Flaming_June,_by_Frederic_Lord_Leighton_(1830-1896)

Chrome orange is a

mixed oxide In chemistry, a mixed oxide is a somewhat informal name for an oxide that contains cations of more than one chemical element or cations of a single element in several states of oxidation.Advanced Inorganic Chemistry, F. A. Cotton, G. Wilkinson ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

Pb₂CrO₅. It can be made by treating a lead(II) salt with an alkaline solution of a chromate or by treating chrome yellow (PbCrO₄) with strongly basic solution..

Synthesis and nanoparticles

Pb₂CrO₅ can be synthesized with a gas-liquid precipitation process. Changing the pH controls whether PbCrO₄ or Pb₂CrO₅ is created.

Orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with ...

nanocrystals can be selectively synthesized in a facile room temperature solution for Pb₂CrO₅. Using a microwave-assisted ionic liquid (MAIL) method, bundle and rod-like nanocrystals of Pb₂CrO₅ were formed. The bundles look like bundles of straw, secured in the middle. In basic solution, single-crystalline Pb₂CrO₅ could be formed by heating lead acetate and potassium dichromate with microwave radiation for only 10 minutes at 90 celsius. The MAIL process is simple, fast, and does not employ surfactants. The presence of hydroxide changes the phase that is formed. Using NaOH,

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

Pb₂CrO₅ is formed. The bundle and rod-shaped structures are sensitive to electron beam irradiation, which will turn them into many small particles.

Properties

The

Gibbs free energy In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature an ...

of Pb₂CrO₅ was determined in 2010 and is given as Δ''_fG''^°_''m''Pb₂CrO₅(s)±0.30/(kJ•mol⁻¹)=-1161.3 +0.4059(T/K) (859≤T/K≤1021).

Visible light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

activity up to 550 nanometers has been recorded for Pb₂CrO₅.

Pigment synthesis

In an catalog published c. 1835, Winsor and Newton paint company identify ten synthetic pathways for producing chrome orange, also called deep yellow. Chrome orange is made of PbCrO₄ mixed with basic lead chromate (Pb₂CrO₅). It has been described as a “yellowish red or sometimes a beautiful deep red” in alkaline conditions. A deep yellow can be created using PbCrO₄ and lead sulfate. There are ten synthetic methods for preparing deep chrome yellow (that made with Pb₂CrO₅), which require a chromate source, a basic lead source, additives, and a sulfate source. CrO₄^2- + H₂SO₄+Pb(Ac)₂ • 2Pb(OH)₂ → PbCrO₄+Pb₂CrO₅ at a pH of approximately seven is the synthesis. Controlling the pH was Winsor and Newton’s method for creating pigments from the pale yellow to the deep chrome orange. The resulting product has a high stability to light, which is always coveted by artists and collectors.

History

The natural mineral crocoite was discovered in 1797 by Louis Vauquelin and chrome orange was synthesized as a pigment for the first time in 1809. Pb₂CrO₅ is found in mineral form as phoenicochroite, which is a

, red, translucent mineral found in various places across the world, including Russia, the USA, and Chile.

Use as a pigment

Chrome orange can range in color from light to deep orange and is no longer in production as a pigment. It has also been known as Derby red, Persian red, and Victoria red. It was first recorded as a pigment in 1809 and was perfect for some impressionist painters in the nineteenth century. The yellow-orange pigment of the boat in Renoir’s 1879 painting, The Seine at Asnières (The Skiff) at the National Gallery, London. Chrome orange was used extensively in

Frederic Leighton Frederic Leighton, 1st Baron Leighton, (3 December 1830 – 25 January 1896), known as Sir Frederic Leighton between 1878 and 1896, was a British painter, draughtsman, and sculptor. His works depicted historical, biblical, and classical subjec ...

's ''

Flaming June ''Flaming June'' is a painting by Sir Frederic Leighton, produced in 1895. Painted with oil paints on a square canvas, it is widely considered to be Leighton's magnum opus, showing his classicist nature. It is thought that the woman portrayed ...

'' (1895; Museo de Arte de Ponce).

Synthesis and nanoparticles

Properties

Pigment synthesis

History

Use as a pigment

See also

References

Further reading