Nickel Fluoride Anhydrous: Properties, Handling & Lab Use

Nickel fluoride, anhydrous is a pale yellow to green inorganic salt with the formula NiF₂ that serves as a versatile source of both nickel(II) and fluoride ions in synthetic, catalytic, and materials science research.

Chemical Formula

NiF₂

CAS Number

10028-18-9

Molar Mass

96.69 g/mol

Appearance

Pale yellow to greenish crystalline solid

Crystal Structure

Rutile-type tetragonal structure

Solubility in Water

Slightly soluble; hydrolyzes slowly in hot water

Melting Point

~1380 °C (decomposes)

Magnetic Properties

Antiferromagnetic below Néel temperature (~73 K)

Chemical Properties and Structure

Nickel fluoride, anhydrous (NiF₂) is an ionic compound in which nickel exists in the +2 oxidation state. It adopts a rutile-type tetragonal crystal structure, where each Ni²⁺ ion is octahedrally coordinated by six fluoride ions, and each F⁻ ion is trigonally coordinated by three Ni²⁺ ions. This high-symmetry arrangement confers considerable lattice stability and contributes to the compound's high melting point and low solubility in water.

NiF₂ is slightly soluble in water and dilute hydrofluoric acid but is practically insoluble in most common organic solvents. In aqueous solution, it releases Ni²⁺ and F⁻ ions; prolonged exposure to hot water or steam can lead to partial hydrolysis. The compound is a mild oxidizer under strongly reducing conditions and exhibits antiferromagnetic ordering below its Néel temperature of approximately 73 K, making it of interest in low-temperature magnetic studies.

The anhydrous form must be distinguished from nickel fluoride hydrates (e.g., NiF₂·4H₂O), which are more soluble and less suitable for moisture-sensitive applications. The absence of water of crystallization is confirmed by thermogravimetric analysis or Karl Fischer titration.

Research and Industrial Applications

Nickel fluoride, anhydrous finds use across several research and applied domains:

• Fluorination chemistry: NiF₂ serves as a mild fluorinating agent and a precursor in the synthesis of complex metal fluorides, fluoride-based glasses, and solid electrolytes for fluoride-ion batteries. Its ability to donate fluoride ions under controlled conditions makes it useful in preparative inorganic chemistry.
• Catalysis: NiF₂ and derived nickel fluoride surfaces are employed as catalysts and catalyst supports in hydrogenation and dehydrofluorination reactions. Surface fluorination by NiF₂ treatment can modify the acidity and selectivity of heterogeneous catalysts.
• Materials science and thin films: NiF₂ is used as a source material in physical vapor deposition (PVD) and chemical vapor deposition (CVD) for the growth of nickel fluoride thin films with optical and electronic applications.
• Battery research: NiF₂ is investigated as a cathode material or conversion-type electrode in fluoride-ion batteries and lithium-ion battery research, where its high theoretical capacity is advantageous.
• Magnetic research: The antiferromagnetic properties of NiF₂ make it a model material for studying exchange interactions, spin structures, and magnetoelectric phenomena at low temperatures.

In all applications, the anhydrous grade is preferred to ensure reproducibility and to prevent premature hydrolysis or side reactions caused by trace moisture.

Safe Handling, Storage, and Waste Disposal

Hazard overview: Nickel fluoride, anhydrous is classified as a toxic and potentially carcinogenic substance. Nickel(II) compounds are classified by IARC as Group 1 carcinogens (nickel compounds). Fluoride ion is acutely toxic at elevated doses. Researchers must consult the current Safety Data Sheet (SDS) before use.

Personal protective equipment (PPE): Always wear chemically resistant nitrile or neoprene gloves, a laboratory coat, and safety goggles. For operations generating dust or aerosols (e.g., weighing, grinding), use a NIOSH-approved half-face respirator equipped with P100 particulate filters and work inside a certified chemical fume hood.

Handling precautions: Minimize dust generation. Avoid inhalation, ingestion, and skin or eye contact. Keep away from strong reducing agents, alkali metals, and moisture. Use clean, dry, fluoride-compatible spatulas (e.g., PTFE or stainless steel). Wash hands thoroughly after handling.

Storage: Store in a tightly sealed container in a cool (15–25 °C), dry, well-ventilated location away from incompatible materials (strong reductants, moisture). The container should be clearly labeled. Shelf life is indefinite when stored properly in the anhydrous form; however, periodic verification of purity is recommended for critical applications.

Waste disposal: Do not dispose of nickel fluoride down the drain. Nickel-containing waste is regulated as hazardous waste in most jurisdictions. Collect solid waste in a sealed, labeled container and arrange disposal through a licensed hazardous waste contractor in accordance with local, national, and institutional regulations.

First aid: In case of skin or eye contact, flush immediately with large amounts of water for at least 15 minutes and seek medical attention. For inhalation, remove the person to fresh air and seek medical evaluation. Ingestion requires immediate medical attention.

Quality, Purity, and Verification

For reproducible research outcomes, it is essential to use nickel fluoride, anhydrous of defined and verified purity. Key quality parameters include:

• Assay (NiF₂ content): High-purity grades typically specify ≥98% assay by complexometric titration or ICP-OES. The exact purity specification for SKU N105100 should be confirmed on the product certificate of analysis (CoA).
• Moisture content: Anhydrous grade is characterized by low water content, typically verified by Karl Fischer titration or thermogravimetric analysis (TGA). Hydrate formation degrades performance in moisture-sensitive applications.
• Heavy metal and trace elemental impurities: For electronic or optical applications, trace impurities (e.g., Cu, Fe, Co, Cr) should be assessed by ICP-MS or ICP-OES.
• Particle size and morphology: Relevant for thin-film deposition and catalysis; consult the CoA or request additional characterization data from Aladdin Scientific if needed.

Always request and review the Certificate of Analysis (CoA) for the specific lot number received. For critical quantitative experiments, independent verification by in-house analytical methods (e.g., XRD for phase purity, ICP for Ni content) is recommended. Contact Aladdin Scientific technical support for custom purity grades or bulk procurement inquiries.

Regulatory and Compliance Considerations

Researchers and procurement personnel should be aware of the following regulatory aspects associated with nickel fluoride, anhydrous:

• GHS Classification: NiF₂ is subject to Globally Harmonized System (GHS) classification for acute toxicity (oral, inhalation, dermal), skin sensitization, respiratory sensitization, carcinogenicity, and reproductive toxicity. Exact GHS hazard and precautionary statements are provided on the SDS; consult the current SDS before ordering or handling.
• REACH and RoHS: Nickel compounds are subject to REACH regulation in the European Union, including restrictions on use in certain consumer articles and occupational exposure limits. Verify compliance requirements applicable to your jurisdiction and use context.
• Occupational exposure limits (OELs): Regulatory bodies in different regions (e.g., OSHA in the US, EH40 in the UK, GESTIS in Germany) set OELs for nickel and its compounds. Specific OEL values should be verified against current national regulations, as they are subject to revision.
• Export controls: Certain nickel compounds and fluoride reagents may be subject to export licensing requirements depending on the country of origin and destination. Consult your institution's export control office if shipping internationally.
• Institutional requirements: Ensure that use of this compound is covered by your institution's chemical inventory, waste management plan, and any required risk assessments or institutional review processes.

Frequently asked questions

What is the difference between nickel fluoride anhydrous and nickel fluoride hydrate?

Nickel fluoride anhydrous (NiF₂) contains no water of crystallization, giving it greater stability in moisture-sensitive reactions, a higher melting point, and lower solubility compared to hydrated forms such as NiF₂·4H₂O. The hydrate is more soluble in water and easier to handle for aqueous-phase chemistry, but it is unsuitable where anhydrous conditions are required. For thin-film deposition, fluoride-ion battery research, and high-temperature synthesis, the anhydrous grade is strongly preferred.

How should nickel fluoride anhydrous be stored to maintain purity?

Store nickel fluoride anhydrous in a tightly sealed, moisture-proof container (preferably with a desiccant or under inert gas) in a cool (15–25 °C), dry, well-ventilated area away from reducing agents and incompatible chemicals. Exposure to atmospheric moisture can cause surface hydration and reduce purity over time. Upon opening, reseal promptly and consider working in a glovebox or dry room if your application demands strict anhydrous conditions. Periodically verify purity by Karl Fischer titration or TGA if the material is stored long-term.

What personal protective equipment is required when handling nickel fluoride anhydrous?

At minimum, wear chemically resistant gloves (nitrile or neoprene), a laboratory coat, and safety goggles with side shields. Because nickel(II) compounds are classified as potential human carcinogens and fluoride is acutely toxic, any operation that generates dust or aerosol—such as weighing or grinding—must be performed in a certified chemical fume hood with a NIOSH-approved particulate respirator (P100 filters). Hands should be washed thoroughly after use. Always consult the current SDS for the most up-to-date hazard and protective equipment guidance.

Can nickel fluoride anhydrous be used as a fluorinating agent?

Yes, NiF₂ can function as a mild fluorinating agent in inorganic synthesis, particularly for preparing mixed metal fluorides or surface-fluorinating other metal oxides or salts. However, it is a relatively moderate fluorinating agent compared to aggressive reagents such as elemental fluorine or ClF₃. Its use as a fluorinating agent is most effective at elevated temperatures or under mechanochemical conditions. Researchers should consult primary literature for specific reaction protocols and optimize conditions for their target synthesis.

Is nickel fluoride anhydrous suitable for battery research applications?

NiF₂ has attracted significant attention as a conversion-type cathode material for fluoride-ion batteries and has also been studied in lithium-ion battery contexts due to its high theoretical energy density. The anhydrous grade is essential for battery research to avoid moisture-induced side reactions that can compromise electrochemical performance. Researchers should characterize phase purity (e.g., by XRD) and confirm particle size distribution before use, as these parameters critically affect electrochemical behavior.

References

1. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 49: Chromium, Nickel and Welding. International Agency for Research on Cancer, 1990.
2. Haynes, W.M. (Ed.). CRC Handbook of Chemistry and Physics, 97th Edition. CRC Press, 2016–2017.
3. NIOSH Pocket Guide to Chemical Hazards: Nickel compounds. National Institute for Occupational Safety and Health, US CDC.
4. European Chemicals Agency (ECHA). Substance Infocard: Nickel difluoride. ECHA, Helsinki.
5. Davis, J.R. (Ed.). Nickel, Cobalt, and Their Alloys. ASM International, 2000.

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