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Lecture

Material Description: Phases and Symmetry

In course

MSE-100: Introduction to materials science

This course relates the structural elements of materials to their mechanical, thermal, electric, magnetic, and optical properties. Hands-on laboratories and team projects offer insight into the profession of materials engineers. ...

Description

This lecture covers the description of materials, focusing on the organic material wood composed of cellulose and lignin, the distinction between condensed phases based on density and mechanical properties, the role of silica and silicates in ceramics, glasses, and cements, the crystalline state with ordered atoms, and the concept of symmetry in geometric operations on structures.

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Instructors (2)

Pierre-Etienne Bourban

Background 1990 Ingénieur en science des matériaux 1993 PhD in materials science Activities 1993-1994 Research at the Center for Composite Materials, University of Delaware, USA (ccm.udel.edu), SNSF grant Since 1994 Research and teaching at EPFL, Composites, (LTC, LPAC) 1995-1999 Coordination Swiss Priority Program on Materials research: 2.2: Composites Since 1998 Biocomposites 2004-2009 Direction of the EPFL Transdisciplinary programme in Sport and Rehabilitation 2005-2008 Member of the EPFL Vice-Presidency for Innovation and Valorisation and direction a.i.EPFL-LTC Since 2016 Direction Discovery Learning Labs Materials/Bioengineering and Engineering

Francesco Stellacci

Francesco Stellacci graduated in Materials Engineering at the Politecnico di Milano in 1998 with a thesis on photochromic polymers with Prof. Giuseppe Zerbi and Mariacarla Gallazzi. In 1999 he moved to the Chemistry Department of the University of Arizona for as a post-doc in the group of Joe Perry in close collaboration with the group of Seth Marder. In 2002 he moved to the Department of Materials Science and Engineering at the Massachusetts Institute of Technology as an assistant professor. He was then promoted to associate without (2006) and with tenure (2009). In 2010 he moved to the Institute of Materials at EPFL as a full Professor. He holds the Alcan EP Chair. Francesco was one of the recipients of the Technology Review TR35 "35 Innovator under 35" award in 2005, and the Popular Science Magazine "Brilliant 10" award in 2007. He has been a Packard Fellow starting 2005.

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Related concepts (24)

Amorphous solid

In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymously with amorphous solid; however, these terms refer specifically to amorphous materials that undergo a glass transition. Examples of amorphous solids include glasses, metallic glasses, and certain types of plastics and polymers. The term comes from the Greek a ("without"), and morphé ("shape, form").

Symmetry

Symmetry () in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is invariant under some transformations, such as translation, reflection, rotation, or scaling. Although these two meanings of the word can sometimes be told apart, they are intricately related, and hence are discussed together in this article.

Symmetry group

In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition. Such a transformation is an invertible mapping of the ambient space which takes the object to itself, and which preserves all the relevant structure of the object. A frequent notation for the symmetry group of an object X is G = Sym(X). For an object in a metric space, its symmetries form a subgroup of the isometry group of the ambient space.

Silicate

In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO4−x(4-2x)− ]n, where 0 ≤ x < 2. The family includes orthosilicate (x = 0), metasilicate (x = 1), and pyrosilicate (x = 0.5, n = 2). The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate.

Rotational symmetry

Rotational symmetry, also known as radial symmetry in geometry, is the property a shape has when it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of distinct orientations in which it looks exactly the same for each rotation. Certain geometric objects are partially symmetrical when rotated at certain angles such as squares rotated 90°, however the only geometric objects that are fully rotationally symmetric at any angle are spheres, circles and other spheroids.

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