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Physical Crystallography Before X-rays
Physical crystallography before X-rays describes how physical crystallography developed as a science up to the discovery of X-rays by Wilhelm Conrad Röntgen in 1895. In the period before X-rays, crystallography can be divided into three broad areas: geometric crystallography culminating in the discovery of the 230 space groups in 1891–4, chemical crystallography and physical crystallography. Physical crystallography is concerned with the Mineralogy#Physical properties, physical properties of crystals, such as their Crystal optics, optical, electrical, and magnetic properties. The effect of electromagnetic radiation on crystals is covered in the following sections: #Double refraction, double refraction, #Rotary polarization, rotary polarization, #Conical refraction, conical refraction, #Absorption and pleochroism, absorption and pleochroism, #Luminescence, fluorescence and phosphorescence, luminescence, fluorescence and phosphorescence, #Reflection from opaque materials, reflecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallography
Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. The word ''crystallography'' is derived from the Ancient Greek word (; "clear ice, rock-crystal"), and (; "to write"). In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming 2014 the International Year of Crystallography.UN announcement "International Year of Crystallography" iycr2014.org. 12 July 2012 Crystallography is a broad topic, and many of its subareas, such as X-ray crystallography, are themselves important scientific topics. Crystallography ranges from the fundamentals of crystal structure to the mathematics of Crystal system, crystal geometry, including those that are Aperiodic crystal, not periodic or quasi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conduction
Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter (rho). The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). For example, if a solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is , then the resistivity of the material is . Electrical conductivity (or specific conductance) is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter (sigma), but ( kappa) (especially in electrical engineering) and (gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rasmus Bartholin
Rasmus Bartholin (; Latinized: ''Erasmus Bartholinus''; 13 August 1625 – 4 November 1698) was a Danish physician and grammarian. Biography Bartholin was born in Roskilde. He was the son of Caspar Bartholin the Elder (1585–1629) and Anna Fincke, daughter of the mathematician Thomas Fincke. As part of his studies, he travelled in Europe for ten years. He stayed in the Netherlands, England, France and Italy. In 1647, he took a Master's degree at the University of Copenhagen. In 1654, he received a Doctoral degree at the University of Padua. He was a professor at the University of Copenhagen, first in Geometry, later in Medicine. He was also dean of the faculty of medicine, librarian, and rector. He wrote, in Latin, the first grammar of the Danish language, the 1657 ''De studio lingvæ danicæ''. Rasmus Bartholin is remembered especially for his discovery (1669) of the double refraction of a light ray by Iceland spar (calcite). He published an accurate description of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisotropy
Anisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance, refractive index, conductivity, and tensile strength. An example of anisotropy is light coming through a polarizer. Another is wood, which is easier to split along its grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions). Fields of interest Computer graphics In the field of computer graphics, an anisotropic surface changes in appearance as it rotates about its geometric normal, as is the case with velvet. Anisotropic filtering (AF) is a method of enhancing the image quality of textures on surfaces that are far away and viewed at a shallow angle. Older ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensor
In mathematics, a tensor is an algebraic object that describes a multilinear relationship between sets of algebraic objects associated with a vector space. Tensors may map between different objects such as vectors, scalars, and even other tensors. There are many types of tensors, including scalars and vectors (which are the simplest tensors), dual vectors, multilinear maps between vector spaces, and even some operations such as the dot product. Tensors are defined independent of any basis, although they are often referred to by their components in a basis related to a particular coordinate system; those components form an array, which can be thought of as a high-dimensional matrix. Tensors have become important in physics because they provide a concise mathematical framework for formulating and solving physics problems in areas such as mechanics ( stress, elasticity, quantum mechanics, fluid mechanics, moment of inertia, ...), electrodynamics ( electromagnetic ten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curie's Principle
Curie's principle, or Curie's symmetry principle, is a maxim about cause and effect formulated by Pierre Curie in 1894: The idea was based on the ideas of Franz Ernst Neumann Franz Ernst Neumann (11 September 1798 – 23 May 1895) was a German mineralogist and physicist. He devised the first formulas to calculate inductance. He also formulated Neumann's law for molecular heat. In electromagnetism, he is credited for ... and Bernhard Minnigerode. Thus, it is sometimes known as the Neuman–Minnigerode–Curie principle. Later physicists have interpreted Curie's principle in the context of thermodynamics. Dynamics close to equilibrium are described by a set of transport coefficients whose symmetries must match the symmetries of the system, according to Curie's principle. References Group theory {{Sci-stub Concepts in physics Symmetry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Curie
Pierre Curie ( ; ; 15 May 1859 – 19 April 1906) was a French physicist, Radiochemistry, radiochemist, and a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. He shared the 1903 Nobel Prize in Physics with his wife, Marie Curie, and Henri Becquerel "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel". With their win, the Curies became the Nobel Prize#Statistics, first married couple to win a Nobel Prize, launching the Nobel Prize#Family laureates, Curie family legacy of five Nobel Prizes. Early life Born in Paris on 15 May 1859, Pierre Curie was the son of Eugène Curie (1827–1910), a doctor of French Huguenot Protestant origin from Alsace, and Sophie-Claire Curie (née Depouilly; 1832–1897). He was educated by his father and in his early teens showed a strong aptitude for mathematics and geometry. When he was 16, he earned his Bachelor of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woldemar Voigt
Woldemar Voigt (; 2 September 1850 – 13 December 1919) was a German mathematician and physicist. Biography Voigt was born in Leipzig, and died in Göttingen. He was a student of Franz Ernst Neumann. Voigt taught at the Georg August University of Göttingen and eventually went on to head the Mathematical Physics Department there. He was succeeded in 1914 by Peter Debye, who took charge of the theoretical department of the Physical Institute. Voigt worked on crystal physics, thermodynamics and electro-optics. His main work was the ''Lehrbuch der Kristallphysik'' (''Textbook on crystal physics''), first published in 1910. He discovered what is now called the Voigt effect in 1898. The word tensor in its current meaning was introduced by him in 1898. Voigt profile and Voigt notation are named after him. He was also an amateur musician and became known as a Bach expert (see External links). He was the first to suggest, in 1886, that Bach's Concerto for two harpsichords in C m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birefringence
Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefringent or birefractive. The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress. Birefringence is responsible for the phenomenon of double refraction whereby a ray of light, when incident upon a birefringent material, is split by polarization into two rays taking slightly different paths. This effect was first described by Danish scientist Rasmus Bartholin in 1669, who observed it in Iceland spar (calcite) crystals which have one of the strongest birefringences. In the 19th century Augustin-Jean Fresnel described the phenomenon in terms of polarization, understanding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franz Ernst Neumann
Franz Ernst Neumann (11 September 1798 – 23 May 1895) was a German mineralogist and physicist. He devised the first formulas to calculate inductance. He also formulated Neumann's law for molecular heat. In electromagnetism, he is credited for introducing the magnetic vector potential. Biography Early life Franz Ernst Neumann was born in Joachimsthal, Margraviate of Brandenburg (near Berlin), the son of Ernst Neumann, a farmer who became a state agent. His mother was a Countess who was not allowed to marry Ernst, and Neumann did not meet her mother until he was 10 years old. Neumann attended a Gymnasium in Berlin, where he excelled in mathematics. However his studies were interrupted by the war with France. In 1815 he paused his education at Berlin to serve as a volunteer in the Hundred Days against Napoleon, and was wounded in the Battle of Ligny. He later returned to finish his studies in Berlin. Subsequently, he enrolled at Berlin University in 1818 as a student of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piezoelectricity
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. The piezoelectric effect is a reversible process: materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect, the internal generation of a mechanical strain resulting from an applied electric field. For example, lead zirconate titanate crystals will generate measurable piezoelectricity when their static structure is deformed by about 0.1% of the original dimension. Conversely, those same crystals will change about 0.1% of their static dimension when an external electric field is applied. The inverse piezoelectric effect is used in the pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastic Properties
Elastic is a word often used to describe or identify certain types of elastomer, elastic used in garments or stretchable fabrics. Elastic may also refer to: Alternative name * Rubber band, ring-shaped band of rubber used to hold objects together * Bungee cord, a cord composed of an elastic core covered in a sheath * Chinese jump rope, a children's game resembling hopscotch and jump rope As a proper name * ''Elastic'' (album), a 2002 album by jazz saxophonist Joshua Redman *"Elastic", a 2018 single by Joey Purp *Elastic, working title of the 2012 Indian film ''Cocktail'' * Elastic NV, the company that releases the Elasticsearch search engine ** Elasticsearch, a search engine based on Apache Lucene * Amazon Elastic Compute Cloud (Amazon EC2), a web service that provides secure, resizable compute capacity in a cloud format * Elastics (orthodontics), rubber bands used in orthodontics See also * Elastic collision, a collision where kinetic energy is conserved * Elastic deformat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
