中文摘要：

通过水热法制备了一系列具有不同锌含量的ZnxFe3-xO4（x=0,0.15,0.30,0.40,0.48,0.60,0.70）纳米颗粒,并利用透射电子显微镜、X射线衍射仪、振动样品磁强计、超导量子干涉仪和穆斯堡尔谱仪对其进行研究.所有样品均为尖晶石结构;随着样品中锌含量的增加,其晶格常数随之增加,晶粒尺寸从18nm减小到9nm.在5K和293K时, ZnxFe3-xO4纳米颗粒的饱和磁化强度首先随着Zn含量的增加而增大,并在x=0.4时达到最大,随后随着Zn含量的增加而减小.室温下穆斯堡尔谱的测量结果表明：随着锌含量的增加,谱线由较为标准的六线峰逐渐转变为双峰,且在x=0.60时表现为明显的双峰结构,而大块材料在x=0.80时才有类似结果.饱和磁化强度和居里温度的测量结果表明,这种现象可能是由于样品中纳米颗粒表现出的超顺磁性导致的.此外,还讨论了离子分布对超精细磁场变化的影响,并利用Yafet-Kittel模型对样品的磁性变化进行解释.

英文摘要：

A series of ZnxFe3-xO4（x = 0, 0. 15, 0. 30, 0o 40, 0. 48, 0. 60, 0. 70 ） nanoparticles prepared by hydrothermal method are studied by use of transmission electron microscope, X-ray diffraction, vibrating sample magnetometer, superconducting quantum interference device magnetometer and Mossbauer spectrometer. All samples present a spinel structure. The lattice constant increases with the increase in the Zn content while the grain size decreases from 18 nm to 9 nm. Moreover, the saturation magnetzafion at 5 K and 293 K increases initially when x ≤ 0. 40 and subsequently decreases when x 〉 0. 40. At room temperature, Mossbauer spectra exhibit a change from a well-defined sextet spectrum to a doublet spectrum as the Zn content increases. The doublet spectrum begins to appear when x = 0. 6, while it begins when x = 0. 80 for the bulk materials. The results of magnetization and Curie temperature measurements indicate that the doublet spectrum is due to the surperparamagnetic state of the nanoparticles. Furthermore, the relationship between the hyperfine field variation and the cation distribution is discussed. The variation of magnetic properties is interpreted by the three-sublattice Yafet-Kittel （Y-K）model.