# Chemicals/Materials

Materials are the matter from which a thing is or can be made.

## Radiation astronomy

Efforts to magnify objects in the sky probably began with the use of crystal lenses. "Lens-shaped crystals have long been known from Bronze Age contexts". These are "usually recognized as short-focus magnifying lenses."
The slightly oval lens [40 x 35 mm] has been roughly ground and has a focal point about 110 millimetres (4.5 in) from the flat side.
Lenses are typically made of glass or transparent plastic. This glass is usually "about 75% silica (SiO$_2$) plus Na$_2$O, CaO, and several minor additives. Glass does not contain the internal subdivisions associated with grain boundaries in polycrystals and hence does not scatter light in the same manner as a polycrystalline material. The surface of a glass is often smooth since during glass formation the molecules of the supercooled liquid are not forced to dispose in rigid crystal geometries and can follow surface tension, which imposes a microscopically smooth surface.

## Minerals

Def. "an advanced form of new ice that forms as a stable sheet with a smooth bottom surface" is called congelation ice.
At the right is a "photograph in natural light of the vertically oriented pores in congelation ice."

## Theoretical materials

Def. matter "which may be shaped or manipulated, particularly in making something" is called a material.

## Alloys

"The dominant group of Al–Si foundry alloys contain between 5 and 25 wt.% Si, with Mg, Ni and Cu additions."
"There is in reality a distribution of magnetic cluster sizes although the smallest magnetic clusters will constitute the dominant group."
"The dominant group is (SiGe)SiH, at T, = 190 "C and is replaced by (Ge,)SiH, at T, = 250 "C."
"Then, metallurgical reactions occur between the fuel slug and the cladding. ... Lanthanide elements, a dominant group of ﬁssion products, will be less signiﬁcant because the solubility of lanthanide elements in the U—Pu—Zr alloys is limited (~O.6 wt% or less)(9) and the eutectic point in the binary system of any lanthanide element and Fe is higher than that in the Pu—Fe system".

## Ceramics

Def. any nonmetallic solid that remains hard when heated is called a ceramic.
"The typology of the lustre ceramics shows that there is a small group (G1 = MZ2 + MZ6 + MZ12) with red lustre decoration on the interior and green-yellow lustre decoration on the exterior and a dominant group (G2) with yellowish lustre on both sides (Table 1)."
"The different settlement ceramic assemblages present dominant technical sub-groups, which are different in aspect from one site to another (tab. 3). ... The ceramic entity A is characterised, from a technical and techno-petrographic point of view, by a discontinuity between one or two dominant sub-groups (quantitatively major) and a few satellite sub-groups (quantitatively minor). Ceramic entity B, on the contrary, shows a petrographic continuity with the dominant sub-groups A."
"Among a variety of tool making materials, sintered carbides are still a dominant group in view of machining technologies. ... Having considered all types of coating materials, the most numerous group is made up by materials with the predominant number of metallic bonds."

## Composites

"Both of the emission spectra present the characteristic emission bands originating from the transition 5 D 4 → 7 F J (J = 6,5,4,3), with the transition 5 D 4 → 7 F 5 green emission as the dominant group."
"Both of the emission spectra present the characteristic emission bands originating from the transition 5 D 4 → 7 F J (J=6,5,4,3), with the transition 5 D 4 → 7 F 5 green emission as the dominant group."
"Both of the emission spectra exhibit the characteristic emission of Tb$^{3+}$ arising from the transition 5 D 4 → 7 F J (J = 6, 5, 4, 3), with the transition 5 D 4 → 7 F 5 green emission as the dominant group."
"Also, the characteristic emission bands originating from the transition 5 D 4 → 7 F J (J = 6, 5, 4, 3), with the transition 5 D 4 → 7 F 5 green emission as the dominant group are observed in the emission spectra of the pure Tb(III) complex (Tb-L) and the hybrid materials as shown".
"The ω-hydroxymonocarboxylates represented the dominant group with a contribution higher than one quarter of the total."

## Crystals

Def. "[a] solid composed of an array of atoms or molecules possessing long-range order and arranged in a pattern which is periodic in three dimensions", from Wiktionary crystal, is called a crystal.
“The dominant group V source is arsenic, although antimony and phosphorous sources are not atypical.”
“We may assume, however, as has been suggested by Dunning (see the discussion in ref. 32) that these macrospirals are the result of a periodic perturbation due to an interaction of the spirals forming the dominant group of cooperating spirals.”

## Diamonds

"For as-deposited diamond, C---H is the dominant group on the hydrogen-terminated surfaces, and it has been found that ---OH [23] and C=O groups [24] are in fact generated on oxidized diamond surfaces."

## Dielectrics

"Our theory applies to parameters (to be identified below) for which the second group is dominant, allowing for the third group, labeled ψ$_{rem}$ (mnemonic remainder) to be neglected in the calculation of the saddle-points." "The dominance requirement constrains the remaining (first and third) terms of ψ$_{rem}$ to be significantly smaller than the terms of the second group along the contour of integration. Since the two terms of the dominant group have comparable magnitudes, it suffices to make the comparison with only the second term in the dominant group."
"Such work indicated that group III interdiffusion in InGaAs/InP is associated with a redshift, while a blueshift is associated with a dominant group V interdiffusion."
"Hence we refer to this dominantly amplified magnon group as the dominant group."

## Fibers

"For example, As$_2$ and P$_2$ can sometimes be the dominant group V species in contrast to the equilibrium calculation, and, in addition, several kinds of internal compound between As and P are found."
"Nearly 90% of L, in the "as-grown" ribbons belongs to class B and class C, with class B being the predominant group (Fig. 3a)."
"Free fatty acids were the most dominant group of lipids in rice straw extract and the second most abundant class of lipophilic substances in rye straw extractives."

## Glasses

Notation: let the symbol KREEP be an acronym for potassium (the chemical symbol is K), rare earth element (REE), and phosphorus (chemical symbol is P).
"Because KREEP glasses are the dominant group at the Fra Mauro sampling site and because the Fra Mauro formation is considered part of the Imbrian ejecta blanket, KREEP basalts appear to have been part of the lunar crust prior to formation of the Imbrium Basin." Bold added.
"This likely is the result of the fact that the six-membered ring group becomes the dominant structural group in the vicinity of x = 0.5, whereas the tetrahedral boron group is becoming the least prominent structural group in the glass."
"In the other series of glasses, Li, Na, and K, in particular, that can be formed out to x = 0.75, the IR spectra clearly show that this structural group becomes the dominant group in the glass at this composition [4,5,43]."
"Thus, it does not appear to be the dominant group in the glass network."

## Martensites

“In Section 3, we use group theory to present the system description of the microstructure of 2H martensite, including the correspondence variant dominant group.”
“The dominant group always consisted of four habit-plane variants grouped round a particular {llO} pole of the austenite, except in the case of the crystal with compression axis close to [001] which developed only two habit planes.”
On the right is a katana of the kobuse type is made in the traditional Japanese style.
"The hardened edge is separated from the softer back by a bright, wavy line, called the nioi. The edge of this bright line, called the hamon, marks the boundary between the martensitic portion (the yakiba) from pearlitic center area (the hira). The wavy shape of the hamon is from the manner in which the insulating clay was appllied before quenching. The inset shows a close-up of the nioi, which is made up of niye. The niye are single, bright grains of martensite surrounded by pearlite, which are seen as the speckled zone between the bright yakiba and the darker hira. The wood-grain appearance comes from alternating layers of steel that have different hardenability."

## Metals

On the right is a series of viewgraphs showing and describing microstructures in a variety of metals.

## Metallurgy

In the image on the right are examples of products made with gunmetal.
"It withstands atmospheric, steam, and seawater corrosion and is suitable for valves, pump parts, and steam fittings."

## Nanomaterials

“Mesopores were still the dominant group of pores for all derivatives, as confirmed by the good agreement between the values of V tot and V mp D.”

## Piezoelectrics

Notation: let the symbol PZT stand for lead zirconate titanate (Pb[Zr$_x$Ti$_{1-x}$]O$_3$, 0 ≤ x ≤ 1).
“Among [the] variety of piezoelectric materials, PZTs have been the dominant group for more than 40 years for their excellent properties.”

## Plastics

Plastics also refers to polymers.
Notation: let the symbol PE stand for polyethylene.
"Finally, there is a dominant group (PE) that is still growing on the market."
"The first class consists of polymers such as cellulose (cotton, wood, etc.) and protein (gelatine, wool, etc.), while the dominant group in the second class is rubber, both synthetic and natural."

## Precious metals

"The alluvial sample shows multiple populations that reflect all the samples collected at the mine, a dominant group which corresponds to the mine shaking table gold, and a minor population with higher silver which is similar to that shown by the soil sample."

## Sands

"The behavior of some sandy soils is conditioned by a dominant group of pores larger than 1.5 µ."
"The dominant group in which the median grain-size falls is indicated (M: mud; FS: fine sand; MS: medium sand) as well as the number of observations in that group (based on sedisurf@database, Gent University, Renard Centre of Marine Geology)."
"In the hypersthene dominant group the hornblende content does not exceed 20 vol.%."

## Semiconductors

Notation: let the symbol CP indicate band structure critical points.
"The dominant group speed of a carrier can be estimated to occur at the energy, above or below the CP where is the reduced effective mass and is Planck's constant." "The largest of the resulting fragments from the break-up of the prior dominant group is a cluster of eight papers dealing almost exclusively with n-type semiconductors, with papers originating primarily from two research labs."
Degradation of "Id-Vd characteristics before and after stressing for (a) the charge-trapping-dominant (group Í) and (b) the interface-trap- generation dominant (group 2) devices. Note the similar degradation characteristics for electron and hoie trappings."
"The blue shift effect which is often observed in multiple quantum well (MQW) structures subjected to heat treatment, is attributed to a dominant group V interdiffusion which can be suppressed by high defect densities in the substrate."

## Stones

"Although calcitic marbles represent the dominant group in the studied rocks, dolomitic marbles are also present (Raspenava marble, Strážné marble, Bílá Voda marble, Bohdaneč marble, Český Šternberk marble)."

## Superconductors

Notation: let the symbol dmit indicate the 2-thioxo-1,3-dithiole-4,5-dithiolate dianion, C$_3$S$_5$$^{2-}$.
"Various crystals, and consequently various conductivities, can be obtained by using different monocations in the 1:2 salts of Z[Ni(dmit)$_2$]$_2$, which form the most dominant group in the Z[M(dmit)$_2$]$_n$ family." Bold added.
Notation: let the symbol ERDA stand for elastic recoil detection analysis.
"The dominant group in the lower half results from the first oxygen-bearing layer in the Si0$_2$(0.5 pm)/Al(0.5 pm)/Si0$_2$(0.5 pm)/Al(2.0 pm) target stack."
Notation: let the symbol TN (or T$_N$) stand for the Néel transition temperature.
"Below TN, the description of the experimental data requires at least a twoband picture with a dominant group of electrons showing standard BCS-Eliashberg-type behavior with a clear single gap whereas a second group of electrons dominates κ(T,H)." Bold added.

## Woods

"The mean ratio of crown width to sapling height (DrIh) was significantly greater for the suppressed saplings than for the apically dominant group (t = 2.78, df= 18, P < .02) (Table 5), and DrIh was negatively correlated with h for the combined data set (r = -0.76, N = 20, P < .001)."
Notation: let the symbol CWH stand for capillary water height.
"There was a significant difference in CWH for sapwood, between specimens from "wet dominant" group and specimens from both "dry suppressed" and "dry dominant" group during absorption for 7 days and 14-15 days."
"The analysis of the the obtained results concerning the selected wood physical and mechanical properties of both pine species (Tables from 2 to 5) showed that the examined wood properties were higher, generally speaking, in the black pine trees in comparison with the Scots pine, with the exception of the co-dominant group of trees in the first of the two pine tree species."

## Kuiper belts

"The depth of the absorption bands and the continuum reflectance of [Kuiper Belt Object] 1996 TO$_{66}$ suggest the presence of a black- to slightly blue-colored, spectrally featureless particulate material as a minority component mixed with the water ice."

## R Sculptoris

"Observations using the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed an unexpected spiral structure in the material around the old star R Sculptoris. This feature has never been seen before and is probably caused by a hidden companion star orbiting the star. This slice through the new ALMA data reveals the shell around the star, which shows up as the outer circular ring, as well as a very clear spiral structure in the inner material." The image band is centered at 870 µm.

## Materials sciences

"Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering."

## Subatlantic history

The "calibration of radiocarbon dates at approximately 2500-2450 BP [2500-2450 b2k] is problematic due to a "plateau" (known as the "Hallstatt-plateau") in the calibration curve [...] A decrease in solar activity caused an increase in production of $^{14}$C, and thus a sharp rise in Δ $^{14}$C, beginning at approximately 850 cal (calendar years) BC [...] Between approximately 760 and 420 cal BC (corresponding to 2500-2425 BP [2500-2425 b2k]), the concentration of $^{14}$C returned to "normal" values."

## Hypotheses

* Materials exist that can store up to 3300 Coulombs of electrons.