{ "spore": "profile", "id": "lithium-hydride", "spore_version": "0.2", "family": "lithium", "name": "Lithium hydride", "abbreviation": "LiH", "role": "neutron shield, hydrogen source and reducing agent", "category": "shielding", "type": "hydrogen-rich-polymers", "summary": "Lithium hydride (LiH) is a white-to-grey powder with a density of 0.78 g/cm3 at 20 °C and a melting point of 688 °C, according to the Albemarle technical data sheet. Its theoretical hydrogen content is 12.7 %. NASA's 1969 shield study calls lithium hydride one of the best neutron shield materials for a space power reactor, and a later NASA paper calls it the most effective neutron shield per unit mass. It hydrolyses rapidly in water and decomposes in humid air, so it must be kept dry and sealed.\n", "best_for": "Neutron shielding in space reactor designs where hydrogen per unit mass matters most (NASA TM X-1874 and the NASA nuclear thermal propulsion shielding paper)", "weakest_at": "Water and humid air: the powder hydrolyses rapidly and releases flammable gas, and NASA reports poor thermal conductivity, which makes active cooling of a LiH shield very difficult", "identity": { "formula": "LiH", "cas": "7580-67-8", "designations": [], "source": "albemarle-tds", "where": "Title block (CAS-No. 7580-67-8; Molecular formula LiH); the product is Lithium Hydride, powder < 100 µm" }, "tags": { "environments": [], "stresses": [ "total-radiation-dose" ], "applications": [ "radiation-shielding", "electronics-and-chips" ] }, "properties": [ { "benchmark": "density", "label": "Density, LiH powder, 20 °C", "value": 0.78, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "temperature": "20 °C", "form": "powder, product 10000103 (< 100 µm)" }, "method": "Density printed in the Albemarle technical data sheet", "status": "ground", "source": "albemarle-tds", "where": "Physical properties, Density row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, LiH powder", "value": 688, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "form": "powder, product 10000103 (< 100 µm)", "atmosphere": "not stated on the data sheet" }, "method": "Melting point or range printed in the Albemarle technical data sheet (single value, no range given)", "status": "ground", "source": "albemarle-tds", "where": "Physical properties, Melting point/range row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "molar_mass", "label": "Molar mass of LiH", "value": 7.95, "bound": "exact", "unit": "g/mol", "scope": "material", "conditions": { "basis": "molecular weight as printed by the supplier" }, "method": "Molecular weight printed in the Albemarle technical data sheet (page 2)", "status": "ground", "source": "albemarle-tds", "where": "Page 2, Molecular weight row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "thermal_decomposition_temperature", "label": "Thermal decomposition temperature of LiH", "value": 800, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "printed": "abt. 800 °C", "atmosphere": "not stated on the data sheet" }, "method": "Thermal stability value printed in the Albemarle technical data sheet, given as an approximate figure", "status": "ground", "source": "albemarle-tds", "where": "Page 2, Thermal Stability row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "theoretical_hydrogen_content", "label": "Theoretical hydrogen content of LiH", "value": 12.7, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "basis": "theoretical, from the formula LiH" }, "method": "Value printed in the Albemarle technical data sheet (Additional Physical Properties)", "status": "calculated", "source": "albemarle-tds", "where": "Page 2, Additional Physical Properties row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hydrogen_yield_from_hydrolysis", "label": "Hydrogen evolved per gram of LiH in hydrolysis", "value": 2.82, "bound": "exact", "unit": "L/g", "scope": "material", "conditions": { "basis": "hydrogen evolved in hydrolysis, as printed in litres of hydrogen per g", "reaction": "reaction with water or moisture" }, "method": "Value printed in the Albemarle technical data sheet (Additional Physical Properties); the supplier does not give the gas temperature or pressure", "status": "calculated", "source": "albemarle-tds", "where": "Page 2, Additional Physical Properties row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hydrogen_equilibrium_pressure", "label": "Hydrogen equilibrium pressure of LiH at 500 °C", "value": 0.09, "bound": "exact", "unit": "mbar", "scope": "material", "conditions": { "temperature": "500 °C" }, "method": "Equilibrium pressure printed in the Albemarle technical data sheet", "status": "ground", "source": "albemarle-tds", "where": "Page 2, Additional Physical Properties row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hydrogen_equilibrium_pressure", "label": "Hydrogen equilibrium pressure of LiH at 850 °C", "value": 1010, "bound": "exact", "unit": "mbar", "scope": "material", "conditions": { "temperature": "850 °C" }, "method": "Equilibrium pressure printed in the Albemarle technical data sheet as approximately 1,010 mbar", "status": "ground", "source": "albemarle-tds", "where": "Page 2, Additional Physical Properties row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "assay", "label": "LiH content, minimum (supplier specification)", "value": 97, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "grade": "product 10000103, powder < 100 µm" }, "method": "Minimum specification printed in the Albemarle technical data sheet", "status": "ground", "source": "albemarle-tds", "where": "Specification table, LiH row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "impurity_sodium", "label": "Sodium content, maximum (supplier specification)", "value": 0.9, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "grade": "product 10000103, powder < 100 µm" }, "method": "Maximum specification printed in the Albemarle technical data sheet (upper bound)", "status": "ground", "source": "albemarle-tds", "where": "Specification table, Na row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "bulk_density", "label": "Bulk density, LiH powder", "value": 290, "value_high": 400, "bound": "range", "unit": "kg/m3", "scope": "material", "conditions": { "form": "powder, product 10000103 (< 100 µm)" }, "method": "Range printed in the Albemarle technical data sheet", "status": "ground", "source": "albemarle-tds", "where": "Physical properties, Bulk density row", "source_detail": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hydrogen_atom_density", "label": "Hydrogen atom density, natural LiH in a reactor shield model", "value": 0.056837, "bound": "exact", "unit": "atoms/barn-cm", "scope": "material", "conditions": { "composition": "natural lithium hydride as modelled in the shield region of a 2.2 MWt fast-spectrum space reactor", "source_table": "Table I" }, "method": "Atom density printed in NASA TM X-1874 for the model; a calculation input, not a measured property", "status": "ground", "source": "nasa-tmx1874", "where": "Table I, Shield, natural lithium hydride, Hydrogen row", "source_detail": { "title": "Comparison of Tungsten and Depleted Uranium in Minimum-Weight, Layered Shields for a Space Power Reactor (NASA TM X-1874, Lahti and Herrmann)", "id": "NASA NTRS 19690026439; NASA TM X-1874 (August 1969)", "url": "https://ntrs.nasa.gov/api/citations/19690026439/downloads/19690026439.pdf", "year": 1969, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "lithium_6_atom_density", "label": "Lithium-6 atom density, natural LiH in a reactor shield model", "value": 0.004217, "bound": "exact", "unit": "atoms/barn-cm", "scope": "material", "conditions": { "composition": "natural lithium hydride as modelled in the shield region of a 2.2 MWt fast-spectrum space reactor", "source_table": "Table I" }, "method": "Atom density printed in NASA TM X-1874 for the model; a calculation input, not a measured property", "status": "ground", "source": "nasa-tmx1874", "where": "Table I, Shield, natural lithium hydride, Lithium-6 row", "source_detail": { "title": "Comparison of Tungsten and Depleted Uranium in Minimum-Weight, Layered Shields for a Space Power Reactor (NASA TM X-1874, Lahti and Herrmann)", "id": "NASA NTRS 19690026439; NASA TM X-1874 (August 1969)", "url": "https://ntrs.nasa.gov/api/citations/19690026439/downloads/19690026439.pdf", "year": 1969, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "lithium_7_atom_density", "label": "Lithium-7 atom density, natural LiH in a reactor shield model", "value": 0.05262, "bound": "exact", "unit": "atoms/barn-cm", "scope": "material", "conditions": { "composition": "natural lithium hydride as modelled in the shield region of a 2.2 MWt fast-spectrum space reactor", "source_table": "Table I" }, "method": "Atom density printed in NASA TM X-1874 for the model; a calculation input, not a measured property", "status": "ground", "source": "nasa-tmx1874", "where": "Table I, Shield, natural lithium hydride, Lithium-7 row", "source_detail": { "title": "Comparison of Tungsten and Depleted Uranium in Minimum-Weight, Layered Shields for a Space Power Reactor (NASA TM X-1874, Lahti and Herrmann)", "id": "NASA NTRS 19690026439; NASA TM X-1874 (August 1969)", "url": "https://ntrs.nasa.gov/api/citations/19690026439/downloads/19690026439.pdf", "year": 1969, "kind": "report", "license": "public domain (NASA)" } } ], "corrosion": [ { "environment": "Water and humid air", "headline": "Lithium hydride hydrolyses rapidly and decomposes in contact with humidity, so it must be kept sealed and dry.", "effect": "The Albemarle data sheet gives water solubility as 'Substance hydrolyses rapidly' and says the material decomposes in contact with humidity. ICSC 0813 says it reacts violently with water, producing corrosive lithium hydroxide fumes. The NASA shield paper says LiH is reactive and must be sealed within containment.", "rating": "severe", "conditions": { "exposure": "contact with water or moist air, at room temperature", "product": "LiH powder, product 10000103" }, "source": "albemarle-tds", "where": "Page 2, Water solubility row; Handling and Storage" }, { "environment": "Light and air at room conditions", "headline": "The solid darkens on exposure to light and is hygroscopic.", "effect": "ICSC 0813 describes lithium hydride as an odourless white-to-greyish hygroscopic solid that darkens with light exposure. The Albemarle data sheet says that stored under exclusion of air and humidity the material is fairly stable and should be retested 6 months after the date of analysis.", "rating": "moderate", "conditions": { "exposure": "light and ambient air; exposure time not stated" }, "source": "icsc-0813", "where": "Physical State; Appearance" }, { "environment": "Molten LiH in a reactor shield", "headline": "Liquid LiH expands in volume, so containment must allow for it.", "effect": "NASA's shielding paper (Caffrey et al.) notes that the large volume expansion of lithium hydride in its melted liquid phase must be accounted for during casting and after containment closure, and that poor thermal conductivity limits cooling of the shield.", "rating": "moderate", "conditions": { "state": "melted liquid phase; expansion figure not given in the paper" }, "source": "caffrey-ntp", "where": "Material Selection section" } ], "risks": { "hazards": [ { "text": "PubChem's GHS summary for lithium hydride (CID 62714) lists the signal word Danger and hazard statement H260 (in contact with water releases flammable gases which may ignite spontaneously, 99.5% of ECHA notifications), H301 (toxic if swallowed, 82.4%) and H314 (causes severe skin burns and eye damage, 100%).", "ghs": [], "source": "pubchem-lih", "where": "GHS Classification, ECHA notified classification ratios" }, { "text": "ICSC 0813 describes the substance as corrosive to the eyes, skin and respiratory tract; inhalation may cause severe swelling of the throat. The card gives a TLV of 0.05 mg/m3 (ceiling value) and an EU-OEL of 0.02 mg/m3 as STEL, both for the inhalable fraction.", "ghs": [], "source": "icsc-0813", "where": "Health Hazards and First Aid; Occupational Exposure Limits" } ], "failure_risks": [ { "mode": "Contact with water or humid air", "trigger": "Water or moisture reaching the powder or a containment that has been opened", "consequence": "Rapid hydrolysis releases flammable gas that may ignite spontaneously (GHS H260) and forms corrosive lithium hydroxide (ICSC 0813).", "severity": "high", "source": "icsc-0813", "where": "Chemical Dangers; GHS hazard statement H260" }, { "mode": "Dust-air mixture", "trigger": "Handling or use of the powder", "consequence": "In use the powder may form flammable or explosive dust-air mixtures.", "severity": "high", "source": "albemarle-tds", "where": "Page 2, Handling" }, { "mode": "Heating above the stable range", "trigger": "Heating of LiH", "consequence": "The Albemarle data sheet gives a thermal decomposition at about 800 °C and a hydrogen equilibrium pressure of 0.09 mbar at 500 °C rising to about 1,010 mbar at 850 °C, so hydrogen is released on heating.", "severity": "moderate", "source": "albemarle-tds", "where": "Page 2, Thermal Stability and Additional Physical Properties rows" } ], "side_effects": [ { "text": "NASA's shielding paper (Caffrey et al.) says LiH's poor thermal conductivity and narrow operating temperature range make effective cooling strategies nearly impossible in high-flux environments, which led the study to set LiH aside in favour of a boron carbide pebble bed.", "affects": "Reactor shield cooling and temperature margins", "source": "caffrey-ntp", "where": "Material Selection section; Shielding Development section on heating" } ], "handling": [ { "text": "Albemarle: handle under an inert gas atmosphere, avoid contact with eyes, skin and clothing, and avoid inhalation. Store in tightly closed containers under exclusion of humidity at gentle temperatures, away from heat, sparks and fire.", "source": "albemarle-tds", "where": "Handling & Storage" }, { "text": "ICSC 0813: keep under mineral oil or inert gas, dry and cool, and separate from incompatible materials; store in an area without drain or sewer access.", "source": "icsc-0813", "where": "Storage" }, { "text": "Transport: UN 1414, class 4.3, packing group I (ADR, RID, IMDG and IATA as printed by Albemarle).", "source": "albemarle-tds", "where": "Transport & Packaging" } ], "mitigations": [ { "text": "Retest the material 6 months after the date of analysis if the certificate of analysis is included, or use the manufacturing date for the calculation if it is not (Albemarle).", "source": "albemarle-tds", "where": "Handling & Storage" }, { "text": "NASA says the reactive nature of LiH mandates that it be sealed within some containment, and NASA's shield designs alternate LiH layers with metal layers to limit secondary gamma production.", "source": "caffrey-ntp", "where": "Material Selection section" } ] }, "uses": [ { "application": "radiation-shielding", "device": "Layered shield for a nuclear space power reactor (NASA TM X-1874 study, ground analysis)", "example": "NASA's 1969 study found an optimized shield weight of 25 300 kg with depleted uranium and 28 500 kg with tungsten, for a 2.2 MW-thermal fast-spectrum reactor, both using natural lithium hydride alternated with four metal layers as the neutron shield.", "source": "nasa-tmx1874", "where": "Abstract; Summary of results, paragraph on the optimized shield weights" }, { "application": "radiation-shielding", "device": "Neutron shield in nuclear thermal propulsion designs (NASA MSFC shielding study)", "example": "NASA's shielding paper calls LiH the most effective neutron shield per unit mass, owing to its hydrogen and to lithium-6, but the study set LiH aside in favour of a boron carbide pebble-bed shield for cooling reasons.", "source": "caffrey-ntp", "where": "Material Selection section; Shielding Development section on heating" }, { "application": "electronics-and-chips", "device": "Industrial reducing agent and high-density hydrogen source (terrestrial chemistry, not a flight application)", "example": "Albemarle lists lithium hydride as a reducing agent, a high-density hydrogen source and a material for producing high-purity monosilanes.", "source": "albemarle-tds", "where": "Application row, first page" } ], "supply": [ { "subject": "Lithium", "producers": [ { "country": "Australia", "share_percent": 31.7, "year": 2025 }, { "country": "China", "share_percent": 21.4, "year": 2025 }, { "country": "Chile", "share_percent": 19.3, "year": 2025 }, { "country": "Zimbabwe", "share_percent": 9.7, "year": 2025 }, { "country": "Argentina", "share_percent": 7.9, "year": 2025 } ], "critical_lists": [], "recycling": "USGS: construction of lithium battery recycling plants continued throughout 2025, and automobile companies and battery recyclers partnered to supply battery materials.", "substitutes": [ "USGS: substitution for lithium compounds is possible in batteries, ceramics, greases and manufactured glass." ], "source": "usgs-mcs2026-lithium", "where": "World Mine Production and Reserves table, 2025 (shares calculated by Space Mushroom against the 290,000 t world total in that table); Recycling; Substitutes" } ], "media": [], "documents": [ { "title": "Albemarle technical data sheet: Lithium Hydride, powder < 100 µm (product 10000103, issued 2025/11/28)", "type": "datasheet", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025 }, { "title": "NASA TM X-1874: Comparison of Tungsten and Depleted Uranium in Minimum-Weight, Layered Shields for a Space Power Reactor (1969)", "type": "report", "url": "https://ntrs.nasa.gov/api/citations/19690026439/downloads/19690026439.pdf", "year": 1969 }, { "title": "Shielding Development for Nuclear Thermal Propulsion (Caffrey, Gomez, Scharber; Oregon State University and NASA Marshall)", "type": "paper", "url": "https://ntrs.nasa.gov/api/citations/20150006884/downloads/20150006884.pdf" }, { "title": "PubChem: Lithium hydride (CID 62714), GHS classification summary", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/62714", "year": 2026 }, { "title": "ICSC 0813: Lithium hydride (International Chemical Safety Card)", "type": "database", "url": "https://www.inchem.org/documents/icsc/icsc/eics0813.htm" }, { "title": "USGS Mineral Commodity Summaries 2026: Lithium", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf", "year": 2026 }, { "title": "IUPAC CIAAW standard atomic weight of lithium", "type": "database", "url": "https://ciaaw.org/lithium.htm", "year": 2009 }, { "title": "IUPAC CIAAW standard atomic weight of hydrogen", "type": "database", "url": "https://ciaaw.org/hydrogen.htm", "year": 2009 } ], "gaps": [ "No media (images or crystal-structure drawings) were added; no licensed image was checked in this run.", "No thermal conductivity or specific heat for LiH was found in a page we could read. Yaws' Handbook of Thermal Conductivity is the likely source but was not opened.", "No lattice constant or crystal system was taken from a fetched primary source; Wikipedia gives an fcc NaCl-type structure but is not used for numbers here.", "No boiling point, flash point or autoignition temperature was taken from a source we could open. Wikipedia lists values, but it is not used for numbers in this profile.", "Sigma-Aldrich safety data sheet (product 323403) timed out and was not read; hazard data rest on PubChem, ICSC 0813 and the Albemarle data sheet.", "Manufacturing route and purity controls beyond the Albemarle minimum assay and sodium and potassium limits were not found in a source we could read.", "Lithium abundance in the Earth's crust, and the USGS and EU critical-mineral list status for lithium, were not read in this run (the USGS 2026 lithium summary was read only for production shares and recycling and substitutes).", "Hydrogen supply and production shares were not read in a fetched source; the supply block covers lithium only.", "Molar mass, bulk density, thermal decomposition temperature and hydrogen equilibrium pressure are not canonical names in spores/property-canon.yaml; they are short snake_case or canonical-alias names and were not mapped to the canon file.", "Atomic weights for the recipe are the lower bounds of the CIAAW intervals (lithium [6.938, 6.997] and hydrogen [1.00784, 1.00811]); the single standard value is not printed by CIAAW.", "Space flight, vacuum and radiation-exposure results for LiH were not found in a source we could open; the NASA shield results are ground design analyses." ], "story": { "why": "Lithium hydride (LiH) is a lithium compound with a high hydrogen content. Albemarle's technical data sheet gives a density of 0.78 g/cm3 and a melting point of 688 °C, and says that the powder decomposes in contact with humidity. NASA's 1969 shield study found LiH to be one of the best neutron shield materials for a space power reactor. A later NASA paper calls it the most effective neutron shield per unit mass, but it sets LiH aside because a simple cooling model could not keep the shield within temperature limits.", "uses": [ { "where": "Space reactor radiation shields", "line": "NASA's 1969 ground study of a 2.2 MW-thermal fast-spectrum reactor found an optimized shield weight of 25 300 kg with depleted uranium and 28 500 kg with tungsten. Both designs used natural lithium hydride as the neutron shield, in four layers alternated with three metal layers." }, { "where": "Nuclear thermal propulsion shielding", "line": "A later NASA shielding paper says lithium hydride is the most effective neutron shield per unit mass, but its poor thermal conductivity makes cooling nearly impossible in a high-flux reactor. The study chose a boron carbide pebble bed instead." }, { "where": "Chemistry", "line": "Albemarle sells lithium hydride as a reducing agent, a high-density hydrogen source and a raw material for high-purity monosilanes. These are terrestrial industrial uses, not space applications." } ], "can_do": [ { "label": "Density", "line": "Lithium hydride powder has a density of 0.78 g/cm3 at 20 °C, per the Albemarle data sheet. Its bulk density is 290 to 400 kg/m3 as a powder.", "benchmark": "density", "scope": "material" }, { "label": "Hydrogen content", "line": "The theoretical hydrogen content is 12.7 %, and the data sheet gives 2.82 litres of hydrogen evolved per gram of LiH in hydrolysis. This is the figure behind its use as a high-density hydrogen source.", "benchmark": "theoretical_hydrogen_content", "scope": "material", "value": "12.7 %" }, { "label": "Melting point", "line": "The data sheet gives a melting point of 688 °C and a thermal decomposition at about 800 °C.", "benchmark": "melting_point", "scope": "material", "value": "688 °C" }, { "label": "Purity", "line": "The supplier specification is a minimum of 97 % LiH, with sodium at most 0.9 % and potassium at most 0.05 %.", "benchmark": "assay", "scope": "material", "value": "97 %" } ], "compare": "Lithium hydride is the most effective neutron shield per unit mass in NASA's reactor-shield studies, but its cooling is difficult. The NASA shielding paper by Caffrey and colleagues says a boron carbide shield has a mass penalty of about 20 % greater than a practical LiH shield, and that boron carbide has excellent thermal conductivity, hardness and chemical stability. The table compares LiH with the reference points in this profile.", "compare_rows": [ { "label": "Density", "benchmark": "density", "scope": "material" }, { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Hydrogen content", "benchmark": "theoretical_hydrogen_content", "scope": "material" } ], "handling": [ "Handle the powder under an inert gas atmosphere, away from water and humidity (Albemarle).", "Store in tightly closed containers, dry, cool and separated from incompatible materials (Albemarle and ICSC 0813).", "Avoid dust. In use the powder may form flammable or explosive dust-air mixtures, and Albemarle says to avoid inhalation.", "Retest the material 6 months after the analysis date (Albemarle)." ], "good_for": [ "Neutron shielding by mass. NASA's studies call LiH the most effective neutron shield per unit mass (NASA shielding paper).", "Hydrogen-dense powder. The theoretical hydrogen content is 12.7 %, and Albemarle sells the powder as a high-density hydrogen source." ], "watch_out": [ "Water and humid air. The powder hydrolyses rapidly and releases flammable gas (H260).", "Poor thermal conductivity. NASA says LiH is hard to cool in a high-flux reactor shield.", "Corrosive and toxic if swallowed. ICSC 0813 and PubChem describe the powder as corrosive (H314) and toxic (H301)." ], "verdict": "Lithium hydride is the hydrogen-rich neutron shield that NASA's studies rate highest per unit mass, but it must be kept dry and sealed, and it is hard to cool in a reactor. Its use in space shielding has been studied on paper and in ground analysis, and no flight result was found.", "recipe": { "line": "LiH is lithium hydride: one lithium atom and one hydrogen atom per formula unit, as printed in the Albemarle molecular formula. The natural lithium used in NASA's shield model is a mix of lithium-6 and lithium-7.", "parts": [ { "name": "Lithium", "symbol": "Li", "role": "The neutron absorber. NASA says lithium-6 has a dominant (n,alpha) reaction and that LiH is an excellent neutron absorber when enriched in Li-6; the NASA model uses natural lithium. The atomic weight is the lower bound of the CIAAW interval [6.938, 6.997].", "atoms": 1, "atomic_weight": 6.938 }, { "name": "Hydrogen", "symbol": "H", "role": "The moderator. NASA says hydrogen sheds fast-neutron energy by collisions with light atoms, and LiH has a high hydrogen density. The atomic weight is the lower bound of the CIAAW interval [1.00784, 1.00811].", "atoms": 1, "atomic_weight": 1.00784 } ] }, "risk_groups": [ { "title": "For people", "lead": "The supplier and ICSC 0813 describe the powder as corrosive and toxic if swallowed, and it releases flammable gas on contact with water.", "points": [ { "label": "The powder", "line": "PubChem's GHS summary lists H314 (severe skin burns and eye damage, 100% of notifications), H301 (toxic if swallowed, 82.4%) and the signal word Danger." }, { "label": "Dust and air", "line": "ICSC 0813 says the solid is corrosive to the eyes, skin and respiratory tract, and inhalation may cause severe swelling of the throat. The TLV is 0.05 mg/m3 as a ceiling value." }, { "label": "Water", "line": "H260 (flammable gas released on contact with water, which may ignite spontaneously) is the main hazard that handlers must avoid." } ], "level": 0, "verdict": "Corrosive, toxic powder that reacts with water" }, { "title": "If the material gets wet or overheats", "lead": "These effects are from supplier and ICSC data, and from NASA design studies, not from incidents.", "points": [ { "label": "Moisture", "line": "The Albemarle data sheet says the material decomposes in contact with humidity and hydrolyses rapidly. Hydrogen is released." }, { "label": "Heat", "line": "The data sheet gives a thermal decomposition at about 800 °C and a hydrogen equilibrium pressure of 0.09 mbar at 500 °C, rising to about 1,010 mbar at 850 °C." } ] }, { "title": "Handling and storage", "points": [ { "label": "Atmosphere", "line": "Albemarle says to handle the powder under an inert gas atmosphere and to store it in tightly closed containers, excluded from humidity." }, { "label": "Transport", "line": "UN 1414, class 4.3, packing group I, as printed by Albemarle for road, rail, sea and air transport." } ] } ] }, "updated": "2026-11-01", "review": { "status": "draft", "method": "assistant", "checked_values": 14, "unreachable": 1, "caveats": 3, "note": "Written by an AI assistant on 2026-11-01 from pages read in this run: 14 property rows from the Albemarle datasheet and the NASA TM X-1874 atom-density table. The Sigma-Aldrich SDS timed out and was not read." }, "sources": { "albemarle-tds": { "title": "Technical Data Sheet: Lithium Hydride, powder < 100 µm (Albemarle, product 10000103)", "id": "Albemarle TDS, date of issue 2025/11/28; CAS 7580-67-8; EC 231-484-3", "url": "https://www.albemarle.com/sites/default/files/2026-01/_TDS_00000138_TDS_ALB_E.PDF", "year": 2025, "kind": "datasheet", "license": "supplier document, linked not reproduced" }, "nasa-tmx1874": { "title": "Comparison of Tungsten and Depleted Uranium in Minimum-Weight, Layered Shields for a Space Power Reactor (NASA TM X-1874, Lahti and Herrmann)", "id": "NASA NTRS 19690026439; NASA TM X-1874 (August 1969)", "url": "https://ntrs.nasa.gov/api/citations/19690026439/downloads/19690026439.pdf", "year": 1969, "kind": "report", "license": "public domain (NASA)" }, "caffrey-ntp": { "title": "Shielding Development for Nuclear Thermal Propulsion (Caffrey, Gomez, Scharber)", "id": "NASA NTRS 20150006884", "url": "https://ntrs.nasa.gov/api/citations/20150006884/downloads/20150006884.pdf", "kind": "paper", "license": "public domain (NASA)" }, "icsc-0813": { "title": "ICSC 0813: Lithium hydride, International Programme on Chemical Safety", "id": "ICSC 0813", "url": "https://www.inchem.org/documents/icsc/icsc/eics0813.htm", "kind": "handbook", "license": "public domain (IPCS/INCHEM)" }, "pubchem-lih": { "title": "PubChem compound record, Lithium hydride (CID 62714)", "id": "CID 62714; EC 231-484-3", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/62714", "year": 2026, "kind": "database", "license": "public domain (NCBI)" }, "usgs-mcs2026-lithium": { "title": "Mineral Commodity Summaries 2026: Lithium", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "ciaaw-lithium": { "title": "IUPAC CIAAW standard atomic weight of lithium", "id": "CIAAW, interval [6.938, 6.997], since 2009", "url": "https://ciaaw.org/lithium.htm", "year": 2009, "kind": "database", "license": "CIAAW web page" }, "ciaaw-hydrogen": { "title": "IUPAC CIAAW standard atomic weight of hydrogen", "id": "CIAAW, interval [1.00784, 1.00811], since 2009", "url": "https://ciaaw.org/hydrogen.htm", "year": 2009, "kind": "database", "license": "CIAAW web page" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/lithium-hydride/" }