Rinman's green

Zinc green

The pigment Rinmans Green (also cobalt green or zinc green ) is mainly used for oil paints and cement paints . The pigment, also known as cobalt green , is a turquoise green powder.

history

The oxide was first mentioned in 1780 by the Swede Sven Rinman (1720–1792). From 1912 Johan Arvid Hedvall examined the formation of Rinman's green in more detail. This first systematic investigation of “the reactivity in the solid state” is considered to be the beginning of solid-state chemistry . He realized "that this substance cannot be a chemical compound, but rather is to be understood as a solid solution between its two components: CoO and ZnO".

Structure and composition

The compound is a solid solution of a few percent cobalt (II) oxide CoO in zinc oxide ZnO . The Co (II) ions occupy lattice sites of the Zn (II) ions in the hexagonal wurtzite structure of the zinc oxide. The information on how much cobalt can be incorporated into the wurtzite lattice of the zinc oxide before the two-phase phase occurs through primary precipitation of cobalt oxide is controversial in the literature and ranges from 6.5% to 30%. The shade of green depends on the cobalt content ; the higher the proportion, the darker the colorant. The annealing temperature also influences the color.

It is a common mistake to ascribe a spinel structure with the composition ZnCo ₂ O ₄ to the common Rinman's green , as described in most textbooks. The common Rinmans green has the hexagonal wurtzite structure of zinc oxide. The cubic zinc-cobalt spinel ZnCo ₂ O ₄ is green-black.

Manufacturing

Rinman's green can be made from mixtures of zinc salts and cobalt salts , which are easily decomposable, such as nitrates , carbonates or oxalates . These salts are pulverized, thoroughly mixed with one another or precipitated together from an aqueous solution and calcined in the furnace.

${\displaystyle \mathrm {(1-x)\ ZnO+x\ Co(NO_{3})_{2}\longrightarrow Zn_{(1-x)}Co_{x}O+2x\ NO_{2}+{\tfrac {1}{2}}x\ O_{2}} }$ , With   ${\displaystyle \mathrm {x} \leq 0{,}02}$

Formation of Rinnman's green when glowing with cobalt nitrate.

application

Rinman's green is a popular proof of zinc. Zinc oxide or zinc hydroxide is mixed with a small amount of a highly diluted cobalt nitrate solution on a magnesia channel . Rinman's green is created when glowing weakly in the oxidizing flame.

Spintronics

The Rinmans green - like other doped zinc oxides - is possibly suitable for use in spintronics technology. Most materials that show the desired properties have to be cooled below 75 K (approx. −200 ° C). Rinman's green, on the other hand, could function at room temperature and thus be of interest for the manufacture of new non-volatile magnetic semiconductor memories.

See also

• Thénards Blue CoAl ₂ O ₄ , a cobalt-containing pigment

Individual evidence

1. ↑ Sven Rinman, Kungl. Svenska vetenskapsakademiens handlingar July, August, September 1780, Om grön Målare-färg af Cobolt. Pages 163-175, online at the Internet Archive
2. ↑ Paul Walden Chronological overview tables: On the history of chemistry from the oldest times to the present . Springer-Verlag, Berlin Göttingen Heidelberg 1952.
3. ^ Johan Arvid Hedvall: About Rinman's Green . In: Journal of Inorganic Chemistry ZAAC . Volume 86, No. 1, pages 201-224, May 5, 1914, doi : 10.1002 / zaac.19140860112
4. ^ Arvid Hedvall: Studies on Rinmansgrün . In: Chemisches Zentralblatt, October 8, 1913, pages 1273-1274.
5. ^ CH Bates, WB White, R. Roy: The solubility of transition metal oxides in zinc oxide and the reflectance spectra of Mn ²⁺ and Fe ²⁺ in tetrahedral fields . In: J. Inorg. Nucl. Chem. , 28 , 1966, 397-405.
6. ↑ R. Rigamonti, Gazz. Chem. Ital. 1946, 76, 476.
7. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1492.
8. ↑ Jander-Blasius: Textbook of analytical and preparative inorganic chemistry . 16th edition, 410.
9. ^ Riedel, Janiak: Inorganic Chemistry . 7th edition, p. 763.
10. ↑ Jander-Blasius: Introduction to the inorganic-chemical practical course . 14th edition 1995.
11. ↑ Michael Snure, Dhananjay Kumar, Ashutosh Tiwari: Progress in ZnO-based Diluted Magnetic Semiconductors . In: JOM - The Journal of The Minerals, Metals & Materials Society, June 2009, Volume 61, Issue 6, pp 72-75, doi : 10.1007 / s11837-009-0092-9
12. ↑ Kevin Kittilstved, Dana Schwartz, Allan Tuan, Steve Heald, Scott Chambers, Daniel Gamelin: Direct Kinetic Correlation of Carriers and Ferromagnetism in Co ²⁺ : ZnO. In: Physical Review Letters. 97, 2006, doi : 10.1103 / PhysRevLett.97.037203 .
13. ↑ Cobalt green as a pillar for the chip alternative . Retrieved August 17, 2008.
14. ↑ Pigment formulated 225 years ago could be key in emerging technologies . Retrieved August 17, 2008.