Na_3AlF_6-AlF_3-LiF-MgF_2-Al_2O_3-Nd_2O_3-CuO熔盐体系电导率的研究

采用TH2810DLCR数字电桥测试仪确定熔盐电阻,通过CVCC法研究Na3AlF6-AlF3-LiF-MgF2-Al2O3-Nd2O3-CuO熔盐体系电导率,并采用最小二乘法对数据进行拟合,确定了温度、熔盐组分与熔盐电导率之间的关系式。研究结果表明,当温度升高或CuO含量增大时,熔盐电导率增大;而当Nd2O3和Al2O3含量增大时,熔盐电导率则逐渐减小;当温度一定时,同时加入相同质量比的Nd2O3和CuO,熔盐体系的电导率随Nd2O3、CuO添加量的增大而增大。     

NaCl-KCl-NaF—SiO2熔盐体系表面张力的研究

采用拉筒法研究了温度及组分对KCl-NaCl-NaF-SiO2熔盐体系表面张力的影响。结果表明：熔盐体系的表面张力与温度具有良好的线性关系,在740～900℃范围内,随着温度的升高体系的表面张力降低;KCl逐步代替NaF时体系的表面张力先逐步减小达到最低值,之后随着KCl含量的增加又逐渐增大;用NaCl逐步代替NaF时,体系的表面张力先逐步减小达到最低值,之后随着NaCl含量的增加又逐渐增大;NaCl与KCl的摩尔比为1时,随着NaF含量的增加,体系的表面张力逐渐增大。     

NaCl-KCl-NaF-SiO2熔盐体系表面张力的研究

采用拉筒法研究了温度及组分对KCl-NaCl-NaF-SiO_2熔盐体系表面张力的影响。结果表明:熔盐体系的表面张力与温度具有良好的线性关系,在740～900℃范围内,随着温度的升高体系的表面张力降低;KCl逐步代替NaF时体系的表面张力先逐步减小达到最低值,之后随着KCl含量的增加又逐渐增大;用NaCl逐步代替NaF时,体系的表面张力先逐步减小达到最低值,之后随着NaCl含量的增加又逐渐增大;NaCl与KCl的摩尔比为1时,随着NaF含量的增加,体系的表面张力逐渐增大。     

Na_3AlF_6-AlF_3-LiF-MgF_2-Al_2O_3-Sm_2O_3熔盐体系表面张力的研究

采用拉筒法测定了在905~1055℃温度范围内Na_3AlF_6-AlF_3(12%)-LiF(5%)-MgF_2(5%)-Al_2O_3-Sm_2O_3熔盐体系的表面张力,研究了温度、Al_2O_3和Sm_2O_3添加量对熔盐表面张力的影响,并用最小二乘法建立了熔盐表面张力与温度、Al_2O_3与Sm_2O_3添加量之间的回归数学模型,确定了熔盐电解制备Al-Sm中间合金较为适宜的电解条件。研究结果表明:熔盐体系表面张力与温度有良好的线性关系,并随着温度的升高而下降;Al_2O_3添加量的递增对熔盐体系表面张力产生线性减小的影响,而Sm_2O_3添加量的递增却对熔盐表面张力产生线性增加的影响;当ω_(Al_2O_3)∶ω_(Sm_2O_3)=9∶1,7∶3或1∶1时,熔盐表面张力随混合氧化物添加量的增大而线性减小,当ω_(Al_2O_3)∶ω_(Sm_2O_3)=3∶7时,熔盐表面张力却随混合氧化物添加量的增大而线性增加;表面张力回归方程为σ=0.21813-0.00146ω_(Al_2O_3)+0.000553343ω_(Sm_2O_3)-0.0000774912 t。     

NdF_3-LiF-Nd_2O_3体系熔盐电导率的研究

采用交流阻抗谱技术测定熔盐电阻,并通过CVCC法研究了在1 020～1 120℃的温度范围内NdF3-LiF-Nd2O3熔盐体系的电导率,确定了温度、Nd2O3含量与熔盐电导率之间的关系,分析了温度和Nd2O3含量之间的相互作用以及对熔盐电导率的影响。研究结果表明,温度增加、Nd2O3含量减少,则电导率增大;在温度为1 080℃,Nd2O3含量为1.5%、2%、3.5%时,熔盐电导率变化幅度小,体系较为稳定。     

LiF-DyF_3-Cu_2O-Dy_2O_3熔盐体系密度的影响因素研究

在探索出制取Dy-Cu中间合金方法的基础上,为了进一步优化电解过程的工艺参数,采用阿基米德法对LiF-DyF_3-Dy_2O_3-Cu_2O熔盐体系的密度进行了研究。考察了温度、单一氧化物(Dy_2O_3或Cu_2O)以及混合氧化物(Dy_2O_3与Cu_2O)对熔盐体系密度的影响,并通过最小二乘法对数据进行了拟合,建立了温度、 Dy_2O_3含量、 Cu_2O含量与熔盐密度之间的数学回归方程。研究结果表明,熔盐体系的密度随温度的升高而线性下降,而随单一氧化物加入量、混合氧化物加入量及混合氧化中w_(Dy_2O_3)与w_(Cu_2O)的比值增大而增大。在温度为910～1030℃,w_(Dy_2O_3)为0%～2.0%(质量分数),w_(Cu_2O)为0%～2.0%范围内,温度(t), Dy_2O_3加入量w_(Dy_2O_3), Cu_2O加入量w_(Cu_2O)与熔盐密度(ρ)的关系可以表示为:ρ=-7.01813-0.00163t+0.01832 w_(Dy_2O_3)+0.10289w_(Cu_2O)。从熔体密度角度来看,在氧化物的加入量满足2.0%≤w_(Dy_2O_3)+w_(Cu_2O)≤3.0%,w_(Dy_2O_3)∶w_(Cu_2O)3∶2,电解温度控制在960～980℃的条件下,电解LiF-DyF_3-Dy_2O_3-Cu_2O熔盐制取Dy-Cu合金较为理想。     

LaCl3-KCl熔盐体系物化性质研究

合理选择熔盐体系在电解法制备稀土金属工业生产过程中至关重要。文中采用阿基米德法、拉筒法和连续变电导池常数法（CVCC）测定了不同配比的LaCl₃-KCl熔盐在1 073~1 223 K下的密度、界面张力和电导率。结果表明,随着温度升高,相同成分的LaCl₃-KCl熔盐的密度（ρ）和界面张力（σ）均呈降低趋势,而电导率（κ）逐渐增大;在相同温度下,随着LaCl₃含量增加,LaCl₃-KCl熔盐的密度和界面张力均逐渐增大,而电导率逐渐减小。通过拟合获得密度、界面张力以及电导率的经验公式分别为ρ=a-b×T×10-3、σ=a-b×T×10-3、κ=A+B×T×10-3+C×T2×10-6,明晰了熔盐的物化性质随温度及组分的变化规律,为熔盐电解法制备镧及其镧合金提供科学依据。      

Na2WO4-ZnO-WO3熔盐体系表面张力的研究

采用拉筒法测定了800～950℃范围内Na2WO4 ZnO WO3熔盐体系的表面张力。结果表明:该体系的表面张力与温度成线性关系,随着温度的升高而降低;在同一温度下,熔盐中的阴离子结构随着WO3摩尔含量的增加趋于复杂,表面张力降低,随ZnO摩尔含量的增加趋于简单,表面张力升高;组元ZnO对表面张力的影响比组元WO3大。     

包裹型ZrB_2-YAG-Al_2O_3复相陶瓷的制备及氧化性能研究

ZrB2具有许多优异性能,应用非常广泛。采用共沉淀法成功合成包裹型A1(OH)3-Y(OH)3/ZrB2复合粉体,再通过600℃煅烧得到了包裹型Al2O3-Y2O3/ZrB2复合粉体。包裹型Al2O3-Y2O3-ZrB2粉体在1 700℃、20MPa、4min的放电等离子烧结(SPS)条件下烧结致密化制备包裹型ZrB2-YAG-Al2 O3陶瓷。复相陶瓷的氧化增重随着氧化温度升高而增大,随着YAG-Al2O3含量增大而减小。     

NaCl-KCl-Na2WO4熔融体系的物理性质研究

针对NaCl-KCl-Na_2WO_4熔融体系,运用阿基米德法、旋转法与拉筒法相结合对熔盐体系的物理性质进行研究。结果表明:在1 173～1 233 K之间,熔融体系的密度随Na_2WO_4含量的增加先增大后减小。10%Na_2WO_4的熔融体系粘度值最小。0%～10%Na_2WO_4的熔融体系表面张力随温度的升高而减小,呈较好的线性关系。15%Na_2WO_4的熔融体系密度随温度的升高而增大,呈较好的线性关系。在0%～15%Na_2WO_4之间,熔融体系的粘度值在温度为1 188 K时最小。0%～10%Na_2WO_4的熔融体系表面张力与Na_2WO_4的含量无关。     

超细WO3粉体的制备及表征

通过胶溶法、溶胶 凝胶法、聚合 络合法合成了超细三氧化钨粉体。并对 3种制备方法的不同制备条件进行了探讨 ,实验发现不同制备条件对三氧化钨粉体粒径有较大影响 ,研究得出了每种方法的最佳制备条件。胶溶法中pH约为 4.60 ,静置 2 4h ,加入十六烷基三甲基溴化铵(CTAB)浓度为 0 .15mol·L- 1 ;溶胶 凝胶法中pH约为 2 .3 1,加入草酸和CTAB浓度分别为 0 .40和 0 .2 0mol·L- 1 ;而聚合 络合法中前驱体在 2 5 0℃干燥后 ,在 60 0℃煅烧接着再在 65 0℃煅烧。用激光粒度仪、比表面测定仪、XRD和TEM对产品进行了表征 ,结果表明所制三氧化钨为正交晶系 ,平均粒径在 5 0～ 2 0 0nm。团聚粒子大小不均 ,粒径范围较宽 ,颗粒为不规则形状。胶溶法制备的粒子的粒径较其他两种方法更小、更均匀。     

Growth and property enhancement of Er3+-doped 0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 single crystal

Er~(3+)-modified 0.68 Pb(Mg_(1/3)Nb_(2/3))O_3-0.32 PbTiO_3(PMN-32 PT) single crystals were grown by using the flux method. The growth mechanism of the crystal and influences of Er~(3+) ions on phase structure,electrical and optical properties were investigated. Results reveal that the crystals are still pure perovskite structure with Er3+ ions doping, but lattice enlarges slightly. The coercive electric field is increased from 4.83 to 6.37 kV/cm for [100]-oriented crystals comparing to undoped PMN-32 PT single crystals.Moreover, the crystal exhibits upconversion emission properties. Green(531 and 552 nm) and red(670 nm) emission bands are recorded under the excitation of 980 nm diode laser, which correspond to the ~2 H_(11/2)→~4 I_(15/2), ~4 S_(3/2)→~4 I_(15/2) and ~4 F_(9/2)→~4 I_(15/2) transitions of Er~(3+) ions. Our results show the feasibility of using this crystal in photoelectric multifunctional devices.     

Red Emitting Phosphor (Y,Gd)BO3:Eu3+ for PDP Prepared by Complex Method

Red phosphor (Y, Gd)BO3:Eu3+ with grain shape, small size, non-agglomerate, high crystallinity and good photoluminescence (PL) intensity was prepared by a complex method that the precursor of the phosphor was prepared by co-precipitation method and the phosphor was prepared by combustion method. The SEM photos and the photoluminescence spectrum excited under VUV show that the morphology and luminescent properties of this phosphor are satisfied when an appropriate amount of urea was adopted as the combustion agent in the preparation procedure.     

3D打印金属粉末的制备方法

3D打印技术是一种新型的打印技术,其突出优点在于无需机械加工或任何模具,就能直接从计算机图形数据中生成任何形状的零件,从而极大地缩短产品的研制周期,提高生产率和降低生产成本。3D打印金属粉末作为金属零件3D打印最重要的原材料,其制备方法备受人们关注。本文主要介绍了目前国内外3D打印金属粉末的制备工艺,气雾化技术的最新进展,并对3D打印金属粉末制备技术的现状进行分析,提出建设性意见。     

Promoting effect of tantalum and antimony additives on deNOx performance of Ce3Ta3SbOx for NH3-SCR reaction and DRIFT studies

A superior Ce-Ta-Sb composite oxide catalyst prepared using homogeneous precipitation method exhibited excellent deNOx efficiency and nearly 100% N_2 selectivity with broad operation temperature window and better resistance to higher space velocity, meanwhile strong resistance to H_2 O and SO_2. This catalyst was systematically characterized using XRD, N_2 adsorption, SEM, TEM, XPS, ESR, Raman, H_2-TPR,NH3-TPD and in situ DRIFTS. There exists a synergistic effect between Ce, Ta and Sb species. It is further indicated that the prominent deNOx performance of the Ce3 Ta3 SbOx catalyst is attributed to the elevated Ce3+ concentrations, abundant active surface oxygen species, as well as surface acidity and reducibility,which is closely linked with the synergistic effect between Ce, Sb and Ta species. Results from DRIFTS reveal that the reaction mechanism of surface-adsorbed NH3 and NO_x species is linked to temperature,the L-H mechanism mainly occurs at low temperature(300 ℃),while the E-R mechanism occurs at high temperature(300 ℃). Overall,these findings indicate that Ce3 Ta3 SbOx is promising for NO_x practical abatement.     

Crystal Growth and Characterization of Ca3NbGa3Si2O14 Single Crystal

Single crystals of Ca3NbGa3Si2O14 (CNGS) with ordered Ca3Ga2Ge4O14 (CGG) structure were successfully grown from stoichiometric melts by conventional Czochralski technique along the a-axis and two large (001) facets and two small (100) facets appear in every crystal. An arrangement of parallel steps and a clear height change were observed in (001) facet by atomic force microscopy (AFM). High-resolution X-ray diffraction (HRXRD) results indicate that CNGS crystals have good quality and free low-angle boundaries. The crystals also exhibit good optical quality and high optical transmittance in c-direction.     

Na3AlF6-K3AlF6-AlF3电解质体系铝溶解度的研究

采用质量差法研究了不通电时Na3AlF6-K3AlF6-AlF3体系中铝的溶解度。实验首先测定了不同时间内铝溶解的情况,并确定铝饱和溶解的时间为3 h。主要研究了初晶温度、过热度、电解质组成,以及电解质融化之后的熔盐深度对铝溶解度的影响。实验选用刚玉坩埚盛装电解质。测试结果表明,初晶温度为670～900℃的电解质,铝的溶解度为0.05%～0.50%(质量分数)。在初晶温度较低的电解质中,铝的溶解度较低,反之较高。对于某个特定体系来说,提高过热度会增加铝的溶解度。电解质的组成对铝溶解度的影响是:增大KR,可以降低铝的溶解度;AlF3含量增加,铝溶解度降低;对于KR=30,AlF3=26%(质量分数)的电解质,出现了异常的情况。另外,减少电解质的用量,降低熔盐的深度,也会造成铝的挥发损失,并最终导致铝的溶解增加。总之,影响铝溶解度的因素是多方面的,抑制铝的溶解损失,可以从改变电解质的组成、降低初晶温度、减少铝的挥发等方面着手。     

Optical and scintillation properties of Bi4Si3O12:RE (RE=Eu3+, Sm3+, Ho3+, Tb3+) single crystals

Bi_4 Si_3 O_(12):RE(BSO:RE, RE = Eu~(3+), Sm~(3+), Ho~(3+), Tb~(3+)) crystals were grown by the modified vertical Bridgeman method, and doping effects on scintillation properties were investigated. Under γ-ray irradiation, the light yield of BSO doped with small doses of Eu~(3+) increases slightly, and the energy resolution improves significantly compared to pure BSO, therefore the ability of distinguishing between particles will be improved for BSO crystals with a small amount of Eu~(3+) dopant. The results show that a small amount of Eu~(3+) doping can sensitize the Bi~(3+) ions. The sensitization effect enables the reduction of intrinsic defects, and thus improves the scintillation properties. However, the relative light yield of BSO:Tb(1.0 mol%) crystal is 4.3%, which is smaller than 5.0% of pure BSO. The improved light yield and energy resolution in the BSO:Eu and BSO:Sm crystals are considered an impressive achievement in the optimization of this scintillator which is already suitable for applications such as dual-readout calorimeters and homogeneous hadron calorimeters.     

SiO_2∶Eu~(3+)的制备与发光性能研究

以三氧化二铕和正硅酸乙酯为原材料,利用溶胶-凝胶法、高温机械力化学法合成了SiO_2∶Eu~(3+)粉体.用X射线衍射(XRD)、扫描电镜(SEM)表征了材料的结构和形貌,采用激发光谱、发射光谱对荧光粉体的发光性能进行了测量.结果说明:溶胶-凝胶法、高温机械力化学法合成样品的发光性能随着热处理温度的增加先增强后减弱,分别在900℃和600℃达到最好,粉体平均粒度分别为2μm与1μm.与溶胶-凝胶法比较,高温机械力化学法的制备温度降低了300℃.且利用高温机械力化学法制备的样品的发光性能要好于溶胶-凝胶法制备的样品.     

Synthesis and Characterization of Er3+∶Y3Al5O12 Nanocrystalline Powders Prepared by Sol-Gel Method

Nano-sized Er3 ∶Y3Al5O12 powders was successfully prepared via a simple sol-gel route at as low a temperature at 800 ℃ whereas a temperature much higher is necessary to obtain this compound by solid state synthesis (about 1500 ℃). The phase purity, composition and microstructural features of the materials were analyzed by means of X-ray diffraction(XRD), infrared spectroscopy(IR) and transmission electron microscopy(TEM), and no other intermediate phase were observed to form in the range of 700～1000 ℃. The luminescence spectra of Er3 substituted for Y3 in YAG in 1% content was characterized on samples at different temperature.