重掺杂Sm时La（0．6-x）SmxSr0．33MnO3的磁电性质

通过测量样品的磁化强度-温度（M-T）曲线、磁化强度-磁场强度（M-T）曲线、电阻率-温度（ρ-T）曲线及磁电阻（magnetoresistance）-温度（MR-T）曲线，研究了Sm重掺杂（x=0．40，0．50，0．60）对La（0．6-x）SmxSr0．33MnO3磁电性质的影响。发现随着Sm掺杂量增加，样品从长程铁磁有序向自旋团簇玻璃态和反铁磁状态转变；x=0．60时的输运性质在其磁背景下发生异常；掺杂引起的磁结构变化和额外磁性耦合将导致庞磁电阻效应。低温金属型导电的输运机制主要是电子．磁子相互作用，     

La0.67-xErxSr0.33MnO3 (0.00≤x≤0.20)体系的磁电特性和低温电阻率反常

实验研究了La0.67-xErxSr0.33MnO3(x=0．00，0．10，0．20)体系的M-T曲线、ρ-T曲线和MR-T曲线。结果发现：随掺杂量增加，体系的磁结构从长程铁磁有序向自旋团簇玻璃态过渡，极低温区出现M-T曲线上翘；体系的电阻率随掺杂量的增加而增加，并出现低温极小值现象。体系磁电性质的变化来源于掺杂引起的额外磁性耦合，以及晶格畸变和局域磁矩引起的类似于磁性杂质对电子自旋散射造成的近藤效应(Kondo Effect)。     

La0.7-xGdxSr0.3MnO3中的相分离和输运行为

研究了La0.7-xGdxSr0.3MnO3(x=0．00，0．10，0．15，0．20，0．30，0．40，0．50，0．60，0．70)体系的M-T曲线、M-H曲线、ESR曲线、ρ-T曲线和MR-T曲线。实验结果表明：随着Gd掺杂的增加，体系从长程铁磁有序向自旋团簇玻璃态和反铁磁状态转变，x=0.30和0.40时，样品在Tc以上温区发生相分离；高掺杂时的输运行为在其磁背景下发生异常，Gd掺杂引起的磁结构的变化将导致CMR效应。     

La0．8Sr0．2Mn1-xCoxO3（x=0，0．3，0．5，1）的磁性转变

采用柠檬酸络合法制备B位掺杂的纳米钙钛矿复合氧化物La0．8Sr0．2Mn1-xCoxO3（x=0，0．3，0．5，1．0）。应用X射线衍射法（XRD）进行结构的测定与分析，并结合扫描电镜（SEM）和热磁曲线（M-T曲线）的实验结果，研究这4种样品的结构和磁性之间的关系。X射线衍射实验分析表明4个样品均属六方晶系，M-T曲线得出的1／χ-T曲线表明：La0．8Sr0．2MnO3是铁磁性，La0.8Sr0．2Mn0．7Co0．3O3和La0．8Sr0．2Mn0.5Co0．5O3是亚铁磁性，而La0．8Sr0．2CoO3是反铁磁性的。利用电镜观察到前3种样品均为颗粒状，颗粒之间首尾相接形成链状结构，并进一步由链状结构支起一个个的空间网状结构，最后一种样品为较为分散的颗粒。     

（La0.5Gd0.2）Sr0.3MnO3中的磁热效应

对A位掺杂的超大磁阻材料(La0.5Gd0.2)Sr0.3MnO3的磁热效应进行了研究，通过不同温度下等温磁化(M-H)曲线的测量和计算，发现伴随铁磁．顺磁相变出现大的磁热效应，额外的磁性交换作用将导致额外的磁熵变化。     

深冷状态下纳米镝铁氧体磁粒子磁性能的研究

采用湿化学法制备出稀土Dy3+掺杂的纳米Fe3O4磁粒子,用月桂酸进行了表面修饰,研究了磁粒子在室温和深冷(200.2～56.5 K)状态下的磁性能.经X射线衍射分析发现,适量的Dy3+掺杂不会改变纳米Fe3O4磁粒子的晶型结构.透射电镜(TEM)照片表明,制备出的纳米磁粒子成球性好,且大部分磁粒子的粒径在14 nm左右.通过磁性测量仪、振动样品磁强计(VSM)对磁性能进行了表征.磁化曲线表明掺杂引起磁性能发生变化,磁粒子室温下无剩磁和矫顽力,具有超顺磁性;深冷状态下出现剩磁和矫顽力,且随温度的降低,剩磁和矫顽力增大,不具有超顺磁性,饱和磁化强度略高于室温值.     

La0.7-xDyxSr0.3MnO3(0.00≤x≤0.70)的TCR研究

研究了La位Dy掺杂对La0.7-xDyxSr0.3MnO3(0.00≤x≤0.70)电阻温度系数(TCR)的影响.实验结果表明:Dy掺杂将引起电阻率曲线的急剧变化,导致出现大的TCR;随Dy掺杂的增加,TCR在x=0.30出现峰值,然后随掺杂量的增加逐步降低.体系出现大的TCR,来源于Dy掺杂引起的晶格畸变和额外磁性耦合.     

LSDA+U方法研究Ni掺杂CuO和Cu掺杂NiO的电子结构和反铁磁学性质（英文）

光催化分解水制H_2和光催化还原CO_2是解决能源危机和全球变暖的有效途径.但是,由于粉末光催化剂存在回收效率低的问题,因而光催化成本很高.而磁性光催化剂便于回收和重复利用,因此人们把目光转向具有磁性的非光催化剂材料,试图通过改性使得磁性材料具有合适的水分解或者还原CO_2的氧化还原电位.同时,对具有光催化活性但是没有磁性的材料进行磁化改性可以得到新型的磁性光催化剂.本文通过对本身具有磁性的NiO材料进行Cu掺杂能带调整,使调整后的NiO具有合适的氧化还原电位;对本身具有良好光催化氧化还原电位的CuO材料进行Ni掺杂磁化调整,使磁化后的CuO既有良好的氧化还原电位又有磁性.最终两种材料经过掺杂变成磁性光催化材料,既有较好的光催化性能,又可高效回收,因此有望在光催化领域具有潜在的应用前景.LSDA(局域自旋密度近似)+U(有效库仑相关能)计算方法能够很好地给出磁矩和禁带宽度等电子结构性质.本文通过LSDA+U计算方法对具有磁性的宽禁带半导体材料NiO进行电子结构改性研究,希望通过降低其禁带宽度、调整其氧化还原电位使之对太阳光有响应.因其同时具有磁性便于回收,使得光催化分解水制H_2和光催化还原CO_2成本高的问题得到解决.对NiO的磁胞进行了Cu掺杂计算,结果发现Cu的掺杂几乎没有引起NiO空间结构的变化,这是因为Cu和Ni的离子半径相近.通过对电子结构的计算发现掺杂体系的禁带变窄,并且在禁带中间出现了两条杂质能级,该杂质能级是由掺杂原子Cu 3d态组成.杂质能级的出现能够降低光生载流子在带隙中的复合,从而提高光催化效率.计算结果同时表明,Cu掺杂的NiO系统具有一个1μB的净磁矩,即Cu的掺杂使得NiO显示出磁性,而Ni的磁矩在掺杂前后几乎保持不变,由纯相的1.67μB增加到掺杂体系中的1.70μB.由于CuO本身低指数(111)面和(011)面具有合适的分解水制H_2和还原CO_2的氧化还原电位,如果对CuO进行磁化改性,可以使光催化剂CuO同时带有磁性,便于回收再利用.本文对CuO磁胞进行了Ni的掺杂计算.结果表明,由于离子半径相近,Ni掺杂几乎没有引起CuO空间结构的变化.掺杂后的体系具有一个1.66μB的净磁矩,同时Ni的掺杂引起多个杂质能级出现,靠近价带的杂质能级由Cu 3d态组成,而在导带底位置出现的杂质能级主要由Ni 3d态组成.整个能带向高能级方向平移.     

LSDA+U方法研究Ni掺杂CuO和Cu掺杂NiO的电子结构和反铁磁学性质

光催化分解水制H2和光催化还原CO2是解决能源危机和全球变暖的有效途径.但是,由于粉末光催化剂存在回收效率低的问题,因而光催化成本很高.而磁性光催化剂便于回收和重复利用,因此人们把目光转向具有磁性的非光催化剂材料,试图通过改性使得磁性材料具有合适的水分解或者还原CO2的氧化还原电位.同时,对具有光催化活性但是没有磁性的材料进行磁化改性可以得到新型的磁性光催化剂.本文通过对本身具有磁性的NiO材料进行Cu掺杂能带调整,使调整后的NiO具有合适的氧化还原电位;对本身具有良好光催化氧化还原电位的CuO材料进行Ni掺杂磁化调整,使磁化后的CuO既有良好的氧化还原电位又有磁性.最终两种材料经过掺杂变成磁性光催化材料,既有较好的光催化性能,又可高效回收,因此有望在光催化领域具有潜在的应用前景.LSDA(局域自旋密度近似)+U(有效库仑相关能)计算方法能够很好地给出磁矩和禁带宽度等电子结构性质.本文通过LSDA+U计算方法对具有磁性的宽禁带半导体材料NiO进行电子结构改性研究,希望通过降低其禁带宽度、调整其氧化还原电位使之对太阳光有响应.因其同时具有磁性便于回收,使得光催化分解水制H2和光催化还原CO2成本高的问题得到解决.对NiO的磁胞进行了Cu掺杂计算,结果发现Cu的掺杂几乎没有引起NiO空间结构的变化,这是因为Cu和Ni的离子半径相近.通过对电子结构的计算发现掺杂体系的禁带变窄,并且在禁带中间出现了两条杂质能级,该杂质能级是由掺杂原子Cu 3d态组成.杂质能级的出现能够降低光生载流子在带隙中的复合,从而提高光催化效率.计算结果同时表明,Cu掺杂的NiO系统具有一个1μB的净磁矩,即Cu的掺杂使得NiO显示出磁性,而Ni的磁矩在掺杂前后几乎保持不变,由纯相的1.67μB增加到掺杂体系中的1.70μB.由于CuO本身低指数(111)面和(011)面具有合适的分解水制H2和还原CO2的氧化还原电位,如果对CuO进行磁化改性,可以使光催化剂CuO同时带有磁性,便于回收再利用.本文对CuO磁胞进行了Ni的掺杂计算.结果表明,由于离子半径相近,Ni掺杂几乎没有引起CuO空间结构的变化.掺杂后的体系具有一个1.66μB的净磁矩,同时Ni的掺杂引起多个杂质能级出现,靠近价带的杂质能级由Cu 3d态组成,而在导带底位置出现的杂质能级主要由Ni 3d态组成.整个能带向高能级方向平移.     

Ni 掺杂ZnO纳米线的电子结构与磁性

采用自旋极化密度泛函理论系统研究了Ni掺杂ZnO纳米线的电子结构、磁学和光学性质.磁学性质计算结果显示六种Ni掺杂ZnO纳米线的磁性耦合体系出现了铁磁(FM)、反铁磁(AFM)和顺磁(PM)二种不同的耦合状态.能量计算结果表明Ni原子在纳米线外表面沿[0001]方向替代Zn原子时能量最低,体系的AFM耦合相对稳定,AFM体系表现出金属性.态密度计算结果显示FM耦合在费米能级附近出现了明显的自旋极化现象,发生了强烈的Ni 3d和O 2p杂化效应,掺杂产生的磁矩主要来源于Ni 3d未成对轨道电子和部分O 2p轨道电子的贡献,FM耦合表现出半金属性.另外,光学性质计算结果显示Ni掺杂ZnO纳米线的远紫外吸收峰发生了红移现象,而380 nm附近的近紫外吸收峰发生了明显的蓝移现象,在整个紫外区都表现出了优异的发光性能.以上结果表明Ni掺杂ZnO纳米线是一种很有前途的磁光电子材料.     

La0.7-xDyxSr0.3MnO3(0.00≤x≤0.30)体系低温磁行为和电阻率的反常

By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping (0.00 ≤ x ≤0.30) on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.     

Phase Separation and Transport Behavior in La0. 67-x Smx Sr0.33 MnO3 System

The magnetic behavior and the transport behavior of La0.67-x Smx Sr0.33 MnO3 （x = 0. 00, 0. 10, 0. 20, 0. 30, 0. 40, 0. 50 and 0. 60 ） systems were studied through measuring the M-T curves, electron spin resonance （ ESR ） curves and ρ-T curves. The samples exhibit a long-range ferromagnetic order when x = 0. 00, 0. 10, a cluster-spin glass state when x = 0. 20 and 0. 30, and an anti-ferromagnetic state at low temperatures when x = 0. 40, 0. 50 and 0. 60. The samples of x = 0. 30 and 0.40 show phase separation at temperatures above Te. The transport behavior of the sample of x = 0. 60 becomes abnormal when the doping is high, and an insulator-metal transition occurs near To and then a metal-insulator transition occurs, which rarely appears in an ABO3 structure. It is concluded that the magnetic and electric behavior changes of the systems depend on the extra magnetism and lattice distortion effect induced by Sm doping.     

Electron spin resonance and optical spectroscopic studies of the conducting polymer precursor: Poly(3,4-diisopropylidene cyclobutene)

The doping process in a recently developed conducting polymer precursor, poly(3,4-diisopropylidene cyclobutene) (PDPCB)¹ was studied by electron spin resonance and optical spectroscopy. Thin films of PDPCB were exposed to several oxidants, I₂, AsF₅, or a combination of AsF₅ and AsCl₃ or AsF₃, and monitored in situ by ESR. At the initial stages of doping, the films developed broad ESR spectra with Gaussian line shape. Except in the case of doping with I₂, resolved hyperfine structures from cation radicals were observed. As the doping progressed, the ESR spectra gradually transformed to narrower line widths with a Lorentzian component. The Lorentzian component can be attributed to charge carrier species developed in the film through doping. The results of optical spectroscopy (UV-visible) are incorporated to elucidate the effect of doping on electronic transitions of the doped PDPCB.     

Magnetic properties of nm-sized iron crystallites and clusters embedded in vacuum-deposited MgO films

Magnetic property of single crystalline iron-MgO composite films was measured with a SQUID magnetometer. The thermo-magnetic (M-T) curves showed splitting of the magnetization in low temperature, depending on zero-field cooling and field cooling cases. The magnetization (M-H) curves at 5 K after the zero-field cooling showed hysteresis with larger coercive force than that of bulky iron. Systematic study of the relationship between the structure of the composite films and the magnetic property showed that nm-sized iron crystallites embedded epitaxially in MgO films play a main role to the property.     

锌掺杂对SrTiO_3光催化性能的影响

制备了锌掺杂的SrTiO3光催化剂,测试了掺杂样品在400 W高压汞灯照射下,分解纯水制氢的活性。考察了锌的掺杂量及样品的焙烧温度对其光催化活性的影响,并对掺锌与未掺杂样品进行了XRD、UV-vis、XPS及SEM表征分析。结果表明,Zn掺入可显著提高SrTiO3的光催化活性,适宜的锌掺杂摩尔分数为1%左右,相应的掺杂量下,适宜的焙烧温度为950℃左右,上述条件制得掺锌SrTiO3的产氢速率较未掺杂样品提高了120%左右。表征结果显示,掺摩尔分数1%的锌未改变SrTiO3的晶体结构及结晶完整性,但样品表面发生了锌的富集,而且在一定的掺杂范围内,锌掺杂使SrTiO3催化剂的粒度有所增大。推测掺入的Zn与存在于SrTiO3表面的富钛相反应生成Zn2TiO4,使SrTiO3表面的缺陷浓度降低,光催化活性提高。     

柠檬酸络合法制备的Co/CeO2催化剂上中温乙醇水蒸气重整性能（英文）

采用柠檬酸络合法制备了Co/CeO2及其钙掺杂系列催化剂,并对催化剂进行了低温N2物理吸附、X射线衍射、H2程序升温还原、傅里叶变换红外光谱、高分辨透射电镜表征以及乙醇水蒸气重整催化性能测试.结果表明,所制Co/CeO2催化剂具有良好的乙醇水蒸气重整催化性能,500oC时乙醇能全部转化为C1,氢气产率高达85%以上.Ca掺杂减小了载体CeO2纳米颗粒尺寸,但对还原后Co0尺寸的影响较小.当Ca掺杂量大于5.0%时,催化剂氧化还原性能和乙醇水蒸气重整催化性能下降.较高的还原温度有利于体相Ce4+还原为Ce3+,并且提高了催化活性,认为金属-氧化物边界的增加提高了催化活性.初步稳定性考察结果表明,5%钙掺杂后的催化剂具有更好的抗积炭性能.     

Synthesis and photoluminescent properties of a Schiff-base ligand and its mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes

Mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes of Schiff-base ligand(HL₁) derived from 8-acetyl-7-hydroxycoumarin and P-phenylenediamine were prepared and characterized by microanalytical, mass, UV–Vis, IR, ¹H NMR, ¹³C NMR, ESR, conductance and fluorescence studies. The measured low molar conductance values in DMSO indicate that the complexes are non-electrolytes. The structures of the solid complexes under study are established by using IR, electronic and ESR spectroscopy suggesting that Zn(II) and Ni(II) complexes are octahedral, Cd(II) complex is tetrahedral, Cu(II) and Pd(II) complexes are square planar. The ESR spectrum of the Cu(II) complex in DMSO at 298 and 150 K was recorded and its salient features are reported, it supports the mononuclear structure. The Schiff base exhibited photoluminescence originating from intraligand (π–π*) transitions. Metal-mediated enhancement is observed on complexation of HL with Zn(II) and Cd(II), whereas metal-mediated fluorescence quenching occurs in Cu(II), Ni(II) and Pd(II).     

Cr2O3在铜基甲醇合成催化剂中的作用

研究了三组份Cu－ZnO－Al_2O_3催化剂添加Cr_2O_3后．铬在催化剂中的存在形式，助催作用本质及其与甲醇含成催化活性的关联。结果表明：在ZnO－Cr_2O_3催化剂中，铬以Cr~(3 )和ZnCr_2O_4形式存在于ZnO晶格中，Cu-ZnO-Al_2O_3-Cr_2O_3催化剂的催化活性与CR~(3 )在ZnO晶格中诱导出来的正一价缺位和催化剂的其它顺磁性物种的ESR强度能很好地关联，在活性测试中，以含1％Cr（原子比）的Cu-ZnO-Al_2O_3-Cr_2O_3的催化活性最高。     

Characterization of neutron transmuted zinc traces in pure copper materials by isotope dilution mass spectrometry

The neutron transmutation doping (NTD) of highly pure copper with zinc was investigated as a promising means of achieving controlled gradation of the zinc content in the range 1-20 microg g(-1). The doping process leads to the enrichment of two stable isotopes 64Zn and 66Zn in a ratio which differs from that of natural isotopic distribution. Mass spectrometric investigations by thermal ionization mass spectrometry (TIMS) were performed to validate the results obtained by gamma spectrometry. The investigations included both determination of the isotopic ratios of the doped zinc isotopes and the analysis of the accumulated zinc contents by isotope dilution (ID) analysis. Thereby a sample-specific correction of the blank could be performed because the isotope 68Zn was not influenced, because of the transmutation process. The results obtained by TIMS prove the strict proportionality of the doped zinc content, in the range 5 to 20 microg g(-1), to the neutron fluence. Comparison with gamma spectrometric results showed a very good agreement within the uncertainties.     

A dependence of electrical conductivity and some properties of paramagnetic centers on the doping level of poly(4-aminoazobenzene) with iodine

The dependences of the electrical conductivity, ESR spectral linewidths, spin concentrations, and g-factor on the level of iodine doping of poly(4-aminoazobenzene), synthesized by the oxidative polymerization of 4-aminoazobenzene with iodine, were studied for the first time. The polymers were studied by ESR and UV spectroscopy. With an increase in the level of iodine doping, the electrical conductivity of the polymers increases from 3·10⁻¹⁰ to 4·10⁻¹ S m⁻¹, the ESR linewidth increases from 0.96 to 1.94 mT, and the g-factor increases from 2.004 to 2.007. The spin concentration changes ambiguously, depending on the doping level. In the iodine-doped polymers, spins are mainly localized on two nitrogen atoms of the azo groups.