Tin dioxide

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Tin dioxide
IUPAC name
Tin (IV) Oxide
Other names
Stannic oxide, Tin(IV) oxide, Flowers of tin, [1] Cassiterite
3D model (JSmol)
ECHA InfoCard 100.038.311
EC Number 242-159-0
PubChem CID
RTECS number XQ4000000
Molar mass 150.71 g·mol−1
Appearance White or light grey powder [2]
Odor Odorless
Density 6.95 g/cm3 (20 °C) [3]
6.85 g/cm3 (24 °C) [4]
Melting point 1,630 °C (2,970 °F; 1,900 K) [3] [4]
Boiling point 1,800–1,900 °C (3,270–3,450 °F; 2,070–2,170 K)
Sublimes [3]
Insoluble [4]
Solubility Soluble in hot concentrated alkalis, [4] concentrated acids
Insoluble in alcohol [3]
−4.1·10−5 cm3/mol [4]
2.006 [5]
Rutile tetragonal, tP6 [6]
P42/mnm, No. 136 [6]
4/m 2/m 2/m [6]
a = 4.737 Å, c = 3.185 Å [6]
α = 90°, β = 90°, γ = 90°
Octahedral (Sn4+)
Trigonal planar (O2−)
52.6 J/mol·K [4]
49.04 J/mol·K [4] [7]
−577.63 kJ/mol [4] [7]
−515.8 kJ/mol [4]
Safety data sheet ICSC 0954
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeTin dioxide
Lethal dose or concentration (LD, LC):
> 20 g/kg (rats, oral) [8]
US health exposure limits (NIOSH):
PEL (Permissible)
none [2]
REL (Recommended)
TWA 2 mg/m3 [2]
IDLH (Immediate danger)
N.D. [2]
Related compounds
Related tin oxides
Tin(II) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tin dioxide (tin(IV) oxide), also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. [9] With many other names, this oxide of tin is the most important raw material in tin chemistry. It is a colourless, diamagnetic, amphoteric solid.

An inorganic compound is typically a chemical compound that lacks C-H bonds, that is, a compound that is not an organic compound, but the distinction is not defined or even of particular interest.

A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than are chemical names and structural formulas.

Cassiterite oxide mineral

Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite has been the chief tin ore throughout ancient history and remains the most important source of tin today.



Tin (IV) oxide fibers (optical microscope) Diossido di stagno 7.jpg
Tin (IV) oxide fibers (optical microscope)

Tin(IV) oxide crystallises with the rutile structure. As such the tin atoms are six coordinate and the oxygen atoms three coordinate. [9] SnO2 is usually regarded as an oxygen-deficient n-type semiconductor. [10]

Rutile oxide mineral

Rutile is a mineral composed primarily of titanium dioxide (TiO2).

Hydrous forms of SnO2 have been described as stannic acid. Such materials appear to be hydrated particles of SnO2 where the composition reflects the particle size. [11]


Tin(IV) oxide occurs naturally. Synthetic tin(IV) oxide is produced by burning tin metal in air. [11] Annual production is in the range of 10 kilotons. [11] SnO2 is reduced industrially to the metal with carbon in a reverberatory furnace at 1200–1300 °C. [12]

Reverberatory furnace

A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. The term reverberation is used here in a generic sense of rebounding or reflecting, not in the acoustic sense of echoing.


Although SnO2 is insoluble in water, it is amphoteric, dissolving in base and acid. [13] "Stannic acid" refers to hydrated tin (IV) oxide, SnO2, which is also called "stannic hydroxide."

Tin oxides dissolve in acids. Halogen acids attack SnO2 to give hexahalostannates, [14] such as [SnI6]2−. One report describes reacting a sample in refluxing HI for many hours. [15]

SnO2 + 6 HI → H2SnI6 + 2 H2O

Similarly, SnO2 dissolves in sulfuric acid to give the sulfate: [11]

SnO2 + 2 H2SO4 → Sn(SO4)2 + 2 H2O

SnO2 dissolves in strong base to give "stannates," with the nominal formula Na2SnO3. [11] Dissolving the solidified SnO2/NaOH melt in water gives Na2[Sn(OH)6]2, "preparing salt," which is used in the dye industry. [11]


In conjunction with vanadium oxide, it is used as a catalyst for the oxidation of aromatic compounds in the synthesis of carboxylic acids and acid anhydrides. [9]

Ceramic glazes

Tin(IV) oxide has long been used as an opacifier and as a white colorant in ceramic glazes. [16] This has probably led to the discovery of the pigment lead-tin-yellow, which was produced using tin(IV) oxide as a compound. [17] The use of tin(IV) oxide has been particularly common in glazes for earthenware, sanitaryware and wall tiles; see the articles tin-glazing and Tin-glazed pottery. Tin oxide remains in suspension in vitreous matrix of the fired glazes, and, with its high refractive index being sufficiently different from the matrix, light is scattered, and hence increases the opacity of the glaze. The degree of dissolution increases with the firing temperature, and hence the extent of opacity diminishes. [18] Although dependent on the other constituents the solubility of tin oxide in glaze melts is generally low. Its solubility is increased by Na2O, K2O and B2O3, and reduced by CaO, BaO, ZnO, Al2O3, and to a limited extent PbO. [19]

SnO2 has been used as pigment in the manufacture of glasses, enamels and ceramic glazes. Pure SnO2 gives a milky white colour; other colours are achieved when mixed with other metallic oxides e.g. V2O5 yellow; Cr2O3 pink; and Sb2O5 grey blue. [11]


Tin(IV) oxide can be used as a polishing powder, [11] sometimes in mixtures also with lead oxide, for polishing glass, jewelery, marble and silver. [1] Tin(IV) oxide for this use is sometimes called as "putty powder" [13] or "jeweler's putty". [1]

Glass coatings

SnO2 coatings can be applied using chemical vapor deposition, vapour deposition techniques that employ SnCl4 [9] or organotin trihalides [20] e.g. butyltin trichloride as the volatile agent. This technique is used to coat glass bottles with a thin (<0.1 μm) layer of SnO2, which helps to adhere a subsequent, protective polymer coating such as polyethylene to the glass. [9]

Thicker layers doped with Sb or F ions are electrically conducting and used in electroluminescent devices. [9]

Gas sensing

SnO2 is used in sensors of combustible gases including carbon monoxide detectors. In these the sensor area is heated to a constant temperature (few hundred °C) and in the presence of a combustible gas the electrical resistivity drops. [21] Doping with various compounds has been investigated (e.g. with CuO [22] ). Doping with cobalt and manganese, gives a material that can be used in e.g. high voltage varistors. [23] Tin(IV) oxide can be doped with the oxides of iron or manganese. [24]

Related Research Articles

Tin Chemical element with atomic number 50

Tin is a chemical element with the symbol Sn (from Latin: stannum) and atomic number 50. It 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, SnO2. 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 and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table, thanks 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, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure. Metallic tin does not easily oxidize in air.

In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid and as a base. Many metals (such as copper, zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Amphoterism depends on the oxidation states of the oxide. Al2O3 is an example of an amphoteric oxide.

Iron(III) oxide chemical compound

Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron for the steel industry. Fe2O3 is readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered an ill-defined material, described as hydrated ferric oxide.

Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is an inorganic compound with the formula SnCl4. It is a colourless hygroscopic liquid, which fumes on contact with air. It is used as a precursor to other tin compounds. It was first discovered by Andreas Libavius (1550–1616) and was known as spiritus fumans libavii.

Vanadium(V) oxide chemical compound

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V2O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

Tin(II) chloride chemical compound

Tin(II) chloride, also known as stannous chloride, is a white crystalline solid with the formula SnCl2. It forms a stable dihydrate, but aqueous solutions tend to undergo hydrolysis, particularly if hot. SnCl2 is widely used as a reducing agent (in acid solution), and in electrolytic baths for tin-plating. Tin(II) chloride should not be confused with the other chloride of tin; tin(IV) chloride or stannic chloride (SnCl4).

Tin(II) oxide chemical compound

Tin(II) oxide is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.

Arsenous acid chemical compound

Arsenous acid (or arsenious acid) is the inorganic compound with the formula H3AsO3. It is known to occur in aqueous solutions, but it has not been isolated as a pure material, although this fact does not detract from the significance of As(OH)3.

Chromium(III) oxide chemical compound

Chromium(III) oxide is the inorganic compound of the formula Cr
. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.

Tin(II) hydroxide chemical compound

Tin(II) hydroxide, Sn(OH)2, also known as stannous hydroxide, is an inorganic compound tin(II). The only related material for which definitive information is available is the oxy hydroxide Sn6O4(OH)4, but other related materials are claimed. They are all white solids that are insoluble in water.

Arsenic pentoxide chemical compound

Arsenic pentoxide is the inorganic compound with the formula As2O5. This glassy, white, deliquescent solid is relatively unstable, consistent with the rarity of the As(V) oxidation state. More common, and far more important commercially, is arsenic(III) oxide (As2O3). All arsenic compounds are highly toxic and thus find only limited commercial applications.

Cadmium oxide chemical compound

Cadmium oxide is an inorganic compound with the formula CdO. It is one of the main precursors to other cadmium compounds. It crystallizes in a cubic rocksalt lattice like sodium chloride, with octahedral cation and anion centers. It occurs naturally as the rare mineral monteponite. Cadmium oxide can be found as a colorless amorphous powder or as brown or red crystals. Cadmium oxide is an n-type semiconductor with a band gap of 2.18 eV at room temperature.


Tin-glazing is the process of giving ceramic items a tin-based glaze that is white, glossy and opaque, which is normally applied to red or buff earthenware. The opacity and whiteness of tin glaze encourage its frequent decoration with overglaze colour. Majolica, delftware and faience are among the terms used for common types of tin-glazed pottery. An alternative is lead-glazing, where the basic glaze is transparent; some types of pottery use both.

Indium(III) oxide chemical compound

Indium(III) oxide (In2O3) is a chemical compound, an amphoteric oxide of indium.

Tin(IV) sulfide chemical compound

Tin(IV) sulfide is a compound with the formula SnS
. The compound crystallizes in the cadmium iodide motif, with the Sn(IV) situated in "octahedral holes' defined by six sulfide centers. It occurs naturally as the rare mineral berndtite. It is useful as semiconductor material with band gap 2.2 eV.

Tin(II) bromide is a chemical compound of tin and bromine with a chemical formula of SnBr2. Tin is in the +2 oxidation state. The stability of tin compounds in this oxidation state is attributed to the inert pair effect.

Fluoroboric acid chemical compound

Fluoroboric acid or tetrafluoroboric acid is an inorganic compound with the chemical formula H

Beryllium chloride chemical compound

Beryllium chloride is an inorganic compound with the formula BeCl2. It is a colourless, hygroscopic solid that dissolves well in many polar solvents. Its properties are similar to those of aluminium chloride, due to beryllium's diagonal relationship with aluminium.

Tin(IV) iodide, also known as stannic iodide, is the chemical compound with the formula SnI4. This tetrahedral molecule crystallises as a bright orange solid that dissolves readily in nonpolar solvents such as benzene.

Antimony sulfate, Sb2(SO4)3, is a hygroscopic material is formed by reacting antimony or its compounds with hot sulfuric acid. It is used in doping of semiconductors and in the production of explosives and fireworks.


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Further reading