Eduard Zintl discovered discrete charges at some intermetallic phases

Eduard Zintl – discoverer of Zintl phases

Category : Personalities
Published by : Data Research Analyst, Worldofchemicals.com

Biography & Contributions

Eduard Zintl was a German chemist born on January 21, 1898 – died on January 17, 1941. He studied the structure of complex anions formed by metals.

Zintl discovered discrete charges at some intermetallic phases i.e., Zintl phases. He investigated about the structure of compounds in the transition region between ionic and metallic states.

Zintl Phase

Zintl phase is the product of a reaction between a group 1 (alkali metal) or group 2 (alkaline earth) and any post transition metal or metalloid (i.e. from group 13, 14, 15 or 16). It is named after the German chemist Eduard Zintl who investigated them in the 1930s.

Zintl phases are a subgroup of brittle, high melting point intermetallic compounds which are diamagnetic or exhibit temperature-independent paramagnetism, are poor conductors or semiconductors.

Zintl noted that there was an atomic volume contraction when these compounds were formed and realized this could indicate cation formation.

He suggested that the structures of Zintl phases were ionic, where there was complete electron transfer from the more electropositive metal.

The structure of the anion (Zintl ion) should then be considered on the basis of the resulting electronic state. These ideas were further developed to become the Zintl rule or Zintl Klemm concept, where the polyanion structure should be similar to an isoelectronic element.

Example for Zintl phases

K4Ge4

Number of outer shell electrons of the anion: 5

Every ion forms 3 covalent bonds (comparable to the structure of an element with 5 outer shell electrons)

In K4Ge4 Ge forms isolated (Ge4)4- ions (comparable to white phosphorus)

CaSi

Number of outer shell electrons of the anion: 6

Every ion forms 2 covalent bonds (comparable to the structure of an element with 6 outer shell electrons)

In CaSi Ge forms (Sin)2n- chains (comparable to grey selenium)

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