Overview

Cadmium oxide is an inorganic compound with the formula CdO. It appears as powders or crystals that range in color from yellow to brown or red-brown and adopts a dense, crystalline lattice related to the rock‑salt structure. The material contains cadmium cations and oxide anions and is commonly discussed in chemical reference works and industrial data sheets (general reference).

Physical and chemical properties

CdO is a solid oxide of a transition metal with semiconducting properties: thin films can conduct electricity while remaining partly transparent in the visible range. It is chemically reactive toward acids (forming soluble cadmium salts) and can interact with strongly basic solutions under certain conditions. The compound is stable at ambient conditions, has a high melting point typical of metal oxides, and occurs in different stoichiometric and nonstoichiometric forms depending on preparation.

Production and occurrence

Industrial and laboratory routes to cadmium oxide include controlled oxidation of metallic cadmium, thermal decomposition of cadmium carbonate or hydroxide, and precipitation from aqueous cadmium salts followed by drying and heating. It does not occur widely in nature as a pure mineral but may form as an alteration product of other cadmium minerals. Technical summaries and safety data often list preparation methods and material specifications (preparation notes).

Uses

  • Precursor in the manufacture of cadmium pigments (for example, in producing cadmium sulfide and cadmium sulfoselenide).
  • Component of transparent conductive oxide films and other electronic or optoelectronic applications where doped CdO can provide n‑type conductivity.
  • Intermediate in electroplating, battery materials, and ceramic or glass processing.

Safety, environmental impact and regulation

Cadmium oxide, like other soluble cadmium compounds, is toxic to humans and wildlife. Chronic or high exposures affect kidneys and bones and cadmium compounds are regarded as carcinogenic by major health authorities. Environmental persistence and bioaccumulation raise concerns for aquatic ecosystems. Handling requires appropriate engineering controls, personal protective equipment, and waste‑management practices; legal limits and restrictions on cadmium use and disposal exist in many jurisdictions (health and regulation).

For further technical properties, analytical methods and regulatory guidance consult specialized chemical databases and material safety resources (technical data).