Editing Materials science (section)

===Structure===
Structure is one of the most important components of the field of materials science. The very definition of the field holds that it is concerned with the investigation of "the relationships that exist between the structures and properties of materials".<ref>{{Cite book |last=Zagorodni |first=Andrei A. |title=Ion Exchange Materials: Properties and Applications |publisher=Elsevier |year=2006 |isbn=978-0-08-044552-6 |location=Amsterdam |pages=xi |language=en}}</ref> Materials science examines the structure of materials from the atomic scale, all the way up to the macro scale.<ref name=":1" /> [[Characterization (materials science)|Characterization]] is the way materials scientists examine the structure of a material. This involves methods such as diffraction with [[X-ray]]s, [[electron]]s or [[neutron]]s, and various forms of [[spectroscopy]] and [[chemical analysis]] such as [[Raman spectroscopy]], [[energy-dispersive X-ray spectroscopy|energy-dispersive spectroscopy]], [[chromatography]], [[thermal analysis]], [[electron microscope]] analysis, etc.

Structure is studied in the following levels.

====Atomic structure====
Atomic structure deals with the atoms of the materials, and how they are arranged to give rise to molecules, crystals, etc. Much of the electrical, magnetic and chemical properties of materials arise from this level of structure. The length scales involved are in angstroms ([[Angstrom|Å]]). The chemical bonding and atomic arrangement (crystallography) are fundamental to studying the properties and behavior of any material.

=====Bonding=====
{{Main|Chemical bonding}}
To obtain a full understanding of the material structure and how it relates to its properties, the materials scientist must study how the different atoms, ions and molecules are arranged and bonded to each other. This involves the study and use of [[quantum chemistry]] or [[quantum physics]]. [[Solid-state physics]], [[solid-state chemistry]] and [[physical chemistry]] are also involved in the study of bonding and structure.

=====Crystallography=====
{{Main|Crystallography}}
[[File:Perovskite.jpg|thumb|Crystal structure of a perovskite with a chemical formula ABX<sub>3</sub><ref>{{cite journal |title= Energetics and Crystal Chemical Systematics among Ilmenite, Lithium Niobate, and Perovskite Structures |author= A. Navrotsky |journal= Chem. Mater. |date= 1998 |volume= 10 |issue= 10 |pages= 2787–2793 |doi= 10.1021/cm9801901}}</ref>]]
Crystallography is the science that examines the arrangement of atoms in crystalline solids. Crystallography is a useful tool for materials scientists. One of the fundamental concepts regarding the crystal structure of a material includes the [[unit cell]], which is the smallest unit of a crystal lattice (space lattice) that repeats to make up the macroscopic crystal structure. Most common structural materials include [[Parallelepiped|parallelpiped]] and hexagonal lattice types.<ref>Callister, Jr.,  Rethwisch. "Materials Science and Engineering – An Introduction" (8th ed.) John Wiley and Sons, 2009</ref> In [[single crystal]]s, the effects of the crystalline arrangement of atoms is often easy to see macroscopically, because the natural shapes of crystals reflect the atomic structure. Further, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important prerequisite for understanding [[crystallographic defect]]s. Examples of crystal defects consist of dislocations including edges, screws, vacancies, self inter-stitials, and more that are linear, planar, and three dimensional types of defects.<ref>Callister, Jr.,  Rethwisch. "Materials Science and Engineering – An Introduction" (8th ed.). John Wiley and Sons, 2009</ref> New and advanced materials that are being developed include [[nanomaterials]], [[biomaterial]]s.<ref>Callister, Jr.,  Rethwisch. Materials Science and Engineering – An Introduction (8th ed.)</ref> Mostly, materials do not occur as a single crystal, but in polycrystalline form, as an aggregate of small crystals or grains with different orientations. Because of this, the [[Powder diffraction|powder diffraction method]], which uses diffraction patterns of polycrystalline samples with a large number of crystals, plays an important role in structural determination. Most materials have a crystalline structure, but some important materials do not exhibit regular crystal structure.<ref>{{Cite journal |last=Gavezzotti |first=Angelo |date=1994-10-01 |title=Are Crystal Structures Predictable? |url=http://dx.doi.org/10.1021/ar00046a004 |journal=Accounts of Chemical Research |volume=27 |issue=10 |pages=309–314 |doi=10.1021/ar00046a004 |issn=0001-4842}}</ref> [[Polymer]]s display varying degrees of crystallinity, and many are completely non-crystalline. [[Glass]], some ceramics, and many natural materials are [[Amorphous solid|amorphous]], not possessing any long-range order in their atomic arrangements. The study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical descriptions of physical properties.

====Nanostructure====
{{Main|Nanostructure}}
[[File:Buckminsterfullerene-perspective-3D-balls.png|thumb|left|upright=0.7|[[Buckminsterfullerene]] nanostructure]]
Materials, which atoms and molecules form constituents in the nanoscale (i.e., they form nanostructures) are called nanomaterials. Nanomaterials are the subject of intense research in the materials science community due to the unique properties that they exhibit.

Nanostructure deals with objects and structures that are in the 1 – 100&nbsp;nm range.<ref>{{cite journal |url= http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=BJIOBN00000200000400MR17000001&idtype=cvips&gifs=Yes |author= Cristina Buzea |author2= Ivan Pacheco |author3= Kevin Robbie |name-list-style= amp |title= Nanomaterials and Nanoparticles: Sources and Toxicity |journal= Biointerphases |volume= 2 |date= 2007 |pages= MR17–MR71 |doi= 10.1116/1.2815690 |pmid= 20419892 |issue= 4 |url-status= live |archive-url= https://archive.today/20120703014917/http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=BJIOBN00000200000400MR17000001&idtype=cvips&gifs=Yes |archive-date= 2012-07-03 |arxiv= 0801.3280 |s2cid= 35457219 }}</ref>  In many materials, atoms or molecules agglomerate to form objects at the nanoscale. This causes many interesting electrical, magnetic, optical, and mechanical properties.

In describing nanostructures, it is necessary to differentiate between the number of dimensions on the [[Nanoscopic scale|nanoscale]].

[[Nanotextured surface]]s have ''one dimension'' on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100&nbsp;nm.

Nanotubes have ''two dimensions'' on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100&nbsp;nm; its length could be much greater.

Finally, spherical [[nanoparticle]]s have ''three dimensions'' on the nanoscale, i.e., the particle is between 0.1 and 100&nbsp;nm in each spatial dimension. The terms nanoparticles and [[ultrafine particle]]s (UFP) often are used synonymously although UFP can reach into the micrometre range. The term 'nanostructure' is often used, when referring to magnetic technology. Nanoscale structure in biology is often called [[ultrastructure]].

====Microstructure====
{{Main|Microstructure}}
[[File:Pearlite.jpg|thumb|right|Microstructure of pearlite]]
Microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification. It deals with objects from 100&nbsp;nm to a few cm. The microstructure of a material (which can be broadly classified into metallic, polymeric, ceramic and composite) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behavior, wear resistance, and so on.<ref>{{Cite journal |last1=Filip |first1=R |last2=Kubiak |first2=K |last3=Ziaja |first3=W |last4=Sieniawski |first4=J |date=2003 |title=The effect of microstructure on the mechanical properties of two-phase titanium alloys |url=http://dx.doi.org/10.1016/s0924-0136(02)00248-0 |journal=Journal of Materials Processing Technology |volume=133 |issue=1–2 |pages=84–89 |doi=10.1016/s0924-0136(02)00248-0 |issn=0924-0136}}</ref> Most of the traditional materials (such as metals and ceramics) are microstructured.

The manufacture of a perfect [[crystal]] of a material is physically impossible. For example, any crystalline material will contain [[crystallographic defect|defects]] such as [[Precipitation (chemistry)|precipitates]], grain boundaries ([[Hall–Petch|Hall–Petch relationship]]), vacancies, interstitial atoms or substitutional atoms.<ref>{{Citation |title=Crystal Structure Defects and Imperfections |date=2021-10-01 |url=http://dx.doi.org/10.31399/asm.tb.ciktmse.t56020001 |work=Crystalline Imperfections: Key Topics in Materials Science and Engineering |pages=1–12 |access-date=2023-10-29 |publisher=ASM International|doi=10.31399/asm.tb.ciktmse.t56020001 |isbn=978-1-62708-389-8 |s2cid=244023491 }}</ref> The microstructure of materials reveals these larger defects and advances in simulation have allowed an increased understanding of how defects can be used to enhance material properties.

====Macrostructure====
Macrostructure is the appearance of a material in the scale millimeters to meters, it is the structure of the material as seen with the naked eye.