【摘要】：鐵氧體是重要的磁性氧化物,用于電子信息、自動化等領(lǐng)域。 本文研究熱處理溫度和氣氛對化學(xué)共沉淀法制備Ni_(0.15)Zn_xFe_(2.85-x)O_4和Ni_xFe_(3-x)4材料相結(jié)構(gòu)和磁性的影響。發(fā)現(xiàn)在空氣中進(jìn)行熱處理時,如果Fe含量大于2.2/分子,多出的Fe容易形成α-Fe_2O_3;在管式爐中通氬氣進(jìn)行熱處理時,如果加熱前排空氣的時間不夠長,熱處理溫度不夠高,也會導(dǎo)致α-Fe_2O_3次相的形成。而在所有的樣品中都沒有發(fā)現(xiàn)與Ni和Zn有關(guān)的次相。說明與Ni~2+和Zn~2+離子相比,Fe~2+離子進(jìn)入尖晶石晶格需要較高的能量和缺氧環(huán)境。對于所制備的單相樣品,采用Tang等人提出的估算尖晶石結(jié)構(gòu)陽離子分布的量子力學(xué)方法估算了樣品中的陽離子分布,擬合了在低溫測得的樣品的飽和磁化強度隨Ni、Zn摻雜量的變化關(guān)系。 我們應(yīng)用荷蘭帕納科公司X’pert Pro型X射線衍射儀(XRD)在室溫下對材料進(jìn)行晶體結(jié)構(gòu)的研究,確定樣品的相組成;應(yīng)用美國Quantum Design公司生產(chǎn)的PPMS綜合物性測量系統(tǒng)測量了樣品的磁性。 通過Rietveld精修數(shù)據(jù)計算了復(fù)合相樣品Ni_(0.15)Zn_xFe_(2.85-x-2z)O_(4-8z/3)/(α-Fe_2O_3)_z的相含量,并研究了尖晶石相中各陽離子含量對樣品室溫比飽和磁化強度的影響。相含量計算結(jié)果表明,在空氣氛圍不同溫度熱處理的樣品中尖晶石相Fe離子含量存在一個臨界值,約為2.2/分子,多余的Fe離子生成了α-Fe_2O_3。這與Fe~2+有效離子半徑和磁矩有很大關(guān)系。 本文通過對樣品的磁性測量發(fā)現(xiàn),對于單相樣品Ni_(0.15)Zn_xFe_(2.85-x)O_4 (x=0.16, 0.23, 0.40, 0.70和0.85),磁化強度隨溫度升高而下降,下降的速率隨Zn離子摻雜量x的增加而增加,但對于樣品x=0.16,0.23和0.40,磁化強度隨溫度下降較緩慢,直到380K,磁化強度最多下降到其最大值的86%;然而,樣品x=0.85的磁化強度隨溫度升高下降十分迅速,到380K時,磁化強度已下降到其最大值的0.8%。 對名義成分為Ni_xFe_(3-x)O_4的樣品,在氬氣氣氛中熱處理前,排空氣時間分別為20、30和40分鐘,經(jīng)1473K熱處理后,樣品中α-Fe2O3次相含量隨排空氣時間的延長而減少。同時,在相同煅燒溫度下,樣品中α-Fe_2O_3次相含量隨Ni摻雜量增加而減少。經(jīng)40分鐘排空氣,1573 K氬氣氣氛熱處理后,系列樣品Ni_xFe_(3-x)O_4(x=0.00, 0.08,0.15, 0.25,0.35)全部形成單相尖晶石結(jié)構(gòu)。最后,本文應(yīng)用Tang等人提出的估算尖晶石鐵氧體陽離子分布的量子力學(xué)方法對單相樣品Ni_xFe_(3-x)O_4和Ni_(0.15)Zn_xFe_(2.85-x)O_4陽離子分布進(jìn)行了研究,發(fā)現(xiàn)通過理論擬合計算得到的磁矩與飽和磁化強度實驗值符合得較好,從而對這兩個系列尖晶石材料飽和磁矩隨摻雜量變化具有不同規(guī)律給出了合理的解釋。
[Abstract]:Ferrite is an important magnetic oxide, used in electronic information, automation and other fields. The effects of heat treatment temperature and atmosphere on the phase structure and magnetic properties of Ni_ (0.15) Zn_xFe_ (2.85-x) O _ 4 and Ni_xFe_ (3-x) _ 4 prepared by chemical coprecipitation were studied. It is found that when heat treated in air, if the Fe content is more than 2.2 / molecule, the extra Fe can easily form 偽-Fe_2O_3;. When argon gas is used for heat treatment in tubular furnace, 偽-Fe_2O_3 secondary phase will be formed if the heating time of the front air is not long enough and the heat treatment temperature is not high enough. No secondary phases related to Ni and Zn were found in all samples. Compared with Ni~2 and Zn~2 ions, Fe~2 ions need higher energy and anoxic environment to enter spinel lattice. For the prepared single-phase samples, the distribution of cations in spinel structure was estimated by using the quantum mechanical method proposed by Tang et al., and the saturation magnetization of samples measured at low temperature was fitted with Ni,. The variation of Zn doping amount. The crystal structure of the material was studied by X'pert Pro X-ray diffractometer (XRD) at room temperature, and the phase composition of the sample was determined. The magnetic properties of the samples were measured by using the PPMS comprehensive physical property measurement system produced by Quantum Design Company, USA. The phase contents of Ni_ (0.15) Zn_xFe_ (2.85-x-2z) O _ (4-8z/3) / (偽 -Fe_2O_3) _ z in composite phase samples were calculated by Rietveld refinement data. The effect of cations in spinel phase on the saturation magnetization at room temperature was studied. The results of phase content calculation show that there is a critical value of Fe ion content in spinel phase at different temperature and heat treatment in air atmosphere, which is about 2.2 / molecule. The excess Fe ion produces 偽-Fe_2O_3.. This is related to the effective ion radius and magnetic moment of Fe~2. In this paper, the magnetization of single-phase sample Ni_ (0.15) Zn_xFe_ (2.85-x) O _ 4 (x _ (0.16,0.23) 0.40, 0.70 and 0.85) decreases with the increase of temperature. The decreasing rate increases with the increase of the doping amount of Zn ion x, but the magnetization decreases slowly with the increase of temperature for the samples x _ (0.16) ~ (0.23) and (0.40), until 380 K, the maximum magnetization decreases to 86% of the maximum value. However, the magnetization of xan0.85 decreases very rapidly with the increase of temperature. At 380 K, the magnetization has decreased to 0.8% of its maximum value. For the sample with nominal composition Ni_xFe_ (3-x) O _ (4), before heat treatment in argon atmosphere, the exhaust air time was 2030 and 40 minutes, respectively. After 1473K heat treatment, the 偽-Fe2O3 secondary phase content in the sample decreased with the prolonging of the exhaust air time. At the same time, the content of 偽-Fe_2O_3 in the sample decreases with the increase of Ni doping content at the same calcination temperature. After 40 minutes of air exhaust and 1573 K argon atmosphere heat treatment, a series of samples Ni_xFe_ (3-x) O _ (4) (x _ (0.00, 0.08) 0.15, 0.25 ~ (0.35) formed a single-phase spinel structure. Last In this paper, the quantum mechanical method for estimating the cationic distribution of spinel ferrites proposed by Tang et al has been applied to the determination of Ni_xFe_ (3-x) O _ 4 and Ni_ (0.15) Zn_xFe_ (2.85-x) O _ 4 positive samples in single-phase samples. Ion distribution was studied. It is found that the magnetic moment obtained by theoretical fitting is in good agreement with the experimental value of saturation magnetization, and the variation of saturation magnetic moment with doping amount of the two series spinel materials is explained reasonably.
【學(xué)位授予單位】：河北師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：O469

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 張變芳,唐貴德,王振彪,鄭喬,劉虎,潘成福;MnFe_2O_4多晶微粉的共沉淀法制備及磁性研究[J];材料科學(xué)與工程學(xué)報;2004年03期

2 孫聆東,付雪峰,錢程,廖春生,嚴(yán)純?nèi)A;水熱法合成CdS/ZnO核殼結(jié)構(gòu)納米微粒[J];高等學(xué)�；瘜W(xué)學(xué)報;2001年06期

3 白一鳴,唐貴德,郭振亞,劉力虎,侯登錄,劉興民,趙旭,潘成福,聶向富;Mn_(0.6)Zn_(0.4)Fe_2O_4/α-Fe_2O_3復(fù)合材料的磁性和電阻率溫度關(guān)系研究[J];南開大學(xué)學(xué)報(自然科學(xué)版);2005年04期

相關(guān)會議論文 前1條

1 張變芳;唐貴德;王振彪;劉虎;杜偉勝;鄧玉林;;CoFe_2O_4納米微粉的制備及磁性[A];第五屆中國功能材料及其應(yīng)用學(xué)術(shù)會議論文集Ⅰ[C];2004年

，

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