#materialsposts

[materialsscienceandengineering]

Alloys: Fernico

The name fernico is given to a family of metallic alloys, including Kovar and Dumet. The name comes from the fact that these alloys primarily consist of iron (Fe), nickel (Ni), and cobalt (Co).

Few commercial applications exist for these alloys. The thermal properties are the primary draw, and allow for these alloys to be used in metal-to-glass seals (because the thermal expansion coefficients of these alloys are close to those of typical glasses).

Sources/Further Reading: (Image 2 - Wikipedia) (Soft Magnetic Alloys) (Make it From) (1941 article)

Image 1 source.

[materialsscienceandengineering]

Ceramics: Yttrium Barium Copper Oxide (YBCO)

The family of ceramic compounds containing yttrium, barium, copper, and oxygen is collectively referred to as yttrium barium copper oxide (or YBCO), though there are several different chemical compositions within the family. One of the most well known is YBa2Cu3O7 (or Y123), but the family also includes other ratios of the four elements. These compounds display high temperature superconductivity; Y123 was the first compound known to display superconductivity at approximately 93K—above the temperature of liquid nitrogen.

These compounds were first studied in the late 1980s and crystallizes in a defect perovskite crystal structures. With Y123 specifically, its tetragonal form is insulating but a slight increase in the oxygen content can lead to an orthorhombic structure, which does display superconductivity. Because the best superconducting properties of these compounds are exhibited in single crystals, YBCOs have not found use in many practical applications. In addition, as a ceramic and an oxide, YBCO tends to be relatively brittle, hindering processing. However, development of a process to produce YBCO wires has been successful in the 2020s.

Sources/Further Reading: (Image 1—Wikipedia) (Image 2—Imperial College London) (Modern Physics)

[materialsscienceandengineering]

Semiconductors: Bismuth telluride

A compound of bismuth and tellurium in the form of Bi2Te3, bismuth telluride (or bismuth (III) telluride) is a semiconductor and a topological insulator. Though the material does exist in nature in the form of the mineral tellurobismuthite, or tellurbismuth, it is considered rare. It has a layered crystal structure crystalizing in the trigonal crystal system, and a narrow band gap.

When alloyed with antimony or selenium, bismuth telluride becomes thermoelectric. These alloys have been been reported to have the highest known efficiency near room temperature. As such, it is the leading thermoelectric material for many applications.

Sources/Further Reading: (Wikipedia—Images 1 and 2) (2019 article) (AZO Materials) (Goodfellow)

[materialsscienceandengineering]

Glasses: Flint Glass

As with many other "types" of glasses, flint glass does not have a set composition, and the name has shifted in meaning over the years. The original flint glasses contained flint, hence the name, however it wasn't long before the term flint glass was used to refer to glass that had relatively high amounts of lead present. Lead is known to have a high refractive index, allowing for brilliant glass pieces when cut. As such, flint glass was often decorative, though also practical in the form of dishware, or used for its optical properties. Flint glass was typically clear, but colors could also be introduced on rare occasions.

Historic flint glass was primarily popular in the United States and United Kingdom in the 1800s. In more modern times, flint glass as a term is used to describe optical glasses regardless of their composition. Some still contain lead, while in others the lead has been replaced by materials such as titanium or zirconium dioxide. Modern day lead glass is more often known as simply that, or as crystal.

Sources/Further Reading: (Images source - Incollect) (Wikipedia) (Pattern Glass) (RP Photonics)

[materialsscienceandengineering]

Minerals: Edingtonite

A zeolite mineral, edingtonite has the chemical formula BaAl2Si3O10·4H2O. It was named in 1825 for Scottish mineralogist James Edington. 

Edingtonite is typically found in white, clear, yellow, or pink colors and is moderately soft, measuring 4-4.5 on the Mohs hardness scale. It crystalizes in the orthorhombic crystal system. The mineral is rare enough that it has no commercial applications, but is often prized by collectors. 

For more in depth information about edingtonite, check out what mindat.org, webmineral.com, handbookofmineralogy.org, and mineralatlas.eu have to say about it.

Sources/Further Reading: ( 1 ) ( 2 - image 2 ) 

Image sources: ( 1 ) ( 3 ) ( 4 )

[materialsscienceandengineering]

Polymers: Polyamide

When monomers are linked with amide bonds—general formula R−C(=O)−NR′R″, where R, R', and R″ represent any group—the resulting polymer is known as a polyamide. This category of polymers includes both natural materials, such as wool and silk, and artificial materials, such as nylons and kevlar. Generally speaking, these polymers are highly durable and strong, with (relatively) high temperature performance and electrical resistance. The properties of specific polyamides depend on which of three general categories they fall into: aliphatic (tough, durable, and lower in cost), aromatic (strong, stiff, and higher in cost), and semi-aromatic, which fall in between the other two categories.

Commercially, polyamides are often used in textiles and other fiber-based applications (like carpeting) as well as in the automobile industry and kitchenware.

Sources/Further Reading: (Images 1 and 4 - Omnexus) (Images 2 and 3 - Contrado) (Wikipedia)

[materialsscienceandengineering]

Minerals: Veatchite

With the chemical formula of Sr2B11O16(OH)5·H2O, veatchite is classified as a borate mineral. The first known discovery of this mineral was in 1938, in a borax mine, and it was named for John Veatch, “the first person to detect boron in the mineral waters of California”.

Veatchite crystalizes in the monoclinic crystal system and has a Mohs hardness of ~2, thereby making it a relatively soft mineral. It is often transparent or translucent, and typically is only found in white and colorless varieties. A relatively rare mineral, veatchite has no known commercial uses.

For more in depth information about veatchite, check out what mindat.org, webmineral.com, handbookofmineralogy.org, and mineralatlas.eu have to say about it.

Sources/Further Reading: ( 1 - image 1 ) ( 2 - image 2 and 3 )

Image 4.

[materialsscienceandengineering]

Minerals: Xenotime

A rare earth phosphate mineral, the primary composition of xenotime is YPO4, though it does form a solid solution with the mineral chernovite-(Y) and may therefore include arsenic impurities. As with many other rare earth minerals, the yttrium is also often substituted with other rare earth elements, including dysprosium, erbium, terbium and ytterbium. Uranium can be found in xenotime as well, so caution should be taken with the mineral as radioactive crystals can be found, though it is typically mild.

Xenotime crystalizes with a tetragonal crystal structure and is typically brownish, yellow, or red in color. On the Mohs hardness scale it has a value of 4.5. Considered a minor accessory mineral, xenotime does not have any large scale applications, but has been processed for its yttrium content when mined in conjunction with other minerals. Ornamental applications also exist.

For more in depth information about xenotime, check out what mindat.org, webmineral.com, minerals.net, handbookofmineralogy.org, and mineralatlas.eu have to say about it.

Sources/Further Reading: (1 - image 1) (2 - image 2) (3 - image 3) (4 - image 4)