BISMUTH OXIDE

EC / List no.: 215-134-7
CAS no.: 1304-76-3
Mol. formula: Bi2O3

Bismuth Oxide is a highly insoluble thermally stable Bismuth source suitable for glass, optic and ceramic applications. 
Bismuth oxide is found naturally as the mineral bismite and sphaerobismoite but can also be achieved as a by-product of the smelting of copper and lead ores. 
Bismuth oxide is the most industrially vital compound of bismuth. 
Oxide compounds are not conductive to electricity. 
However, certain perovskite structured oxides are electronically conductive finding application in the cathode of solid oxide fuel cells and oxygen generation systems. 
They are compounds containing at least one oxygen anion and one metallic cation. 
They are typically insoluble in aqueous solutions (water) and extremely stable making them useful in ceramic structures as simple as producing clay bowls to advanced electronics and in light weight structural components in aerospace and electrochemical applications such as fuel cells in which they exhibit ionic High Purity (99.999%) Bismuth Oxide(Bi2O3) Powderconductivity. 
Metal oxide compounds are basic anhydrides and can therefore react with acids and with strong reducing agents in redox reactions. 
Bismuth Oxide is also available in pellets, pieces, powders, sputtering targets, tablets, and nanopowder 

Bismuth oxide is usually available in various concentration. 
Special packaging requirements are available upon request. 
Bismuth oxide is stored in original packing and under conditions mentioned on the safety data sheet (SDS).

Description
Information not available

Appearance
Bismuth oxide is an odourless yellow powder characterised by rhombic-shaped crystals.

Solubility
Bismuth oxide is insoluble in water but soluble in Hydrogen fluoride (HF) and Nitric acid (HNO3).

Uses:
Bismuth oxide is one of the bismuth compounds widely spread in the industry. 
Bismite ore is the raw material of which it is produced. 
Bismuth trioxide is a raw material for the ceramic, glass and electrotechnical sector.

Classification
Request safety data sheet (SDS) and refer to points 4, 5, 6, 8, 10,13, 14, 15. 
Technical specifications are provided on request according to the application.

Safety
Request safety data sheet (SDS) and refer to points 4, 5, 6, 7, 8, 10, 13.

Specifications
Technical specifications are provided on request according to the application: bismuth oxide is stored in original packing and under conditions mentioned on the safety data sheet (SDS).

Synonyms
Bismuth trioxide, yellow bismuth oxide, dibismuth trioxide, Bismuth oxide.

Chemical Properties    
Bismuth oxide is the compound produced by heating the metal, or its carbonate, in air. 
Bismuth oxide is definitely a basic oxide, dissolving readily in acid solutions, and unlike the arsenic or antimony compounds, not amphiprotic in solution, although it forms stoichiometric addition compounds on heating with oxides of a number of other metals. 
Bismuth oxide exists in three modifications, white rhombohedral, yellow rhombohedral, and gray-black cubical. Bismuth(II) oxide, BiO, has been produced by heating the basic oxalate.

Physical properties    
Yellow monoclinic crystal or powder; density 8.90 g/cm3; melts at 817°C; vaporizes at 1,890°C; insoluble in water; soluble in acids.

Occurrence    
Bismuth oxide occurs in nature as mineral bismite. 
The oxide is used in fireproofing of papers and polymers; in enameling cast iron ceramic; and in disinfectants.

Uses:    
Bismuth oxide is used in the preparation of BiFeO3perovskite nanoparticles. 
Bismuth oxide finds use in disinfectants, magnets, glass, rubber, vulcanization, fireproofing papers and polymers and catalysts. 
Bismuth Oxidetrioxide brings about the "dragon's eggs" effect in fireworks, as a replacement of red lead. 
Bismuth Oxidecompounds are attractive reagents and catalysts in organic synthesis because of their low cost and ease of handling. 
Bismuth oxide nanoparticles also play an important role in high energy gas generators. 
The alpha crystalline form of Bismuth oxide has p-type electronic conductivity.
In disinfectants, magnets, glass, rubber vulcanization; in fireproofing of papers and polymers; in catalysts.

Preparation    
Bismuth trioxide is commercially made from bismuth subnitrate.
The latter is produced by dissolving bismuth in hot nitric acid. 
Addition of excess sodium hydroxide followed by continuous heating of the mixture precipitates bismuth trioxide as a heavy yellow powder.
Also, the trioxide can be prepared by ignition of bismuth hydroxide.

General Description    
Bismuth oxide is a yellow, monoclinic crystalline powder. 
Bismuth oxide is insoluble in water and hydroxide solutions but dissolves in acids to form bismuth (III) salts. 
Bismuth oxide can be prepared by heating bismuth in air or by heating hydroxides, carbonates or nitrates of bismuth.

Bismuth oxide is the most important industrial compound of bismuth, and a starting point for bismuth chemistry. 
Bismuth oxide is found naturally as the mineral bismite, but it is usually obtained as a by-product of the smelting of copper and lead ores. 
Bismuth oxide may also be prepared by burning bismuth metal in air. 
Bismuth oxide is commonly used to produce the "Dragon's eggs" effect in fireworks, as a replacement of red lead.

Bismuth oxide has seen interest as a material for solid oxide fuel cells or SOFCs since it is an ionic conductor, i.e. oxygen atoms readily move through it. 
Pure bismuth oxide, Bi2O3 has four crystallographic polymorphs. 
Bismuth oxide has a monoclinic crystal structure, designated α- Bi2O3, at room temperature. 
This transforms to the cubic fluorite-type crystal structure, δ-Bi2O3, when heated above 727°C, which remains the structure until the melting point, 824°C, is reached. 
The behaviour of Bi2O3 on cooling from the δ-phase is more complex, with the possible formation of two intermediate metastable phases; the tetragonal β-phase or the body centred cubic γ-phase. 
The γ-phase can exist at room temperature with very slow cooling rates, but α- Bi2O3 always forms on cooling the β-phase.

δ- Bi2O3 has the highest reported conductivity. 
At 750°C the conductivity of δ- Bi2O3 is typically about 1 Scm-1, about three orders of magnitude greater than the intermediate phases and four orders greater than the monoclinic phase. 
The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the main charge carrier. 
The α-phase exhibits p-type electronic conductivity (the charge is carried by positive holes) at room temperature which transforms to n-type conductivity (charge is carried by electrons) between 550°C and 650°C, depending on the oxygen partial pressure. 
Bismuth oxide is therefore unsuitable for electrolyte applications. 
δ- Bi2O3 has a defective fluorite-type crystal structure in which two of the eight oxygen sites in the unit cell are vacant. These intrinsic vacancies are highly mobile due to the high polarisability of the cation sub-lattice with the 6s2 lone pair electrons of Bi3+. 
The Bi-O bonds have covalent bond character and are therefore weaker than purely ionic bonds, so the oxygen ions can jump into vacancies more freely.

The arrangement of oxygen atoms within the unit cell of δ- Bi2O3 has been the subject of much debate in the past. 
Three different models have been proposed. 
Sillen (1937) used powder X-ray diffraction on quenched samples and reported the structure of Bi2O3 was a simple cubic phase with oxygen vacancies ordered along<111>, i.e. along the cube body diagonal (Figure 2a). Gattow and Schroder (1962) rejected this model, preferring to describe each oxygen site (8c site) in the unit cell as having 75% occupancy. 
In other words, the six oxygen atoms are randomly distributed over the eight possible oxygen sites in the unit cell. 
Currently, most experts seem to favour the latter description as a completely disordered oxygen sub-lattice accounts for the high conductivity in a better way.

Willis (1965) used neutron diffraction to study the fluorite (CaF2) system. 
He determined that it could not be described by the ideal fluorite crystal structure, rather, the fluorine atoms were displaced from regular 8c positions towards the centres of the interstitial positions (Figure 2c). 
Shuk et al. (1996) and Sammes et al. (1999) suggest that because of the high degree of disorder in δ- Bi2O3, the Willis model could also be used to describe its structure.

In addition to electrical properties, thermal expansion properties are very important when considering possible applications for solid electrolytes. 
High thermal expansion coefficients represent large dimensional variations under heating and cooling which would limit the performance of an electrolyte. 
The transition from the high-temperature δ- Bi2O3 to the intermediate β- Bi2O3 is accompanied by a large volume change and consequently, a deterioration of the mechanical properties of the material. 
This, combined with the very narrow stability range of the δ-phase (727-824oC), has led to studies on its stabilization to room temperature.

Bi2O3 easily forms solid solutions with many other metal oxides. 
These doped systems exhibit a complex array of structures and properties dependent on the type of dopant, the dopant concentration and the thermal history of the sample. 
The most widely studied systems are those involving rare earth metal oxides, Ln2O3, including yttria, Y2O3. 
Rare earth metal cations are generally very stable, have similar chemical properties to one another and are similar in size to Bi3+, which has a radius of 1.03 Å, making them all excellent dopants. 
Furthermore, their ionic radii decrease fairly uniformly from La3+ (1.032 Å), through Nd3+, (0.983 Å), Gd3+, (0.938 Å), Dy3+, (0.912 Å) and Er3+, (0.89 Å), to Lu3+, (0.861 Å) (known as the ‘lanthanide contraction’), making them useful to study the effect of dopant size on the stability of the Bi2O3 phases.

Preparation of new stabilized, oxide ion-conducting, bismuth vanadate phases by a microwave assisted method, from V2O5, Bi2O3 and other solid oxides, was reported. 
These ceramics show promise in solid oxide fuel cells, water-vapor electrolyzers and oxygen sensors.

Bismuth oxide thin films still prove attractive to both scientists and engineers due to their semiconducting behavior, large energy bandgap and high refractive index, despite their often complex structure, both polymorphic and polycrystalline. 
We present here a summary and a comparison of the morpho-structural and optical properties of such films prepared through three physical vapor deposition (PVD) techniques on several types of substrates kept at different temperatures. 
Thermal vapor deposition, thermal oxidation in air and pulsed laser deposition are discussed as largely used PVD methods. 
Bismuth oxide is proved that the physical properties of the bismuth oxide thin films can be tailored by changing the substrate nature and its temperature during the deposition process in a way even more relevant than even the chosen deposition method. 
Thus, bismuth oxide thin films with energy bandgaps ranging from the infrared up to near-ultraviolet can be obtained, depending on their structure and morphology. 
High refractive index of the films can be also attained for specific spectral ranges. 
When deposited on certain conductive substrates, the films have much lower electrical resistance and even became sensitive to water vapor. 
Therefore, humidity sensing and optoelectronic applications of the analyzed bismuth oxide thin films can be easily found and used in both science and technology.

Bismuth oxide, also known as bismite and bismuth trioxide, is a chemical compound. 
Its chemical formula is Bi2O3. 
Bismuth oxide has bismuth and oxide ions in it. 
The bismuth is in its +3 oxidation state.

Properties
Bismuth oxide is a pale yellow solid. 
Bismuth oxide does not dissolve in water. 
Bismuth oxide dissolves in acids to make other bismuth(III) salts.
When it is electrolyzed, it makes a bright red solid, bismuth(V) oxide. 
Bismuth oxide has several different crystal structures that have been studied. 
Bismuth oxide reacts with rare earth metal oxides and the products are being studied.

Occurrence
Bismite is the mineral form of Bismuth oxide. 
Bismuth oxide is an ore of bismuth. 
Its Mohs hardness is 4.5 to 5 and its specific gravity is quite high, around 8 or 9. 
Bismuth oxide is made when bismuthinite is oxidized. 
Bismuth oxide was first found in Nevada in 1868.

Preparation
Bismuth oxide can be made by reacting sodium hydroxide with a bismuth salt such as bismuth chloride. 
Bismuth oxide can also be made by igniting powdered bismuth metal. 
Another way of making it is to react bismuth nitrate (made by dissolving bismuth in nitric acid) with concentrated sodium hydroxide.

Uses:
Bismuth oxide is used in pyrotechnics to make fireworks that burn with an effect called "dragon's eggs". 
Lead(II,IV) oxide was used for this in the past, but now is considered too toxic to use. 
Bismuth oxide is also used in research and the making of other bismuth compounds.

Properties
Chemical
Like other oxides, on addition to an acid the bismuth salt and water are formed. 
Bismuth oxide is therefore a useful stating point in creating bismuth compounds such as bismuth nitrate.

A bismuthate ion exists and it is a very powerful oxidizer, able to oxidize chromates and manganates. 
Bismuth oxide can be produced from bismuth trioxide by heating with a molten alkali hydroxide.

Its reaction with magnesium and aluminium powders is exceptionally violent for a thermite, and will explode due to the density of the oxide and the low reactivity of bismuth, reaction similar to copper(II) oxide. 
Therefore this is not a viable way of producing the metal from the oxide as any metal produced is vaporized.

Pyrotechnic mixes of magnesium and bismuth trioxide are labelled "Dragon's Eggs", where pellets are designed to explode after a short period of burning.

Molten bismuth oxide is an extremely powerful oxidizer that can dissolve platinum.

Physical
A yellow solid that can appear with a slight green tinge in impure samples, Bi2O3 is remarkably dense.

Availability
Pyrotechnic supplies will most likely sell Bi2O3. 
Bismuth oxide has no shipping restrictions, so pyrotechnic grade oxide can be found online reasonably priced, and it's often relative pure.

Preparation
Burning bismuth metal by a blow torch is an uncontrolled way to make Bi2O3, and much of it escapes if there is not a good method of catching it as it is created.

Physical Properties
Sintered pieces, targets, granules and powder

Chemical Properties
Purities available from 98% (industrial grade) to 99.9995% (ultra high purity grade)

Typical Applications
Optical glasses, to replace lead oxide in whitewares (bone china, etc.), fluxes, varistor formulations, and ceramic capacitor formulations

Description
Derived from the ignition of bismuth nitrate. Insoluble in water but soluble in acids.

Bismuth Oxide Powder Formula: Bi2O3

CAS Number: 1304-76-3
Chemical Formula: Bi2O3
Availability: R and D quantities only. Please contact ABSCO for delivery time
Description: ABSCO Limited supplies high purity bismuth oxide as small pieces or powder

Bismuth oxide has the chemical formula Bi2O3 which is a yellow solid with melting point of 825oC. 
This material has alpha (>729oC pseudo-orthorombic), beta (650-729oC orthorombic), gama (629-650oC bcc) and delta (<629oC cubic) polymorphs. 
Bi2O3 has excellent optical and electrical properties such as wide band gap, high refractive index, high dielectric permitivity and high photoconductivity. 
Bi2O3 can be produced from bismuth hydroxide, bismuth carbonate and bismuth nitrate.

Bismuth Oxidecan be used in medical devices (dental treatments etc), solid oxide fuel cells (SOFCs), bio medical applications (cancer imaging), glass industry as colorant, electroceramics (lead free ferroelectrics) and superconductors. Bi2O3 is a key raw material for sodium bismuth titanate based lead free piezoceramics which are alternatives for toxic lead based piezoceramics. 
Bi2O3 is also an important raw material for bismuth layer-structured ferroelectrics (BLSFs) which have high Curie temperatures (generally higher than 500oC). 
Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Bi4TiO3, BaBi4T4O15, Bi3TiNO9 (N=Nb,Ta) are examples of bismuth based ferroelectrics.

Photocatalytic activity of bismuth oxide is another important property for water treatment applications.
 Bismuth Oxidecan be seen that nano bismuth oxide particles (average particle size is 20 nm) have high efficiencies for degradation and mineralization of atrazine in water*. 
(*Sudrajat, H., Sujaridworakun, P., “Correlation between particle size of Bi2O3 nanoparticles and their photocatalytic activity for degradation and mineralization of atrazine”, Journal of Molecular Liquids, 242,2017) Nano Bi2O3 particles can be synthesized by sol-gel method. 
Particle size control is avaliable with this route for variable synthesis temperatures.

The production of Bi2O3 is generally begins with the metallic bismuth. 
Three commercial metods are avaliable for producing bismuth oxide. 
In the first technique metallic bismuth powder dissolved in nitric acid, then heating process is applied for calcination bismuth nitrate. 
The second technique is similar to calcination method. 
Neutralization is added with caustic soda and 5N+ purity bismuth oxide can be produced by this tecnique. 
Final commercial method is direct calcination of metallic bismuth to provide formation of bismuth oxide. High quality raw materials must be used to produce high purity bismuth oxide. 
These raw materials and products are analysed by inductively coupled plasma optical emission spectrometry (ICP-OES), x-ray fluoresence (XRF), energy dispersive spectrometry (EDX) and glow discharge mass spectrometry (GDMS) methods. Glow discharge mass spectrometry enables direct analysis of high purity solid samples.

An excellent flux, can make a low temperature frit, color, and glaze

TYPICAL PHYSICAL PROPERTIES
Chemical Formula: Bi2O3
Color: Bright yellow powder
True Density, g/cc: 8.9
Crystal Phase: Tetragonal
Morphology: Equi-axed, faceted
Purity: 99.5+%

Bismuth Oxide is perhaps the most industrially important compound of bismuth. 
Bismuth Oxide is also a common starting point for bismuth chemistry. 
Bismuth Oxide is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare), but it is usually obtained as a by-product of the smelting of copper and lead ores. 
Dibismuth trioxide is commonly used to produce the "Dragon's eggs" effect in fireworks, as a replacement of red lead.

Bismuth Oxide is perhaps the most industrially important compound of bismuth. 
Bismuth Oxide is also a common starting point for bismuth chemistry. 
Bismuth Oxide is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare), but it is usually obtained as a by-product of the smelting of copper and lead ores. 
Dibismuth trioxide is commonly used to produce the "Dragon's eggs" effect in fireworks, as a replacement of red lead.

Structure
The structures adopted by Bi2O3 differ substantially from those of arsenic(III) oxide, As2O3, and antimony(III) oxide, Sb2O3.

Existence domains of the four polymorphs of Bi2O3 as a function of temperature. (a) The α-phase transforms to the δ-phase when heated above 727 °C, which remains the structure until the melting point, 824 °C, is reached. 
When cooled, the δ-phase transforms into either the β-phase at 650 °C, shown in (b), or the γ-phase at 639 °C, shown in (c). 
The β-phase transforms to the α-phase at 303 °C. 
The γ-phase may persist to room temperature when the cooling rate is very slow, otherwise it transforms to the α-phase at 500 °C.
Bismuth oxide, Bi2O3 has five crystallographic polymorphs. 
The room temperature phase, α-Bi2O3 has a monoclinic crystal structure. 
There are three high temperature phases, a tetragonal β-phase, a body-centred cubic γ-phase, a cubic δ-Bi2O3 phase and an ε- phase. 
The room temperature α-phase has a complex structure with layers of oxygen atoms with layers of bismuth atoms between them. 
The bismuth atoms are in two different environments which can be described as distorted 6 and 5 coordinate respectively.

β-Bi2O3 has a structure related to fluorite.

γ-Bi2O3 has a structure related to that of Bi12SiO20 (sillenite), where a fraction of the Bi atoms occupy the position occupied by Si, and may be written as Bi12Bi0.8O19.2.

δ- Bi2O3 has a defective fluorite-type crystal structure in which two of the eight oxygen sites in the unit cell are vacant. 
ε- Bi2O3 has a structure related to the α- and β- phases but as the structure is fully ordered it is an ionic insulator. 
Bismuth Oxide can be prepared by hydrothermal means and transforms to the α- phase at 400 °C.

The monoclinic α-phase transforms to the cubic δ-Bi2O3 when heated above 729 °C, which remains the structure until the melting point, 824 °C, is reached. 
The behaviour of Bi2O3 on cooling from the δ-phase is more complex, with the possible formation of two intermediate metastable phases; the tetragonal β-phase or the body-centred cubic γ-phase. 
The γ-phase can exist at room temperature with very slow cooling rates, but α- Bi2O3 always forms on cooling the β-phase. 
Even though when formed by heat, it reverts to α- Bi2O3 when the temperature drops back below 727 °C, δ-Bi2O3 can be formed directly through electrodeposition and remain relatively stable at room temperature, in an electrolyte of bismuth compounds that is also rich in sodium or potassium hydroxide so as to have a pH near 14.

Conductivity
The α-phase exhibits p-type electronic conductivity (the charge is carried by positive holes) at room temperature which transforms to n-type conductivity (charge is carried by electrons) between 550 °C and 650 °C, depending on the oxygen partial pressure. 
The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the main charge carrier. 
Of these δ- Bi2O3 has the highest reported conductivity. 
At 750 °C the conductivity of δ- Bi2O3 is typically about 1 Scm, about three orders of magnitude greater than the intermediate phases and four orders greater than the monoclinic phase. 
δ- Bi2O3 has a defective fluorite-type crystal structure in which two of the eight oxygen sites in the unit cell are vacant. 
These intrinsic vacancies are highly mobile due to the high polarisability of the cation sub-lattice with the 6s lone pair electrons of Bi. 
The Bi-O bonds have covalent bond character and are therefore weaker than purely ionic bonds, so the oxygen ions can jump into vacancies more freely.

The arrangement of oxygen atoms within the unit cell of δ-Bi2O3 has been the subject of much debate in the past. 
Three different models have been proposed. 
Sillén (1937) used powder X-ray diffraction on quenched samples and reported the structure of Bi2O3 was a simple cubic phase with oxygen vacancies ordered along, i.e. along the cube body diagonal. 
Gattow and Schroder (1962) rejected this model, preferring to describe each oxygen site (8c site) in the unit cell as having 75% occupancy. 
In other words, the six oxygen atoms are randomly distributed over the eight possible oxygen sites in the unit cell. 
Currently, most experts seem to favour the latter description as a completely disordered oxygen sub-lattice accounts for the high conductivity in a better way.

Willis (1965) used neutron diffraction to study the fluorite (CaF2) system. 
He determined that it could not be described by the ideal fluorite crystal structure, rather, the fluorine atoms were displaced from regular 8c positions towards the centres of the interstitial positions. Shuk et al. (1996) and Sammes et al. (1999) suggest that because of the high degree of disorder in δ- Bi2O3, the Willis model could also be used to describe its structure.

Use in Solid-oxide fuel cells (SOFCs)
Interest has centred on δ- Bi2O3 as it is principally an ionic conductor. 
In addition to electrical properties, thermal expansion properties are very important when considering possible applications for solid electrolytes. 
High thermal expansion coefficients represent large dimensional variations under heating and cooling, which would limit the performance of an electrolyte. 
The transition from the high-temperature δ- Bi2O3 to the intermediate β- Bi2O3 is accompanied by a large volume change and consequently, a deterioration of the mechanical properties of the material. 
This, combined with the very narrow stability range of the δ-phase (727–824 °C), has led to studies on its stabilization to room temperature.

Bi2O3 easily forms solid solutions with many other metal oxides. 
These doped systems exhibit a complex array of structures and properties dependent on the type of dopant, the dopant concentration and the thermal history of the sample. 
The most widely studied systems are those involving rare earth metal oxides, Ln2O3, including yttria, Y2O3. 
Rare earth metal cations are generally very stable, have similar chemical properties to one another and are similar in size to Bi, which has a radius of 1.03 Å, making them all excellent dopants. 
Furthermore, their ionic radii decrease fairly uniformly from La+ (1.032 Å), through Nd, (0.983 Å), Gd, (0.938 Å), Dy, (0.912 Å) and Er, (0.89 Å), to Lu, (0.861 Å) (known as the ‘lanthanide contraction’), making them useful to study the effect of dopant size on the stability of the Bi2O3 phases.

Bi2O3 has also been used as sintering additive in the Sc2O3- doped zirconia system for intermediate temperature SOFC.

Preparation
The trioxide can be prepared by ignition of bismuth hydroxide. 
Bismuth trioxide can be also obtained by heating bismuth subcarbonate at approximately 400 °C.

Reactions
Atmospheric carbon dioxide or CO2 dissolved in water readily reacts with Bi2O3 to generate bismuth subcarbonate. 
Bismuth oxide is considered a basic oxide, which explains the high reactivity with CO2. 
However, when acidic cations such as Si(IV) are introduced within the structure of the bismuth oxide, the reaction with CO2 do not occur.

Bismuth oxide reacts with a mixture of concentrated aqueous sodium hydroxide and bromine or aqueous potassium hydroxide and bromine to form sodium bismuthate or potassium bismuthate, respectively.

Medical device usage
Bismuth oxide is occasionally used in dental materials to make them more opaque to X-rays than the surrounding tooth structure. 
In particular, bismuth (III) oxide has been used in hydraulic silicate cements (HSC), originally in "MTA" (a trade name, standing for the chemically-meaningless "mineral trioxide aggregate") from 10 to 20% by mass with a mixture of mainly di- and tri-calcium silicate powders. 
Such HSC is used for dental treatments such as: apicoectomy, apexification, pulp capping, pulpotomy, pulp regeneration, internal repair of iatrogenic perforations, repair of resorption perforations, root canal sealing and obturation. 
MTA sets into a hard filling material when mixed with water. 
Some resin-based materials also include an HSC with bismuth oxide. 
Problems have allegedly arisen with bismuth oxide because it is claimed not to be inert at high pH, specifically that it slows the setting of the HSC, but also over time can lose color by exposure to light or reaction with other materials that may have been used in the tooth treatment, such as sodium hypochlorite.

About Bismuth oxide
Helpful information
Bismuth oxide is registered under the REACH Regulation and is manufactured in and / or imported to the European Economic Area, at ≥ 1 000 to < 10 000 tonnes per annum.

Bismuth oxide is used by consumers, in articles, by professional workers (widespread uses), in formulation or re-packing, at industrial sites and in manufacturing.

Consumer Uses
Bismuth oxide is used in the following products: coating products, adhesives and sealants, fillers, putties, plasters, modelling clay and lubricants and greases. Other release to the environment of Bismuth oxide is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters), outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids), outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials) and indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment).

Article service life
Release to the environment of Bismuth oxide can occur from industrial use: formulation of mixtures, in the production of articles and formulation in materials.
Other release to the environment of Bismuth oxide is likely to occur from: indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment) and outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials).
Bismuth oxide can be found in complex articles, with no release intended: machinery, mechanical appliances and electrical/electronic products (e.g. computers, cameras, lamps, refrigerators, washing machines), vehicles and electrical batteries and accumulators.
Bismuth oxide can be found in products with material based on: plastic (e.g. food packaging and storage, toys, mobile phones), metal (e.g. cutlery, pots, toys, jewellery) and rubber (e.g. tyres, shoes, toys).
Widespread uses by professional workers
Bismuth oxide is used in the following products: laboratory chemicals, coating products, metal surface treatment products, inks and toners, biocides (e.g. disinfectants, pest control products), adhesives and sealants and lubricants and greases.
Bismuth oxide is used in the following areas: health services, building & construction work, scientific research and development and mining.
Bismuth oxide is used for the manufacture of: electrical, electronic and optical equipment, machinery and vehicles and chemicals.
Other release to the environment of Bismuth oxide is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use.
Formulation or re-packing
Bismuth oxide is used in the following products: metal surface treatment products, fillers, putties, plasters, modelling clay, semiconductors, coating products, laboratory chemicals, inks and toners, metals, explosives and polymers.
Release to the environment of Bismuth oxide can occur from industrial use: formulation of mixtures, formulation in materials and in the production of articles.
Uses at industrial sites
Bismuth oxide is used in the following products: metal surface treatment products, laboratory chemicals, coating products, inks and toners, semiconductors, fillers, putties, plasters, modelling clay and lubricants and greases.
Bismuth oxide is used in the following areas: formulation of mixtures and/or re-packaging and building & construction work.
Bismuth oxide is used for the manufacture of: machinery and vehicles, electrical, electronic and optical equipment, plastic products, mineral products (e.g. plasters, cement), fabricated metal products, chemicals and textile, leather or fur.
Release to the environment of Bismuth oxide can occur from industrial use: in the production of articles, in processing aids at industrial sites, as an intermediate step in further manufacturing of another substance (use of intermediates), of substances in closed systems with minimal release and as processing aid.
Manufacture
Release to the environment of Bismuth oxide can occur from industrial use: manufacturing of the substance, as an intermediate step in further manufacturing of another substance (use of intermediates) and as processing aid.

Applications
Bismuth trioxide is raw material for catalysts, ceramic pigments and bismuth salts as bismuth chloride , bismuth vanadate , bismuth germanate , bismuth tungstate, sodium bismuthate, bismuth iodide and bismuth fluoride .

Bismuth oxide is yellow heavy powder or monoclinic crystal, which is odorless and stable in air.
There are two types for pure bismuth trioxide, α type and β type. 
α-bismuth(III) oxide is yellow monoclini crystal with relative density 8.9 and melting point 825℃, which is soluble in acid, however not soluble in water and alkali. 
β-bismuth(III) oxide is bright yellow to orange tetragonal powder with relative density 8.55 and melting point860℃, which is soluble in acid, however not soluble in water. 
They can reduced to bismuth metal by hydrogen and hydrocarbon. 
Bismuth nitrate or bismuth metal is the raw material.

IUPAC NAMES:
[(oxobismuthanyl)oxy]bismuthanone
Bismut(III)-oxid
Bismuth oxide
Bismuth oxide
Bismuth oxide (Bi2O3)
Bismuth trioxide
bismuth trioxide
Bismuth Trioxide
Bismuth Oxide
Bismuthoxide
Dibismuth Trioxide
Dibismuth trioxide
dibismuth trioxide
Dibismuth trioxide
dibismuth trioxide
Dioxodibismoxane

SYNONYMS:
Bismuth(III) oxide
NCGC00166095-01
Bismuth Yellow
Dibismuth trioxide
Bismuth sesquioxide
Bismuthous oxide
Bismutum-oxydatumWimut(III)-oxid
Bismuth(3+) oxide
Bismuth oxide (BiO1.5)
Bismuth sesquioxide (Bi2O3)
oxo(oxobismuthanyloxy)bismuthane
EINECS 215-134-7
Bismuth( cento) oxide
C.I. 77160
DSSTox_CID_26537
DSSTox_RID_81701
DSSTox_GSID_46537
DTXSID8046537
Bismuth(III) oxide, 99.99%
Bismuth( cento) oxide,99.999%
Bismuth(III) oxide, p.a., 98%
Tox21_112312
AKOS015903964
Bismuth( cento) oxide,99.9%,Nanopowder
CAS-1304-76-3
Bismuth(III) oxide, purum, >=98.0% (KT)
EC 215-134-7
Bismuth(III) oxide, >=99.5% (complexometric)
Q252536
Bismuth(III) oxide, powder, 99.999% trace metals basis
Bismuth(III) oxide, nanopowder, 90-210 nm particle size, 99.8% trace metals basis
Bismuth(III) oxide, ReagentPlus(R), powder, 10 mum, 99.9% trace metals basis
BISMUTH OXIDE, (III) 99.9999%
Bismuth(III) oxide,99.9%
Bismuth(III) oxideBismuth trioxide
Bismuth(III) oxide, NanoArc BI-7300, 99.5+%
Bismuth(III) oxide, NanoArc|r BI-7300, 99.5+%
Bismuth(III) oxide, Puratronic (metals basis)
Bismuth (III) oxide NanoArc? BI-7300
Bismuth(III) oxide , powder,sphere (Bi2O3)
High Pure Alpha-Bismuth(Iii) Oxide
Bismuch Trioxide
Bismuth Oxide(Analytically pure)
Bismuth Oxide(High purity)
Bi2-O3
Bismite
Bismuth oxide (Bi2O3)
Bismuth sesquioxide
Bismuth yellow
Bismuthous oxide
bismuthousoxide
bismuthoxide(bi2o3)
BISMUTHOXIDE,99.999%
bismuthsesquioxide
bismuthyellow
C.I. 77160
Bismuth(III) oxide, Puratronic(R), 99.9995% (metals basis)
Bismuth(III) oxide, 99.5% (metals basis)
Bismuth(III) oxide, typically 99.99% (metals basis)
Bismuth(III) oxide, Puratronic(R), 99.999% (metals basis)
Bismuth(III) oxide, 99.975% (metals basis)
BISMUTH OXIDE extrapure
Bismuth(III) oxide, Puratronic, 99.999% (metals basis)
Bismuth (III) oxide, 99,94%
Bismuth(III) oxide, NanoArc, 99.5%
Bismuth(III) oxide, Puratronic, 99.9995% (metals basis)
c.i.77160
Dibismuth trioxide
dibismuthtrioxide
Flowers of bismuth
Bismuthoxideyellowpowder
BISMUTH(III) OXIDE
BISMUTH(III) OXIDE V
BISMUTH(+3)OXIDE
BISMUTH OXIDE
BISMUTH TRIOXIDE
Bismuth(III) oxide, 99.90%
Bismuth(III) oxide, 99.9999%
BISMUTH OXIDE, REAGENT
Bismuth(Ⅲ) oxide
Bismuth(Ⅲ) oxide,99.999%
Bismuth(Ⅲ) oxide,99.9%,Nanopowder
Bismuth(III)oxide(99.9%-Bi)
Bismuth(III)oxide(99.999%-Bi)PURATREM
Bismuth(III)oxide(99.9998%-Bi)PURATREM
bismuth(iii) oxide, puratronic
BISMUTH()OXIDE,99.9%,NANOPOWDER
BISMUTHTRIOXIDE,REAGENT
Dibismuttrioxid
Bismuth(III) oxide, nanopowder, 99.9+% metals basis