Magnesium metasilicate

Crystal structure
__ Mg 2+      __ Si 4+      __ O 2−
General
Surname	Magnesium metasilicate
Ratio formula	MgSiO 3
Brief description	white solid
External identifiers / databases
CAS number 13776-74-4 EC number 237-413-2 ECHA InfoCard 100.033.998 PubChem 61680 Wikidata Q18211718
properties
Molar mass	100.39 g mol −1
Physical state	firmly
density	3.19 g cm −3
Melting point	1550 ° C (decomposition)
solubility	practically insoluble in water sparingly soluble in hydrofluoric acid
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Magnesium metasilicate is an inorganic chemical compound of magnesium from the group of silicates , more precisely the magnesium salt of silicic acids .

Occurrence

Magnesium metasilicate occurs naturally in the form of some minerals . So the minerals from the pyroxene group ortho- , proto- and clinoenstatite , as well as a garnet ( majorite ) and a modification each with ilmenite ( akimotoite ) and perovskite structure ( bridgmanite ). Enstatite is a common rock-forming mineral of the earth's mantle , the lower crust of the earth , basic magmatites and granulite-facial metabasites , metapelites and metamorphic calcium silicate rocks , as well as in certain meteorites . The orthorhombic orthoenstatite is the stable enstatite modification that forms during crystallization at low temperatures. When heated to over 1200 ° C, it changes to the protoenstatite form. However, since the recrystallization between the three modifications is very slow and involves little change in properties, the transitions are difficult to see. Protoenstatite normally does not revert to orthoenstatite when it cools down. The monoclinic clinoenstaite is a low temperature form of protoenstatite. The tetragonal yarn is a form of high pressure and temperature that forms at around 18 GPa pressure and over 2000 K. From 20 GPa the modification forms with an ilmenite structure and from 23 GPa with a perovskite structure.

Extraction and presentation

Magnesium metasilicate can be obtained by thermal decomposition of talc .

${\displaystyle \mathrm {Mg_{3}[Si_{4}O_{10}](OH)_{2}\longrightarrow 3\ MgSiO_{3}+SiO_{2}+H_{2}O} }$

It can also be calcined of magnesium oxide with silicon dioxide are obtained at 1300 ° C. It is also possible to obtain it by reacting magnesium nitrate with 1,2-diformylhydrazine and pyrogenic silicon dioxide at 400 ° C and subsequent calcination at 1350 ° C.

properties

Magnesium metasilicate is a white solid that is practically insoluble in water. The compound occurs in at least six modifications (some sources speak of four enstatites for a total of seven modifications). These are the forms known from the corresponding minerals proto-, ortho- and clinoenstantite, garnet ( majorite ), ilmenite ( akimotoite ) and perovskite ( bridgmanite ). Enstatite crystallizes orthorhombically in the space group Pbca (space group no. 61) with the lattice parameters a  = 18.24  Å ; b  = 8.82 Å; c  = 5.18 Å and 8 formula units per unit cell . Protoenstatite has an orthorhombic crystal structure with the space group P 2 ₁ cn (space group no. 33, position 4) . Klinoenstatite has a monoclinic crystal structure with space group P 2 ₁ / c (space group no. 14) (low-P) or space group C 2 / c (space group no. 15) .

use

Magnesium metasilicate can be used in electronics as a ceramic material for high frequency applications.

Individual evidence

1. ↑ ^{a b c d e f g} William M. Haynes: CRC Handbook of Chemistry and Physics, 94th Edition . CRC Press, 2016, ISBN 978-1-4665-7115-0 , pp. 108 ( limited preview in Google Book search).
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ Surendra K. Saxena, Nilanjan Chatterjee, Yingwei Fei, Guoyin Shen: Thermodynamic Data on Oxides and Silicates An Assessed Data Set Based on Thermochemistry and High Pressure Phase Equilibrium . Springer Science & Business Media, 1993, ISBN 978-3-642-78332-6 , pp. 427 ( limited preview in Google Book search).
4. ↑ Felix Singer, Sonja S. Singer: Industrial ceramics, second volume - masses, glazes, color bodies manufacturing processes . Springer-Verlag, 1969, ISBN 978-3-642-92989-2 , pp. 120 ( limited preview in Google Book search).
5. ^ Eugene F. Milone, William JF Wilson: Solar System Astrophysics Background Science and the Inner Solar System . Springer Science & Business Media, 2014, ISBN 978-1-4614-8848-4 , p. 184 ( limited preview in Google Book search).
6. ↑ ^{a b} Olga Fabrichnaya, Surendra K. Saxena, Pascal Richet, Edgar F. Westrum: Thermodynamic Data, Models, and Phase Diagrams in Multicomponent Oxide Systems An Assessment for Materials and Planetary Scientists Based on Calorimetric, Volumetric and Phase Equilibrium Data . Springer Science & Business Media, 2013, ISBN 978-3-662-10504-7 , pp. 12 ( limited preview in Google Book search).
7. ↑ Erich Thilo: Chemical investigations of silicates, VII. Communication: About the magnesium metasilicate formed during the thermal decomposition of talc. In: Reports of the German Chemical Society (A and B Series). 70, 1937, p. 2373, doi : 10.1002 / cber.19370701209 .
8. ↑ Harry G. Brittain: Profiles of Drug Substances, Excipients and Related Methodology . Academic Press, 2011, ISBN 978-0-12-387667-6 , pp. 282 ( limited preview in Google Book search).
9. ↑ Joseph R. Smyth: Protoenstatite: a crystal-structure refinement at 1100C. In: Journal of Crystallography - Crystalline Materials. 134, 1971, doi : 10.1524 / zkri.1971.134.3-4.262 .
10. ↑ S. Jahn, R. Martonak: phase behavior of protoenstatite at high pressure of studied by atomistic simulations. In: American Mineralogist. 94, 2009, p. 950, doi : 10.2138 / am.2009.3118 .
11. ↑ Tibor Gasparik: Phase Diagrams for Geoscientists An Atlas of the Earth's Interior . Springer Science & Business Media, 2013, ISBN 978-1-4614-5776-3 , pp. 24 ( limited preview in Google Book search).
12. ↑ Relva C. Buchanan: Ceramic Materials for Electronics, Third Edition . CRC Press, 2004, ISBN 978-0-8247-4028-3 , pp. 77 ( limited preview in Google Book search).