热处理温度和气氛对共沉淀法制备Ni-Zn铁氧体中阳离子分布的影响
发布时间：2018-11-14 17:10
【摘要】：铁氧体是重要的磁性氧化物,用于电子信息、自动化等领域。 本文研究热处理温度和气氛对化学共沉淀法制备Ni_(0.15)Zn_xFe_(2.85-x)O_4和Ni_xFe_(3-x)4材料相结构和磁性的影响。发现在空气中进行热处理时,如果Fe含量大于2.2/分子,多出的Fe容易形成α-Fe_2O_3;在管式炉中通氩气进行热处理时,如果加热前排空气的时间不够长,热处理温度不够高,也会导致α-Fe_2O_3次相的形成。而在所有的样品中都没有发现与Ni和Zn有关的次相。说明与Ni~2+和Zn~2+离子相比,Fe~2+离子进入尖晶石晶格需要较高的能量和缺氧环境。对于所制备的单相样品,采用Tang等人提出的估算尖晶石结构阳离子分布的量子力学方法估算了样品中的阳离子分布,拟合了在低温测得的样品的饱和磁化强度随Ni、Zn掺杂量的变化关系。 我们应用荷兰帕纳科公司X’pert Pro型X射线衍射仪(XRD)在室温下对材料进行晶体结构的研究,确定样品的相组成;应用美国Quantum Design公司生产的PPMS综合物性测量系统测量了样品的磁性。 通过Rietveld精修数据计算了复合相样品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阳离子含量对样品室温比饱和磁化强度的影响。相含量计算结果表明,在空气氛围不同温度热处理的样品中尖晶石相Fe离子含量存在一个临界值,约为2.2/分子,多余的Fe离子生成了α-Fe_2O_3。这与Fe~2+有效离子半径和磁矩有很大关系。 本文通过对样品的磁性测量发现,对于单相样品Ni_(0.15)Zn_xFe_(2.85-x)O_4 (x=0.16, 0.23, 0.40, 0.70和0.85),磁化强度随温度升高而下降,下降的速率随Zn离子掺杂量x的增加而增加,但对于样品x=0.16,0.23和0.40,磁化强度随温度下降较缓慢,直到380K,磁化强度最多下降到其最大值的86%;然而,样品x=0.85的磁化强度随温度升高下降十分迅速,到380K时,磁化强度已下降到其最大值的0.8%。 对名义成分为Ni_xFe_(3-x)O_4的样品,在氩气气氛中热处理前,排空气时间分别为20、30和40分钟,经1473K热处理后,样品中α-Fe2O3次相含量随排空气时间的延长而减少。同时,在相同煅烧温度下,样品中α-Fe_2O_3次相含量随Ni掺杂量增加而减少。经40分钟排空气,1573 K氩气气氛热处理后,系列样品Ni_xFe_(3-x)O_4(x=0.00, 0.08,0.15, 0.25,0.35)全部形成单相尖晶石结构。最后,本文应用Tang等人提出的估算尖晶石铁氧体阳离子分布的量子力学方法对单相样品Ni_xFe_(3-x)O_4和Ni_(0.15)Zn_xFe_(2.85-x)O_4阳离子分布进行了研究,发现通过理论拟合计算得到的磁矩与饱和磁化强度实验值符合得较好,从而对这两个系列尖晶石材料饱和磁矩随掺杂量变化具有不同规律给出了合理的解释。
[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 伪-Fe_2O_3;. When argon gas is used for heat treatment in tubular furnace, 伪-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) / (伪 -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 伪-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 伪-Fe2O3 secondary phase content in the sample decreased with the prolonging of the exhaust air time. At the same time, the content of 伪-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.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：O469
本文编号：2331789
[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 伪-Fe_2O_3;. When argon gas is used for heat treatment in tubular furnace, 伪-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) / (伪 -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 伪-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 伪-Fe2O3 secondary phase content in the sample decreased with the prolonging of the exhaust air time. At the same time, the content of 伪-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.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：O469
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