Preparation and characterization of metal titanate materials

Kobese, Pakamisa (2002-03)

Thesis (MSc)--Stellenbosch University, 2002.

Thesis

ENGLISH ABSTRACT: Thin films and powders of Ni.Tiï), and CoxTi03 (where x = 0.005 - 0.9) with different stiochiometric ratios were prepared using sol gel techniques. These metal oxides were prepared by spin coating on silicon and titanium substrates followed, by annealing at 400°C and 800°C respectively under a temperature program. A range of films with MxTiOy (where x = 0.005 - 0.9) were prepared and then characterized by optical methods such as Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Rutherford Backscattering Spectroscopy (RBS). X-ray powder diffraction was also used to determine the structural properties of these metal oxides. XRD pattern peaks showed that the powder forms of these metal oxides were well crystallized. Thin films could be amorphous because strong peaks were not present. For nickel titanates preparation, the best trend is at the low concentration of Ni that is 0.3:1 Ni:Ti. It is pure with no impurities of NiO and Ti02. High concentration of Co ranging from 0.7-1:1 Co:Ti forms a C02Ti04 structure with cubic phase. The best route for the CoTi03 preparation is at the low cobalt concentration that is 0.5:1 Co:Ti. Scanning Electron Microscopy (SEM) shows that a film deposited on silicon or a titanium substrate is smooth, uniform and crack-free. It also shows that a cobalt titanate film deposited on a Si substrate is rough, with cracks, whereas on the Ti substrate, it is smooth, uniform and crack-free. AFM studies show that as the concentration of Ni:Ti is reduced and the roughness of the thin film is increased. SEM, FTIR, XRD and RBS suggest that the 0.3:1 and 0.5:1Ni:Ti films with 10nm and 11nm thickness, respectively, iii Stellenbosch University http://scholar.sun.ac.za iv have the same structure. RBS suggests that the 1:1 and 0.5:1 Co:Ti have C0I.39Ti02.29and CoTi04.2 structures with 13nm and 16nm respectively. XRD reveals that NiTi03 and CoTi03 have rhombohedral crystal structure.

AFRIKAANSE OPSOMMING: Dunlagies en poeiers van NixTi03 en CoxTi03 (waar x = 0.005 - 0.9) met verskillende stoigiometriese verhoudings was voorberei deur gebruik te maak van sol gel tegnieke. Hierdie metaaloksiedes was voorberei deur gebruik te maak van "spin coating" op substrate van silikon en titaan gevolg deur konstante verhitting by 'n 400°C en 800°C temperatuur program onderskeidelik. 'n Reeks van lagies met MxTiOy (waar x = 0.005 - 0.9) was voorberei en gekarakteriseer met optiese metodes soos Skandeer Elektron Mikroskopie (SEM), Atoom Interaksie Mikroskopie (AFM) en "Rutherford Backscattering Spectroscopy (RBS)." X-straal Poeier Diffraksie was ook gebruik om die strukturele eienskappe van hierdie metaaloksiedes te bepaal. XRD patroon pieke wys dat die poeier vorms van hierdie metaaloksiedes goed gekristalliseer was. Dunlagies mag ook amorf wees aangesien sterk pieke nie teenwoordig was nie. Vir nikkel titaniete is hierdie die algemene roete vir die NiTi03 voorbereiding. Die beste tendens is by lae konsentrasies van Ni naamlik 0.3:1 Ni:Ti. Dit is suiwer en het geen onsuiwerhede van NiO en Ti02 nie. Hoë konsentrasies van Co vanaf 0.7 - 1:1 Co:Ti vorm 'n Co2Ti04 struktuur met 'n kubiese fase. Die beste roete vir die CoTi03 voorbereiding is by lae kobalt konsentrasie naamlik 0.5 -1:1 Co:Ti. Skandeer Elektron Mikroskopie (SEM) wys dat 'n NiTi03 laag gedeponeer op silikon en titaan substrate gelyk was, eenvorming en sonder krake. Dit wys ook dat die kobalt titaan laag oppervlakte gedeponeer op 'n silikon substraat grof was en het krake getoon. Vir die Ti substraat het dit gewys dat die oppervlaktes gladwas, univormig en sonder krake. AFM studies wys dat as die konsentrasie Ni:Ti verminder word die grofheid van die dunlaag verminder. SEM, FTIR, XRD en RBS dui aan dat die 0.3:1 en 0.5:1 Ni:Ti dunlaag dieselfde struktuur het met 10nm en 11nm dikte onderskeidelik. RBS dui aan dat die 1:1 en 0.5:1 Co:Ti het C01.39Ti02.29en CoTi04.2 strukture onderskeidelik met 13nm en 16nm diktes. XRD toon aan dat NiTi03 en CoTi03 rhombohedrale kristal strukture het.

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