Prepn. of fine-crystalline alpha-quartz

Fine-crystalline alpha-quartz of crystal size 0.08-0.8 mm is obtd. by crystallising amorphous SiO2 in a water vapour atmos. in the presence of a crystallisation promoter (I) at 300-500 deg.C and pressure 20-400 atmos. for 5-100 hrs. (I) is a basic material used in an amt. 0.001-1 wt.% an amorphous S...

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Hauptverfasser:	TORBIN SERGEI NIKOLAEVICH, VOROSHILOV IGOR LEONIDOVICH, KREISBERG VALERY ABRAMOVICH, DANCHEVSKAYA MAIRINA NIKOLAEVICH, PANASJUK GEORGY PAVLOVICH, BUDOVA GALINA PAVLOVNA, LAZAREV VLADISLAV BORISOVICH, ONAIKO VLADIMIR ALEXEEVICH, GAVRILKO VLADIMIR MOISEEVICH
Format:	Patent
Sprache:	eng ; ita
Schlagworte:	AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE APPARATUS THEREFOR CHEMISTRY CRYSTAL GROWTH METALLURGY PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE REFINING BY ZONE-MELTING OF MATERIAL SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE SINGLE-CRYSTAL-GROWTH UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL
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Beschreibung
Zusammenfassung:	Fine-crystalline alpha-quartz of crystal size 0.08-0.8 mm is obtd. by crystallising amorphous SiO2 in a water vapour atmos. in the presence of a crystallisation promoter (I) at 300-500 deg.C and pressure 20-400 atmos. for 5-100 hrs. (I) is a basic material used in an amt. 0.001-1 wt.% an amorphous SiO2 wt. (I) is pref. an alkali metal hydroxide used in an amt. (on wt.% of amorphous SiO2) 0.001-0.1, NH4OH or a quat. ammonium base used in an amt. 0.02-1; polyelectrolyte-polyethylene-imines of mol. wt. 190-50.000 used in an amt. 0.001-0.1, or hydrazine (alkyl deriv.) used in an amt. 0.02-1.