Phosphoric acid, barium salt (2:3) (13466-20-1) Physical and Chemical Properties
Phosphoric acid, barium salt (2:3)
Tribarium diphosphate is an inorganic barium phosphate supplied as a fine powder for use in ceramic precursors, specialty coatings and materials research where controlled trace-metal and particle specifications are required.
| CAS Number | 13466-20-1 |
| Family | Barium phosphates (metallic phosphates) |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP |
Phosphoric acid, barium salt (2:3) is an inorganic metal phosphate belonging to the class of barium phosphates / metallic phosphate salts. Structurally it is an ionic, extended-network solid composed of barium cations coordinated to a phosphate-derived anionic framework; the stoichiometric formula is \(\ce{Ba3O8P2}\). The material is best regarded as a tribarium–diphosphate type salt with strong P–O covalent character within phosphate units and predominantly ionic Ba–O interactions that stabilize an extended lattice.
Electronically the material contains closed-shell \(\ce{Ba^2+}\) cations and oxygen-rich phosphate anions; it is formally electrically neutral (formal charge 0). The phosphate-derived oxyanions present multiple basic sites (oxygen lone pairs) but no free acidic protons in the solid-state stoichiometry, so classical Brønsted acidity is absent for the bulk solid — acid–base behavior manifests through dissolution/hydrolysis equilibria that release phosphate species. As a metal phosphate, the substance is polar and nonvolatile; lipophilicity is negligible and transport in aqueous systems is governed by solid–liquid solubility, particle size and surface chemistry rather than vapour-phase properties.
In applied contexts barium phosphates are used where insoluble or sparingly soluble, high–atomic-weight metal phosphates are required (ceramics, inorganic pigments, phosphor hosts and certain catalysts or catalyst supports). Material selection is driven by thermal stability, lattice composition and the potential for releasing \(\ce{Ba^2+}\) under acidic or complexing conditions — a toxicologically relevant consideration for process and environmental control.
Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting or Decomposition Point
No experimentally established value for this property is available in the current data context.
Solubility in Water
Barium phosphate is reported as soluble in water. Solubility of metal phosphates is strongly dependent on pH, ionic strength and the presence of complexing anions; local dissolution may produce soluble barium species and various protonation states of phosphate. In practice, measured solubility can vary from low to moderate depending on particle size, preparation route and solution chemistry, and dissolution commonly increases in acidic media where protonation of phosphate shifts equilibria toward soluble species.
Solution pH (Qualitative Behavior)
When dispersed or partially dissolved in water the phosphate-derived anions released from the solid will establish equilibria characteristic of phosphoric acid/base chemistry. Depending on the extent of dissolution and the dominant phosphate species in solution, aqueous suspensions are commonly neutral to slightly basic at equilibrium under low total phosphate concentrations; however, local pH and speciation will shift toward acidic values if excess strong acid is present (which also increases the extent of dissolution and free \(\ce{Ba^2+}\) concentration). The term \(\mathrm{pH}\) of bulk suspension is therefore strongly conditioned by solid loading and solution composition.
Chemical Properties
Acid–Base Behavior
The solid contains phosphate-derived anions but no exchangeable acidic protons in its stoichiometry; acid–base phenomena arise via dissolution and subsequent protonation/deprotonation of phosphate in solution. The parent acid is phosphoric acid (a triprotic acid), so the anionic speciation in solution may include mono-, di- and polyphosphate species depending on \(\mathrm{pH}\) and concentration. Reaction with strong acids converts the solid into more protonated phosphate species and increases the concentration of soluble \(\ce{Ba^2+}\) in the aqueous phase.
Reactivity and Stability
As a bulk inorganic phosphate, the material is generally chemically stable under neutral and basic conditions. It will react with strong acids to yield soluble barium salts and phosphoric acid derivatives; reductive or oxidative reactions are not typical for the covalent P–O network under normal handling conditions. Thermal decomposition under high temperatures may ultimately yield barium oxide and phosphorus oxides or volatilized phosphorus-containing species, but no specific decomposition temperature is provided in the available data. Solid-state reactivity can also be influenced by particle surface area and impurities introduced during manufacture.
Molecular and Ionic Parameters
Formula and Molecular Weight
- Molecular formula: \(\ce{Ba3O8P2}\)
- Molecular weight: 601.9 (as reported)
Additional computed identifiers and parameters:
- Exact mass / Monoisotopic mass: 603.622582
- Topological polar surface area (TPSA): 173
- Formal charge: 0
- Hydrogen bond donor count: 0
- Hydrogen bond acceptor count: 8
- Rotatable bond count: 0
- Heavy atom count: 13
- Complexity: 36.8
Constituent Ions
The solid lattice contains barium cations nominally represented as \(\ce{Ba^2+}\) coordinated to an oxygen-rich phosphate anionic framework. In aqueous environments the dominant mobile ionic species of toxicological and process relevance is \(\ce{Ba^2+}\); the anionic phosphate fragments will be present in protonation states derived from phosphoric acid and their distribution depends on \(\mathrm{pH}\) and concentration.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 13466-20-1
- European Community (EC) numbers appearing in associated identifiers: 237-582-2; 236-856-9
- InChI:
InChI=1S/3Ba.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6 - InChIKey:
WAKZZMMCDILMEF-UHFFFAOYSA-H - SMILES:
[O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Ba+2].[Ba+2].[Ba+2]
Synonyms and Common Names
Available depositor-supplied synonyms and alternative names include (selection of recorded strings):
- Phosphoric acid, barium salt (2:3)
- Barium phosphate, tribasic
- Tribarium diphosphate
- Barium phosphate (also recorded as "Bariumphosphat", "Barium phosphate(V)")
- Barium phosphate, powder, -200 mesh, 99.9% trace metals basis
- Ba3O8P2
- Barium phosphate, monobasic (listed among synonyms)
(These synonyms are drawn from supplied identifier lists and may represent alternative nomenclature, historical names or vendor descriptions.)
Industrial and Commercial Applications
Functional Roles and Use Sectors
Materials of the barium phosphate family are mainly used where inorganic, thermally stable, and high–atomic-number phosphate phases are required. Functional roles include components in ceramic formulations, inorganic pigments, host lattices for phosphors, and catalyst or catalyst-support materials in heterogeneous catalysis. Their selection in formulations is typically motivated by thermal stability, compatibility with oxide matrices, and specific optical or electronic properties imparted by the lattice.
Typical Application Examples
- Ceramic and refractory compositions where phosphate phases modify sintering or grain growth.
- Phosphor host lattices or precursor materials for luminescent materials.
- Inorganic pigments or mattifying agents where low solubility and chemical stability are desired.
- As components in specialty coatings and catalyst supports where phosphate anchoring groups confer surface stability.
If no product- or process-specific application data is supplied, material selection is typically governed by the general properties described above (thermal stability, lattice composition, and potential for releasing \(\ce{Ba^2+}\) under certain conditions).
Safety and Handling Overview
Health and Environmental Hazards
Hazard classifications associated with commercial notifications include acute toxicity and irritation endpoints. Reported hazard statements (as supplied) include: H302 (Harmful if swallowed), H332 (Harmful if inhaled), H315 (Causes skin irritation) and H319 (Causes serious eye irritation). These statements indicate acute oral/inhalation toxicity potential and local irritation hazards.
Toxicological risk from barium-containing solids is largely related to the potential for dissolution and liberation of soluble \(\ce{Ba^2+}\) ions, which are systemically toxic if absorbed in sufficient quantities. Environmental mobility depends on solubility and solution chemistry; in acidic or complexing environments the propensity to release \(\ce{Ba^2+}\) increases. Reported occupational exposure guideline values associated with barium (as Ba) appearing in available metadata include maximum allowable concentrations of \(0.5\ \mathrm{mg}\,\mathrm{m^{-3}}\) (MAK / PEL / TLV contexts) and an IDLH value of \(50.0\ \mathrm{mg}\,\mathrm{m^{-3}}\) (all values expressed as barium basis). Users should treat airborne dusts and respirable fractions as the primary inhalation exposure pathway.
Storage and Handling Considerations
Handle as an inorganic particulate: minimize dust generation, use local exhaust ventilation where particles or powders are handled, and employ appropriate respiratory protection for operations that can generate airborne dust. Use protective gloves and eye/face protection to prevent skin and eye contact; standard industrial respiratory and dust controls are recommended. Avoid contact with strong acids during storage or processing to prevent increased dissolution and release of soluble barium species. Store in a cool, dry, well-ventilated area in compatible containers.
For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
