Preparation And Properties Of Rare-earth Doped Zirconia Nanotube Arrays

The zirconium alloys doped with Eu,Tm and Ce were prepared by a powder metallurgical method in this thesis,then the Eu-doped,Tm-doped and Ce-doped ZrO₂nanotube arrays and undoped ZrO₂ nanotube arrays were prepared by anodising corresponding alloys in formamide+glycerol?denoted by FA+GE?organic electrolytes and?NH₄?₂SO₄ aqueous solution containing F^-,respectively.The morphologies,crystal structure,elemental valence,UV-vis diffuse reflectance spectra and photoluminescence properties were characterized by SEM,XRD,XPS,UV-Vis and PL,respectively.1.The morphologies,crystal structures and properties of Eu³⁺-doped ZrO₂ nanotube arrays which were obtained in two kinds of electrolytes by anodisation method were investigated.Results show that the optimal preparation conditions in organic and inorganic electrolyte were:FA+GE?volume ratio 1:1?+1 wt.%H₂O+1 wt.%NH₄F,20°C,50 V,3 h and 0.5 M?NH₄?₂SO₄+0.25 wt%NH₄F,20°C,40 V,3 h,respectively.The samples obtained in organic electrolyte which were crystallised annealed at above 400°C were mainly monoclinic phase;the samples obtained in inorganic electrolyte were mainly tetragonal phase.Under different excitation wavelengths,the samples crystallised well had emission peaks at 593 nm,598 nm,609 nm and 615 nm,the emission peaks at 598 nm and615 nm corresponded to the ⁵D₀?⁷F₁ and ⁵D₀?⁷F₂ transitions mostly from Eu³⁺ions in monoclinic ZrO₂ and the peaks at 593 nm and 609 nm corresponded to the ⁵D₀?⁷F₁ and⁵D₀?⁷F₂ transitions mostly from Eu³⁺ions in tetragonal ZrO₂ respectively.2.The morphologies,crystal structures and properties of Tm³⁺-doped ZrO₂ nanotube arrays obtained in two kinds of electrolytes were investigated.Results show that the morphologies and crystal structures of the samples obtained in the two kinds of electrolytes were similar to that of Eu³⁺-doped ZrO₂ nanotube arrays.The samples crystallised well had emission peaks at 454 nm and 460 nm under the excitation at 358 nm,362 nm and 367 nm.The monoclinic phase was conductive to the emission at 454 nm while the tetragonal phase was conductive to the emission at 460 nm.3.The morphologies,crystal structures and properties of Ce³⁺-doped ZrO₂ nanotube arrays obtained in two kinds of electrolytes were investigated.Results show that the samples annealed at above 600°C obtained in organic electrolyte and the samples annealed at above 400°C obtained in inorganic electrolyte had obvious diffraction peaks of Ce₂Zr₂O_7.04 compound oxides.There was no obvious emission peak in the emission spectra.4.For the samples prepared in organic electrolyte,Eu³⁺ion could stabilise the tetragonal phase;the introduction of Tm³⁺ion could raise the crystallization temperature and stabilise the tetragonal phase in a certain degree;the doping of Ce³⁺introduced the Ce₂Zr₂O_7.04 composite oxides.For the samples prepared in inorganic electrolyte,the doping of Eu³⁺,Tm³⁺and Ce³⁺decreased the degree of order,raised the thermostability and stabilised the tetragonal phase of nanotube arrays in some level.