Alkali gallates with mullite-type structure

✍ Scribed by P. Angerer; R.X. Fischer; M. Schmücker; H. Schneider

• Book ID: 104022720
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 281 KB
• Volume: 28
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2007.03.011

✦ Synopsis

Silica-free alkali gallates with mullite-type structure were synthesized by reaction of a stoichiometric mixture of the nitrates with glycerol and subsequent thermal treatment between 700 and 900 • C. The crystallization behavior of the compounds has been studied: specimens of the type potassium gallate K 0.67 Ga 6 3+ O 9.33 and rubidium gallate Rb 0.67 Ga 6 3+ O 9.33 have been prepared. The lattice constants (potassium gallate: a = 8.0065(12) Å, b = 8.0063(10) Å, c = 3.0359(5) Å; rubidium gallate: a = 8.0106(17) Å, b = 8.0161(17) Å, c = 3.0439(6) Å) were determined by refinement of the X-ray powder diffraction patterns which show a very close relationship to the alkali aluminate compounds with mullite-type structure. Furthermore isotypes of the composition Me 0.67 + (Fe 3+ , Ga) 6 O 9.33 and Me 0.67 + (Fe 3+ , Al) 6 O 9.33 (Me + = Rb or K) with an Fe(III) content of 20-30% have been prepared.