【摘要】：20世紀(jì)70年代以來(lái),磁性納米材料經(jīng)歷了從產(chǎn)生到發(fā)展再到壯大的過(guò)程,漸漸成為一種新型磁性材料。磁性納米顆粒的特殊效應(yīng)(量子尺寸效應(yīng)、小尺寸效應(yīng)、表面效應(yīng)和宏觀量子隧道效應(yīng)等)將會(huì)引起其磁特性發(fā)生強(qiáng)烈的變化,表現(xiàn)出獨(dú)有的磁特性,受到了人們的廣泛關(guān)注。磁性顆粒的磁性質(zhì)可以采用組分控制、制備工藝調(diào)節(jié)、熱處理等多種方法來(lái)進(jìn)行調(diào)控。本文我們側(cè)重探討缺陷和顆粒之間的磁相互作用對(duì)磁性顆粒靜態(tài)和動(dòng)態(tài)磁性質(zhì)的影響特征。主要工作如下:(1)通過(guò)微磁學(xué)模擬,探討了不同位置、不同大小的孔洞形和坑形缺陷對(duì)矩形鐵磁性納米片的靜態(tài)磁矩分布和磁譜的影響。結(jié)果表明,孔洞形或坑形缺陷對(duì)矩形鐵磁性納米片的磁性能的影響依賴于缺陷位置的變化以及缺陷的尺寸和形狀的變化。一般這些缺陷可能導(dǎo)致磁譜的主共振峰移動(dòng)到較低的頻率位置上。這些結(jié)果為通過(guò)圖案化方法來(lái)控制和設(shè)計(jì)矩形鐵磁性納米片的靜態(tài)和動(dòng)態(tài)特性提供了參考。(2)用微磁學(xué)模擬方法研究了相對(duì)位置、顆粒間距和磁各向異性方向?qū)删匦舞F磁性納米片磁性能的影響特征。結(jié)果表明,相對(duì)位置、顆粒間距影響兩矩形鐵磁性納米片共振峰頻率的分布,當(dāng)兩矩形納米片磁各向異性方向所呈角度由0°增加到30°時(shí),其磁性質(zhì)沒(méi)有明顯的變化,而從30°到90°時(shí),其磁性質(zhì)對(duì)磁各向異性方向變化比較敏感。此外,結(jié)果還表明改變兩個(gè)矩形鐵磁性納米片的磁各向異性方向可顯著影響共振峰的數(shù)目、強(qiáng)度、峰寬和頻率分布。因此,我們可以通過(guò)改變納米片相對(duì)位置、顆粒間距以及磁各向異性方向來(lái)調(diào)控鐵磁性納米片的磁性質(zhì)�？捎糜谥苽渚哂懈鞣N頻率和較寬吸收頻帶的微波吸收材料。
[Abstract]:Since the 1970s, magnetic nanomaterials have undergone a process from generation to development and then to growth, and have gradually become a new type of magnetic materials. The special effects of magnetic nanoparticles (quantum size effect, small size effect, surface effect and macroscopic quantum tunneling effect) will cause strong changes in their magnetic properties, showing unique magnetic properties, which have attracted widespread attention. The magnetic properties of magnetic particles can be controlled by component control, preparation process adjustment, heat treatment and so on. In this paper, we focus on the influence of the magnetic interaction between defects and particles on the static and dynamic magnetic properties of magnetic particles. The main work is as follows: (1) the effects of different positions and sizes of holes and pit-shaped defects on the static magnetic moment distribution and magnetic spectrum of rectangular ferromagnetic nanocrystals are investigated by micromagnetic simulation. The results show that the effect of hole or pit defects on the magnetic properties of rectangular ferromagnetic nanocrystals depends on the change of defect location and the size and shape of defects. In general, these defects may cause the main resonance peak of the magnetic spectrum to move to a lower frequency position. These results provide a reference for controlling and designing the static and dynamic characteristics of rectangular ferromagnetic nanocrystals by patterning method. (2) the relative position is studied by micromagnetic simulation. The effect of particle spacing and magnetic anisotropy on the magnetic properties of two rectangular ferromagnetic nanocrystals. The results show that relative position and particle spacing influence the frequency distribution of the resonance peak of the two rectangular ferromagnetic nanocrystals. When the angle of the anisotropic direction of the two rectangular ferromagnetic nanocrystals increases from 0 擄to 30 擄, the magnetic properties of the two rectangular ferromagnetic nanocrystals have no obvious change. From 30 擄to 90 擄, the magnetic properties are sensitive to the direction of magnetic anisotropy. The results also show that the number, intensity, width and frequency distribution of the resonance peaks can be significantly affected by changing the magnetic anisotropy direction of the two rectangular ferromagnetic nanocrystals. Therefore, we can adjust the magnetic properties of ferromagnetic nanocrystals by changing the relative position, the distance between particles and the direction of magnetic anisotropy. It can be used to prepare microwave absorbing materials with various frequencies and wider absorption bands.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB383.1;O482.5

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