【作者】 朱瑞；

【导师】 濮琳；

【作者基本信息】 南京大学 ， 微电子学与固体电子学， 2016， 硕士

【摘要】 Ni-Mn-X(X=In,Sn,Sb)铁磁形状记忆合金被报道以来,该体系由于丰富的物理内涵和其多功能特性称为材料学领域的一个研究热点。磁热效应、巨磁致应变效应、磁电阻效应、压热效应等的发现,使这类材料展现了广阔的应用前景,如在磁致冷中作为制冷剂、作为磁驱动器的驱动材料、磁电传感器等。本论文主要由以下两部分内容：1.Fe掺杂对Mn50Ni41-xFexSn9合金的相变、磁热效应和交换偏置效应的影响通过电弧熔炼的方法制备了Mn50Ni41-FexSn9(x=0,2,4)合金,并采用X射线衍射(XRD)、综合物性测试系统(PPMS).振动样品磁强计(VMS)对合金的晶体结构、相变、磁热效应和交换偏置效应进行了研究。研究表明随着Fe掺杂含量的增加,马氏体转变温度逐渐降低、马氏体和奥氏体居里温度逐渐增加。Fe的加入使材料马氏体相变附近的磁化强度的变化增加,从而使其具有较大的磁热效应。另外,Fe的加入使材料的交换偏置场逐渐降低,这可以用Fe掺杂导致的铁磁交换作用的增强来解释。2.熔体快淬法制备Mn50Ni49X(X=Sn,In)合金条带及其磁性研究采用熔体快淬法制备了Mn50Ni41 In9合金和Mn50Ni41 Sn9合金条带。这种方法得到的样品具有较小晶粒,其尺度在3微米左右。Mn50Ni41 Sn9合金条带在低温下表现为金属自旋玻璃行为,具有较大零场冷交换偏置效应。零场冷交换偏置效应对最大磁场非常敏感,只有磁场高于临界值时才出现零场冷交换偏置效应,说明单向各向异性可以在初始磁化过程中建立。随温度的增加,交换偏置场和矫顽力逐渐减小。而Mn50Ni41 In9合金条带则不具有明显的自旋玻璃行为,其场冷交换偏置效应非常小,同时不具有零场冷交换偏置效应。更多还原

【Abstract】 Functional material of Ni-Mn-X (X=In, Sn, or Sb) ferromagentic shape memory al-loy is hot recently because of underlying physics such as the giant magnetocaloric effect, magnetostricitve effect, magnetoresistance effect, and barocaloric effect. Based on these magnetic effects, the alloy will play its due roles in new concept refrigerator, sensor, and drivers. In this paper, we report some detailed studies on the Mn-based alloys of Mn5oNi41Sn9(Fe-doped), Mn5oNi49Sn and Mn5oNi49ln:1. The influence of Fe doping on the phase transitions, magnetocaloric effect, and ex-change bias in Mn50Ni41-xFexSn9 alloys.Mn50Ni41-xFexSn9 (x=0,2,4) alloys were prepared by the arc melting method. The crystal structure, phase transition, magnetocaloric effect, and exchange bias were investi-gated by X-ray diffraction (XRD), physical property measurement system (PPMS), and vi-brating sample magnetometer (VSM). It’s elucidated that the martensitic transformation tem-perature will decrease with increased content of Fe, while the Curie temperature of the martensitic or austenitic phase increases gradually. And the doped Fe leads to the increase in the magnetization change across the martensitic transformation, which gives rise to relatively large magnetocaloric effect. Furthermore, the exchange bias field will decrease with the in-creasing Fe concentration, because the doping of Fe can enhance the ferromagnetic interac-tion in the alloy.2. The magnetism of the Mn50Ni49X (X=Sn, In) ribbonsThe Mn5oNi49X (X=Sn, In) ribbons with an average grain size of 3 um were pre-pared by the melt-spinning technique. Mn50Ni41Sn9 exhibits spin glass behavior at low tem-perature, and shows large zero-field cooled exchange-bias. When the magnetic field is larger than the critical field, there is the zero-field cooled exchange-bias (very sensitive to maxi-mum magnetic field), and this indicates the formation of unidirectional anisotropy during the initial magnetization process. It’s found that the exchange-bias field as well as the coercivity decrease with increasing temperature. By contrast, the Mn50Ni41In9 alloy does not exhibit spin glass property at low temperature, and its field cooled exchange-bias is very small and shows no zero-field cooled exchange-bias effect.更多还原