistors, especially for temperature measurement applications. A main advantage of thermistors for temperature measurement is their extremely high sensitivity. For example, a 2252 Ω thermistor has a sensitivity of -100 Ω/°C at room temperature. Higher resistance thermistors can exhibit temperature coefficients of -10 kΩ/°C or more. In comparison, a 100 Ω platinum RTD has a sensitivity of only 0.4 Ω/°C. The physically small size of the thermistor bead also yields a very fast response to temperature changes. Another advantage of the thermistor is its relatively high resistance. Thermistors are available with base resistances (at 25° C) ranging from hundreds to millions of ohms. This high resistance diminishes the effect of inherent resistances in the lead wires, which can cause significant errors with low resistance devices such as RTDs. For example, while RTD measurements typically require 3-wire or 4-wire connections to…
Superfluids inside neutron stars, proposed as early as 1959, offered an alternative to the Urca process. Created in laboratories by chilling liquids to ultracold temperatures, superfluids have mind-boggling abilities to climb walls and leak through solid glass containers. And they make great coolants: Superfluid helium keeps the superconducting magnets in the world’s most powerful particle collider chilled to just 1.9 degrees above absolute…
Krim, Jacqueline. "Superconductors." NCSU Department of Physics. 12 June 2002. NCSU. 11 Nov 2008 .…
Buckyballs, which are explicitly similar to other supermaterials like graphene and CNTs, are known for their superconductivity. Therefore, while combining buckyballs and rubidium, the researchers created a complex structure that seemed to conduct, insulate, and magnetize simultaneously while acting as a metal. This behaviour is far beyond what ordinary matter exhibit.…
In the essay “Phenomena of superconductors: Josephson Junctions”, most information comes from the published physicals books for instance Compound and Josephson High-Speed Devices and The Gale Encyclopedia of Science. Besides, there are some articles published in Scientific American. These are my primary resources. I did not employ a lot website information in the essay except a basic introduction from website of Georgia State University. Some book I used in the essay was published very long time ago. Hence, I probably would need to renew them.…
^ a b J. Bardeen, L. N. Cooper and J. R. Schrieffer (1957). "Theory of Superconductivity". Physical Review 108 (5): 1175–1205. Bibcode:1957PhRv..108.1175B. doi:10.1103/PhysRev.108.1175.…