中文摘要：

采用水热法制备了Gd2O3：Yb^3＋／Er^3＋纳米线和纳米片，并研究了制备过程中溶液的pH值对产物形貌的影响以及样品形貌对发光性质的影响。将稀土氧化物溶于硝酸并与NaOH反应，使溶液pH值至预期值，将生成物离心、烘干和灼烧，得到最终产物。研究发现，制备样品过程中，中性溶液中易于形成纳米片，而碱性溶液中则会形成纳米线，而且碱性越强越容易形成纳米线。在980nm激光激发下，与纳米片相比，纳米线中ER^3＋的^4I13/2→^4I15/2的红外发射强度显著减弱，而^2H11/2／^4S3/2→^415/2和^4F9/2→^4I15/2的上转换发射相对增强，而且^2H11/2／^4S3/2→^4I15/2与^4F9/2→^4I15/2的荧光分支比略有增大。纳米线与纳米片相比，比表面积减小，由表面效应引起的无辐射弛豫过程的减弱导致了上述光谱的变化。

英文摘要：

Recently, low-dimensional structures, such as nanowires, nanoslices and nanotubes, have aroused remarkable attentions due to a great deal potential applications in data storage, advanced catalyst, photoelectronic devices etc. In this paper nanowires were prepared by the hydrothermal method. Appropriate amounts of high purity Gd2O3, Yb2O3 and Er2O3 were dissolved into concentrated HNO3 solution. Diluted NaOH solution was dripped into the solution to adjust the pH values for an appropriate value. After well stirred, the resultants of RE（ OH）3 （RE = Gd, Yb, Er） colloidal solution was heated and then was centrifuged and dried. The dried RE（OH）3 powders were calcined, and finally Gd2O3： Er^3＋/Yb^3＋ nanowires and nanoslices were obtained. The morphology and size of nanowires were obtained by transmission electron micrograph and X-ray diffraction patterns. By controlling the pH values, the shape of the nanocrystals varied from two-dimensional nanoslices to one-dimensional nanowires. It was found that the nanoslices were yielded in the chemically neutral conditions and nanowires were yielded in the alkalescent conditions. Emission spectra were studied under the 980 nm diode laser pumping. Green upconversion luminescence of ^2H11/2→^4I15/2, red upconversion luminescence of ^4F9/2→^4I15/2 and infrared emissions of ^4I13/2→^4I15/2 were observed. The infrared emissions of ^4I13/2→^4I15/2 gradually decreased with the increase of pH value and the forming of nanowires, while the visible upconversion luminescence of ^2 H11/2/^4S3/2→^4I15/2 and ^4F9/2→^4I15/2 gradually increased, indicating more efficient upconversion luminescence. The relative intensity of the green emissions to the red emissions also increased with the increase of pH value. Electronic relaxation processes dominates the intensity ratio of the upconversion luminescence to the infrared emissions. The ratio of surface atoms to inner atoms in nanowires was decreased in comparison to that in nanoslices, and the nonradiative relaxation wa