中文摘要：

采用固相反应法制备了Nd1.2-xTbxSr1.8Mn2O7（x=0,0.10,0.15）系列多晶样品,通过样品的XRD谱线,磁化强度随温度、外加磁场的变化曲线（M-T、M-H）等研究样品的晶体结构和磁性。研究结果表明,随掺杂量的增加,样品的结构没有发生明显变化,均为单相的Sr3Ti2O7型四方结构,空间群为I4/mmm。在测量温度范围内,随温度的降低,三个样品分别先后经历了顺磁态、铁磁-顺磁共存态和反铁磁-铁磁共存态的转变。三样品体系中均存在类Griffiths相,在类Griffiths相温度（TG≈275 K）以上,样品处于顺磁态;在类Griffiths相温区（θ〈T〈275K，其中θ为居里温度）范围内，样品处于铁磁-顺磁共存态；在奈尔温度（TN）以下，样品铁磁性减弱，反铁磁性增强，铁磁和反铁磁性相互竞争导致类自旋玻璃行为出现。此外Tb元素的掺杂对系统中类Griffiths相温度基本没有影响，但对类Griffiths相温区有一定影响。

英文摘要：

Series polycrystalline samples of manganites Nd1.2-xTbxSr1.8Mn2O7（x=0,0.10,0.15） were prepared by solid - state reaction. The crystallographic structure and the magnetism properties of such samples were characterized by X - ray diffraction （XRD）, temperature -dependent curves of magnetization （M -T curves） and the magnetization vs. external mag- netic field （ M - H） curves etc. Research showed that the crystal structure of these samples didn＇ t change obviously, both samples with I4mmm space groups were of the Sr3Ti2O7 - type tetragonal structures. In the measuring temperature range, with the decreasing temperature, the samples successively experienced the transitions of paramagnetic state, ferromagnetic - paramagnetic state and coexistence of antiferromagnetic and ierromagnetic respectively. Griffiths - like phase existed in every sam- ple. Above the Griffiths - like temperature TG （TG≈275 K） the samples transformed into a paramagnetic state ; In the Griffiths - like phase temperature range （ 0 〈 T 〈 280 K, where θ is paramagnetic Curie temperature）, coexistence of ferromagnetic and paramagnetic phase characteristics were observed; The ferromagnetism of the samples reduced and the antiferromagnetism enhanced below Neel temperature （TN ） , the interplay between antiferromagnetic and ferromagnetic exchanged couplings display indications of spin - glass - like state. In addition, Tb element doping had little effect on Griffiths - like phase temperature, but has a certain effect on temperature range of Griffiths - like phase.