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为了研究Co空位对Mn_3CoN化合物磁性质和热膨胀性能的影响,采用固相烧结法制备了名义配比为Mn_3Co_(1-x)N(x=0,0.1,0.2,0.3)的反钙钛矿结构化合物,并研究了该类化合物的晶格、磁转变和热膨胀性能。结果表明:所有的样品均显示出2个磁转变点;随着x的增加,低温磁转变点往高温移动,高温磁转变点往低温移动;同时,所有的样品中都发现了反常热膨胀行为,包括低于270K的低热膨胀和270K附近的负热膨胀;低热膨胀区间的线膨胀系数随着x的增加而呈现出减小的趋势;值得注意的是,当x=0.3时,样品在100~240 K温度区间内显示出近零热膨胀行为,其热膨胀系数α=9.70×10~(-7) K~(-1);Mn_3Co_(1-x)N化合物中的反常热膨胀行为可能是磁体积效应所致。
In order to study the effect of Co vacancies on the magnetic properties and thermal expansion properties of Mn_3CoN compounds, the perovskite structure with the nominal composition of Mn_3Co_ (1-x) N (x = 0,0.1,0.2,0.3) was prepared by solid-state sintering Compounds, and study of such compounds lattice, magnetic transition and thermal expansion properties. The results show that all the samples show two magnetic transition points. With the increase of x, the low temperature magnetic transition point moves to high temperature and the high temperature magnetic transition point moves to low temperature. At the same time, the abnormal thermal expansion behavior is found in all the samples, Including low thermal expansion below 270 K and negative thermal expansion around 270 K; the linear thermal expansion coefficient in the low thermal expansion range tends to decrease as x increases; notably, when x = 0.3, The thermal expansion coefficient α = 9.70 × 10 -7 K -1, and the anomalous thermal expansion behavior in the Mn_3Co_ (1-x) N compounds may be due to the magnetocaloric effect To