中文摘要：

利用非模板水热法合成了Pd掺杂的SnO2纳米颗粒,并利用透射电镜（TEM）、X射线衍射（XRD）和X光电子能谱（XPS）表征了Pd掺杂对晶体结构、表面形貌、微观结构、热稳定性和表面化学状态的影响。研究发现：水热过程中Pd掺杂对形成的SnO2纳米颗粒大小几乎没有影响,在500℃以下的煅烧过程中,掺杂的Pd可以有效抑制颗粒的生长,但在700℃以上时颗粒生长迅速。XPS结果显示合成样品中Pd的化学状态有三种：Pd^0、Pd^2＋和Pd^4＋,其中的主化学状态Pd^4＋有效促进了气敏性能的提高。为了同时提高气敏性能和热稳定性,Pd的最佳掺杂量为2.0%？2.5%（摩尔分数）。

英文摘要：

SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.