Influence Of Cr And Eu Doping On The Performance Of ZnO Powders And Films

As a metal oxide semiconductor material with a direct wide band gap,Zinc Oxide(ZnO)has an extensive application prospect owing to its excellent optical,electrical and magnetic properties.However it is still controversial topic on the origin of room temperature ferromagnetism in the academic fields.Therefore,the optical and magnetic properties of porous ZnO powders and films were studied in detail by controlling its structure and doping metal elements,and the related mechanisms are discussed.The main contents are as follows:The porous ZnO microspheres were prepared using zinc acetate(Zn(CH3COO)2)as the zinc source and the composite crystal of cationic surfactant fourteen alkyl methyl ammonium bromide(TTAB)-anionic polyelectrolyte polyacrylic acid(PAA)as templates.It is investigated that the effects of annealing temperature and the dosage of PAA on the microstructure,morphology and properties of ZnO microspheres by X ray diffraction(XRD),X ray photoelectron spectroscopy(XPS),nitrogen adsorption and desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),fluorescence spectrometer(PL)and the department of physics test system(PPMS).The results showed that the optimum conditions were obtained when the annealing temperature was 600 ml and the content of PAA was 3 ml.At that time,the specific surface area of the as-prepared porous ZnO microspheres was as high as 35.98 cm2·g-1,and the pore size was between 6 nm~20 nm,and the luminescence was the strongest,and possess a certain room temperature ferromagnetism.Both the luminescence and ferromagnetism are related to the concentration of oxygen vacancies on the porous ZnO microspheres.Cr doped ZnO(Zn1-xCrxO)microspheres were prepared by hydrothermal method.It was investigated that the effects of Cr doping on the structure,morphology and properties of ZnO microspheres in detail.The results show that the Zn1-xCrxO microspheres is wurtzite structure,and no Cr metal clusters and its oxides were determined when the Cr content is in the range of 4%-16%.With the increase of Cr content,the specific surface area,it is found that the luminescence intensity and the saturation magnetization increased first and then decreased.This largely depends on the oxygen vacancy concentration.Eu doped porous ZnO(Zn1-xEuxO)powders were prepared by hydrothermal method.The effects of Eu doping on the structure,morphology and properties of ZnO microspheres was investigated in detail by XRD,BET,SEM,TEM,PLand PPMS.The results show that the as-prepared Zn1-xEuxO powder,without Eu metal clusters and its oxide,is still wurtzite structure when the Eu content is in range of 2%-11%.It is also found that the specific surface area and the luminescent properties of the samples increased first and then decreased with the increase of the Eu content,.The PPMS test showed that the samples had obvious hysteresis loops,and the saturation magnetization increased and then decreased with the increase of the dosage.Eu doped porous ZnO(Zn1-xEuxO)films were prepared by homogenization method.The structure,morphology and properties of ZnO microspheres were investigated by XRD,BET,SEM,TEM,PL and PPMS.The results show that Zn1-xEux O thin film is wurtzite structure when the Eu content is no more than9%,and Eu metal and its oxide were not determined within in the XRD limit.With the increase of Eu content,the specific surface area,luminescence intensity and saturation magnetization of the ZnO(Zn1-xEuxO)films show the same variation law as that of the corresponding Zn1-xEuxO powders.