Up-conversion luminescence of Er~（3＋）-doped and Yb~（3＋）/Er~（3＋） co-doped 12CaO·7Al_2O_3 poly-crystals

The optical properties of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the intensity ratio of red to green up-conversion emission had an increase in Yb3+ (1.0 mol.%, 2.0 mol.%, 10. 0 mol.%)/Er3+ (fixed at 1.0 mol.%). This detailed study of the up-conversion processes allowed us to identify the dominant up-conversion mechanisms in Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals.     

微波场中ChCl/CrCl_3·6H_2O离子液体的吸波特性研究

研究了不同温度(298K,313K,333K,353K,和373K)下Ch Cl/Cr Cl3·6H2O离子液体微波波谱图,结果显示333K以下介电常数(εˊ)和介电损耗(ε〞)均随温度的增加而增加。这是由于不同离子赋存形态的极化现象影响了介电损耗。介电品质因数随着Cr Cl3·6H2O摩尔分数的增加而减小,这是由于电导率的增加而造成的。     

La2O2CO3 supported Ni-Fe catalysts for hydrogen production from steam reforming of ethanol

La2O2CO3 was prepared by calcination of La2 (CO3)3 in the air. Catalysts Ni-Fe/La2O2CO3 with different mole ratios of Ni to Fe, Ni/La2O2CO3 and Fe/La2O2CO3 were prepared by impregnation method. The catalytic properties were evaluated on steam reforming of ethanol (SRE) from 300 to 700 ℃ under atmospheric pressure and the samples were characterized by Brunauer-Emmett-Teller method (BET), X-ray diffraction (XRD) and temperature programmed reduction (TPR). The results showed that Ni-Fe bimetallic catalysts exh...     

基于正交实验设计方法的APS喷涂Al_2O_3涂层性能的研究

采用正交实验方法研究了大气等离子喷涂工艺参数主气流量、喷涂功率和送粉量对Al2O3陶瓷涂层结合强度和显微硬度的影响,通过X射线衍射仪和扫描电子显微镜研究了粉末和涂层的组织结构,采用WDW-50微机控制电子万能试验机、HV-1000维氏硬度计测量了涂层的结合强度、截面硬度,结合涂层组织结构并应用极差和方差分析方法对实验结果进行了分析,得到了优化后的工艺参数。结果表明,涂层由熔融和未熔融区域混合而成,截面形貌凹凸咬合,以机械结合为主。影响大气等离子喷涂Al2O3涂层性能工艺参数的主次顺序依次为:喷涂功率、主气流量、送粉量,随着功率和主气流量的升高,涂层的结合强度和硬度均出现先增加后降低的趋势。大气等离子喷涂Al_2O_3最优工艺参数为喷涂功率44KW,主气流量40L/min,送粉量40g/min,制备的涂层结合强度52MPa,显微硬度1219.4HV0.3,孔隙率值为4.00%。     

Vacuum ultraviolet excited photoluminescence properties of Gd2O2CO3：Eu^3＋ phosphor

The Gd2O2CO3：Eu^3＋ with type-Ⅱ structure phosphor was successfully synthesized via flux method at 400 ℃ and their photoluminescence properties in vacuum ultraviolet （VUV） region were examined. The broad and strong excitation bands in the range of 153-205 nm owing to the CO3^2- host absorption and charge transfer （CT） of Gd^3＋-O2^- were observed for Gd2O2CO3：Eu^3＋. Under 172 nm excitation, Gd2O2CO3：Eu^3＋ exhibited strong red emission with good color purity, indicating Eu^3＋ ions located at low symmetry sites and the chromaticity coordination of luminescence for Gd2O2CO3：Eu^3＋ was （x=0.652, y=0.345）. The photoluminescence quenching concentration of Eu^3＋ excited by 172 nm for Gd2O2CO3：Eu^3＋ was about 5%. Gd2O2CO3：Eu^3＋ would be a potential VUV-excited red phosphor applied in mercury-free fluorescent lamps.     

Study on Sulfation of CeO2/γ-Al2O3 Sorbent in Simulated Flue Gas

It is well known that sulfur dioxide(SO2) , morethan50%of which arise fromcombustion of fossil fu-els ,are precursors of acidrain andtheir emission pos-es a global threat tothe atmosphere .Environmental a-gencies have ,therefore ,regulated emissions of SO…     

不同喷涂工艺对Cr~(3+)掺杂Al_2O_3陶瓷涂层相结构及发光性能影响研究

通过火焰喷涂工艺和等离子喷涂工艺制备了Cr~(3+)掺杂Al_2O_3陶瓷涂层。采用扫描电镜、X射线衍射、荧光光谱仪等方法表征了涂层的微观形貌、孔隙率、相结构及发光性能等。对比两种不同工艺制备的Cr~(3+)掺杂Al_2O_3陶瓷涂层性能结果表明:等离子喷涂制备的涂层形貌、颗粒熔化状态、厚度均一性均优于火焰喷涂涂层,但火焰喷涂工艺涂层的发光性能远优于等离子工艺涂层,其原因是火焰喷涂制备的涂层中Al_2O_3粒子的熔融状态更差,保留了更多的α-Al_2O_3相,未熔粒子部分将以喷涂原粉中稳定的α-Al_2O_3结构存在涂层中进而影响其光学性能。     

Partial oxidation of methane on Ni/CeO2-ZrO2/γ-Al2O3 prepared using different processes

The influences of CeO2-ZrO2 and γ-Al2O3 mixing methods on the catalytic activity and stability of partial oxidation of methane （POM） were investigated over Ni/Ce0.7Zr0.3O2-Al2O3 catalysts. The catalysts were characterized by XRD, TPR, H2-chemsorption, and TG-DTA. For fresh catalysts, the results showed that the salt precursor mixing catalyst （ATOM） presented better performance than the catalysts prepared by the precipitator mixing method （MOL） and the powder mechanically mixing method （MECH）. The result of XRD suggested that the interaction between CeO2-ZrO2 and Al2O3 in ATOM sample was stronger than the others, which led to more lattice defects and thereby better initial activity. Moreover, the MECH sample had the best stability and the least coke deposition in 24 h stability tests. The results of TPR and H2-chemsorption indicated that the intimate contact of Ni-Al in MECH sample enhanced the ability of resisting coke deposition and metal sintering.     

Luminescent properties of β-Lu2Si2O7:RE(RE=Ce, Tb) nanoparticles by sol-gel method

Nanoscale RE³⁺ (RE=Ce, Tb) doped and codoped lutetium pyrosilicate Lu₂Si₂O₇ (LPS) phosphors were prepared by using the sol-gel method. Heat treatment was performed in the temperature range from 900 to 1100 °C. The crystal structure was analyzed by X-ray diffraction (XRD). The results showed that the β-type structure of LPS was obtained at 1100 °C. The excitation spectra in the UV and VUV ranges and the emission spectra of the samples were measured at room temperature, and their luminescent properties were studied. The energy transfer from Ce³⁺ to Tb³⁺ in the codoped samples were observed and discussed.     

Leaching of a sphalerite concentrate with H2SO4–HNO3 solutions in the presence of C2Cl4

The enhanced leaching of sphalerite concentrates in H₂SO₄–HNO₃ solutions and the extraction of sulfur with tetrachloroethylene were studied. Variables of the process were investigated including leaching temperature, reaction time, liquid / solid ratio, and tetrachloroethylene concentration. The number of cycles that tetrachloroethylene could be recycled did not have a significant effect on zinc extraction. The results indicated that 99.6% zinc extraction was obtained after three hours of leaching at 85 °C and 0.1 MPa O₂, when 20 g of sphalerite concentrate were leached in a 200 ml solution containing 2.0 mol/L H₂SO₄ and 0.2 mol/L HNO₃, in the presence of 10 ml C₂Cl₄. Leaching rates were significantly improved under these conditions.     

Oxygen adsorption/desorption behavior of YBaCo4O7+δ and its application to oxygen removal from nitrogen

A new medium-temperature (200-400℃) adsorbent material for oxygen removal and air separation, YBaCo4O7+β, was prepared by the solid-state reaction method. This new adsorbent could adsorb a large quantity of oxygen in the temperature range of 200-370 ℃. Ad-sorbed oxygen could be released by raising temperature over 400 ℃ or by switching the atmosphere from oxygen to nitrogen. This oxygen adsorption and desorption process had good reproducibility. Taking advantage of this unique oxygen intake/release behavior, a nitrogen puri-fication process was investigated. The results showed that YBaCo4O7+δ material was a promising candidate for the oxygen sorption process and could be used to produce high-purity nitrogen or to remove trace oxygen from other gases.     

Phase control of magnetron sputtering deposited Gd2O3 thin films as high-κ gate dielectrics

Gd2O3 thin films as high-κ gate dielectrics were deposited directly on Si（001） substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the films grown from 450 to 570 ℃ were crystalline, and the Gd2O3 thin films consisted of a mixture of cubic and monoclinic phases. The growth temperature was a critical parameter for the phase constituents and their relative amount. Low temperature was favorable for the formation of cubic phase while higher temperature gave rise to more monoclinic phase. All the Gd2O3 thin films grown from different temperatures exhibited acceptable electrical properties, such as low leakage current density （JL） of 10-5 A/cm^2 at zero bias with capacitance equivalent SiO2 thickness in the range of 6-13 nm. Through the comparison between films grown at 450 and 570 ℃, the existence of monoclinic phase caused an increase in JL by nearly one order of magnitude and a reduction of effective dielectric constant from 17 to 9.     

Low-field magnetic entropy changes in （Gd1-xYx）3Al2 alloys

The effects of Y substitution on the magnetic properties and magnetocaloric effect of(Gd1-xYx)3Al2(x=0-0.3) alloys were investigated by X-ray diffraction and magnetization measurements.All samples crystallized in single phase with Zr3Al2-type tetragonal structure.The lattice parameters and magnetic transition temperature decreased obviously with increasing Y content.The magnetic entropy change and refrigerant capacity of these alloys were calculated.The adjustable transition temperature and favorable proper...