Low temperature synthesis of pure and Fe-doped HfSiO4: determination of Si and Fe fractions by neutron activation analysis

Abstract A new method of synthesis of hafnium silicate HfSiO 4 (also known as hafnon) is reported. We observed a self-controlled incorporation of SiO 2 from the quartz tube in which a sample of hafnium oxide nanoparticles was heated. This approach was then adapted to Fe-doped hafnon production. Sample structure, morphology and composition were characterized by X-ray diffraction, electron microscopy and neutron activation analysis. Diffraction data has shown that lattice parameters of doped HfSiO 4 thus obtained are very close to those previously known for bare hafnon. The hafnon-like phase stabilized at T = 900 °C which is about 500 °C lower than the corresponding transition of bare bulk hafnium silicate. The fractions of Si and Fe in the composite matrices were determined with neutron activation analysis. These results completed by X-ray diffraction data allowed to assume that (i) Fe initially substituted Hf in the HfO 2 lattice; (ii) there was no migration of iron atoms from Hf to Si sites at the formation of hafnon-like phase; (iii) doped and undoped hafnium oxide has taken as much Si from the quartz as was needed for the arrangement of Fe 1-x Hf x SiO 4 tetragonal system, 0≤x