Nickel Oxide: Material Profile, Structure, and Applications

What is Nickel Oxide?

Nickel oxide appears as a green-black, crystalline solid. Chemists recognize its formula as NiO and its molecular weight stands at 74.69 g/mol. Most supplies of nickel oxide arrive as heavy green powders or as dark, dense pearls. Sometimes, small flakes may show up depending on how the material was processed. Some manufacturers deliver it as pellets or sintered shapes for specialized industrial uses. You won’t see liquid or dissolved forms sold in standard markets since nickel oxide does not dissolve in water or most organic solvents. Instead, its structure clings together in a robust face-centered cubic lattice, a feature that gives it hardness and a high melting point.

Properties and Physical Data

A trained eye spots its density at about 6.67 g/cm³. Heating pushes nickel oxide to a melting point near 1,955°C, well above the capability of common furnaces, emphasizing its stability under strenuous thermal stress. Industrial labs turn to this property for producing refractory ceramics and catalysts. In its pure state, nickel oxide holds its greenish-black color but starts absorbing more heat and turning deeper tones once impurities enter the mix. Its insolubility stands out, so while powders may cake if exposed to air moisture, they never form a true solution in water. This trait matters during storage and handling because inhalable dust can become hazardous if proper safeguards fall short.

Chemical Behavior and Structural Features

Solid nickel oxide resists most corrosive attacks from acids, yet strong acids can reduce it to soluble nickel salts under intense conditions. Its face-centered cubic structure maintains electrical insulating qualities, yet scientists have tailored thin films to behave as semiconductors — essential for sensors or battery electrodes. Most metallurgists use nickel oxide as a raw material for alloy additives, glass tinting, or as part of chemical catalysts in hydrogenation reactions. In the paint and ceramic industry, powdered nickel oxide seeds the distinctive green shades found in certain glazes and enamels. Anyone handling this solid should recognize its reactivity with hydrogen and carbon monoxide, both of which can transform the oxide to pure nickel metal at high temperature.

Specifications and Standard Identifiers

Looking at batch certifications, standard-grade nickel oxide (HS Code: 28255010) arrives with specified purities, sometimes up to 99.5%. Manufacturers offer technical data sheets outlining major specifications, usually breaking down maximum iron, cobalt, copper, and sulfur content. Each kilogram carries a CAS number: 1313-99-1. No one in the industry ignores these details; each impacts the end-product quality, whether you’re refining stainless steel or producing catalysts used in renewable energy setups.

Forms and Material Safety

Supply catalogs list nickel oxide under multiple forms: flakes, granules, dense powder, and pressed pellets. These forms stem from differing production routes — from direct combustion of nickel in air to precipitation from nickel salt solutions, then calcination. Although people don’t often see nickel oxide as a liquid or solution, chemists sometimes suspend fine particles in suitable carriers for research or coating applications. Handling and storage demand care. Nickel oxide dust can harm respiratory organs after inhalation; researchers have linked chronic exposure with higher risks of lung conditions and nickel sensitivity. The European Union and other health agencies list nickel oxide as a suspected carcinogen, so facilities enforce strict PPE policies, use closed systems, and issue workplace exposure limits to protect staff during weighing and mixing.

Role in Industry and Raw Material Value

As a raw material, nickel oxide powers several essential industries. Refiners blend it with iron ores to raise the nickel content in stainless steels, a product found in kitchens, hospitals, and vehicles worldwide. Glassmakers add it for coloring and ultraviolet absorption — an invisible but essential function in specialty optics. Energy technologists see nickel oxide as the backbone of battery cathodes, especially in nickel-metal hydride and emerging solid-state batteries, due to its sturdy, redox-active lattice. Catalysis researchers count on its surface area and crystalline defects to support chemical reactions needed for renewable fuels.

Quality, Hazard, and Solutions

Ensuring consistent quality of nickel oxide matters because impurity levels affect everything from battery performance to the safety of finished consumer goods. Most buyers insist on strict supplier audits and frequent material testing, not just for purity but also particle size, morphology, and moisture content. Waste management presents a thorny issue. Spent nickel oxide or contaminated workplace dusts demand proper hazardous waste handling under local regulations, with recycling an urgent goal for sustainability. Safer substitutes don’t always exist, especially in high-temperature or electronic roles, so innovation continues in engineering less hazardous processing routes and in designing protective equipment that keeps workers safe and environmental releases low. The story of nickel oxide keeps expanding, touching areas from clean energy to advanced ceramics, all while demanding both scientific rigor and real-world caution at every stage.