electricity conducting: metallic conductor‚ semiconductor‚ and superconductor. Metallic conductors allow the free flow of ions and electrons through a sample; and its conductivity decreases as the temperature increases. Semiconductors allow the flow of both ions and electrons through the sample but not completely free; and its conductivity increases with increasing temperature. Superconductors are a class of metallic conductor whose resistance drops to zero suddenly below a certain critical temperature
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Landau Until 2004… R. E. Peierls Angela Intermite The rise of graphene‚ 18/10/2010 5/16 The bridge between theory and experimental evidence Graphene • metastable state but strong interatomic bonds 1 layer Boron Nitride no thermal fluctuations • crumpling in the third dimension ½ layer BSCCO gain in elastic energy Angela Intermite The rise of graphene‚ 18/10/2010 6/16 Graphene electronic structure: semimetal Semiconductor with direct gap Graphene Semiconductor
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November 24th‚ 2008 Geology MW 7:45 Extra Credit Diamonds are a Girl’s Best Friend A diamond is considered to be one of the most precious and rare stones on earth. These stones “are rare for three reasons: they form deep within the Earth in very localized places beneath continents‚ an extremely unusual kind of volcanic activity is needed to bring [diamonds] to the surface‚ and only about 20 per cent of them are gem quality” (Fleet‚ Hart‚ Wall 23). Not all diamonds are good enough to sell for
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CHAPTER 1 THE PROBLEM AND ITS SETTINGS Background of the Study Styrofoam is an important part of the modern economy. It ’s a very versatile product‚ used for cups‚ plates‚ and even some interior decorating items. Another very popular use is that of packing material. Packing Styrofoam comes in either loose form‚ or as "peanuts." As consumers‚ we use this product every day. However one has to understand that the utility of Styrofoam extends greatly from the common household
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A pH meter is an electronic device used for measuring the pH (acidity or alkalinity) of a liquid (though special probes are sometimes used to measure the pH of semi-solid substances). A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading. A colorimeter is a device used in colorimetry. In scientific fields the word generally refers to the device that measures the absorbance of particular wavelengths
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Gas Chromatography (GC) Definition: Gas chromatography is a physical method of separation in which the components to be separated are distributed between two phases‚ one being a stationary bed of large surface area‚ and the other a gas that percolates through the stationary bed. When the stationary phase is a solid‚ the separation process is more precisely called gas-solid chromatography. Introduction: Gas Chromatography is a technique widely used to separate complex mixtures of substances. Compounds
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NATIONAL DIPLOMA IN ENGINEERING UNIT 10 – PROPERTIES AND APPLICATIONS OF ENGINEERING MATERIALS ASSIGNMENT 1: Structures and Properties of Engineering Materials. Special attention should be paid to the Grading Criteria‚ as this will influence the way you answer each of the tasks. For each question all tasks need to be answered correctly to achieve the relevant criteria. Question 1: (P1) With the aid of clear‚ annotated diagrams‚ describe the structure associated with the following engineering
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Carbon Nanotubes Abstract Carbon nanotubes (CNTs) are a recently discovered allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology‚ electronics‚ optics‚ and other fields of materials science. They exhibit extraordinary strength and unique electrical properties‚ and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. A nanotube is a member
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SILVER By: Wahida Gh-Sakhi What is Silver? Silver is a chemical element with the chemical symbol Ag and atomic number 47. A soft‚ white‚ lustrous transition metal‚ it possesses the highest electrical conductivity of any element and the highest thermal conductivity of any metal. Element Symbol • Ag • Silver‚ Symbol Element Name • Silver Atomic Mass • The atomic mass is 107.8682 Atomic Number • The atomic number is 47 Bohr-Rutherford Diagram The Story of its Discovery Unknown since prehistoric
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Van der Waal’s forces -- Electrons will not be evenly spread around an atom/molecule at any given time‚ meaning the molecule will have a slight +ve charge on one end‚ and a -ve at the other. this temporary state may cause attraction between two molecules‚ pulling them together (also known as London dispersion forces). The magnitude pof Van der Waals force depends on the relative molecular mass‚ high mass produces a larger force. Boiling points of the alkanes data and alkenes data These very
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