======================================================================
= Tin =
======================================================================
Introduction
======================================================================
Tin is a chemical element; it has symbol Sn () and atomic number 50. A
silvery-colored metal, tin is soft enough to be cut with little force,
and a bar of tin can be bent by hand with little effort. When bent, a
bar of tin makes a sound, the so-called "tin cry", as a result of
twinning in tin crystals.
Tin is a post-transition metal in group 14 of the periodic table of
elements. It is obtained chiefly from the mineral cassiterite, which
contains stannic oxide, . Tin shows a chemical similarity to both of
its neighbors in group 14, germanium and lead, and has two main
oxidation states, +2 and the slightly more stable +4. Tin is the 49th
most abundant element on Earth, making up 0.00022% of its crust, and
with 10 stable isotopes, it has the largest number of stable isotopes
in the periodic table, due to its magic number of protons.
It has two main allotropes: at room temperature, the stable allotrope
is β-tin, a silvery-white, malleable metal; at low temperatures it is
less dense grey α-tin, which has the diamond cubic structure. Metallic
tin does not easily oxidize in air and water.
The first tin alloy used on a large scale was bronze, made of tin and
copper (12.5% and 87.5% respectively), from as early as 3000 BC. After
600 BC, pure metallic tin was produced. Pewter, which is an alloy of
85-90% tin with the remainder commonly consisting of copper, antimony,
bismuth, and sometimes lead and silver, has been used for flatware
since the Bronze Age. In modern times, tin is used in many alloys,
most notably tin-lead soft solders, which are typically 60% or more
tin, and in the manufacture of transparent, electrically conducting
films of indium tin oxide in optoelectronic applications. Another
large application is corrosion-resistant tin plating of steel. Because
of the low toxicity of inorganic tin, tin-plated steel is widely used
for food packaging as "tin cans". Some organotin compounds can be
extremely toxic.
Physical
==========
Tin is a soft, malleable, ductile and highly crystalline silvery-white
metal. When a bar of tin is bent a crackling sound known as the "tin
cry" can be heard from the twinning of the crystals. This trait is
shared by indium, cadmium, zinc, and mercury in its solid state. Tin
melts at about 232 C, the lowest in group 14, and boils at 2602 C, the
second lowest (ahead of lead) in its group. The melting point is
further lowered to 177.3 C for 11 nm particles.
β-tin, also called 'white tin', is the allotrope (structural form) of
elemental tin that is stable at and above room temperature. It is
metallic and malleable, and has body-centered tetragonal crystal
structure. α-tin, or 'gray tin', is the nonmetallic form. It is stable
below 13.2 C and is brittle. α-tin has a diamond cubic crystal
structure, as do diamond and silicon. α-tin does not have metallic
properties because its atoms form a covalent structure in which
electrons cannot move freely. α-tin is a dull-gray powdery material
with no common uses other than specialized semiconductor applications.
γ-tin and σ-tin exist at temperatures above 161 C and pressures above
several GPa.
In cold conditions β-tin tends to transform spontaneously into α-tin,
a phenomenon known as "tin pest" or "tin disease". Some unverifiable
sources also say that, during Napoleon's Russian campaign of 1812, the
temperatures became so cold that the tin buttons on the soldiers'
uniforms disintegrated over time, contributing to the defeat of the
Grande Armée, a persistent legend.
The α-β transformation temperature is 13.2 C, but impurities (e.g. Al,
Zn, etc.) lower it well below 0 C. With the addition of antimony or
bismuth the transformation might not occur at all, increasing
durability.
Commercial grades of tin (99.8% tin content) resist transformation
because of the inhibiting effect of small amounts of bismuth,
antimony, lead, and silver present as impurities. Alloying elements
such as copper, antimony, bismuth, cadmium, and silver increase the
hardness of tin. Tin easily forms hard, brittle intermetallic phases
that are typically undesirable. It does not mix into a solution with
most metals and elements so tin does not have much solid solubility.
Tin mixes well with bismuth, gallium, lead, thallium and zinc, forming
simple eutectic systems.
Tin becomes a superconductor below 3.72 K and was one of the first
superconductors to be studied. The Meissner effect, one of the
characteristic features of superconductors, was first discovered in
superconducting tin crystals.
Chemical
==========
Tin resists corrosion from water, but can be corroded by acids and
alkalis. Tin can be highly polished and is used as a protective coat
for other metals. When heated in air it oxidizes slowly to form a thin
passivation layer of stannic oxide () that inhibits further oxidation.
Isotopes
==========
Tin has ten stable isotopes, the greatest number of any element. Their
mass numbers are 112, 114, 115, 116, 117, 118, 119, 120, 122, and 124.
Tin-120 makes up almost a third of all tin. Tin-118 and tin-116 are
also common. Tin-115 is the least common stable isotope. The isotopes
with even mass numbers have no nuclear spin, while those with odd mass
numbers have a nuclear spin of 1/2. It is thought that tin has such a
great multitude of stable isotopes because of tin's atomic number
being 50, which is a "magic number" in nuclear physics.
Tin is one of the easiest elements to detect and analyze by NMR
spectroscopy, which relies on molecular weight and its chemical shifts
are referenced against tetramethyltin ().
Of the stable isotopes, tin-115 has a high neutron capture cross
section for fast neutrons, at 30 barns. Tin-117 has a cross section of
2.3 barns, one order of magnitude smaller, while tin-119 has a
slightly smaller cross section of 2.2 barns. Before these cross
sections were well known, it was proposed to use tin-lead solder as a
coolant for fast reactors because of its low melting point. Current
studies are for lead or lead-bismuth reactor coolants because both
heavy metals are nearly transparent to fast neutrons, with very low
capture cross sections. In order to use a tin or tin-lead coolant, the
tin would first have to go through isotopic separation to remove the
isotopes with odd mass number. Combined, these three isotopes make up
about 17% of natural tin but represent nearly all of the capture cross
section. Of the remaining seven isotopes tin-112 has a capture cross
section of 1 barn. The other six isotopes forming 82.7% of natural tin
have capture cross sections of 0.3 barns or less, making them
effectively transparent to neutrons.
Tin has 33 unstable isotopes, ranging in mass number from 98 to 140.
The unstable tin isotopes have half-lives of less than a year except
for tin-126, which has a half-life of about 230,000 years.
Tin-100 and tin-132 are two of the very few nuclides with a "doubly
magic" nucleus which despite being unstable, as they have very uneven
neutron-proton ratios, are the endpoints beyond which tin isotopes
lighter than tin-100 and heavier than tin-132 are much less stable.
Another 30 metastable isomers have been identified for tin isotopes
between 111 and 131, the most stable being tin-121m, with a half-life
of 43.9 years.
The relative differences in the abundances of tin's stable isotopes
can be explained by how they are formed during stellar
nucleosynthesis. Tin-116 through tin-120, along with tin-122, are
formed in the 's'-process (slow neutron capture) in most stars which
leads to them being the most common tin isotopes, while tin-124 is
only formed in the 'r'-process (rapid neutron capture) in supernovae
and neutron star mergers. Tin isotopes 115, 117 through 120, and 122
are produced via both the 's'-process and the 'r'-process, The two
lightest stable isotopes, tin-112 and tin-114, cannot be made in
significant amounts in the 's'- or 'r'-processes and are among the
p-nuclei whose origins are not well understood. Some theories about
their formation include proton capture and photodisintegration.
Tin-115 might be partially produced in the 's'-process, both directly
and as the daughter of long-lived indium-115, and also from the decay
of indium-115 produced via the 'r'-process.
Etymology
======================================================================
The word 'tin' is shared among Germanic languages and can be traced
back to reconstructed Proto-Germanic ; cognates include German ,
Swedish and Dutch . It is not found in other branches of
Indo-European, except by borrowing from Germanic (e.g., Irish from
English).
The Latin name for tin, , originally meant an alloy of silver and
lead, and came to mean 'tin' in the fourth century--the earlier Latin
word for it was , or "white lead". apparently came from an earlier
(meaning the same substance), the origin of the Romance and Celtic
terms for 'tin', such as French , Spanish , Italian , and Irish . The
origin of / is unknown; it may be pre-Indo-European.
The suggests instead that came from Cornish , and is evidence that
Cornwall in the first centuries AD was the main source of tin.
History
======================================================================
Tin extraction and use can be dated to the beginnings of the Bronze
Age around 3000 BC, when it was observed that copper objects formed of
polymetallic ores with different metal contents had different physical
properties. The earliest bronze objects had a tin or arsenic content
of less than 2% and are believed to be the result of unintentional
alloying due to trace metal content in the copper ore. The addition of
a second metal to copper increases its hardness, lowers the melting
temperature, and improves the casting process by producing a more
fluid melt that cools to a denser, less spongy metal. This was an
important innovation that allowed for the much more complex shapes
cast in closed molds of the Bronze Age. Arsenical bronze objects
appear first in the Near East where arsenic is commonly found with
copper ore, but the health risks were quickly realized and the quest
for sources of the much less hazardous tin ores began early in the
Bronze Age. This created the demand for rare tin metal and formed a
trade network that linked the distant sources of tin to the markets of
Bronze Age cultures.
Cassiterite (), the oxide form of tin, was most likely the original
source of tin. Other tin ores are less common sulfides such as
stannite that require a more involved smelting process. Cassiterite
often accumulates in alluvial channels as placer deposits because it
is harder, heavier, and more chemically resistant than the
accompanying granite. Cassiterite is usually black or dark in color,
and these deposits can be easily seen in river banks. Alluvial
(placer) deposits may incidentally have been collected and separated
by methods similar to gold panning.
Compounds and chemistry
======================================================================
In the great majority of its compounds, tin has the oxidation state II
or IV. Compounds containing bivalent tin are called while those
containing tetravalent tin are termed .
Inorganic compounds
=====================
Halide compounds are known for both oxidation states. For Sn(IV), all
four halides are well known: SnF4, SnCl4, SnBr4, and SnI4. The three
heavier members are volatile molecular compounds, whereas the
tetrafluoride is polymeric. All four halides are known for Sn(II)
also: SnF2, Tin(II) chloride, SnBr2, and SnI2. All are polymeric
solids. Of these eight compounds, only the iodides are colored.
Tin(II) chloride (also known as stannous chloride) is the most
important commercial tin halide. Illustrating the routes to such
compounds, chlorine reacts with tin metal to give SnCl4 whereas the
reaction of hydrochloric acid and tin produces and hydrogen gas.
Alternatively SnCl4 and Sn combine to stannous chloride by a process
called comproportionation:
:SnCl4 + Sn → 2
Tin can form many oxides, sulfides, and other chalcogenide
derivatives. The dioxide (cassiterite) forms when tin is heated in
the presence of air. is amphoteric, which means that it dissolves in
both acidic and basic solutions. Stannates with the structure []2−,
like [], are also known, though the free stannic acid [] is unknown.
Sulfides of tin exist in both the +2 and +4 oxidation states: tin(II)
sulfide and tin(IV) sulfide (mosaic gold).
Hydrides
==========
Stannane (), with tin in the +4 oxidation state, is unstable.
Organotin hydrides are however well known, e.g. tributyltin hydride
(Sn(C4H9)3H). These compounds release transient tributyl tin radicals,
which are rare examples of compounds of tin(III).
Organotin compounds
=====================
Organotin compounds, sometimes called stannanes, are chemical
compounds with tin-carbon bonds. Of the tin compounds, the organic
derivatives are commercially the most useful. Some organotin compounds
are highly toxic and have been used as biocides. The first organotin
compound to be reported was diethyltin diiodide ((C2H5)2SnI2),
reported by Edward Frankland in 1849.
Most organotin compounds are colorless liquids or solids that are
stable to air and water. They adopt tetrahedral geometry. Tetraalkyl-
and tetraaryltin compounds can be prepared using Grignard reagents:
: + 4 RMgBr → + 4 MgBrCl
The mixed halide-alkyls, which are more common and more important
commercially than the tetraorgano derivatives, are prepared by
redistribution reactions:
: + → 2 R2
Divalent organotin compounds are uncommon, although more common than
related divalent organogermanium and organosilicon compounds. The
greater stabilization enjoyed by Sn(II) is attributed to the "inert
pair effect". Organotin(II) compounds include both stannylenes
(formula: R2Sn, as seen for singlet carbenes) and distannylenes
(R4Sn2), which are roughly equivalent to alkenes. Both classes exhibit
unusual reactions.
Organotin compounds are organometallic compounds containing tin-carbon
bonds. Worldwide industrial production of organotin compounds likely
exceeds 50,000 tonnes.
Occurrence
======================================================================
Tin is generated via the long 's'-process in low-to-medium mass stars
(with masses of 0.6 to 10 times that of the Sun), and finally by beta
decay of the heavy isotopes of indium.
Tin is the 49th most abundant element in Earth's crust, representing 2
ppm compared with 75 ppm for zinc, 50 ppm for copper, and 14 ppm for
lead.
Tin does not occur as the native element but must be extracted from
various ores. Cassiterite () is the only commercially important source
of tin, although small quantities of tin are recovered from complex
sulfides such as stannite, cylindrite, franckeite, canfieldite, and
teallite. Minerals with tin are almost always associated with granite
rock, usually at a level of 1% tin oxide content.
Because of the higher specific gravity of tin dioxide, about 80% of
mined tin is from secondary deposits found downstream from the primary
lodes. Tin is often recovered from granules washed downstream in the
past and deposited in valleys or the sea. The most economical ways of
mining tin are by dredging, hydraulicking, or open pits. Most of the
world's tin is produced from placer deposits, which can contain as
little as 0.015% tin.
World tin mine reserves (tonnes, 2011)
!Country Reserves
| 1,500,000
| 250,000
| 310,000
| 800,000
| 590,000
| 400,000
| 350,000
| 180,000
| 170,000
| Other 180,000
| Total 4,800,000
Economically recoverable tin reserves
!Year !Million tonnes
|1965 4,265
|1970 3,930
|1975 9,060
|1980 9,100
|1985 3,060
|1990 7,100
|2000 7,100
|2010 5,200
About 253,000 tonnes of tin were mined in 2011, mostly in China
(110,000 t), Indonesia (51,000 t), Peru (34,600 t), Bolivia (20,700 t)
and Brazil (12,000 t). Estimates of tin production have historically
varied with the market and mining technology. It is estimated that, at
current consumption rates and technologies, the Earth will run out of
mine-able tin in 40 years. In 2006 Lester Brown suggested tin could
run out within 20 years based on conservative estimates of 2% annual
growth.
Scrap tin is an important source of the metal. Recovery of tin through
recycling is increasing rapidly as of 2019. Whereas the United States
has neither mined (since 1993) nor smelted (since 1989) tin, it was
the largest secondary producer, recycling nearly 14,000 tonnes in
2006.
New deposits are reported in Mongolia, and in 2009, new deposits of
tin were discovered in Colombia.
Production
======================================================================
Tin is produced by carbothermic reduction of the oxide ore with carbon
or coke. Both reverberatory furnace and electric furnace can be used:
: SnO2 + C Sn + CO2↑
Industry
==========
The ten largest tin-producing companies produced most of the world's
tin in 2007.
Most of the world's tin is traded on LME, from 8 countries, under 17
brands.
Largest tin producing companies (tonnes)
!Company Polity 2006 2007 2017 2006-2017 % change
Yunnan Tin China |52,339 61,129 74,500 42.3
PT Timah Indonesia |44,689 58,325 30,200 −32.4
Malaysia Smelting Corp Malaysia |22,850 25,471 27,200 19.0
Yunnan Chengfeng China |21,765 18,000 26,800 23.1
Minsur Peru |40,977 35,940 18,000 −56.1
EM Vinto Bolivia |11,804 9,448 12,600 6.7
Guangxi China Tin China |/ / 11,500 /
Thaisarco Thailand |27,828 19,826 10,600 −61.9
Metallo-Chimique Belgium |8,049 8,372 9,700 20.5
Gejiu Zi Li China |/ / 8,700 /
The International Tin Council was established in 1947 to control the
price of tin. It collapsed in 1985. In 1984, the Association of Tin
Producing Countries was created, with Australia, Bolivia, Indonesia,
Malaysia, Nigeria, Thailand, and Zaire as members.
Price and exchanges
======================================================================
Tin is unique among mineral commodities because of the complex
agreements between producer countries and consumer countries dating
back to 1921. Earlier agreements tended to be somewhat informal and
led to the "First International Tin Agreement" in 1956, the first of a
series that effectively collapsed in 1985. Through these agreements,
the International Tin Council (ITC) had a considerable effect on tin
prices. ITC supported the price of tin during periods of low prices by
buying tin for its buffer stockpile and was able to restrain the price
during periods of high prices by selling from the stockpile. This was
an anti-free-market approach, designed to assure a sufficient flow of
tin to consumer countries and a profit for producer countries.
However, the buffer stockpile was not sufficiently large, and during
most of those 29 years tin prices rose, sometimes sharply, especially
from 1973 through 1980 when rampant inflation plagued many world
economies.
During the late 1970s and early 1980s, the U.S. reduced its strategic
tin stockpile, partly to take advantage of historically high tin
prices. The 1981-82 recession damaged the tin industry. Tin
consumption declined dramatically. ITC was able to avoid truly steep
declines through accelerated buying for its buffer stockpile; this
activity required extensive borrowing. ITC continued to borrow until
late 1985 when it reached its credit limit. Immediately, a major "tin
crisis" ensued--tin was delisted from trading on the London Metal
Exchange for about three years. ITC dissolved soon afterward, and the
price of tin, now in a free-market environment, fell to $4 per pound
and remained around that level through the 1990s. The price increased
again by 2010 with a rebound in consumption following the 2008
financial crisis and the Great Recession, accompanying restocking and
continued growth in consumption.
London Metal Exchange (LME) is tin's principal trading site. Other tin
contract markets are Kuala Lumpur Tin Market (KLTM) and Indonesia Tin
Exchange (INATIN).
Due to factors involved in the 2021 global supply chain crisis, tin
prices almost doubled during 2020-21 and have had their largest annual
rise in over 30 years. Global refined tin consumption dropped 1.6
percent in 2020 as the COVID-19 pandemic disrupted global
manufacturing industries.
Applications
======================================================================
In 2018, just under half of all tin produced was used in solder. The
rest was divided between tin plating, tin chemicals, brass and bronze
alloys, and niche uses.
Pigments
==========
Pigment Yellow 38, tin(IV) sulfide, is known as mosaic gold.
Purple of Cassius, Pigment Red 109, a hydrous double stannate of gold,
was mainly, in terms of painting, restricted to miniatures due to its
high cost. It was widely used to make cranberry glass. It has also
been used in the arts to stain porcelain.
Lead-tin yellow (which occurs in two yellow forms -- a stannate and a
silicate) was a pigment that was historically highly important for oil
painting and which had some use in fresco in its silicate form. Lead
stannate is also known in orange form but has not seen wide use in the
fine arts. It is available for purchase in pigment form from
specialist artists' suppliers. There is another minor form, in terms
of artistic usage and availability, of lead-tin yellow known as
Lead-tin Antimony Yellow.
Cerulean blue, a somewhat dull cyan chemically known as cobalt
stannate, continues to be an important artists' pigment. Its hue is
similar to that of Manganese blue, Pigment Blue 33, although it lacks
that pigment's colorfulness and is more opaque. Artists typically must
choose between cobalt stannate and manganese blue imitations made with
phthalocyanine blue green shade (Pigment Blue 15:3), as industrial
production of manganese blue pigment ceased in the 1970s. Cerulean
blue made with cobalt stannate, however, was popular with artists
prior to the production of Manganese blue.
Pigment Red 233, commonly known as Pinkcolor or Potter's Pink and more
precisely known as Chrome Tin Pink Sphene, is a historically important
pigment in watercolor. However, it has enjoyed a large resurgence in
popularity due to Internet-based word-of-mouth. It is fully lightfast
and chemically stable in both oil paints and watercolors. Other
inorganic mixed metal complex pigments, produced via calcination,
often feature tin as a constituent. These pigments are known for their
lightfastness, weatherfastness, chemical stability, lack of toxicity,
and opacity. Many are rather dull in terms of colorfulness. However,
some possess enough colorfulness to be competitive for use cases that
require more than a moderate amount of it. Some are prized for other
qualities. For instance, Pinkcolor is chosen by many watercolorists
for its strong granulation, even though its chroma is low. Recently,
NTP Yellow (a pyrochlore) has been brought to market as a non-toxic
replacement for lead(II) chromate with greater opacity, lightfastness,
and weathering resistance than proposed organic lead chromate
replacement pigments possess. NTP Yellow possesses the highest level
of color saturation of these contemporary inorganic mixed metal
complex pigments. More examples of this group include Pigment Yellow
158 (Tin Vanadium Yellow Cassiterite), Pigment Yellow 216 (Solaplex
Yellow), Pigment Yellow 219 (Titanium Zinc Antimony Stannate), Pigment
Orange 82 (Tin Titanium Zinc oxide, also known as Sicopal Orange),
Pigment Red 121 (also known as Tin Violet and Chromium stannate),
Pigment Red 230 (Chrome Alumina Pink Corundum), Pigment Red 236
(Chrome Tin Orchid Cassiterite), and Pigment Black 23 (Tin Antimony
Grey Cassiterite). Another blue pigment with tin and cobalt is Pigment
Blue 81, Cobalt Tin Alumina Blue Spinel.
Pigment White 15, tin(IV) oxide, is used for its iridescence, most
commonly as a ceramic glaze. There are no green pigments that have
been used by artists that have tin as a constituent and purplish
pigments with tin are classified as red, according to the Colour Index
International.
Solder
========
Tin has long been used in alloys with lead as solder, in amounts of 5
to 70% w/w. Tin with lead forms a eutectic mixture at the weight
proportion of 61.9% tin and 38.1% lead (the atomic proportion: 73.9%
tin and 26.1% lead), with melting temperature of 183 °C (361.4 °F).
Such solders are primarily used for joining pipes or electric
circuits. Since the European Union Waste Electrical and Electronic
Equipment Directive (WEEE Directive) and Restriction of Hazardous
Substances Directive came into effect on 1 July 2006, the lead content
in such alloys has decreased. While lead exposure is associated with
serious health problems, lead-free solder is not without its
challenges, including a higher melting point, and the formation of tin
whiskers that cause electrical problems. Tin pest can occur in
lead-free solders, leading to loss of the soldered joint. Replacement
alloys are being found, but the problems of joint integrity remain. A
common lead-free alloy is 99% tin, 0.7% copper, and 0.3% silver, with
melting temperature of 217 °C (422.6 °F).
Tin plating
=============
Tin bonds readily to iron and is used for coating lead, zinc, and
steel to prevent corrosion. Tin-plated (or tinned) steel containers
are widely used for food preservation, and this forms a large part of
the market for metallic tin. A tinplate canister for preserving food
was first manufactured in London in 1812. Speakers of British English
call such containers "tins", while speakers of U.S. English call them
"cans" or "tin cans". One derivation of such use is the slang term
"tinnie" or "tinny", meaning "can of beer" in Australia. The tin
whistle is so called because it was mass-produced first in tin-plated
steel.
Copper cooking vessels such as saucepans and frying pans are
frequently lined with a thin plating of tin, by electroplating or by
traditional chemical methods, since use of copper cookware with acidic
foods can be toxic.
Specialized alloys
====================
Tin in combination with other elements forms a wide variety of useful
alloys. Tin is most commonly alloyed with copper. Pewter is 85-99%
tin, and bearing metal has a high percentage of tin as well. Bronze is
mostly copper with 12% tin, while the addition of phosphorus yields
phosphor bronze. Bell metal is also a copper-tin alloy, containing 22%
tin. Tin has sometimes been used in coinage; it once formed a
single-digit percentage (usually five percent or less) of American and
Canadian pennies.
The niobium-tin compound Nb3Sn is commercially used in coils of
superconducting magnets for its high critical temperature (18 K) and
critical magnetic field (25 T). A superconducting magnet weighing as
little as two kilograms is capable of producing the magnetic field of
a conventional electromagnet weighing tons.
A small percentage of tin is added to zirconium alloys for the
cladding of nuclear fuel.
Most metal pipes in a pipe organ are of a tin/lead alloy, with 50/50
as the most common composition. The proportion of tin in the pipe
defines the pipe's tone, since tin has a desirable tonal resonance.
When a tin/lead alloy cools, the lead phase solidifies first, then
when the eutectic temperature is reached, the remaining liquid forms
the layered tin/lead eutectic structure, which is shiny; contrast with
the lead phase produces a mottled or spotted effect. This metal alloy
is referred to as spotted metal. Major advantages of using tin for
pipes include its appearance, workability, and resistance to
corrosion.
Manufacturing of chemicals
============================
Tin compounds are used in the production of various chemicals,
including stabilizers for PVC and catalysts for industrial processes.
Tin in form of ingots provide the raw material necessary for these
chemical reactions, ensuring consistent quality and performance.
Optoelectronics
=================
The oxides of indium and tin are electrically conductive and
transparent, and are used to make transparent electrically conducting
films with applications in optoelectronics devices such as liquid
crystal displays.
Other applications
====================
Punched tin-plated steel, also called pierced tin, is an artisan
technique originating in central Europe for creating functional and
decorative housewares. Decorative piercing designs exist in a wide
variety, based on local tradition and the artisan. Punched tin
lanterns are the most common application of this artisan technique.
The light of a candle shining through the pierced design creates a
decorative light pattern in the room where it sits. Lanterns and other
punched tin articles were created in the New World from the earliest
European settlement. A well-known example is the Revere lantern, named
after Paul Revere.
In America, pie safes and food safes were in use in the days before
refrigeration. These were wooden cupboards of various styles and sizes
- either floor standing or hanging cupboards meant to discourage
vermin and insects and to keep dust from perishable foodstuffs. These
cabinets had tinplate inserts in the doors and sometimes in the sides,
punched out by the homeowner, cabinetmaker, or a tinsmith in varying
designs to allow for air circulation while excluding flies. Modern
reproductions of these articles remain popular in North America.
Window glass is most often made by floating molten glass on molten tin
(float glass), resulting in a flat and flawless surface. This is also
called the "Pilkington process".
Tin is used as a negative electrode in advanced Li-ion batteries. Its
application is somewhat limited by the fact that some tin surfaces
catalyze decomposition of carbonate-based electrolytes used in Li-ion
batteries.
Tin(II) fluoride is added to some dental care products as stannous
fluoride (SnF2). Tin(II) fluoride can be mixed with calcium abrasives
while the more common sodium fluoride gradually becomes biologically
inactive in the presence of calcium compounds. It has also been shown
to be more effective than sodium fluoride in controlling gingivitis.
Tin is used as a target to create laser-induced plasmas that act as
the light source for extreme ultraviolet lithography.
PVC stabilizers
=================
The major commercial application of organotin compounds is in the
stabilization of PVC plastics. In the absence of such stabilizers, PVC
would rapidly degrade under heat, light, and atmospheric oxygen,
resulting in discolored, brittle products. Tin scavenges labile
chloride ions (Cl−), which would otherwise strip HCl from the plastic
material. Typical tin compounds are carboxylic acid derivatives of
dibutyltin dichloride, such as dibutyltin dilaurate.
Biocides
==========
Some organotin compounds are relatively toxic, with both advantages
and problems. They are used for biocidal properties as fungicides,
pesticides, algaecides, wood preservatives, and antifouling agents.
Tributyltin oxide is used as a wood preservative. Tributyltin is used
for various industrial purposes such as slime control in paper mills
and disinfection of circulating industrial cooling waters. Tributyltin
was used as additive for ship paint to prevent growth of fouling
organisms on ships, with use declining after organotin compounds were
recognized as persistent organic pollutants with high toxicity for
some marine organisms (the dog whelk, for example). The EU banned the
use of organotin compounds in 2003, while concerns over the toxicity
of these compounds to marine life and damage to the reproduction and
growth of some marine species (some reports describe biological
effects to marine life at a concentration of 1 nanogram per liter)
have led to a worldwide ban by the International Maritime
Organization. Many nations now restrict the use of organotin compounds
to vessels greater than 25 m long. The persistence of tributyltin in
the aquatic environment is dependent upon the nature of the ecosystem.
Because of this persistence and its use as an additive in ship paint,
high concentrations of tributyltin have been found in marine sediments
located near naval docks. Tributyltin has been used as a biomarker for
imposex in neogastropods, with at least 82 known species. With the
high levels of TBT in the local inshore areas, due to shipping
activities, the shellfish had an adverse effect. Imposex is the
imposition of male sexual characteristics on female specimens where
they grow a penis and a pallial vas deferens. A high level of TBT can
damage mammalian endocrine glands, reproductive and central nervous
systems, bone structure and gastrointestinal tract. Tributyltin also
affect mammals, Including sea otters, whales, dolphins, and humans.
Organic chemistry
===================
Some tin reagents are useful in organic chemistry. In the largest
application, stannous chloride is a common reducing agent for the
conversion of nitro and oxime groups to amines. The Stille reaction
couples organotin compounds with organic halides or pseudohalides.
Li-ion batteries
==================
Tin forms several inter-metallic phases with lithium metal, making it
a potentially attractive material for battery applications. Large
volumetric expansion of tin upon alloying with lithium and instability
of the tin-organic electrolyte interface at low electrochemical
potentials are the greatest challenges to employment in commercial
cells. Tin inter-metallic compound with cobalt and carbon was
implemented by Sony in its Nexelion cells released in the late 2000s.
The composition of the active material is approximately
Sn0.3Co0.4C0.3. Research showed that only some crystalline facets of
tetragonal (beta) Sn are responsible for undesirable electrochemical
activity.
Precautions
======================================================================
Cases of poisoning from tin metal, its oxides, and its salts are
almost unknown. On the other hand, certain organotin compounds are
almost as toxic as cyanide.
Exposure to tin in the workplace can occur by inhalation, skin
contact, and eye contact. The US Occupational Safety and Health
Administration (OSHA) set the permissible exposure limit for tin
exposure in the workplace as 2 mg/m3 over an 8-hour workday. The
National Institute for Occupational Safety and Health (NIOSH)
determined a recommended exposure limit (REL) of 2 mg/m3 over an
8-hour workday. At levels of 100 mg/m3, tin is immediately dangerous
to life and health.
See also
======================================================================
* Cassiterides (the mythical Tin Islands)
* Stannary
* Terne
* Tin pest
* Tin mining in Britain
* Tinning
* Whisker (metallurgy) (tin whiskers)
External links
======================================================================
* [
http://www.periodicvideos.com/videos/050.htm Tin] at 'The Periodic
Table of Videos' (University of Nottingham)
* [
https://theodoregray.com/PeriodicTable/Elements/050/index.s7.html
Theodore Gray's Wooden Periodic Table Table]: Tin samples and castings
* [
http://www.basemetals.com/html/sninfo.htm Base Metals: Tin]
* [
https://www.cdc.gov/niosh/npg/npgd0613.html CDC - NIOSH Pocket
Guide to Chemical Hazards]
*
[
https://web.archive.org/web/20140222181950/http://helgilibrary.com/indicators/index/tin-usd-cents-per-kg
Tin (USD cents per kg) ]
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL:
http://creativecommons.org/licenses/by-sa/3.0/
Original Article:
http://en.wikipedia.org/wiki/Tin
