Chrome orange

Source: Wikipedia, the free encyclopedia.
Chrome orange was used extensively in Frederic Leighton's Flaming June (1895; Museo de Arte de Ponce).[1]
Chrome orange

Chrome orange is a mixed oxide with the chemical formula 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.[2]

Synthesis and nanoparticles

Pb2CrO5 can be synthesized with a

gas-liquid precipitation process.[3] Changing the pH controls whether PbCrO4 or Pb2CrO5 is created.[3]

Orthorhombic nanocrystals can be selectively synthesized in a facile room temperature solution for Pb2CrO5.[4]

Using a

microwave-assisted ionic liquid (MAIL) method, bundle and rod-like nanocrystals of Pb2CrO5 were formed.[5] The bundles look like bundles of straw, secured in the middle.[5] 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.[5] The MAIL process is simple, fast, and does not employ surfactants.[5] The presence of hydroxide changes the phase that is formed. Using NaOH, monoclinic Pb2CrO5 is formed.[5] The bundle and rod-shaped structures are sensitive to electron beam irradiation, which will turn them into many small particles.[5]

Properties

The Gibbs free energy of Pb2CrO5 was determined in 2010 and is given as

ΔfG°mPb2CrO5(s)±0.30/(kJ•mol−1)=-1161.3 +0.4059(T/K) (859≤T/K≤1021).[6]

Visible light activity up to 550 nanometers has been recorded for Pb2CrO5.[7]

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.[8] Chrome orange is made of PbCrO4 mixed with basic lead chromate (Pb2CrO5).[8] It has been described as a “yellowish red or sometimes a beautiful deep red” in alkaline conditions.[8] A deep yellow can be created using PbCrO4 and lead sulfate.[8] 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.[8] CrO42- + H2SO4+Pb(Ac)2 • 2Pb(OH)2 → PbCrO4+Pb2CrO5 at a pH of approximately seven is the synthesis.[8]

Controlling the pH was Winsor and Newton’s method for creating pigments from the pale yellow to the deep chrome orange.[8] The resulting product has a high stability to light, which is always coveted by artists and collectors.[8]

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.[9] Pb2CrO5 is found in mineral form as phoenicochroite, which is a monoclinic, red, translucent mineral found in various places across the world, including Russia, the USA, and Chile.[10]

Use as a pigment

Chrome Orange
 
CIELChuv (L, C, h)
(51, 147, 16°)
SourceColourLex[11]
B: Normalized to [0–255] (byte)

Chrome orange can range in color from light to deep orange and is no longer in production as a pigment.[9] It has also been known as Derby red, Persian red, and Victoria red.[9] 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.[9] Chrome orange was used extensively in Frederic Leighton's Flaming June (1895; Museo de Arte de Ponce).[1]

See also

References

  1. ^
    ISBN 9781907317958
    .
  2. ISBN 3527306730.{{cite encyclopedia}}: CS1 maint: location (link
    ).
  3. ^
    ISSN 0032-5910
    .
  4. ISSN 0025-5408
    .
  5. ^
    ISSN 1528-7483
    .
  6. S2CID 55549520
    .
  7. ISSN 1932-7447
    .
  8. ^
    S2CID 138176187
    – via EBSCO Host.
  9. ^ a b c d "Pigments through the Ages - Overview - Chrome orange". webexhibits.org. Retrieved 2022-05-11.
  10. ^ "Phoenicochroite". mindat.org. Retrieved 2022-05-11.
  11. ^ "Chrome orange - ColourLex". ColourLex. Retrieved 22 December 2022.

Further reading

  • Kühn, H. and Curran, M., Chrome Yellow and Other Chromate Pigments, in Artists’ Pigments. A Handbook of Their History and Characteristics, Vol. 1, L. Feller, Ed., Cambridge University Press, London 1986, p. 208 – 211.
  • Chrome Orange at ColourLex
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