發(fā)布時間：2018-03-03 16:22

  本文選題：W型鐵氧體　切入點：陶瓷法　出處：《安徽大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：目前以SrO·6Fe_2O_3為代表的磁鉛石型六角晶系鐵氧體即M型鐵氧體已成為鐵氧體燒結(jié)磁體的主流,對于該M型鐵氧體磁體,人們著眼于使鐵氧體晶粒粒徑接近單磁疇粒徑、使鐵氧體晶粒在磁晶各向異性方向上保持一致以及使燒結(jié)體高密度化,繼續(xù)進行著高性能化的研究。該研究的結(jié)果是M型鐵氧體磁體的特性接近其上限,其磁性能也很難飛速的提高。作為可能表現(xiàn)出比M型鐵氧體磁體性能更高的鐵氧體磁體中,熟知的有W型鐵氧體。W型鐵氧體磁體比M型鐵氧體磁體的飽和磁化高10%左右,其各向異性磁場程度相同,而且W型鐵氧體具有2個陽離子晶位,可進行多種2價陽離子或3價陽離子替換,能夠比M型鐵氧體更廣泛的改變磁性。因此需要找到高性能且穩(wěn)定的永磁材料,W型鐵氧體就是其中一個重要的方向。W型鐵氧體具有較大的飽和磁化強度、較強的磁晶各向異性、化學(xué)性能穩(wěn)定等優(yōu)點,已被廣泛應(yīng)用于磁光材料及磁記錄、微毫米波段材料和永磁材料領(lǐng)域。W型鐵氧體的磁性能的改善可以通過摻雜取代來實現(xiàn)。本論文采用溶膠-凝膠法和固相反應(yīng)法制備離子摻雜取代的系列W型鐵氧體樣品。樣品的微觀結(jié)構(gòu)利用X射線衍射儀(XRD)、X射線光電子能譜儀(XPS)和掃描電子顯微鏡(SEM)進行表征,樣品的磁性能利用振動樣品磁強計(VSM)和永磁材料自動測量裝置進行表征。具體的實驗結(jié)果如下:1.采用溶膠-凝膠法制備了非稀土離子Ca摻雜取代的W型鐵氧體Ba1-xCaxCo_2Fe16027(x = 0,0.1,0.3,0.4和0.5),并研究熱處理溫度和Ca含量對其微觀結(jié)構(gòu)和磁性能的影響。XRD結(jié)果證明適量Ca離子摻雜取代的鐵氧體均為單一、穩(wěn)定的純相。取代后產(chǎn)物的晶胞參數(shù)a幾乎不變,而晶格參數(shù)c減小,晶胞體積V減小,導(dǎo)致晶格收縮變形,這一晶格畸變行為意味著Ca離子成功進入晶體晶格中,SEM觀察到所有樣品都有著較好的六方結(jié)構(gòu),顆�；旧戏植季鶆�。隨著取代量x的增加,樣品的比飽和磁化強度σs增大,在x = 0.50時有最大值σs=63.6A·m2/kg,說明鈣的摻雜量越大磁體的磁性能越好。2.采用固相反應(yīng)法制備了不同La~(3+)摻雜的W型鐵氧體Ba_(1-x)La_xZn_2Fe_(16)O_(27)Cx=0-0.25),并研究了 La含量對其微觀結(jié)構(gòu)和磁性能的影響。XRD結(jié)果顯示,當(dāng)x≤0.20時樣品是單一的磁鉛石型W相,然而當(dāng)x=0.25時,La_2O_3相出現(xiàn)。樣品形成了六角片狀結(jié)構(gòu),而且顆粒分布均勻。隨著La~(3+)摻雜含量的增加,樣品的晶格常數(shù)a和c不斷減小,導(dǎo)致晶胞體積V也隨著減小,同時空隙率增加。樣品的飽和磁化強度Ms先增加后減小,當(dāng)輕稀土 La~(3+)取代量x=0.10時,樣品的飽和磁化強度Ms達到峰值71.38emu/g,較未摻雜樣品的飽和磁化強度提高約22.1%。其矯頑力Hc先增加后減小再增大。X射線光電子能譜研究結(jié)果分析表明,取代前Fe分別主要以Fe~(3+)三價態(tài)存在,取代后,可以看出有La~(3+)譜存在,而Fe則以Fe~(3+)(三價)+Fe2+(二價)混合價態(tài)的形式存在。利用X射線光電子能譜證實了 La~(3+)離子取代能使部分Fe~(3+)離子轉(zhuǎn)變成Fe2+離子。這表明La能進入W型鐵氧體的A位,并且顯著提高樣品的磁性能。3.采用固相反應(yīng)法制備了不同Gd~(3+)離子摻雜的W型鐵氧體BaFe~(2+)2Fe~(3+)_(16-x)Gd_xO_(27)(x=0-0.20),并研究了熱處理的干燥溫度和燒結(jié)溫度對Fe2W鐵氧體樣品相結(jié)構(gòu)的影響,以及Gd~(3+)離子摻雜含量對鐵氧體樣品微觀結(jié)構(gòu)和磁性能的影響。對于干燥溫度的影響,當(dāng)干燥溫度為170℃時有Fe3O4相出現(xiàn),干燥溫度180-200℃可以獲得單一的磁鉛石型相,干燥溫度為210℃時樣品中除了Fe2W相結(jié)構(gòu),同時還有一些M型鐵氧體和α-Fe_2O_3的相。對于燒結(jié)溫度的影響,當(dāng)燒結(jié)溫度在1100℃時,樣品中除了 Fe2W相結(jié)構(gòu),同時還有一些M型鐵氧體相。在此條件下獲得W單相的鐵氧體,適宜的燒結(jié)溫度為1120-1200℃。對于Gd~(3+)離子含量的影響,當(dāng)x0.15時樣品是單一的磁鉛石型W相,然而當(dāng)x=0.20時,Gd2O_3相出現(xiàn)。SEM顯示樣品形成了六角狀結(jié)構(gòu)。隨著Gd~(3+)離子摻雜含量的增加,樣品的晶格常數(shù)a和c均增大,導(dǎo)致晶胞體積V也隨著增大。X射線光電子能譜顯示取代后有Gd~(3+)離子譜存在。當(dāng)Gd~(3+)離子摻雜含量x從0增加到0.05時,樣品的飽和磁化強度(Ms)、剩磁(Br)和最大磁能積[(BH)max]均增大,x從0.05增加到0.15時,隨后減小。當(dāng)Gd~(3+)離子摻雜含量x從0增加到0.10時,內(nèi)稟矯頑力(Hcj)和磁感應(yīng)矯頑力(Hcb)均增,x從0.10增加到0.15時,隨后減小。這說明Gd~(3+)離子能夠進入W型鐵氧體晶位中,并且明顯改變其磁性能。
[Abstract]:Magnetoplumbite type six angle crystal ferrite at SrO and 6Fe_2O_3 as the representative of the M has become the mainstream of ferrite sintered ferrite magnet, ferrite magnet for the M, people focus on the ferrite grain size close to single domain size, the ferrite grain is consistent and the sintered body of high density in the magnetocrystalline anisotropy direction, continue to carry out the research of high performance. The results of this study are the properties of M type ferrite magnets close to its upper limit, its magnetic properties are difficult to rapidly increase. The ferrite magnets as may exhibit than M ferrite the magnet performance higher, with about W ferrite.W ferrite magnet than M ferrite magnets with high saturation magnetization of 10%, the same degree of anisotropy of magnetic field, and W ferrite with 2 cationic sites, for a variety of 2 divalent cations or 3 divalent cations can replace. The change of magnetic M ferrite is more than enough widely. So we need to find a permanent magnetic material with high performance and stable, W ferrite is one of the important direction of.W ferrite has larger saturation magnetization, magnetic anisotropy is strong, has the advantages of stable chemical properties, has been widely used in magneto optical materials and magnetic recording, magnetic field of micro millimeter band material and permanent magnet material.W ferrite can be improved by substitution to achieve. This paper adopts W series ferrite sol-gel method and solid-state reaction method for preparing substituted ion doped samples. The microstructure of the body by using X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) properties of the samples were characterized by vibrating sample magnetometer (VSM) and permanent magnet material automatic measuring device was investigated. The specific results are as follows 1.: sol gel W ferrite Ba1-xCaxCo_2Fe16027 non Ca doped rare earth ions substituted by (x = 0,0.1,0.3,0.4 and 0.5), ferrite and Research on heat treatment temperature and the influence of Ca content on the microstructure and magnetic properties of the.XRD results show that the amount of Ca ions substituted for a single, stable pure phase. After replacing the lattice parameters of the products a is almost the same, while the lattice parameter C decreases, the cell volume of V decreases, cause the lattice contraction deformation, the lattice distortion behavior means that Ca ions successfully enter the crystal lattice, SEM observed that all the samples have six good particle structure, basically evenly distributed. With the increase of substitution amount of X, specific saturation magnetization increase of s samples, at x = 0.50 has the maximum value. S=63.6A m2/kg, it shows that the magnetic doping calcium more magnets can better.2. by solid-state reaction method to prepare La~ (3 different +) W ferrites doped with Ba_ (1-x) La_xZn_2Fe_ (16) O_ (27) Cx=0-0.25), and to study the effect of La content on the microstructure and magnetic properties of.XRD showed that when x is less than or equal to 0.20 when the sample is magnetoplumbite type W single phase, however, when x=0.25, La_2O_3. Samples form six angle sheet structure, and uniform particle distribution. With the increase of doping content of La~ (3+), the lattice constants A and C decreases, resulting in cell volume V with decreased and porosity increased. The saturation magnetization Ms of samples increased first and then decreased, when the light rare earth La~ (3+) to replace the amount of x=0.10, the saturation magnetization Ms samples reached the peak of 71.38emu/g, compared with the undoped saturation magnetization of the samples increased by about 22.1%. the coercivity of Hc increase first and then decrease and then increase.X X-ray photoelectron spectroscopy study results show that replacing the former Fe respectively to Fe~ (3+) trivalent state, 鍙栦唬鍚，

本文編號：1561780