本文研究了RECo_5在居里温度附近热膨胀反常的特点。利用高温X射线衍射方法从室温到600℃测定了CeCo_5,Ce(Co_(0.6)Cu_(0.2))_5和Ce(Co_(0.9)Fe_(0.1))_5晶格常数α和c随温度的变化。在居里点附近,CeCo_5的晶格常数c随温度的变化存在明显的拐折,在磁有序区域内具有因瓦反常,而晶格常数α随温度基本保持连续线性的变化,没有反常效应.用Cu原子部分取代Co原子以后,Ce(Co_(0.3)Cu_(0.2))_5沿c轴的热膨胀反常显著减弱。利用中子衍射研究了RE(Co,Cu)_5结构的有序性,从中子衍射的谱线分析表明,在CaCu_5型结构的RE(Co,Cu)_5金属间化合物中,Cu原子优先占据2c位置,由此解释了RECo_5热膨胀反常的原因。
The temperature dependence of the lattice constants of the compounds CeCo_5, Ce (Co_(0.8) Cu_(0.2))_5 and Ce (Co_(0.9) Fe_(0.1))_5 in the range from room temperature to 600℃ has been studied. CeCo_5 shows an invar-type thermal expansion anomalies in axis c below the Curie temperature. But the anomalies are considerably reduced on the partial substitution of the Co atoms by the Cu atoms. Studies of the neutrons diffraction have been carried out on the compounds Y (Co_(0.8) Cu_(0.2))5, and it has been found that the Cu atoms prefer to occupy the site 2c. There by the thermal expansion anomalies along axis c of the compounds RECo_5 is explained.
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