【摘要】：ZnO具有較高的激子束縛能(60 meV)和較寬的禁帶寬度(3.37 eV),在壓電、光電設(shè)備等領(lǐng)域表現(xiàn)出巨大的應(yīng)用潛力。通過向ZnO中摻入其他元素,可以有效地調(diào)整其內(nèi)部結(jié)構(gòu)和形貌,改善其性能,從而擴(kuò)大ZnO的應(yīng)用范圍,所以近年來有關(guān)納米ZnO摻雜的研究迅速發(fā)展起來。Co作為一種典型的過渡金屬元素,具有豐富的表面態(tài)和與Zn~2+相似的離子半徑,更容易進(jìn)入到ZnO晶格與之溶為一相,可以有效調(diào)節(jié)ZnO的禁帶寬度,進(jìn)而調(diào)控其光學(xué)性能和應(yīng)用。同時(shí),Co具有磁性,摻入到ZnO晶格內(nèi)可形成ZnO基稀磁半導(dǎo)體(DMS),從而將ZnO的應(yīng)用擴(kuò)展到電子自旋設(shè)備、探測器等領(lǐng)域。于是,制備和研究集光、磁效應(yīng)于一體的ZnO基稀磁半導(dǎo)體材料具有極其重要的意義。本論文以ZnCl_2、CoCl_2為原料,分別選用NaOH和NH_3·H_2O為沉淀劑,采用常壓沸騰回流法,成功制備了ZnO:Co納米粉體,利用XRD、FESEM、EDS和XPS對產(chǎn)品的結(jié)構(gòu)和形貌進(jìn)行了表征,利用UV-vis、PL和PPMS研究了樣品的光學(xué)性質(zhì)和磁性質(zhì)。 本論文的主要內(nèi)容如下: (1)以ZnCl_2、CoCl_2為原料,選用NaOH和NH_3·H_2O為沉淀劑,采用常壓沸騰回流法成功制備了ZnO:Co納米粉體,探索了藥品滴加順序、溶液堿度、初始Zn~2+離子濃度、沸騰回流時(shí)間等最適宜合成條件。以NaOH為沉淀劑,在鋅堿比1:3.6～1:4.0的中堿度溶液中制備了摻雜效果良好,長約3μm,平均直徑200 nm,長徑比高達(dá)15的ZnO:Co納米晶須;在鋅堿比1:9.0的高堿度溶液中,通過對前驅(qū)物進(jìn)行40℃預(yù)攪拌處理,制備出長徑比較大、形貌規(guī)則的ZnO:Co納米棒。以NH_3·H_2O為沉淀劑,在鋅堿比1:4.0的溶液中制備了形貌特殊的ZnO:Co放射性納米管團(tuán)簇。 (2)以ZnCl_2、CoCl_2為原料,選用NaOH和NH_3·H_2O為沉淀劑,在ZnO:Co最適宜的合成條件下制備了不同摻雜濃度的ZnO:Co納米粉體,考察了摻雜濃度對樣品結(jié)構(gòu)和形貌的的影響,研究了樣品的光學(xué)性質(zhì)和磁性質(zhì)。結(jié)果表明,Co以+2價(jià)的Co~2+形式進(jìn)入到ZnO晶格取代了部分Zn~2+,沒有改變ZnO六方纖鋅礦的結(jié)構(gòu);摻雜以后樣品的形貌發(fā)生較大變化。Co~2+摻雜后導(dǎo)致ZnO禁帶寬度變窄,樣品的紫外吸收帶邊和紫外發(fā)光峰位均向高波長紅移;由于氧空位缺陷引起的黃綠光發(fā)射能量與Co~2+的4~A_2(F)→2~A1(G)電子躍遷能量發(fā)生共振產(chǎn)生能量轉(zhuǎn)移,導(dǎo)致?lián)诫s樣品的黃綠光發(fā)射發(fā)生猝滅現(xiàn)象。樣品在合適的Co摻雜濃度下表現(xiàn)出室溫鐵磁性,源于氧空位引起的雜質(zhì)帶上Co~2+-Co~2+鐵磁性耦合作用;摻雜濃度較高時(shí),占據(jù)晶格中彼此相鄰最近格位的摻雜離子之間發(fā)生Co~2+-Co~2+反鐵磁性耦合作用,而使樣品在外加磁場作用下表現(xiàn)為順磁性。
[Abstract]:ZnO has a high exciton binding energy (60 meV) and a wide band gap (3.37 eV), which shows great potential applications in piezoelectric, optoelectronic devices and other fields. By adding other elements into ZnO, the internal structure and morphology of ZnO can be adjusted effectively, its performance can be improved, and the application of ZnO can be expanded. Therefore, in recent years, the research on nano-ZnO doping has developed rapidly. As a typical transition metal element,. Co has abundant surface states and ionic radii similar to Zn~2, so it is easier to enter the ZnO lattice and dissolve into one phase. The band gap of ZnO can be adjusted effectively, and then its optical properties and applications can be regulated. At the same time, Co is magnetic and doped into ZnO lattice to form ZnO based dilute magnetic semiconductor (DMS), which extends the application of ZnO to electronic spin equipment, detector and so on. Therefore, the preparation and study of ZnO based diluted magnetic semiconductor materials with optical and magnetic effects are of great significance. In this paper, ZnCl2CoCl2 was used as raw material, NaOH and NH_3 H2O were used as precipitators respectively, and ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling refluxing method. The structure and morphology of the products were characterized by XRD-FESEMEDS and XPS. The optical and magnetic properties of the samples were studied by UV-vis PL and PPMS. The main contents of this thesis are as follows: (1) NaOH and NH_3 H _ 2O were used as precipitators and ZnCl _ 2CoCl _ 2 was used as raw material, ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling reflux method. The order of dropping, the alkalinity of solution and the initial concentration of Zn~2 ion were explored. Boiling reflux time is the most suitable synthetic condition. Using NaOH as precipitant, ZnO:Co nanocrystalline whiskers with a length of about 3 渭 m, an average diameter of 200nm and a aspect ratio of up to 15 were prepared in a medium alkalinity solution with a ratio of 1: 3.6 to 1: 4.0, and a high alkalinity ratio of 1: 9.0. By pre-stirring the precursor at 40 鈩，

本文編號：2175893