09 August 2013
There may be more kinds of stuff than we thought. A team of researchers has reported possible evidence for a new category of solids, things that are neither pure glasses, crystals, nor even exotic quasicrystals. Something else.*
"Very weird. Strangest material I ever saw," says materials physicist Lyle Levine of the National Institute of Standards and Technology (NIST).
The research team from NIST and Argonne National Laboratory has analyzed a solid alloy that they discovered in small discrete patches of a rapidly cooled mixture of aluminum, iron and silicon.
The material appears to have none of the extended ordering of atoms found in crystals, which would make it a glass, except that it has a very defined composition and grows outward from "seeds"—things that glasses most assuredly do not do.
The solids catalog used to be pretty straightforward. Solid stuff was either a crystal or a glass. Crystals fill up space with atoms or molecules in specific, fairly rigid patterns. The positions of the atoms are fixed such that if you take any section of pure crystal and slide it up, down, in, out or sideways a given distance, it will fit perfectly in the new position. That's translational symmetry. You can also spin the crystal through certain angles and the atoms also will line up; that's rotational symmetry.
03 August 2013
Dear students,
The Lesson 3 of our course has been uploaded!
In the third lecture of Materials for Photonic Applications course, we will see the basics for glasses optical properties. You will find at our e-Learning Portal the Lesson and some related papers.
24 June 2013
Vienna-based scientists say new technique stores quantum information for long enough to create optical global quantum networks.
Quantum of knowledge? Atoms, coupled to a glass fiber.
Researchers at the Vienna University of Technology have demonstrated “quantum mechanical coupling” of atoms to glass fiber cables. Now, they say that their technique is enabling storage of quantum information for a sufficiently long period of time to achieve global quantum networks based on optical fibers.
05 June 2013
In the second lecture of Materials for Photonic Applications course, we will revise the main concepts and definitions behind the very general term –glass. You will find at our web site some papers and interesting features mentioned here.
28 April 2013
Last week, the first lesson of Materials for Photonic Applications online course was uploaded.
In his lecture, Prof. Sidney Ribeiro mentions ancient glasses with special properties, in particular, the roman Lycurgus Cup.
11 April 2013
Introduction
Photonics is related to generation, guiding and detection of light and lies at the heart of modern society activities. Gathering interdisciplinary efforts from Physics, Chemistry and Materials Science the study of Photonic Materials is considered in this course focused on Glasses, Optical Fibers and Organic-inorganic hybrid materials.
-Glasses were the first materials prepared by man. Isotropic in nature, with optical properties easily tuned for specific applications. Glasses play a fundamental hole in photonics;
-Optical fibers, prepared from optical glasses, are the choice for guiding media for applications in communications, sensing and light transmission with special new applications as active media in photonics derived new areas such as plasmonics and biophotonics;
-Sol-Gel based materials and processes and the derived organic-inorganic hybrids are becoming more and more popular in the preparation of colloidal suspensions, special optical thin films, nanoparticles among others.
08 April 2013
Glass doesn't have to be brittle, as new research explains. The key is temperature.Glass doesn’t have to be brittle.
In a paper published online in the journal Nature Communications, a Yale University team and collaborators propose a way of predicting whether a given glass will be brittle or ductile — a desirable property typically associated with metals like steel or aluminum — and assert that any glass could have either quality.
Ductility refers to a material’s plasticity, or its ability to change shape without breaking.