In condensed matter physics and materials science, an amorphous 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.
Gadolinium is a chemical element; it has symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is a malleable and ductile rare-earth element. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare earths because of their similar chemical properties.
Solid-state chemistry, also sometimes referred as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials. It therefore has a strong overlap with solid-state physics, mineralogy, crystallography, ceramics, metallurgy, thermodynamics, materials science and electronics with a focus on the synthesis of novel materials and their characterization. A diverse range of synthetic techniques, such as the ceramic method and chemical vapour depostion, make solid-state materials. Solids can be classified as crystalline or amorphous on basis of the nature of order present in the arrangement of their constituent particles. Their elemental compositions, microstructures, and physical properties can be characterized through a variety of analytical methods.
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces. It includes the fields of surface chemistry and surface physics. Some related practical applications are classed as surface engineering. The science encompasses concepts such as heterogeneous catalysis, semiconductor device fabrication, fuel cells, self-assembled monolayers, and adhesives. Surface science is closely related to interface and colloid science. Interfacial chemistry and physics are common subjects for both. The methods are different. In addition, interface and colloid science studies macroscopic phenomena that occur in heterogeneous systems due to peculiarities of interfaces.
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a detector such as a scintillator attached to a charge-coupled device or a direct electron detector.
Electron diffraction is a generic term for phenomena associated with changes in the direction of electron beams due to elastic interactions with atoms. It occurs due to elastic scattering, when there is no change in the energy of the electrons. The negatively charged electrons are scattered due to Coulomb forces when they interact with both the positively charged atomic core and the negatively charged electrons around the atoms. The resulting map of the directions of the electrons far from the sample is called a diffraction pattern, see for instance Figure 1. Beyond patterns showing the directions of electrons, electron diffraction also plays a major role in the contrast of images in electron microscopes.
Scanning probe microscopy (SPM) is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. SPM was founded in 1981, with the invention of the scanning tunneling microscope, an instrument for imaging surfaces at the atomic level. The first successful scanning tunneling microscope experiment was done by Gerd Binnig and Heinrich Rohrer. The key to their success was using a feedback loop to regulate gap distance between the sample and the probe.
Electron backscatter diffraction (EBSD) is a scanning electron microscopy (SEM) technique used to study the crystallographic structure of materials. EBSD is carried out in a scanning electron microscope equipped with an EBSD detector comprising at least a phosphorescent screen, a compact lens and a low-light camera. In the microscope an incident beam of electrons hits a tilted sample. As backscattered electrons leave the sample, they interact with the atoms and are both elastically diffracted and lose energy, leaving the sample at various scattering angles before reaching the phosphor screen forming Kikuchi patterns (EBSPs). The EBSD spatial resolution depends on many factors, including the nature of the material under study and the sample preparation. They can be indexed to provide information about the material's grain structure, grain orientation, and phase at the micro-scale. EBSD is used for impurities and defect studies, plastic deformation, and statistical analysis for average misorientation, grain size, and crystallographic texture. EBSD can also be combined with energy-dispersive X-ray spectroscopy (EDS), cathodoluminescence (CL), and wavelength-dispersive X-ray spectroscopy (WDS) for advanced phase identification and materials discovery.
Electron crystallography is a subset of methods in electron diffraction focusing just upon detailed determination of the positions of atoms in solids using a transmission electron microscope (TEM). It can involve the use of high-resolution transmission electron microscopy images, electron diffraction patterns including convergent-beam electron diffraction or combinations of these. It has been successful in determining some bulk structures, and also surface structures. Two related methods are low-energy electron diffraction which has solved the structure of many surfaces, and reflection high-energy electron diffraction which is used to monitor surfaces often during growth.
Sir John Meurig Thomas, also known as JMT, was a Welsh scientist, educator, university administrator, and historian of science primarily known for his work on heterogeneous catalysis, solid-state chemistry, and surface and materials science.
Ernst G. Bauer is a German-American physicist known for his studies in the field of surface science, thin film growth and nucleation mechanisms and the invention in 1962 of the Low Energy Electron Microscopy (LEEM). In the early 1990s, he extended the LEEM technique in two directions by developing Spin-Polarized Low Energy Electron Microscopy (SPLEEM) and Spectroscopic Photo Emission and Low Energy Electron Microscopy (SPELEEM). He is currently Distinguished Research Professor Emeritus at the Arizona State University.
In materials science, paracrystalline materials are defined as having short- and medium-range ordering in their lattice but lacking crystal-like long-range ordering at least in one direction.
In microscopy, conductive atomic force microscopy (C-AFM) or current sensing atomic force microscopy (CS-AFM) is a mode in atomic force microscopy (AFM) that simultaneously measures the topography of a material and the electric current flow at the contact point of the tip with the surface of the sample. The topography is measured by detecting the deflection of the cantilever using an optical system, while the current is detected using a current-to-voltage preamplifier. The fact that the CAFM uses two different detection systems is a strong advantage compared to scanning tunneling microscopy (STM). Basically, in STM the topography picture is constructed based on the current flowing between the tip and the sample. Therefore, when a portion of a sample is scanned with an STM, it is not possible to discern if the current fluctuations are related to a change in the topography or to a change in the sample conductivity.
Pressure-induced hydration (PIH), also known as “super-hydration”, is a special case of pressure-induced insertion whereby water molecules are injected into the pores of microporous materials. In PIH, a microporous material is placed under pressure in the presence of water in the pressure-transmitting fluid of a diamond anvil cell.
Paul Anthony Midgley FRS is a Professor of Materials Science in the Department of Materials Science and Metallurgy at the University of Cambridge and a fellow of Peterhouse, Cambridge.
Brent Fultz is an American physicist and materials scientist and one of the world's leading authorities on statistical mechanics, diffraction, and phase transitions in materials. Fultz is the Barbara and Stanley Rawn Jr. Professor of Applied Physics and Materials Science at the California Institute of Technology. He is known for his research in materials physics and materials chemistry, and for establishing the importance of phonon entropy to the phase stability of materials. Additionally, Fultz oversaw the construction of the wide angular-range chopper spectrometer (ARCS) instrument at the Spallation Neutron Source and has made advances in phonon measuring techniques.
Structural chemistry is a part of chemistry and deals with spatial structures of molecules and solids. For structure elucidation a range of different methods is used. One has to distinguish between methods that elucidate solely the connectivity between atoms (constitution) and such that provide precise three dimensional information such as atom coordinates, bond lengths and angles and torsional angles.
Sergei V. Kalinin is the Weston Fulton Professor at the Department of Materials Science and Engineering at the University of Tennessee-Knoxville.
Liquid-phase electron microscopy refers to a class of methods for imaging specimens in liquid with nanometer spatial resolution using electron microscopy. LP-EM overcomes the key limitation of electron microscopy: since the electron optics requires a high vacuum, the sample must be stable in a vacuum environment. Many types of specimens relevant to biology, materials science, chemistry, geology, and physics, however, change their properties when placed in a vacuum.
This is a timeline of crystallography.
