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1.
The microstructural,optical,and magnetic properties and room-temperature photoluminescence(PL) of Mn-doped ZnO thin films were studied.The chemical compositions were examined by energy dispersive X-ray spectroscopy(EDS) and the charge state of Mn ions in the ZnO:Mn films was characterized by X-ray photoelectronic spectrometry(XPS).From the X-ray diffraction(XRD) data of the samples,it can be found that Mn doping does not change the orientation of ZnO thin films.All the films prepared have a wurtzite stru... 相似文献
2.
为探寻ZnO稀磁半导体材料的室温铁磁性来源,采用溶胶凝胶法制备掺Mn量为0、1%、2%和3%的ZnO粉体,利用X射线衍射仪、扫描电子显微镜、X射线光电子能谱仪以及振动样品磁强计,研究粉体的形貌特征、物相、电子结构以及室温磁性能。结果表明:掺Mn可使粉体粒度减小;Mn以离子形式取代Zn的位置,保持了本征ZnO的六方纤锌矿结构,无第二相形成;掺Mn形成的Zn—Mn键和Mn—O—Mn键改变了本征ZnO的缺陷结构,从而导致磁性变化;样品中的氧空位浓度决定ZnO的室温铁磁性;掺Mn量为1%时为最优掺入量,具有最大的饱和磁矩22.599×10?2 emu/g。 相似文献
3.
NiCr_2O_4(NCO)spinel composites with different Mn/Ni atomic ratios(Mn/Ni=0.05,0.10,0.15,and 0.20)were synthesized via solid state reaction method.Phase compositions and microstructure of samples were characterized by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The TG-DSC curves showed that the appropriate baking temperature for Mn-doped NCO spinel preparation was approximately 1 320℃.X-ray diffraction patterns exhibited the formation of NCO spinel with Fd-3m space group.Valence state of the Mn ions was determined from 2p and 3s X-ray photoelectron spectra.Manganese ions were mostly in divalent and trivalent states,and the ratio of Mn~(2+)/Mn~(3+)was 0.78-0.98.Fourier transform infrared spectroscopy(FTIR)was used to analyze the spectral emissivity of Mn doped NCO spinel.It was revealed that the infrared emissivity of Mn-doped NCO spinel in 1.8-5μm could be significantly enhanced with increasing content of Mn~(2+),reaching as high as 0.9398.Mn-doped NCO spinel showed excellent radiation performance and good prospect in high emissivity applications in the temperature range of 800-1 200℃. 相似文献
4.
采用溶胶-凝胶工艺制备了La0.67Sr0.33Mn1-xFexO3多晶样品,并研究了其晶体结构、磁热效应及室温下的磁致伸缩效应.其X射线衍射谱表明,所有样品均为钙钛矿结构单相,分析表明,随Fe含量的增加,材料的铁磁居里温度(TC)下降,磁致伸缩系数先增加后降低. 相似文献
5.
GUO Aiyun XUE Yiyu ZHU Xuanmin ZHANG Guangyong GUO Peitao HU Xiaofeng 《武汉理工大学学报(材料科学英文版)》2006,21(2):101-104
TiO2 thin films were prepared with Ti2O3, Ti3O5 and TiO2 as raw materials, by electron-beam evaporation deposition, using O^2- ion beam ( O2 purity up to 99.99% ) as auxiliary means. The crystal structures of the samples were inspected by the X-ray diffraction (XRD) method, and the evaporation character of warious raw materials was analyzed. Transmittance spectra were measured through a U-3310 spectrophotometer ( wavelength ranging from 200 nm to 900 nm). The refractive index n and the thickness of films were determined from transmission spectra. The experimental results show that the thin films taking Ti2O3 as their raw material have a strong absorption, when taking Ti3O5 and TiO2 as raw materials, the thin films would have good optical properties. The experiments also show that, the crystal structure of all thin films is amorphous before post-annealing and the Ti3O5 is a congruent evaporation phase in the Ti-O system. 相似文献
6.
1INTRODUCTION TiO2hassomespecialpropertiesincludingphotocatalyticactivity,chemicalstability,andre sistancetowear,non poisonlowcostandcanbepreparedatlowcost.Ifmodifiedwithproperinter mingle,itcanbedirectlyusedinthesunlight.Sotitaniumdioxideisoneofthemostpotentialphoto catalyzers[1,2].Itsphotocatalyticoxidationabilityincreasesrapidlywiththedecreaseofparticledi ameter.Whenitsdiameterreaches10100nm,itwillshowobvioussurfaceeffectandquantumeffect.Moreover,itwillshowhighphotocatalyticactivityif… 相似文献
7.
宋晓岚 《武汉理工大学学报(材料科学英文版)》2000,15(4)
The structure around Ti~(4 ) in BaO-SiO_2-B_2O_3-TiO_2 had been studied by X-ray fluorescence spectra. The results show that the Ti~(4 ) mainly exists in the [TiO_4] and enters the network of [SiO_4]. [TiO_4] has the tendency to change to [TiO_6] with the increase of TiO_2 content. When the TiO_2 content increases to about 20mol% the tendency reaches its maximum. 相似文献
8.
采用溶胶凝胶法制备了Pr1-xCaxMnO3(0.4≤x≤0.5)系列纳米样品,对其磁性质进行了研究.所有样品在M-T曲线中250K附近的电荷有序转变和170K附近的顺磁-反铁磁转变都消失,与Dong等人的理论模拟计算相符.所有样品在40K都出现了Reentrant spin glass(RSG)态.随着Ca2+掺杂浓度的增加,Mn3+/Mn4+的比例迅速变小,破坏了Mn-O-Mn导电通道,导致磁化强度M逐渐变小. 相似文献
9.
采用固相反应法制备了A位无序掺杂锰氧化物La2/3-xYxCa1/3-ySryMnO3系列样品;利用Rigaku Dmax-rB 12 kW转靶X-ray衍射仪和振动样品磁强计Lakeshore7300对样品进行表征,并通过Rietveld方法对X-ray衍射谱进行结构精修。讨论了A位掺杂无序度σ2对样品的相、微结构(Mn—O键长、Mn—O—Mn键角等参数)和居里温度的影响。结果表明:随着掺杂浓度x和无序度σ2的增加,样品仍然保持单相性较好的钙钛矿正交结构,晶格常数a,b,c和晶胞体积V没有发生大的变化;Mn—O—Mn键角增加和Mn O键长减小;样品的居里温度下降,但x=0.20时,La2/3-xYxCa1/3-ySryMnO3居里点反而拉伸增大。 相似文献
10.
应用扩展X射线精细结构研究(EXAFS)技术研究了改性MnO_2结构变化.结果表明:改性后MnO_2中第1配位壳层Mn-O配位数降低,第2壳层没有变化,第3壳层的Mn-Mn配位消失.说明掺杂原子进入了MnO_2晶格中,并且增大MnO_2的不同壳层配位无定形.在线EXAFS吸收谱分析表明:在MnO_2放电还原过程中,与未改性相比,随着还原深度加大,掺杂改性后的MnO_2中Mn的第1、第2壳层配位向无定形转变减慢,配位数变化不明显,而且在一电子放电深度,没有发生结构重排. 相似文献
11.
Transport-magnetism Correlation and Colossal Magnetoresistance in Mixed-valent Manganites 总被引:1,自引:1,他引:0
LIJianqing YUANSongliu 《武汉理工大学学报(材料科学英文版)》2005,20(2):49-52
A phenomenological model based on phase separation between ferromagnetic metallic and paramagnetic insulating domains was applied to analyze the electrical transport and colossal magntoresistance for mixed-valent manganites of RE2/3 AE1/3 MnO3 . The results show that the model can yield results in agreement with experimental observatioas in these mangardtes. The present approach provides a simple picture to visualize the reason that the temperature dependence of resistance ( with and without applied magnetic fields ) in these compounds has the peculiar shape, without invoking any complicated concept. 相似文献
12.
杨应平 《武汉理工大学学报(材料科学英文版)》2002,17(4)
1 IntroductionManganeseperovskites ,suchasR1-yAyMnO3 (R =rare earthelement,A =divalentelement) ,areattractingconsiderabletheoreticandtechnologicalinterestsbyvirtueofthediscoveryofthecolossalmagnetoresistance(CMR) [1,2 ] .CMRiscausedbythecomplexnatureofin terplayof… 相似文献
13.
《武汉理工大学学报(材料科学英文版)》2016,(2)
To extend the absorption capability of TiO_2 into visible light region and inhibit the recombination of photogenerated electrons and holes,we put forward an effective strategy of the coupling of TiO_2 with a suitable semiconductor that possesses a narrow band gap.Meanwhile,Ag_3PO_4-TiO_2 heterostructuralnanotube arrays were prepared by the two-step anodic oxidation to obtain the TiO_2 nanotube arrays and then by a deposition-precipitation method to load Ag_3PO_4.The samples were characterized by field emission scanning electron microscopy(FESEM),energy dispersive spectrometry(EDS),X-ray diffraction(XRD),and UV-vis diffuse reflectance spectroscopy(UV-vis DRS).The experimentalresults showed that Ag_3PO_4 nanoparticles were uniformly dispersed on the highly ordered TiO_2 nanotube arrays,which increased the visible-light absorption of TiO_2 photocatalyst.The photocurrent density and photocatalytic degradation of methylorange indicated that the performance of Ag_3PO_4-TiO_2 heterostructuralnanotube arrays was better than that of the TiO_2 nanotube arrays,which could be attributed to the effective electron-hole separation and the improved utilization of visible light. 相似文献
14.
研究了用稳定元素Mn、Mo、Al和V代替非磁性的Si和Ge对Gd5Ge2Si2化合物的居里温度的影响;并且研究了Gd5(Ge2-xSi2-xM2x)(M=Mn、Mo、Al和V)样品退火处理对居里温度的影响.结果表明少量的合金化元素替代会提高Gd5Ge2Si2化合物的居里温度;退火后居里温度随替代元素的含量变化比退火前更敏感.X射线粉末衍射分析表明少量的合金化元素(Mn、Mo、Al和V)替代不会影响母体Gd5Ge2Si2化合物的晶体结构.对样品的晶态显微组织和表面微结构研究发现退火后组织分布比退火前更均匀。 相似文献
15.
LIU Jiajia LEI Tianmin ZHANG Yuming CHEN Delin GUO Hui ZHANG Zhiyong 《西安电子科技大学学报(自然科学版)》2015,42(4):76
Based on the density functional theory, the total magnetic moment and the density of states of Mn-doped graphene are calculated in the case of different impurity concentrations and lattice positions. The results show that the total magnetic moment goes up with the increase of doping concentration. Under the condition of the same impurity concentration, the Mn atoms in different spin directions can make the magnetism stronger. Meanwhile, it is found that the ability to gain and lose electrons of impurities, and the magnetic properties of the supercell are associated with the lattice positions occupied by Mn atoms. Doping in the same lattice has an advantage to enhance the magnetism, meaning that the magnetism of graphene can likely be controlled by changing doping conditions. By analyzing the total and partial density of states, it is concluded that the magnetic mechanism of Mn-doped graphene is relevant to the p-d exchange correlation function of Mn-d and C-p electrons. 相似文献
16.
在1673K下,应用Fe_2O_3-MnO_2熔剂对高炉锰铁熔体进行了预脱硅的实验研究。研究了Fe_2O_3与MnO_2的配比和添加CaO对脱硅保锰的影响。结果表明:当熔剂用量为合金量的5%时,可获得70%的脱硅率,并对锰的氧化有所抑制。分析了脱硅保锰的热力学条件和工艺条件。 相似文献
17.
郭洪影 JIANG Shan WANG Chaoyuan LI Shenwan FENG Jianjian 孙红梅 ZHU Hongda GUO Huiling LIU Mingxing SUN Honghao 《武汉理工大学学报(材料科学英文版)》2019,(2)
A mild chemistry route was developed to prepare carbonaceous nanofibers-titanium dioxide(CNF-TiO_2) nanocomposites for removal of dye pollutants. In the process of the template-directed hydrothermal carbonization(HTC), ultrathin Te nanowires were adopted as templates and glucose as the carbon source, and TiO_2 was decorated on CNF via the hydrolysis of tetrabutyltitanate in the presence of CNF in ethanol. The as-prepared materials were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy-dispersive X-ray(EDX) and X-ray diffraction(XRD). SEM and TEM observations displayed that TiO_2 nanoparticles were anchored on the CNF. EDX and XRD data confirmed that the assynthesized samples were CNF-TiO_2, and TiO_2 belonged to anatase titania. Taking advantage of combined benefits of carbonaceous nanofibers and titanium dioxide, these CNF-TiO_2 nanocomposites exhibited higher removal efficiency in a short time and showed good reusability. It was showed that over 97% of Rhodamine B could be removed in 15 min without generating the solid and liquid wastes. The removal efficiency of dyes was still over 80% after reuse in five cycles. All the results demonstrate that the as-prepared CNF-TiO_2 composites are effective materials for fast and effective removal of dye pollutants and thus can provide a new platform for dye decontamination. 相似文献
18.
《武汉理工大学学报(材料科学英文版)》2017,(2)
A novel photocatalytic cement based material was prepared. The distribution of TiO_2 on the surface of cement was characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD), which showed the relationship of photocatalysis and presence of TiO_2. TiO_2 also had an impact on cement hydration, which was studied by thermal analysis. With 300 W UV illuminations, formaldehyde and benzene were degraded efficiently by the prepared photocatalytic cement based materials. 15wt% TiO_2/cement showed the highest degradation efficiency and capability. The results show that formaldehyde and benzene can be degraded within 4 and 9 hours, respectively. Besides, inorganic ions can induce TiO_2 agglomeration. As a result, the presence of inorganic ions in cement is unfavorable for degradation. The photocatalytic cement based materials were fabricated and the degradation efficiency of formaldehyde was measured on building roof under sunlight illumination. Formaldehyde in glass chamber can be degraded thoroughly within 10 days. 相似文献
19.
Li2Fe0.9Mn0.1SiO4/C composites were synthesized by using glucose as carbon source. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurements. All Li2Fe0.9Mn0.1SiO4/C composites are of the similar crystal structure. With increasing the carbon content in the range of 5%-20% (mass fraction), the diffraction peaks in XRD patterns broaden and the particle sizes and the tap density of samples decrease. The Li2Fe0.9Mn0.1SiO4/C composites with carbon content of 14.12% show excellent the capacity retention remains 92.2% after 30 cycles. 相似文献
20.
Tao Li~ 《北京科技大学学报(英文版)》2008,15(1)
LiMn_2O_4 powder as a cathode materials for rechargeable lithium-ion batteries was prepared by solid-state reaction from Li_2CO_3 and electrolytic MnO_2 at different sintering periods(2,6,18,and 32 h).X-ray diffraction(XRD)patterns of the prepared samples are identified as the spinel structure with a space group of Fd(?)m.The lattice parameters almost remain the same as the sin- tering periods increase.The sample with a sintering period of 32 h shows good cycling performance at both low and high current densities,and also elevated temperature.It is believed that the excellent electrochemical behavior of this sample results from its good crystallinity and large grain size compared with other samples.Different electrochemical measurements were conducted to investi- gate the electrochemical properties of spinel LiMn_2O_4. 相似文献