Microstructural evolution of the system Ni-ZrO2-SiO2 synthesized by the sol-gel process

The analysis of the structural changes corresponding with composition and temperature is fundamental for understanding the applications of ceramic glass In particular, the system ZrO2-SiO2 is commonly used in the ceramic industry due to the high chemical stability and superior resistance for dissolution during firing in glazes This work is focused on the synthesis of Ni doped ZrO2-SiO2 powders with different Zr center dot Si molar ratios (20 80, 50 50 and 70.30) by sol-gel process. For purposes of comparison, un-doped ZrO2-SiO2 systems were also prepared. TEOS, zirconium propoxide and nickel chloride hexahydrate were used as precursors of the SiO2, ZrO2 and ion dopant, respectively. The obtained xerogels were thermally treated from 300 to 1300 degrees C in order to follow their structural evolution FT-IR results show the corresponding bands of the M-O bonds related to the formation of zircon at high temperatures, while XRD analyses display t-ZrO2 with traces of m-ZrO2 at the evaluated temperatures, also, between 1200 and 1300 degrees C, the zircon compound (ZrSiO4) was detected It was observed that inserting nickel as a dopant has a significant effect on the structural and morphological characteristics From the comparison of the doped and un-doped specimens, we hypothesize that the presence of Ni and the heat treatment promote the stabilization and crystallization of the zircon phase at molar ratios higher than 50Zr 50Si, or Ni is incorporating Into the ZrO2 phase, provoking oxygen vacancies and leading to tetragonal phase stabilization (C) 2009 Elsevier B V All rights reserved