Molybdenumblauw

Molybdenumblauw, or molybdenum blue, is not a single chemical compound but a class of blue pigments based on reduced molybdenum oxides. It refers to deep blue to gray-blue solids produced by partial reduction of molybdate species, resulting in mixed-valence Mo(V)–Mo(VI) oxides. The exact structure is variable, and these pigments are often described as amorphous or nanostructured rather than as a defined crystalline compound.

Chemical nature and color mechanism: The color arises from intervalence charge transfer between molybdenum centers in different oxidation states, rather than from a fixed lattice. Composition can be represented as MoO3−x or related cluster species, with variations depending on preparation conditions. Factors such as the reducing agent, pH, aging, particle size, and the presence of other ions influence color strength and shade.

Production and forms: In practice, pigments are obtained by reducing aqueous molybdate solutions in alkaline media using sulfur-containing or organic reducing agents, followed by precipitation and drying to form a powder. They are used as pigments in paints, ceramic glazes, and glass, where their blue hue can be tuned by formulation.

Properties and performance: Molybdenum blue pigments offer high tinting strength, good opacity at certain loadings, and strong lightfastness. They exhibit good thermal stability in high-temperature applications such as enamels and glass coloring. They are typically insoluble in water and most solvents, with binder compatibility varying by formulation.

History and safety: The use of molybdenum blue pigments reflects a long history in inorganic pigment chemistry and art materials. When used as manufactured pigments, they are generally considered low hazard in normal use, though standard pigment safety practices apply.

See also: Molybdate pigments, inorganic blue pigments, pigments for ceramics.