Calcium hexaboride CaB6
CaB6 · CAS 12007-99-7 · cubic, Pm-3m
Also known as Calcium boride, Calcium hexaboride
Calcium hexaboride (CaB6, CAS 12007-99-7) is a black cubic boride powder.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Recipe, share of the weight
- Ca not statedCalcium
- B not statedBoron
Best for
Deoxidising copper melts and adding boron to refractories, where the boride is a powder and an oxidation start near 1273 K is acceptable
Weakest at
Oxidation in air from 1273 K (hot-pressed sintered body) and reaction with strong oxidising agents; no hardness or electrical value with a printed unit was found in a source read
Risk at a glance
- People None found. Irritant: H315, H319 and H335
- If it fails Moderate. Oxidation of hot-pressed CaB6 in air
- Corrosion Moderate. Oxidation starts near 1273 K in a hot-pressed sintered body, and weight gain rises with temperature.
Quick facts: CaB6
| Property | Value | Basis |
|---|---|---|
| Density | 2.3 to 2.33 g/cm³ | 4 sourced values across conditions |
| Melting point | 2,200 to 2,235 °C | 4 sourced values across conditions |
What is the density of Calcium hexaboride (CaB6)?
Calcium hexaboride (CaB6) has a density of 2.3 to 2.33 g/cm³. The range covers 4 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the melting point of Calcium hexaboride (CaB6)?
Calcium hexaboride (CaB6) has a melting point of 2,200 to 2,235 °C. The range covers 4 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Calcium hexaboride (CaB6)?
Calcium hexaboride (CaB6) is also written as Calcium boride, Calcium hexaboride. Each code is printed in the source listed beside it in the designations table.
What is Calcium hexaboride (CaB6) used for?
Uses recorded in the sources include Deoxidiser for high-conductivity (oxygen-free) copper melts; Neutron-protection material in the nuclear industry; Boron additive for dolomite carbon and magnesia dolomite refractories.
Why it exists
Calcium hexaboride (CaB6) is a cubic boride powder. Vendors sell it for three jobs: as a deoxidiser that removes oxygen from copper melts, as a boron additive for refractories, and as a neutron-protection material. The vendors' data sheets and the two supplier SDS documents agree on a density of 2.3 to 2.33 g/cm3 and a melting point of 2230 °C to 2235 °C. The 1999 oxidation abstract sets the main limit: oxidation starts at 1273 K in air.
Where it's used
Copper refining
The vendor says CaB6 is a deoxidising and degassing agent for high-conductivity copper. The page gives no test result for the copper.
Refractories
Vendors add CaB6 as a boron-containing additive to dolomite and magnesia dolomite refractories (vendor pages).
Nuclear shielding
FUSnano lists CaB6 as a neutron protection material for the nuclear industry. No shielding value is given on the page.
Recipe
CaB6
CaB6 is calcium hexaboride: one calcium atom for every six boron atoms in a cubic framework (space group Pm-3m). The boron atoms form octahedral cages around the centre of the cube, and the calcium sits at the cube corners (AFLOW prototype; Lee and Wang 2005).
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Calcium Ca | not stated | Sits at the cube corners of the unit cell and sets the cubic lattice with the boron framework. The vendor uses calcium as the metal in the boride. |
| Boron B | not stated | Forms B6 octahedra that give the boride its hardness and high melting point. Boron is also the part that stays dissolved in copper when CaB6 is used as a deoxidiser (vendor description). |
Weight shares are as printed in the sources.
What it can do
Melt deoxidation
The vendor says it is used as a deoxidising and degassing agent for high-conductivity copper. The page gives no test result for the copper.
Air limit
Oxidation in air starts at 1273 K for a hot-pressed sintered body (Matsushita and Komarneni 1999). Above that temperature it is not a suitable choice for air exposure, according to this one abstract.
Melting point
The vendor gives 2230 °C and the Stanford Advanced Materials SDS gives 2235 °C for the melting point.
Solubility
Insoluble in water and in several acids, per the vendor page and the BeanTown SDS.
How it compares
Within this profile, CaB6 has a density of 2.33 g/cm3 on the vendor pages and 2.3 g/cm3 on the SDS documents, and a melting point of 2230 °C (vendor) or 2235 °C (SDS). The sources read do not give CaB6 values for a direct ranking against other borides or against metals used for deoxidation, so no ranking is claimed here. No copper deoxidation test was read.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | CaB6 | CrB2 | LaB6 | TM borides | MoSi2 | TiB2 | MSi2 |
|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | |||||||
| Melting point, CaB6 powder (Heeger Materials, More info text) | 2230 °C5 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C | 2160 °C |
| Melting point, CaB6 powder (Heeger Materials, bulleted list) | 2200 °C6 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C | 2160 °C |
| Melting point, CaB6 powder (FUSnano) | 2230 °C7 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C | 2160 °C |
| Melting point, calcium boride (Stanford Advanced Materials SDS) | 2235 °C8 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C | 2160 °C |
| Oxidation start temperature, hot-pressed CaB6 sintered body | 1273 K11 | no data | 500 °C | no data | no data | no data | no data |
| Physical and electrical | |||||||
| Relative density, CaB6 powder (Heeger Materials) | 2.33 g/cm³1 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ | 9.3 g/cm³ |
| Relative density, CaB6 powder (FUSnano) | 2.33 g/cm³2 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ | 9.3 g/cm³ |
| Density at 20 °C, calcium boride (BeanTown SDS) | 2.3 g/cm³3 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ | 9.3 g/cm³ |
| Density, calcium boride (Stanford Advanced Materials SDS) | 2.3 g/cm³4 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ | 9.3 g/cm³ |
| Other measurements | |||||||
| Molecular weight, CaB6 | 104.9 g/mol9 | no data | no data | no data | no data | no data | no data |
| Molecular weight, calcium boride (Stanford Advanced Materials SDS) | 104.9 g/mol10 | no data | no data | no data | no data | no data | no data |
| Purity, CaB6 powder grade (Heeger Materials, vendor grade) | 99.9 %12 | no data | no data | no data | no data | no data | no data |
| Purity, CaB6 powder (FUSnano general range) | 99 to 99.9 %13 | no data | no data | no data | no data | no data | no data |
Why choose it, and why not
Good for
- Deoxidising copper melts, as the vendor describes (vendor page, no test result given).
- Adding boron to refractories as a dolomite additive (vendor).
Watch out for
- Oxidation in air from 1273 K for a hot-pressed sintered body (Matsushita and Komarneni 1999).
- Irritation hazards H315, H319 and H335 on both supplier safety data sheets.
- Melting point conflicts between sources: 2200 °C and 2230 °C on one vendor page, 2235 °C on the SDS, and Undetermined on another SDS.
CaB6 is a dense, high-melting boride powder sold for copper deoxidation, refractory additives and neutron shielding. The sources read support its melting point and density, and they show oxidation in air from 1273 K. Hardness, conductivity and space test data are missing from the sources read.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | Calcium boride, Calcium hexaboride |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Relative density, CaB6 powder (Heeger Materials) | Printed as "Relative density" with the value 2.33 and the unit g/cm (the superscript 3 is missing on the page); the unit is taken as g/cm3 by convention, and the printed form is kept in the source | form powder, product HM-CaB6 seriestemperature not stated | — |
| 2 | Relative density, CaB6 powder (FUSnano) | Printed as "Relative density: 2.33g/cm" on the product page (unit printed without the superscript 3) | form powder, CaB6 grades MI325 and MI325Ltemperature not stated | — |
| 3 | Density at 20 °C, calcium boride (BeanTown SDS) | Section 9 of the safety data sheet, printed as "Density at 20 °C (68 °F): 2.3 g/cm³" | temperature 20 °Cform solid, powder | — |
| 4 | Density, calcium boride (Stanford Advanced Materials SDS) | Section 9 of the safety data sheet, printed as "Density: 2.3 g/cc" (unit g/cc read as g/cm3) | form powdertemperature not stated | — |
| 5 | Melting point, CaB6 powder (Heeger Materials, More info text) | Printed as "2230℃" in the More info text of the product page | form powderatmosphere not stated | The same product page gives 2200 °C in its bulleted property list. The two values are kept side by side. |
| 6 | Melting point, CaB6 powder (Heeger Materials, bulleted list) | Printed as "2200°C" in the bulleted property list of the same product page | form powderatmosphere not stated | Conflicts with the 2230 °C value on the same page; kept so that the conflict is visible. |
| 7 | Melting point, CaB6 powder (FUSnano) | Printed as "2230 ℃" in the property list of the product page | form powderatmosphere not stated | — |
| 8 | Melting point, calcium boride (Stanford Advanced Materials SDS) | Section 9 of the safety data sheet, printed as "Melting Point: 2235 °C" | form black powder | The BeanTown Chemical safety data sheet for the same CaB6 product lists the melting point as "Undetermined" (Section 9). |
| 9 | Molecular weight, CaB6 | Printed as "Molecular weight 104.94 g/mol" on the specification sheet (not a measured value); a custom property name, as it is not in spores/property-canon.yaml | basis CaB6 formula weight as printed on the specification sheet | — |
| 10 | Molecular weight, calcium boride (Stanford Advanced Materials SDS) | Section 9 of the safety data sheet, printed as "Molecular weight: 104.94 g/mol"; a custom property name | form powder, CaB6 (100 wt%) | — |
| 11 | Oxidation start temperature, hot-pressed CaB6 sintered body | Quoted in the abstract: "The oxidation of samples started at 1273 K"; the abstract gives no weight-gain magnitude. Custom property name; the start of oxidation, not a service limit | sample hot-pressed CaB6 sintered bodyatmosphere not stated in the abstracttime not stated in the abstract | The abstract gives weight gain rising with oxidation temperature but no magnitude. A separate 2009 abstract for a nickel-sintered CaB6 reports catastrophic oxidation from 1273 K; it was not read in full and is not used. |
| 12 | Purity, CaB6 powder grade (Heeger Materials, vendor grade) | Printed as "Purity: 99.9%" in the data sheet section of the product page | grade vendor data sheet grade HM-CaB6 (200 mesh, 500 mesh and 20 µm listed)basis vendor product grade, not an intrinsic property of CaB6 | — |
| 13 | Purity, CaB6 powder (FUSnano general range) | Printed as "Purity (general): 99% - 99.9%" on the product page; vendor claim, not a test result | basis general range offered by the vendor; the page's table also lists a grade with purity of 95% or moregrade general range | The FUSnano table lists a lower-purity grade (CaB6-MI325L), so this range is not the lowest grade offered. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at high temperature (hot-pressed CaB6 sintered body) | moderate | Oxidation starts near 1273 K in a hot-pressed sintered body, and weight gain rises with temperature.1 |
| Water, acids, alkali and strong oxidants (temperatures and concentrations not stated) | low | CaB6 is insoluble in water and in some acids, but strong oxidants attack it.2 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at high temperature (hot-pressed CaB6 sintered body) | Matsushita and Komarneni (1999) investigated the high-temperature oxidation of hot-pressed CaB6 to judge its use at high temperature. The oxidation of samples started at 1273 K, and weight gain increased with oxidation temperature. The abstract gives no atmosphere, time or weight-gain magnitude. | sample hot-pressed CaB6 sintered bodyatmosphere not stated in the abstracttime not stated in the abstract |
| 2 | Water, acids, alkali and strong oxidants (temperatures and concentrations not stated) | The Heeger Materials page says the powder is stable in air at high temperature, is insoluble in hydrochloric, hydrofluoric and dilute sulfuric acid, does not react with water, and is attacked by strong oxidants such as chlorine, fluorine, nitric acid and hydrogen peroxide. It reacts very slowly with alkali. The BeanTown SDS also says it is insoluble in water and dissolves slowly in acids. | basis vendor product page and supplier SDS; test temperatures and concentrations not given |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Both supplier safety data sheets classify the powder as an irritant. Neither gives toxicology values.
- Skin and eyes
- Causes skin irritation (H315) and serious eye irritation (H319), per the Stanford Advanced Materials SDS. The BeanTown SDS gives the same skin and eye hazards.
- Dust
- May cause respiratory irritation (H335). Avoid breathing the dust, and use a dust respirator, gloves and eye protection.
- In a fire
- The SDS lists borane and boron oxides and calcium oxide as decomposition products.
If the powder is heated in air
These results come from one 1999 abstract for a hot-pressed sintered body, not from field incidents.
- Oxidation start
- Oxidation of hot-pressed CaB6 starts at 1273 K, and weight gain rises as the oxidation temperature goes up (Matsushita and Komarneni 1999).
- Oxidising agents
- The SDS says the powder reacts with oxidising agents, so keep it away from them.
Handling and storage
- Storage
- Store the powder sealed in a dry, cool place. Long exposure to air can cause moisture agglomeration (vendor).
- Spills
- Vacuum spills with a HEPA filter and avoid raising dust (Stanford Advanced Materials SDS).
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Oxidation of hot-pressed CaB6 in airmoderate severity | Heating a hot-pressed sintered body in air from about 1273 KOxidation starts at 1273 K and weight gain rises with temperature (Matsushita and Komarneni 1999). The abstract does not report the oxidation products or their phases. |
| Moisture agglomeration of the powderlow severity | Long exposure to moist airThe vendor says long air exposure can cause moisture agglomeration, so the powder should be stored sealed in a dry, cool place. |
| Reaction with strong oxidising agentsmoderate severity | Contact with oxidising agentsThe safety data sheet lists oxidizing agents as the substance it reacts with, and says it is stable under recommended storage conditions. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Surrounding material and people in a fire or thermal decomposition | On decomposition the Stanford Advanced Materials safety data sheet lists borane and boron oxides and calcium oxide as hazardous decomposition products. |
Handling and storage
- Keep the container tightly closed in a dry, cool, well-ventilated place away from moisture and oxidising agents (Stanford Advanced Materials SDS and vendor pages).
- Vacuum up spills with a HEPA filter and place them in a closed container, taking care not to raise dust (Stanford Advanced Materials SDS).
- Wear a dust respirator, rubber gloves and safety glasses or goggles (Stanford Advanced Materials SDS, PPE section).
Mitigations
- Avoid long air exposure and heavy pressure on the powder, and keep it away from oxidants (Heeger Materials product page).
Supply and geography
How common the raw materials are and where they come from.
Boron (the boron half of CaB6)
USGS 2026: the 2025 world production total is withheld (XX), so shares are not calculated. 2025 production as printed: Turkey 1,500 thousand t of refined borates, Bolivia 380 thousand t of ulexite, Peru 220 thousand t of crude borates, and China 230 thousand t as boric oxide equivalent.
- Critical mineral lists
- US: listed
- Recycling
- USGS: insignificant.
- Substitutes
- USGS: boron can be substituted in detergents, enamels, insulation and soaps (the chapter does not discuss boride powders).
Calcium
Not found in any source read in this run.
- Recycling
- Not found in any source read in this run.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: calcium-hexaboride
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Calcium hexaboride
abbreviation: CaB6
role: hard boride powder used as a copper deoxidiser, refractory additive and neutron-protection material
category: ceramics
type: ultra-high-temperature-ceramics
summary: |
Calcium hexaboride (CaB6, CAS 12007-99-7) is a black cubic boride powder. Vendor datasheets give a relative density of 2.33 g/cm3 and a melting point of 2230 °C, and a supplier safety data sheet gives 2235 °C. Matsushita and Komarneni (1999) report that hot-pressed CaB6 begins to oxidise at 1273 K. Suppliers sell it as a deoxidiser for high-conductivity copper and as a boron additive for refractories.
best_for: Deoxidising copper melts and adding boron to refractories, where the boride is a powder and an oxidation start near 1273 K is acceptable
weakest_at: Oxidation in air from 1273 K (hot-pressed sintered body) and reaction with strong oxidising agents; no hardness or electrical value with a printed unit was found in a source read
identity:
formula: CaB6
cas: 12007-99-7
crystal_system: cubic
space_group: Pm-3m
source: aflow-cab6
where: 'AFLOW prototype A6B_cP7_221_e_b-001 (CaB6): Pearson symbol cP7, space group Pm-3m (No. 221); CAS 12007-99-7 from samaterials-sds-cab6, Section 3'
designations:
- system: Trade name
code: Calcium boride
source: samaterials-sds-cab6
where: Section 1, Trade Name line
- system: Trade name
code: Calcium hexaboride
source: beantown-sds-cab6
where: Section 1, Trade name line
tags:
environments: []
stresses:
- extreme-heat
applications:
- radiation-shielding
- electronics-and-chips
- structures
properties:
- benchmark: density
label: Relative density, CaB6 powder (Heeger Materials)
value: 2.33
unit: g/cm3
scope: material
conditions:
form: powder, product HM-CaB6 series
temperature: not stated
method: Printed as "Relative density" with the value 2.33 and the unit g/cm (the superscript 3 is missing on the page); the unit is taken as g/cm3 by convention, and the printed form is kept in the source
status: ground
source: heeger-cab6
where: Product page, More info text and property list (Relative density)
- benchmark: density
label: Relative density, CaB6 powder (FUSnano)
value: 2.33
unit: g/cm3
scope: material
conditions:
form: powder, CaB6 grades MI325 and MI325L
temperature: not stated
method: 'Printed as "Relative density: 2.33g/cm" on the product page (unit printed without the superscript 3)'
status: ground
source: fusnano-cab6
where: Product page, property list (Relative density)
- benchmark: density
label: Density at 20 °C, calcium boride (BeanTown SDS)
value: 2.3
unit: g/cm3
scope: material
conditions:
temperature: 20 °C
form: solid, powder
method: 'Section 9 of the safety data sheet, printed as "Density at 20 °C (68 °F): 2.3 g/cm³"'
status: ground
source: beantown-sds-cab6
where: Section 9, Physical and chemical properties
- benchmark: density
label: Density, calcium boride (Stanford Advanced Materials SDS)
value: 2.3
unit: g/cm3
scope: material
conditions:
form: powder
temperature: not stated
method: 'Section 9 of the safety data sheet, printed as "Density: 2.3 g/cc" (unit g/cc read as g/cm3)'
status: ground
source: samaterials-sds-cab6
where: Section 9, Physical and Chemical Characteristics
- benchmark: melting_point
label: Melting point, CaB6 powder (Heeger Materials, More info text)
value: 2230
unit: °C
scope: material
conditions:
form: powder
atmosphere: not stated
method: Printed as "2230℃" in the More info text of the product page
status: ground
note: The same product page gives 2200 °C in its bulleted property list. The two values are kept side by side.
source: heeger-cab6
where: Product page, More info text (Melting point)
- benchmark: melting_point
label: Melting point, CaB6 powder (Heeger Materials, bulleted list)
value: 2200
unit: °C
scope: material
conditions:
form: powder
atmosphere: not stated
method: Printed as "2200°C" in the bulleted property list of the same product page
status: ground
note: Conflicts with the 2230 °C value on the same page; kept so that the conflict is visible.
source: heeger-cab6
where: Product page, bulleted list (Melting point)
- benchmark: melting_point
label: Melting point, CaB6 powder (FUSnano)
value: 2230
unit: °C
scope: material
conditions:
form: powder
atmosphere: not stated
method: Printed as "2230 ℃" in the property list of the product page
status: ground
source: fusnano-cab6
where: Product page, property list (Melting point)
- benchmark: melting_point
label: Melting point, calcium boride (Stanford Advanced Materials SDS)
value: 2235
unit: °C
scope: material
conditions:
form: black powder
method: 'Section 9 of the safety data sheet, printed as "Melting Point: 2235 °C"'
status: ground
note: The BeanTown Chemical safety data sheet for the same CaB6 product lists the melting point as "Undetermined" (Section 9).
source: samaterials-sds-cab6
where: Section 9, Physical and Chemical Characteristics
- benchmark: molar_mass
label: Molecular weight, CaB6
value: 104.94
unit: g/mol
scope: material
conditions:
basis: CaB6 formula weight as printed on the specification sheet
method: Printed as "Molecular weight 104.94 g/mol" on the specification sheet (not a measured value); a custom property name, as it is not in spores/property-canon.yaml
status: calculated
source: molekula-spec-cab6
where: Page 1, header table and product table (Molecular weight)
- benchmark: molar_mass
label: Molecular weight, calcium boride (Stanford Advanced Materials SDS)
value: 104.94
unit: g/mol
scope: material
conditions:
form: powder, CaB6 (100 wt%)
method: 'Section 9 of the safety data sheet, printed as "Molecular weight: 104.94 g/mol"; a custom property name'
status: ground
source: samaterials-sds-cab6
where: Section 9, Physical and Chemical Characteristics
- benchmark: oxidation_onset_temp
label: Oxidation start temperature, hot-pressed CaB6 sintered body
value: 1273
unit: K
scope: material
conditions:
sample: hot-pressed CaB6 sintered body
atmosphere: not stated in the abstract
time: not stated in the abstract
method: 'Quoted in the abstract: "The oxidation of samples started at 1273 K"; the abstract gives no weight-gain magnitude. Custom property name; the start of oxidation, not a service limit'
status: ground
note: The abstract gives weight gain rising with oxidation temperature but no magnitude. A separate 2009 abstract for a nickel-sintered CaB6 reports catastrophic oxidation from 1273 K; it was not read in full and is not used.
source: matsushita-1999
where: Abstract
- benchmark: purity
label: Purity, CaB6 powder grade (Heeger Materials, vendor grade)
value: 99.9
unit: '%'
scope: material
conditions:
grade: vendor data sheet grade HM-CaB6 (200 mesh, 500 mesh and 20 µm listed)
basis: vendor product grade, not an intrinsic property of CaB6
method: 'Printed as "Purity: 99.9%" in the data sheet section of the product page'
status: ground
source: heeger-cab6
where: Product page, data sheet (Purity)
- benchmark: purity
label: Purity, CaB6 powder (FUSnano general range)
value: 99
value_high: 99.9
bound: range
unit: '%'
scope: material
conditions:
basis: general range offered by the vendor; the page's table also lists a grade with purity of 95% or more
grade: general range
method: 'Printed as "Purity (general): 99% - 99.9%" on the product page; vendor claim, not a test result'
status: ground
note: The FUSnano table lists a lower-purity grade (CaB6-MI325L), so this range is not the lowest grade offered.
source: fusnano-cab6
where: Product page, general product description (Purity)
corrosion:
- environment: Air at high temperature (hot-pressed CaB6 sintered body)
headline: Oxidation starts near 1273 K in a hot-pressed sintered body, and weight gain rises with temperature.
effect: Matsushita and Komarneni (1999) investigated the high-temperature oxidation of hot-pressed CaB6 to judge its use at high temperature. The oxidation of samples started at 1273 K, and weight gain increased with oxidation temperature. The abstract gives no atmosphere, time or weight-gain magnitude.
rating: moderate
conditions:
sample: hot-pressed CaB6 sintered body
atmosphere: not stated in the abstract
time: not stated in the abstract
source: matsushita-1999
where: Abstract
- environment: Water, acids, alkali and strong oxidants (temperatures and concentrations not stated)
headline: CaB6 is insoluble in water and in some acids, but strong oxidants attack it.
effect: The Heeger Materials page says the powder is stable in air at high temperature, is insoluble in hydrochloric, hydrofluoric and dilute sulfuric acid, does not react with water, and is attacked by strong oxidants such as chlorine, fluorine, nitric acid and hydrogen peroxide. It reacts very slowly with alkali. The BeanTown SDS also says it is insoluble in water and dissolves slowly in acids.
rating: low
conditions:
basis: vendor product page and supplier SDS; test temperatures and concentrations not given
source: heeger-cab6
where: Product page, chemical resistance statement
risks:
hazards:
- text: 'Supplier safety data sheet (Stanford Advanced Materials, Calcium Boride): classified with hazard statements H315 (causes skin irritation), H319 (causes serious eye irritation) and H335 (may cause respiratory irritation); signal word Warning.'
ghs:
- H315
- H319
- H335
source: samaterials-sds-cab6
where: Section 2, Hazards Identification
- text: 'BeanTown Chemical safety data sheet for calcium hexaboride (OSHA HCS format): skin irritation category 2 (H315) and serious eye irritation category 2A (H319). It gives no H335 entry.'
ghs:
- H315
- H319
source: beantown-sds-cab6
where: Section 2, Hazard(s) identification, GHS classification
failure_risks:
- mode: Oxidation of hot-pressed CaB6 in air
trigger: Heating a hot-pressed sintered body in air from about 1273 K
consequence: Oxidation starts at 1273 K and weight gain rises with temperature (Matsushita and Komarneni 1999). The abstract does not report the oxidation products or their phases.
severity: moderate
source: matsushita-1999
where: Abstract
- mode: Moisture agglomeration of the powder
trigger: Long exposure to moist air
consequence: The vendor says long air exposure can cause moisture agglomeration, so the powder should be stored sealed in a dry, cool place.
severity: low
source: heeger-cab6
where: Product page, storage statement
- mode: Reaction with strong oxidising agents
trigger: Contact with oxidising agents
consequence: The safety data sheet lists oxidizing agents as the substance it reacts with, and says it is stable under recommended storage conditions.
severity: moderate
source: samaterials-sds-cab6
where: Section 10, Reactivity
side_effects:
- text: On decomposition the Stanford Advanced Materials safety data sheet lists borane and boron oxides and calcium oxide as hazardous decomposition products.
affects: Surrounding material and people in a fire or thermal decomposition
source: samaterials-sds-cab6
where: Section 10, Hazardous Decomposition Products
handling:
- text: Keep the container tightly closed in a dry, cool, well-ventilated place away from moisture and oxidising agents (Stanford Advanced Materials SDS and vendor pages).
source: samaterials-sds-cab6
where: Section 7, Storage Conditions
- text: Vacuum up spills with a HEPA filter and place them in a closed container, taking care not to raise dust (Stanford Advanced Materials SDS).
source: samaterials-sds-cab6
where: Section 6, Accidental Release Measures
- text: Wear a dust respirator, rubber gloves and safety glasses or goggles (Stanford Advanced Materials SDS, PPE section).
source: samaterials-sds-cab6
where: Section 8, Exposure Controls
mitigations:
- text: Avoid long air exposure and heavy pressure on the powder, and keep it away from oxidants (Heeger Materials product page).
source: heeger-cab6
where: Product page, storage and handling statements
uses:
- application: electronics-and-chips
device: Deoxidiser for high-conductivity (oxygen-free) copper melts
example: The vendor says CaB6 is a deoxidising and degassing agent for high-conductivity copper. The page gives no test result or copper conductivity value.
source: heeger-cab6
where: Product page, applications list (deoxidizing and degassing agent for high-conductivity copper)
- application: radiation-shielding
device: Neutron-protection material in the nuclear industry
example: The FUSnano page lists CaB6 as a neutron protection material for the nuclear industry. No neutron cross-section or shielding thickness is given on the page.
source: fusnano-cab6
where: Product page, applications list
- application: structures
device: Boron additive for dolomite carbon and magnesia dolomite refractories
example: The Heeger Materials page lists CaB6 as a boron-containing additive for dolomite and magnesium dolomite refractories; the FUSnano page lists the same use for dolomite carbon and magnesia dolomite carbon refractories.
source: heeger-cab6
where: Product page, applications list
supply:
- subject: Boron (the boron half of CaB6)
abundance: 'USGS 2026: the 2025 world production total is withheld (XX), so shares are not calculated. 2025 production as printed: Turkey 1,500 thousand t of refined borates, Bolivia 380 thousand t of ulexite, Peru 220 thousand t of crude borates, and China 230 thousand t as boric oxide equivalent.'
producers: []
critical_lists:
- list: USGS Final 2025 List of Critical Minerals, published 7 Nov 2025 (boron added in the 2025 list)
listed: true
recycling: 'USGS: insignificant.'
substitutes:
- 'USGS: boron can be substituted in detergents, enamels, insulation and soaps (the chapter does not discuss boride powders).'
source: usgs-mcs2026-boron
where: World Production and Reserves table, 2025 column; Recycling; Substitutes; Events, Trends and Issues (critical minerals paragraph)
- subject: Calcium
abundance: Not found in any source read in this run.
producers: []
critical_lists: []
recycling: Not found in any source read in this run.
substitutes: []
source: usgs-mcs2026-boron
where: Left empty. No calcium producer or feedstock source was read; the USGS boron chapter does not cover calcium.
media: []
documents:
- title: Heeger Materials, Calcium Hexaboride (CaB6) Powder product page
type: datasheet
url: https://heegermaterials.com/boride-powders/1321-calcium-hexaboride-cab6-powder.html
year: 2026
- title: FUSnano, Calcium Hexaboride Powder product page
type: datasheet
url: https://www.fusnano.com/boride/calcium-hexaboride-powder.html
year: 2026
- title: Stanford Advanced Materials, Safety Data Sheet, Calcium Boride (CaB6)
type: sds
url: https://samaterials.com/tds/sc/1735206667-BR0228.pdf
year: 2024
- title: BeanTown Chemical, Safety Data Sheet, Calcium hexaboride (article 216185, reviewed 07/08/2024)
type: sds
url: https://s3.amazonaws.com/beantown/216185.pdf
year: 2024
- title: Molekula Ltd, Technical Data Sheet, Calcium hexaboride (product 90027985, v1)
type: datasheet
url: https://molekula.com/specification/90027985.pdf
year: 2026
- title: USGS Mineral Commodity Summaries 2026, Boron
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
year: 2026
- title: Matsushita J and Komarneni S, High temperature oxidation behavior of CaB6 sintered body, J. Mater. Sci. 34(13), 3043-3046
type: paper
url: https://pure.psu.edu/en/publications/high-temperature-oxidation-behavior-of-cabsub6sub-sintered-body/
year: 1999
- title: Lee B and Wang L-W, Electronic Structure of Calcium Hexaborides (Lawrence Berkeley National Laboratory, eScholarship)
type: paper
url: https://escholarship.org/content/qt0370311w/qt0370311w.pdf
year: 2005
- title: AFLOW Encyclopedia of Crystallographic Prototypes, A6B_cP7_221_e_b-001 (CaB6)
type: database
url: https://aflow.org/p/A6B_cP7_221_e_b-001
year: 2026
gaps:
- No hardness value with a printed unit was found in a source read. The Heeger Materials page gives a hardness figure with no scale or unit, so it is left out. Wikipedia's microhardness figure is not used because Wikipedia is limited to composition and history here.
- No thermal conductivity, electrical resistivity, elastic modulus or thermal expansion value for CaB6 was found in a source read in this run.
- 'The vendor''s Curie temperature claim for spintronic use (Heeger Materials page) is not used: no test source was read and the vendor gives no measurement method.'
- 'Melting point is not settled: 2200 °C and 2230 °C are both printed on the Heeger Materials page, FUSnano gives 2230 °C, the Stanford Advanced Materials SDS gives 2235 °C, and the BeanTown SDS lists it as Undetermined. Wikipedia''s melting point figure is not used.'
- Density is 2.33 g/cm3 from two vendor pages and 2.3 g/cm3 from two SDS documents; a higher Wikipedia density figure is not used.
- 'Calcium supply and producers: no source read in this run. The supply entry for calcium is empty.'
- 'The PubChem record (CID 16212529, named in Wikipedia) could not be opened: the browser check blocked the page. The GHS hazard entries rest on two supplier safety data sheets, not on PubChem''s aggregated classification.'
- Copper deoxidation performance is not tested here. The 3M datasheet returned HTTP 403, and no copper conductivity figure was read from a fetched page. Only the vendor's use statement is recorded.
- The 1999 oxidation abstract gives no atmosphere, time or weight-gain magnitude. A 2009 abstract for nickel-sintered CaB6 reports fast oxidation from 1273 K but was not read in full, so it is not used.
- The 2019 high-pressure CaB6 study (cpb.iphy.ac.cn) returned a 404 page, so its lattice and bulk-modulus values are not used.
- Lattice constant and internal parameter x are not recorded as properties. The 2005 LBNL paper (Lee and Wang) gives an experimental lattice-constant range and an internal-parameter range, but its eScholarship copy blocked the automated check (HTTP 403), so the values could not be matched to the page. The paper is kept as a source for the crystal-structure text only.
- No UNS, EN, DIN, JIS or AISI designation is printed for CaB6 in a source read. The EC number 234-525-3 is printed on two SDS documents but is not in the designation systems this profile uses.
- Hazard data rest on two supplier safety data sheets; both report H315, H319 and H335 or H315 and H319, and neither gives toxicology values.
- No space flight or space-environment test of CaB6 was found in a source read. Its listed use in spacecraft or nuclear shielding is a vendor claim with no test data.
sources:
heeger-cab6:
title: Heeger Materials, Calcium Hexaboride (CaB6) Powder product page (reference HMBP-1321)
url: https://heegermaterials.com/boride-powders/1321-calcium-hexaboride-cab6-powder.html
kind: web
license: vendor web page, cited not reproduced
fusnano-cab6:
title: FUSnano, Calcium Hexaboride Powder product page
url: https://www.fusnano.com/boride/calcium-hexaboride-powder.html
kind: web
license: vendor web page, cited not reproduced
samaterials-sds-cab6:
title: Stanford Advanced Materials, Safety Data Sheet, Calcium Boride (CaB6)
url: https://samaterials.com/tds/sc/1735206667-BR0228.pdf
kind: datasheet
license: supplier SDS, cited not reproduced
beantown-sds-cab6:
title: BeanTown Chemical, Safety Data Sheet, Calcium hexaboride (article 216185), printed 07/09/2024
url: https://s3.amazonaws.com/beantown/216185.pdf
kind: datasheet
license: supplier SDS, cited not reproduced
molekula-spec-cab6:
title: Molekula Ltd, Technical Data Sheet, Calcium hexaboride (product 90027985)
url: https://molekula.com/specification/90027985.pdf
kind: datasheet
license: supplier specification, cited not reproduced
usgs-mcs2026-boron:
title: USGS Mineral Commodity Summaries 2026, Boron
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
kind: report
license: US government work, public domain
matsushita-1999:
title: Matsushita J and Komarneni S, High temperature oxidation behavior of CaB6 sintered body, Journal of Materials Science 34(13), 3043-3046 (1999)
url: https://pure.psu.edu/en/publications/high-temperature-oxidation-behavior-of-cabsub6sub-sintered-body/
kind: paper
license: research-output record (abstract read)
lee-wang-2005:
title: Lee B and Wang L-W, Electronic Structure of Calcium Hexaborides (Lawrence Berkeley National Laboratory, 2005), eScholarship item 0370311w
url: https://escholarship.org/content/qt0370311w/qt0370311w.pdf
kind: paper
license: open repository (eScholarship)
aflow-cab6:
title: AFLOW Encyclopedia of Crystallographic Prototypes, A6B_cP7_221_e_b-001 (CaB6, ICSD 26753)
url: https://aflow.org/p/A6B_cP7_221_e_b-001
kind: database
license: AFLOW public database
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 13
unreachable: 3
caveats: 4
note: 'Written on 2026-11-01 from the Heeger Materials and FUSnano product pages, the Stanford Advanced Materials and BeanTown Chemical safety data sheets, the Molekula specification, USGS MCS 2026 boron, Matsushita and Komarneni (1999) abstract, Lee and Wang (2005) LBNL paper (saved PDF), and the AFLOW prototype page. Unreachable: PubChem (browser check), the 3M datasheet (403), the 2019 high-pressure CaB6 page (404).'
story:
recipe:
line: 'CaB6 is calcium hexaboride: one calcium atom for every six boron atoms in a cubic framework (space group Pm-3m). The boron atoms form octahedral cages around the centre of the cube, and the calcium sits at the cube corners (AFLOW prototype; Lee and Wang 2005).'
parts:
- name: Calcium
symbol: Ca
role: Sits at the cube corners of the unit cell and sets the cubic lattice with the boron framework. The vendor uses calcium as the metal in the boride.
- name: Boron
symbol: B
role: Forms B6 octahedra that give the boride its hardness and high melting point. Boron is also the part that stays dissolved in copper when CaB6 is used as a deoxidiser (vendor description).
risk_groups:
- title: For people
level: 0
verdict: 'Irritant: H315, H319 and H335'
lead: Both supplier safety data sheets classify the powder as an irritant. Neither gives toxicology values.
points:
- label: Skin and eyes
line: Causes skin irritation (H315) and serious eye irritation (H319), per the Stanford Advanced Materials SDS. The BeanTown SDS gives the same skin and eye hazards.
- label: Dust
line: May cause respiratory irritation (H335). Avoid breathing the dust, and use a dust respirator, gloves and eye protection.
- label: In a fire
line: The SDS lists borane and boron oxides and calcium oxide as decomposition products.
- title: If the powder is heated in air
lead: These results come from one 1999 abstract for a hot-pressed sintered body, not from field incidents.
points:
- label: Oxidation start
line: Oxidation of hot-pressed CaB6 starts at 1273 K, and weight gain rises as the oxidation temperature goes up (Matsushita and Komarneni 1999).
- label: Oxidising agents
line: The SDS says the powder reacts with oxidising agents, so keep it away from them.
- title: Handling and storage
points:
- label: Storage
line: Store the powder sealed in a dry, cool place. Long exposure to air can cause moisture agglomeration (vendor).
- label: Spills
line: Vacuum spills with a HEPA filter and avoid raising dust (Stanford Advanced Materials SDS).
why: 'Calcium hexaboride (CaB6) is a cubic boride powder. Vendors sell it for three jobs: as a deoxidiser that removes oxygen from copper melts, as a boron additive for refractories, and as a neutron-protection material. The vendors'' data sheets and the two supplier SDS documents agree on a density of 2.3 to 2.33 g/cm3 and a melting point of 2230 °C to 2235 °C. The 1999 oxidation abstract sets the main limit: oxidation starts at 1273 K in air.'
uses:
- where: Copper refining
line: The vendor says CaB6 is a deoxidising and degassing agent for high-conductivity copper. The page gives no test result for the copper.
- where: Refractories
line: Vendors add CaB6 as a boron-containing additive to dolomite and magnesia dolomite refractories (vendor pages).
- where: Nuclear shielding
line: FUSnano lists CaB6 as a neutron protection material for the nuclear industry. No shielding value is given on the page.
can_do:
- label: Melt deoxidation
line: The vendor says it is used as a deoxidising and degassing agent for high-conductivity copper. The page gives no test result for the copper.
- label: Air limit
line: Oxidation in air starts at 1273 K for a hot-pressed sintered body (Matsushita and Komarneni 1999). Above that temperature it is not a suitable choice for air exposure, according to this one abstract.
- label: Melting point
line: The vendor gives 2230 °C and the Stanford Advanced Materials SDS gives 2235 °C for the melting point.
- label: Solubility
line: Insoluble in water and in several acids, per the vendor page and the BeanTown SDS.
compare: Within this profile, CaB6 has a density of 2.33 g/cm3 on the vendor pages and 2.3 g/cm3 on the SDS documents, and a melting point of 2230 °C (vendor) or 2235 °C (SDS). The sources read do not give CaB6 values for a direct ranking against other borides or against metals used for deoxidation, so no ranking is claimed here. No copper deoxidation test was read.
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Oxidation start in air
benchmark: oxidation_onset_temp
handling:
- Keep the powder sealed in a dry, cool, well-ventilated place away from moisture and oxidising agents (Stanford Advanced Materials SDS).
- Wear a dust respirator, rubber gloves and eye protection when handling it (Stanford Advanced Materials SDS).
- Above about 1273 K in air the powder oxidises (Matsushita and Komarneni 1999).
good_for:
- Deoxidising copper melts, as the vendor describes (vendor page, no test result given).
- Adding boron to refractories as a dolomite additive (vendor).
watch_out:
- Oxidation in air from 1273 K for a hot-pressed sintered body (Matsushita and Komarneni 1999).
- Irritation hazards H315, H319 and H335 on both supplier safety data sheets.
- 'Melting point conflicts between sources: 2200 °C and 2230 °C on one vendor page, 2235 °C on the SDS, and Undetermined on another SDS.'
verdict: CaB6 is a dense, high-melting boride powder sold for copper deoxidation, refractory additives and neutron shielding. The sources read support its melting point and density, and they show oxidation in air from 1273 K. Hardness, conductivity and space test data are missing from the sources read.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
Updated