【摘要】 本文采用直流电弧等离子体喷射化学气相沉积法(DC Arc Plasma Jet CVD),在氢气和氩气的高温等离子体作用下直接分解硝酸镁,在Mo衬底上制备了单晶MgO纳米带,并采用SEM、TEM及XRD等测试手段进行了形貌与结构表征,研究了生长时间对MgO纳米带形貌的影响。结果表明,生长时间为0.5 min时,生长出顶部带有Mo纳米颗粒的"蝌蚪状"MgO纳米带,而整个纳米结构被较多的非晶MgO覆盖;当生长时间增加到2 min时,顶部的Mo纳米颗粒几乎脱落,同时长出若干个纳米带,形成"树枝状";生长时间进一步增加到5 min时,形成完整的"带状",其宽度约30~50 nm;而生长时间达到12 min时,纳米带又转变为"棒状"。机理分析表明,Mo催化VLS生长模式和VS生长模式共同作用下生长了MgO纳米带。另外,通过FTIR谱结合PL谱分析了缺陷及其引起的光致发光性能。由于MgO纳米带存在低配位氧离子(OLC2-)空位等结构缺陷,具有紫蓝发光特性,而随着生长时间的增加,结构缺陷变少,随之紫蓝发射峰强度变弱。本文首次采用该方法制备了单晶MgO纳米带,该方法工艺简单,生长速率快,是非常经济、有效和环境友好的方法。更多还原

【Abstract】 Single-crystal MgO nanobelts were synthesized by direct current(DC) arc plasma jet chemical vapor deposition(CVD) on Mo substrates.An attempt has been made to prepare MgO nanobelts through decomposition of magnesium nitrate under argon and hydrogen flow at 950 ℃ for different durations.The MgO nanobelts were characterized by scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and powder X-ray diffraction(XRD) pattern.When reaction time was increased from 0.5 to 12 min,the initially formed "tadpole-like" MgO nanostructures transformed into "dendrite-like" structures,nanobelts,and finally nanorods.The "tadpole-like" nanostructures are mainly belts with Mo nanoparticles capped at the MgO nanobelts’ ends,and the nanostructure is covered by an amorphous layer.The nanobelts prepared after 5 min with widths ranging from 30 to 50 nm.The growth of MgO nanobelts was initiated by Mo catalyst nanoparticles via a catalystassisted vapor-liquid-solid(VLS) process,and a side growth along the belt width direction via a vapor-solid(VS) process was also suggested.Moreover,the MgO nanobelts exhibited strong ultraviolet-blue emission.The strong optical properties were correlated with large surface area and presence of oxide ions in low coordination(LC) OLC2(where LC =5C,4C and 3C for terrace,edge,corner and kink sites,respectively) along with defects,which was revealed by fourier transform Infrared(FTIR) spectrometer and photoluminescence(PL) spectroscopy studies.Our group for the first time reported the DC arc plasma jet CVD method to obtain single crystalline MgO nanobelts,which possesses the advantages of being simple,economical,fast,effective and environmentally benign.更多还原