煅烧温度对Li0.33La0.56TiO3固态离子电容器性能的影响

本文采用固相法在900、1000、1100和1200℃煅烧温度条件下合成了Li_0.33La_0.56TiO₃(LLTO)固态电解质材料, 并将其组装为LLTO固态离子电容器。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、电化学阻抗谱(EIS)和循环伏安法(CV)等技术研究了煅烧温度对LLTO固态电解质和固态离子电容器的显微结构、形貌、离子电导率和储能性能的影响。实验表明, 较高的煅烧温度有利于获得性能优异的LLTO固态离子电容器。在室温下, 1200℃煅烧温度制备的固态离子电容器晶粒离子电导率高达 9.6×10^-4 S/cm, 且具有明显的双电层电容特性, 在4 V电压窗口下比电容为3.52 mF/g。此外, 固态离子电容器比电容随晶粒电导率的增大而增大, 同时受电极与固态电解质接触面积的影响。     

以废旧干电池电解质为原料制备Mn-Zn铁氧体及磁性能研究

以废旧干电池电解质、氧化铁为原料,固相法成功地制备Mn-Zn铁氧体粉体。通过X射线衍射仪、场发射电子显微镜和激光粒度分析仪等测试手段分析了其物相、微观结构和形貌,用振动样品磁强计测量其室温下磁性能。结果表明:650℃煅烧3h,废旧干电池电解质主要组成为ZnMn2O4。基于Mn-Zn铁氧体的化学计量比,称取废旧干电池电解质和氧化铁,900℃煅烧3h,可以获得尖晶石型Mn-Zn铁氧体粉体,平均颗粒尺寸约2μm。室温下,样品磁滞回线显示了典型软磁材料特性,其比磁饱和强度和矫顽力分别为17.68A·m2/kg和203A/m。     

Yb2O3掺杂8YSZ电解质材料的制备和性能研究

用共沉-胶化-低温干燥制备2Yb-8YSZ粉末,喷雾制粒获得球状颗粒.用激光粒度分析,X射线衍射仪(XRD),比表面测定仪(BET)和扫描电子显微镜(SEM)检测粉末和陶瓷体的性能,组织结构和相组成.结果表明,煅烧粉末的粒径为0.86μm,喷雾造粒的颗粒尺寸为17 μm,晶粒尺寸为100 nm,BET=26.66 m2/g.粉末和陶瓷体材料为面心立方结构.高于1 400 ℃烧结陶瓷体的烧结密度大于98%理论密度.陶瓷体电导率的测定结果表明,在1 400～1 600 ℃之间烧结,对材料的电导率影响不明显.2Yb-8YSZ具有高的离子电导率,操作温度大于600 ℃下的电导率达1×10-3 S/m.2Yb-8YSZ材料完全适用于作中温固体氧化物燃料电池(SOFC)的电解质.     

常压固相反应合成LaB6粉末及其反应机理

以La2O3和B4C为原料,在常压下合成了LaB6粉末.计算了常压合成LaB6的热力学条件,采用XRD、SEM、激光粒度分析表征了不同温度和保温时间合成的LaB6粉末的物相组成、颗粒形貌和粒度分布,探讨了LaB6粉末的合成反应机理.结果表明,常压下1650℃保温2h的产物经酸洗后,能得到纯度为99.22%具有立方体结构的LaB6粉末.当La2O3颗粒尺寸远小于B4C时,合成过程中LaB6首先在B4C表面生成,随温度升高和保温时间延长,未反应的La2O3和LaBO3通过LaB6壳不断扩散到B4C核表面直至反应完全.合成LaB6粉末的初始形貌和尺寸主要取决于反应物B4C原料.     

中温固体电解质LaGaO3的制备

分别采用固相反应法、凝胶燃烧法分别制备了镓酸镧基固体电解质粉体(La0．9Sr0.1Ga0．8Mg0．2O3-δ)．讨论了煅烧温度对粉体物相的影响,比较了两种方法所制备粉体的特点．X射线衍射分析表明．固相反应法制备需经1250℃下预烧15h,1500℃下煅烧24h．得到La0．9Sr0.1Ga0．8Mg0．2O3-δ粉体颗粒尺寸在1μm,而凝胶燃烧法仅需在1400℃煅烧10h可以合成La0．9Sr0.1Ga0．8Mg0．2O3-δ粉体,粉体颗粒尺寸150nm。     

两种添加剂对溶胶-凝胶法制备LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的影响

由溶胶-凝胶法制备了LiNi1/3Co1/3Mn1/3O2粉体,对比研究了聚乙二醇和柠檬酸2种添加剂对其界面和结晶度的影响,利用扫描电子显微镜、x射线衍射仪和热分析仪器分析了其形貌和物相等。结果表明,900℃煅烧15h时粉末粒度为1μm左右,并发生软团聚,从单个颗粒来看,样品表面光滑,界面清晰,分散较为均匀;添加聚乙二醇时粒度为1μm左右,粒子呈类球状;添加柠檬酸时粒子粒度为1~2μm左右,粉末结晶度较好。     

微波加热焦碳与石英砂合成SiC粉体

以粒度为～2μm,5～20μm,100～200μm的焦炭颗粒,粒度为～1μm的石英砂粉体为原料,采用微波加热合成了碳化硅粉体.在1600℃下保温30min,反应能完全进行,合成产物中β-SiC的含量达到98%以上.得到的SiC粉体具有与焦炭颗粒近似的颗粒尺寸.研究表明,微波加热具有节能快速的优点,能显著地促进反应的进行.     

激光防护材料SmBO_3的制备及其光学吸收特性

利用固相法制备了SmBO3粉体,讨论了煅烧温度对粉体合成及光学吸收特性的影响.结果表明:原料经800℃煅烧后,即可获得单相的三斜SmBO3,粉体呈不规则颗粒状,颗粒大小主要分布在500～600nm;1200℃煅烧后,三斜SmBO3完全转变为六方SmBO3,颗粒尺寸长大至1～2μm.反射率图谱表明,在1.05～1.15μm?长范围?两种晶?SmBO3粉体?光均存?较强的?收,并?在1.07μm波长附近反射率达最低值.红外图谱显示,三斜SmBO3在500～1400cm-1波数范围内,存在较为集中的吸收峰;六方SmBO3在944 cm-1(10.6μm波长)处的吸收峰宽化,并且吸收明显增强.因此SmBO3是一种能兼容1.06和10.6μm波长的激光防护吸收剂材料.     

用喷雾热分解法制备Gd2O3-Y2O3-ZrO2电解质材料的性能

用喷雾热分解方法制备了2 mol%Gd2O3-8YSZ的粉末,用激光粒度分析,X射线衍射(XRD),BET法和扫描电子显微镜(SEM)检测粉末和陶瓷体的性能和结构.结果表明,获得的粉末粒径为12.18 μm,晶粒尺寸为100 nm,比表面积为25.09 m2/g.粉末和陶瓷体材为立方结构.陶瓷体的烧结密度大于98%理论密度.在操作的温度高于600℃下的电导率达2×10-3 S/cm.证实Gd2O3-8USZ材料完全适用于作中温固体氧化物燃料电池(SOFC)的电解质.     

喷射-共沉淀法合成纳米晶CoFe2O4及磁性能

用喷射-共沉淀法成功地制备了纳米晶CoFe2O4铁氧体粉料.研究了不同合成温度对产物晶体结构、微观形貌和磁性能影响.结果表明:喷射-共沉淀法制备的粉料颗粒细小均匀、形状完整.600℃下煅烧1.5h,样品晶粒尺寸为29nm左右,平均颗粒尺寸小于100nm.室温下,样品比饱和磁化强度随煅烧温度增加而增大.850℃煅烧1.5 h时,其比饱和磁化强度Ms为88.6A·m2·kg-1.当晶粒大小为29nm时,纳米晶CoFe2O4铁氧体矫顽力达到最大值64.5kA·m-1,随后又随晶粒尺寸增大而减小.这可能归因于纳米磁性材料存在强烈的晶粒尺寸效应.     

Photostriction of CH3NH3PbBr3 Perovskite Crystals

Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH₃NH₃PbBr₃ is investigated using high‐resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH₃NH₃PbBr₃ is calculated as 2.08 × 10^?8 m² W^?1 at room temperature under visible light illumination. The significant photostriction of CH₃NH₃PbBr₃ is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH₃NH₃PbI₃, it is noted that the photostriction of CH₃NH₃PbBr₃ is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH₃NH₃PbBr₃ for applications in next‐generation optical micro‐electromechanical devices.     

(La2/3Ca1/3)(Mn(3-x)/3)Fex/3)O3体系磁电阻行为的研究

通过系统地测量（La_2/3Ca_1/3）（Mn_{（3-x）／3}Fe_x／3）O₃（x＝0、0.1、0．2、0．3的体系样品的电阻率-温度关系以及一定温度下磁电阻率与磁场的关系,发现随x的变化其磁电阻率峰和电阻率峰均发生位移,磁电阻率峰值增大,并伴生磁电阻率峰展宽效应．作者认为由于Fe的替代,引起体系中Mn³⁺／Mn⁴⁺比率及磁矩的变化,加之外场对磁有序结构的调制作用,从而影响了Mn³⁺－O^－Mn⁴⁺的双交换作用,最终导致磁电阻行为发生变化．     

Constitution of the Ni3Cr-Ni3Al-Ni3W system

Isothermal sections of the Ni-Cr-Al-W system have been investigated at 75 at % Ni and temperatures of 1523 and 1273 K, by means of phase compositional analysis, X-ray diffraction and microscopical examination. The alloys studied lay in the range 2.5 to 10 at % Cr, 12.5 to 20 at% Al, 2.5 to 6.25 at % W, The phases formed were, and the bcc solid solution based on tungsten (designated ₂). The maximum extent of the region was found to be 3 at % each of chromium and tungsten. Preferential partitioning of tungsten to occurred. Study of an Ni-10Cr-12.5Al-2.5W alloy aged at 1273 and 1073 K, after quenching from 1573 K, showed that changes in and compositions and lattice parameters occur as a function of ageing time.     

PbZrO3-CdTiO3 solid solutions

The structural, nonlinear optical, and dielectric properties of (1-x)PbZrO₃ ·xtCdTiO₃ solid solutions were studied. The phase relations in the composition rangesx = 0–0.3 and 0.85-1.0 were established. The results suggest that the ferrielectric ordering in CdTiO₃ persists up to 730 K.     

Multicolor up-conversion emissions of Tm3+/Er3+/Yb3+ tri-doped YF3 phosphors

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (approximately 291 nm and approximately 347 nm), a four-photon process (approximately 362 nm and approximately 452 nm), and a three-photon process (approximately 475 nm) were identified in the UC spectra. The UC emissions from the Er3+ were: approximately 380 nm, approximately 408 nm, approximately 521 nm, approximately 537 nm, and approximately 652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped system are currently being investigated.     

Phase equilibria in the system LaMnO3 + δ-SrMnO3-LaFeO3-SrFeO3 − d

We have revealed the formation of a continuous series of orthorhombic LaMn_{1 ? y} Fe_yO₃ solid solutions (0<y<1); La_{1 ? x} Sr_xFeO₃ solid solutions in the composition range 0 < x ≤ 0.8, with an orthorhombic structure at 0 < x ≤ 0.6 and a cubic structure at 0.6 < x ≤ 0.8; and a tetragonal SrMn_{1 ? y} Fe_yO₃ phase in the range 0.6 ≤ y ≤ 1. The composition stability limits of the perovskite phase La_{1 ? x} Sr_xMn_{1 ? y} Fe_yO₃ have been determined, and the 1100°C isotherm of the La₂O₃-SrO-Mn₃O₄-Fe₂O₃ system in air has been constructed.     

3 Cr3 Mo3 VNb 在热冲孔中的应用研究

高合金钢热冲孔冲头寿命关系到模具与产品成本、生产效率、自动化设备的使用,因此,应注重冲头的选材、材料制备与冲头制造工艺。 用 3 Cr3Mo3 VNb 作为高合金钢热冲孔冲头,为提高模具寿命,在材料制备上,优化了成分,采用电渣重熔冶炼,减少杂质,毛坯锻造两次,用大锻造比锻造,冲头热处理用真空炉,三次回火,热处理硬度取 HRC42 ~ 46 ,冲头表面处理采用镀铬工艺,开展了热冲孔工艺试验。 结果表明,用3 Cr3Mo3 VNb 可使冲孔冲头寿命平均达到 800 件以上。     

Sintering and piezoelectric properties of Pb(Ni1/3Sb2/3)O3-PbZrO3-PbTiO3 ceramics

The sintering and piezoelectric properties of Pb(Ni_1/3Sb_2/3)O₃-PbZrO₃-PbTiO₃ ceramics have been investigated. When the powders contain 48 mol% PbTiO₃ and less than 10 mol% Pb(Ni_1/3Sb_2/3)O₃ followed by calcination at 850°C for 2 h, the calcine only contains the perovskite structure; but if the Pb(Ni_1/3Sb_2/3)O₃ content is between 12 mol% and 14 mol%, both tetragonal and rhombohedral phases are obtained. The composition of the morphotropic phase boundary(MPB) in the Pb(Ni_1/3Sb_2/3)O₃-PbZrO₃-PbTiO₃ system is Pb(Ni_1/3Sb_2/3)O₃ = 12 mol%, PbZrO₃ = 40 mol% and PbTiO₃ = 48 mol%. As the composition at the MPB is sintered at 1260°C and 1280°C for 2 h, respectively, the maximum density (7.8 g/cm³) is obtained. The SEM micrographs indicate that a decrease in porosity with increasing sintering temperature is attained at 1280°C, which is due to a decrease in the number and size of pores. When the sintering temperature is higher than 1280°C, the porosity increases due to PbO evaporation leading to an increase of the number of pore sites and in enlargement of the pore diameter. When the compact composition at MPB is sintered at 1280°C for 2 h, the planar coupling coefficient (K _p) and mechanical quality coefficient (Q _m) tend to approach the maximum (0.488) and minimum values (292.5), respectively.