Аннотации:
Gels were prepared via sol-gel method by addition of zirconium oxychloride solution into sodium metasilicate (SZ) and sodium metasilicate solution into zirconium oxychloride (ZS) at varying final pH. Si/Zr molar ratio equaled 1/1. Synthesized gels were dried with calcium chloride until they reached a constant mass. SEM and nitrogen adsorption analysis have shown that SZ gels have surface area 175-200 m 2 g -1, consist of 20-30 nm grains. ZS samples have surface area about 1 m 2 g -1, consist of grains smaller than 10 nm. Thermal and X-ray phase analysis have shown that transition of amorphous ZrO 2 to crystalline form shifts from 430 to 850-870 °C for SZ gels. Unlike zirconia gels phase transitions that proceed in order: "amorphous (430 °C) - tetragonal (800 °C) - monoclinic (1,000 °C) phases", themonoclinic phase inZSgels appears immediately after transition from amorphous to crystalline state; the tetragonal phase in SZ samples is stable until 1,000 °C. © Akadémiai Kiadó, Budapest, Hungary 2012.