Tantalum (IV) selenide

Crystal structure
__ Ta 4+      __ Se 2−
General
Surname	Tantalum (IV) selenide
other names	Tantalum diselenide
Ratio formula	TaSe 2
Brief description	silver-gray solid
External identifiers / databases
CAS number 12039-55-3 EC number 234-898-2 ECHA InfoCard 100,031,713 PubChem 82873 Wikidata Q24629587
properties
Molar mass	338.87 g mol −1
Physical state	firmly
density	6.7 g cm −3
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 301-331-373-410 P: 260-304 + 340 + 312-403 + 233
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Tantalum (IV) selenide is an inorganic chemical compound of tantalum from the group of selenides . In addition to TaSe ₃ , Ta ₂ Se and Ta ₆ Se, other tantalum selenides are known.

Extraction and presentation

Tantalum (IV) selenide can be obtained by reacting tantalum with selenium at temperatures above 600 ° C, with the 2H form being created as a stable low-temperature form on slow cooling. The 3R shape can be obtained by heating the 1T shape to 300 to 500 ° C. At 800 ° C, the 3R shape changes to the 6R shape.

${\displaystyle \mathrm {Ta+2\ Se\longrightarrow TaSe_{2}} }$

properties

Tantalum (IV) selenide is a solid that occurs in many modifications (similar to tantalum (IV) sulfide ), which also include the non-stoichiometric range Ta _{1 + x} Se ₂ (x between 0.35 and 0.15). These not only have different crystal structures, but also differ in their properties and production. 1T form has a golden metallic color, 2H (a) form silver and other modifications black. The 1T form is stable at temperatures above 800 ° C and can also be obtained at room temperature by quenching. Three different modifications are known of the 4H form. A 3R and 6R form are also known. The modifications have the crystal structures : 1T trigonal with the space group P 3 m 1 (space group no.164) , 2H hexagonal with the space group P 6 ₃ / mmc (space group no.194) , 3R and 6R each rhombohedral with the space group R. 3 m (room group no.160) . The hexagonal layered crystal structure of tantalum diselenide represents Se-Ta-Se layers in different stacking arrangements. The layer structure enables lamination or peeling of the layers.

use

Pure tantalum diselenide is used as a sputtering target to produce lubricant films and coatings. Two-dimensional layered inorganic nanomaterials such as tantalum (IV) selenide have recently attracted considerable attention due to their thickness-dependent physical and chemical properties. You will find applications in photocatalysis, photovoltaics, gas sensors, lithium-ion batteries, field effect transistors, spintronics, etc.

Individual evidence

1. ↑ ^{a b c} R.MA Lieth: Preparation and Crystal Growth of Materials with Layered Structures . Springer Science & Business Media, 2013, ISBN 978-94-017-2750-1 , pp. 189 ( limited preview in Google Book search).
2. ↑ ^{a b c d e} data sheet Tantalum diselenide, Crystal, 99.995% from Sigma-Aldrich , accessed on January 4, 2017 ( PDF ).
3. ^ William M. Haynes: CRC Handbook of Chemistry and Physics, 93rd Edition . CRC Press, 2016, ISBN 978-1-4398-8050-0 , pp. 93 ( limited preview in Google Book search).
4. ↑ RJH Clark, D. Brown: The Chemistry of vanadium, niobium and tantalum Pergamon text in Inorganic Chemistry . Elsevier, 2013, ISBN 978-1-4831-8170-7 , pp. 600 ( limited preview in Google Book Search).
5. ^ Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . CRC Press, 2016, ISBN 978-1-4398-1462-8 , pp. 412 ( limited preview in Google Book search).
6. ↑ Werner Baumann, Bettina Herberg-Liedtke: Chemicals in metal processing Data and facts on environmental protection . Springer-Verlag, 2013, ISBN 978-3-642-61004-2 , p. 1451 ( limited preview in Google Book search).