La0.67-xDyxSr0.33MnO3(0.00≤x≤0.30)中的晶格效应

用固相反应法在La0．67-xDyxSr0．33MnO3中进行了Dy掺杂研究。结果发现，随着Dy掺入量的增加，样品的金属一绝缘体相变温度逐渐降低，对应的峰值电阻渐渐增大，居里温度下降，样品的磁电阻效应迅速增加，对Dy掺杂的作用可以用晶格效应来解释。     

Magnetic Properties of La1-xSrxCoO3 （0 ≤ x ≤ 0. 5）

The measurements of temperature dependence of the magnetic susceptibility of La1-xSrxCoO3 perovskite oxides at different Sr doping （0 ≤x ≤0.5） and annealing temperature were presented. For the sample with x = 0.1, a shoulder was observed around 150 K, and a peak which is one feature of spin glass appeared around 50 K in the curve of susceptibility versus temperature. The high-temperature （250 - 420 K）susceptibility fits well with Curie-Weiss law for all samples. Weiss constant and effective magnetic moment were determined and their variations with Sr doping and oxygen annealing condition were obtained. The Weiss constant increases monotonously with Sr content for x 〉 0.2. The values of effective moments were interpreted with the spin state of cobalt ions. Studies on the susceptibilities of the samples with x = 0.2 under different preparation temperatures and annealing temperatures show that the rising of sintering temperature and annealing temperature will increase the para-ferromagnetic transition temperature, and reduce the effective moment to normal value. Our result shows that both Co^3＋ and Co^4＋ ions should be in IS state after annealing and the oxygen annealing causes the transition of Co^3＋ spin state from HS to IS.     

CaMn1-xWxO3(0.05≤x≤0.20)体系电荷有序的建立与消失

通过对样品磁化强度-温度（M-T）曲线、磁化强度-磁场强度（M-H）曲线、电阻率-温度（ρ-T）曲线及部分样品ESR谱的测量，研究了Mn位w掺杂对Cabin1-x，WxO3（x=0．05，0．07，0．10，0．12，0．14，0．16，0．20）体系磁结构的影响。结果表明，随着W掺杂量的增加，体系磁结构发生了复杂的变化过程。当掺杂量x≤0．07时，体系为铁磁（FM），反铁磁（AFM）和顺磁（PM）态的共存，随掺杂量增加，FM态减弱，AFM态增强；当x=0．10，0．12时，体系建立电荷有序（charge ordering，CO）态，AFM／CO态共存于相变温度以下，且电荷有序温度TCO随掺杂量增加而增加；当x≥0．14时，体系电荷有序（CO）态减弱并消失。     

Extraordinary Transport Behaviors of La0.67Sr0.33Mn1-xCrxO3（0.00≤x ≤0.30）

M-T curves, ρ-T curves and MR-T curves of La0.67Sr0.33Mn1-xCrxO3（0.00≤ x ≤0.30） were studied. Experimental results indicate that the substitution of Cr on Mn sites is impotent in driving Tc, but with an increase of Cr content, there appear two peaks in resistivity and MR response, thus the temperature range of CMR response is significantly broadened. The extraordinary transport behavior and the abnormal CMR effect could be the results of coexistence and competition of Mn^3 ＋ -O-Mn^4 ＋ and Mn^3＋ -O-Cr^3 ＋ channels.     

钙钛矿锰氧化物Pr1-xCaxMnO3 (0.3≤x≤0.5)的磁跳变现象研究

通过固相反应法合成了Pr1-xCaxMnO3系列多晶样品(x＝0.3,0.4和0.5),并对样品的结构和磁性进行了研究.通过XRD检测结果发现样品均为单相,空间群为Pbnm.通过PPMS对样品在低温下的磁行为作了研究,对于Pr0.6Ca0.4MnO3样品,在温度为2K时,观察到了多级磁跳变现象.这是因为在2K下加场,样品长程磁有序消失,在某一临界场,反铁磁(antiferromagnetic AFM)区会突然全部转化为铁磁(ferromagnetic FM)区,磁化强度出现跳跃式变化.     

p≤10的二次D-最优设计

Kiefer给出的在区域－1≤xi≤1（i＝1，2，…，p）上的二次D－最优设计[1]不适用于因子数p＞5的情形，因为此时出现了负测度，所以是无意义的．用数值方法给出了p≤10的二次（近似）D－最优设计．     

Spin-Dependent Electroresistance Behaviour of Nd0.67Sr0.33MnO3-δ(0≤δ≤0.20)

Oxygen deficient Nd0.67Sr0.33MnO3-δ ceramic samples were prepared using conventional ceramic technology. A colossal electroresistance (CER) effect was found in Nd0.67Sr0.33MnO3-δ series. The electrical transport is magnetically coupled and spin-dependent over grain or phase boundaries. Electrical-field-induced changes of the spin array orientations inside of and between the magnetic domains by grain or phase boundaries have to be concluded for the strong electroresistive effect in Nd0.67Sr0.33MnO3-δ series.     

Sr2.7Eu0.2P2-x VxO8(0≤x≤2)的光致发光性质

用溶胶-凝胶方法制备Sr2.7 Eu0.2 P2-x Vx O8(0≤x≤2)样品.采用X射线衍射(XRD)和光致发光谱(PL)来表征样品的晶体结构和发光性能.XRD结果表明:随着x的增大,晶体结构由Sr3 P2 O8相过渡到Sr3 V2 O8相.PL光谱结果表明:适量的P5+掺杂使得Sr2.7 Eu0.2 P2-x Vx O8的发光增强,激发VO43-比直接激发Eu3+更有利于Sr2.7 Eu0.2 P2-x Vx O8的发光.     

Extraordinary Transport Behaviors of La0.67Sr0.33Mn1-x CrxO3（0.00≤x≤0.30）

The M-T curves, ρ-T curves and MR-Tcurves of La0.67Sr0.33 Mn1-xCrxO3 (0.00≤x≤0.30)were studied. The experimental results indicate that the substitution with Cr on Mn sites is impotent indriving Tc, but with the increase of Cr content, which leads to the appearance of two peaks in resistivity andCMR response, the temperature range of CMR response is significantly broadened. The extraordinary transport behavior and the abnormal CMR effect could be the results of the coexistence and competition of these Mn^3 -O-Mn^4 and Mn^3 -O-Cr^3 channels.     

Transport Property of La0.67-xSmxSr0.33MnO3 at Heavy Samarium Doping （0.40≤x≤0.60）

The influence of heavy samarion （Sm） doping （0.40≤x≤0.60） on magnetic and electric properties of La0.67-xSmxSr0.33MnO3 was investigated by measuring the magnetization-temperature （M - T） curves, magnetization-magnetic density （ M - H） curves, resistivity-temperature （ρ- T） curves and magnetoresistivity-temperature （ MR - T） curves of the samples under different temperatures. It is found that, form from long-range ferromagnetic order to spin-cluster glass with the increase of Sm doping amount, the samples transstate and anti-ferromagnetic state; and when x = 0.60, the transport property becomes abnormal under magnetic background; and the magnetic structure changes and extra magnetic coupling induced by doping leads to colossal magnetoresistance effect. The transport mechanism of metallic conduction at low temperature is mainly electron-magneton interaction and can be fitted by the formula ρ = ρ0 ＋ AT^4.5, and the insulatorlike transport mechanism on high temperature range is mainly the function of variable-range hopping and can be fitted by the formula ρ = ρ0exp（T0/T）^1/4. In the formulas above, p is resistivity, T is temperature, and A, ρ0, T0 are constants.     

Research of Colossal Magnetoresistance in La0.67Ca0.33Mn1-xCrxO3 （0.00 ≤x≤0.15）

The extraordinary colossal magnetoresistance (CMR) behavior in Mn-site doped system La0.67Ca0.33Mn1-xCrxO3(0.00≤x≤0.15) was reported. It was found that the substitution with Cr on Mn sites introduces an additional bump in zero-field resistivity. With increasing Cr content, this additional bump grows up drastically while the original resistivity peak associated with magnetic order transition diminishes gradually. Under the applied magnetic field, both bumps of resistivity are deeply compressed, which leads to the appearance of two peaks in CMR response. As a result, the temperature range of CMR response is significantly broadened, spanned from the lowest to near room temperature. These results suggest that Mn-site element substitution could be a potent way of tuning CMR response.     

降低烧结矿≤10mm粒级率的生产实践

介绍武钢烧结各车间生产现状,降低烧结矿≤10mm粒级率的生产措施、实践及取得的效果,并提出进一步努力的方向.     

Magnetic and magnetotransport behavior of overdoped nanocrystalline Nd_(1-x)Sr_xMnO_3 (0.50≤x≤0.63)

The nanocrystalline samples of Nd1-xSrxMnO3 (NSMO) (x=0.5, 0.55, 0.60, 0.63) were synthesized by sol-gel based polymeric pre-cursor route. Structural, magnetic and magnetotransport properties were studied systematically. It was found that in the composition range (x=0.50-0.63), Nd1-xSrxMnO3 showed paramagnetic to ferromagnetic (PM-FM) transition in the vicinity of TC～270 K but the FM phase was weakened as the Sr concentration increased. The appearance of weak ferromagnetism was explained in terms of the cor...     

Influence of annealing on spin state of cobalt ions in La1-xSrxCoO3（0≤x≤0.5） system

Perovskite oxide La1-xSrxCoO3 (0≤x≤0.5) series were prepared and effect of oxygen annealing on crystal structure and magnetic susceptibility were studied. High-temperature susceptibility could be well fitted by Curie-Weiss law for all Sr-doped samples. Weiss constant and effective magnetic moment were determined, and their variations with Sr doping and oxygen annealing condition were obtained. The result suggested that by assuming that the Co3+ ions were in the intermediate-spin (IS) state, most of the Co4+ ions in the as-prepared samples might be in the high-spin (HS) state, but both the Co3+ and Co4+ ions might be in the IS state after oxygen annealing, which indicated that annealing in flowing oxygen could cause transition of the spin state of Co4+ ions from the HS state to IS state.     

钙钛矿化合物SrFe_(1-x)Cu_xO_(3-δ)(0≤x≤0.3)的制备及磁性

采用溶胶-凝胶法制备钙钛矿结构化合物Sr Fe1-xCuxO3-δ(0≤x≤0.3)的多晶样品,通过X射线衍射(XRD)结合Rietveld结构精修方法研究该化合物的晶体结构,并使用物性综合测量系统(PPMS)研究其磁性能。精修结果表明掺Cu可使样品发生结构转变,x=0的样品为I4/mmm点群的正方结构,而x=0.1,0.2,0.3的样品均为Pm 3 m点群的立方结构,晶格常数随Cu含量的增加而减小。磁性测量的结果表明Cu含量越高,造成铁磁和反铁磁相互作用的竞争越激烈,形成自旋玻璃态;x=0.1,0.2,0.3的样品转变温度低于x=0的样品,但随Cu含量增加,x=0.1,0.2,0.3的样品转变温度逐渐升高;随Cu含量增加,Fe/Cu位的有效磁矩减小。     

Li+ doping induced zero-thermal quenching in Cs3Zn6-x-yB9O21:xEu3+,yLi+(0≤x≤0.10,0.06≤y≤0.16)

Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs₃Zn_5.94B₉O₂₁:0.06Eu³⁺ possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li⁺ ions into the lattice,the sample exhibits high color ...     

Synthesis, and measurement of structural and magnetic properties, of La1-xNaxFeO3(0.0≤x≤0.3) perovskite oxides

Polycrystalline La_1-xNa_xFeO₃ (0.0≤x≤0.3) solid solutions were synthesized by a solution combustion method using glycine as a fuel. The combustion synthesized compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance (DR) in the UV-vis, and magnetic measurements. The crystal structure examined by X-ray powder diffraction indicated that the samples were single phase and crystallized in an orthorhombic (space group, Pbnm no.62) structure. The parent and sodium-substituted compounds showed canted anti-ferromagnetic behavior associated with an increase in magnetic moment as Na content increased. The changes in magnetic properties of the materials were correlated to the changes in structural features, as shown by Rietveld structural refinement of the materials.