STUDY OF INTERFACES AND SURFACES OF YBa_2Cu_3O_(7-x)-Ag

Interfaces and surfaces of YBa_2Cu_3O_(7-x)(YBCO)-Ag have been studied by SEM-EDXand AES.No effect of Ag on 123 structure in X-ray diffraction pattern was observedfor 0.4 mol Ag doped YBCO.AES analysis indicated that Ag segregated on surfaceof YBCO and resulted in decrease of YBCO-metal lead resistance.In addition,solutionand segregation of Ag as elemental state were often appeared on interfaces and surfacesof high temperature annealed YBCO,whether elemental Ag or compound Ag_2O andAgNO_3 adopted as doping material.     

快速凝固粉末冶金Mg_(80)Cu_(10)Y_(10)合金的组织与力学性能

采用快速凝固粉末冶金技术制备热挤压Mg_(80)Cu_(10)Y_(10)合金棒材,研究了快速凝固Mg_(80)Cu_(10)Y_(10)合金薄带及热挤压后合金的相结构,并对热处理工艺对合金棒材组织结构及力学性能的影响进行了分析.研究表明,采用单辊快速凝固法在辊速为1800 r/min下制备的Mg_(80)Cu_(10)Y_(10)合金薄带为完全非晶态;在热挤压过程中Mg_(80)Cu_(10)Y_(10)合金中有Mg_2Cu和Mg晶体相析出,其显微硬度比薄带有所提高,这与合金中细小Mg_2Cu颗粒的弥散析出有关;在450 ℃保温4 h后的热挤压Mg_(80)Cu_(10)Y_(10)合金中没有新相析出;随着热处理温度的升高或保温时间的延长,由于Mg_2Cu颗粒出现重溶及聚集长大现象,使得热挤压Mg_(80)Cu_(10)Y_(10)合金的显微硬度表现出逐渐下降的变化趋势.     

微量钇合金化及Y_2O_3－Al_2O_3复合涂层对M38合金高温氧化的影响

研究了镍基铸造高温合金Ｍ３８及其含微量Ｙ的合金在１０００℃空气中的高温氧化行为，以及表面施加（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３）复合氧化物薄膜对上述的种合金氧化行为的影响．发现Ｍ３８，Ｍ３８＋（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３），Ｍ３８＋Ｙ＋（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３）的氧化动力学基本呈抛物线规律，而Ｍ３８＋Ｙ开始增重较快，而后趋于平缓，偏离抛物线规律．２００ｈ的氧化增重顺序为：Ｍ３８＞Ｍ３８＋（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３）＞Ｍ３８＋Ｙ＋（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３）＞Ｍ３８＋Ｙ．钇合金化及表面沉积（Ｙ_２Ｏ_３－Ａｌ_２Ｏ_３）复合氧化物薄膜显著地改变了Ｍ３８合金氧化物的表面形貌和组成，细化了氧化物晶粒，不同程度地促进了Ｃｒ和Ａｌ的选择氧化．     

涂层导体用金属基带研究进展

目前,低成本、高性能的YBa2Cu3O7-x涂层导体制备技术已成为国际实用化高温超导材料的研究重点.由于金属基带的特性(织构、表面粗糙度等)直接决定了阻隔层的特性,进而影响到YBCO层的超导性能.因此,制备高质量的金属基带是涂层导体制备技术的关键核心技术之一.本研究对金属基带的性能、选材、制备技术以及国内外的研究状况给予了较系统的总结和评述,并对其发展和应用前景进行了一些探讨.     

Thermodynamics of solubility of Cu_2(OH)_2CO_3 in ammonia-ammonium chloride-ethylenediamine(En)-water system

In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores.The thermodynamic model was constructed and the solubility of malachite Cu2(OH)2CO3 in the ammonia-ammonium chloride-ethylenediamine(En)-water system was calculated using the exponential computation method based on both mass balance and charge balance.It is found that the solubility of copper c...     

DEPENDENCE OF SINTERABILITY ON STATE OF AGGLOMERATION OF ULTRAFINE ZrO_2，（Y_2O_3） POWDERS

ＤＥＲＳＤＥＰＥＮＤＥＮＣＥＯＦＳＩＮＴＥＲＡＢＩＬＩＴＹＯＮＳＴＡＴＥＯＦＡＧＧＬＯＭＥＲＡＴＩＯＮＯＦＵＬＴＲＡＦＩＮＥＺｒＯ_２，（Ｙ_２Ｏ_３）ＰＯＷＤＥＲＳ￥Ｇｅ，Ｒｏｎｇｄｅ；Ｌｉｕ，Ｚｈｉｈｏｎｇ；Ｃｈｅｎ，Ｈｕｉｇｕａｎｇ；Ｚｈａｎｇ，...     

Nd_2（Fe，Co）_（14）B／Nd_2（Fe，Co）_（17）双相HDDR

研究了由Ｎｄ_２（Ｆｅ，Ｃｏ）_（１４）Ｂ和Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）双相组成的ＨＤＤＲ高矫顽力磁粉的微观结构及磁性。发现在单相Ｎｄ_２（Ｆｅ，Ｃｏ）_（１４）Ｂ化合物的基础上降低Ｂ含量，导致Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）相出现，且随Ｂ含量降低该相逐渐增多．适量的Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）相的存在对用性有一定有益的作用，过量则导致磁性严重恶化，这可能与该相的尺寸和存在形式密切相关．     

退火温度对Fe72.5Cu1Nb2V2Si13.5B9软磁合金微结构的影响

用Ｘ射线射,透射电子显微镜,数字图像分析等实验技术,系统研究了快淬制制备的Ｆｅ７２．５Ｃｕ１Ｎｂ２Ｖ２Ｓｉ１３．５Ｂ９非晶条带经５００－７５０℃０．５ｈ退火后合金的相组成,晶格参数和晶粒尺寸随温度的变化规律。结果表明,在５３０－５４５℃,退火０．５ｈ,电子数字定量金相测量得到的α－Ｆｅ纳米固溶相平均晶粒尺寸为１３．７－１４．９ｎｍ,当退火温度高于５６０℃时,晶粒体大速度显著磁特性。 时,α－Ｆｅ（     

In2O3：Sn（ITO）薄膜的光学特性研究

对掺三氧化铟（Ｓｎ－ｄｏｐｅｄ Ｉｎ２Ｏ３简称ＩＴＯ）薄膜光学特性进行了研究。结果表明,该薄膜在可见光区具有高的透射率;低电阻率的ＩＴＯ薄膜在红外区的反射率随薄膜广场电阻的减小而增大,表现在金属性质,ＩＴＯ薄膜的电磁本构特性参数光学折射率ｎ和消光系数Ｋ在４５０－８００ｎｍ区间的色散很弱,基于对薄膜光学吸收及收系线性拟事表明,薄膜在Ｋ＝０处价速写对导带的跃迁是禁戒跃迁。     

固相反应合成Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)磷酸盐粉体

以SrCO_3、SiO_2、ZrO_2和(NH_4)H_2PO_4为实验原料,采用固相反应法制备出磷酸盐Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体.XRD和SEM分析表明:在1100 ℃,4 h温度下煅烧能够合成单相Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体,1100 ℃,4 h条件下制备的Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体成球状,平均粒径在300～500 nm之间.在1100 ℃煅烧温度下适当延长保温时间,有利于Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)单相粉体的形成.     

LiOH-Li_2CO_3低共熔混合锂盐体系合成LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

利用低共熔组成的0.24LiCO3-0.76LiOH混合锂盐体系,与钴、镍、锰的球形氢氧化物按1.1:1混合,无需前期球磨,直接经二段控温程序制备出锂离子正极材料LiNi1/3Co1/3Mn1/3O2。X射线衍射分析表明合成的Li(Ni1/3Co1/3Mn1/3)O2结晶度高,具有规整的层状α-NaFeO2结构,扫描电镜显示产物颗粒均匀,振实密度高达2.89g·cm-3,显著高于用单一锂盐制备的同样产品(2.4g·cm-3)。充放电测试表明,材料具有良好的电性能,首次充放电容量为176和166mhA·g-1,循环50次后,材料的电性能没有明显的衰减。     

（Al2O3）p和SiCp多元增强铝基复合材料

利用Ａｌ２（ＳＯ４）３ 分解反应所制备的多元增强铝基复合材料,其中Ａｌ２Ｏ３ 和ＳｉＣ 颗粒和基体结合良好,分解的ＳＯ３ 对ＳｉＣｐ／ Ａｌ 复合材料熔体进行精炼、除气,试样中没有发现气孔、团聚、集聚、偏析,克服了传统搅拌铸造所带来的铸造缺陷,解决了回收利用重熔过程中的吸气、精炼问题;从而为颗粒增强铝基复合材料走向实用化打下了基础。     

原位合成(Al_2O_3+Al_3Ti)_P/Al复合材料的制备研究

通过对Al-TiO_2-SiO_2体系混合粉末固-液原位合成制备出了(Al_2O_3+Al_3Ti)_P/Al复合材料.利用X射线衍射仪、扫描电镜等方法观察分析了其物相和显微组织形貌.结果表明:原位反应制备的(Al_2O_3+Al_3Ti)_P/Al复合材料,金属间化合物增强相Al_3Ti均匀分布于基体,陶瓷相Al_2O_3颗粒非常细小,弥散分布于基体中,使材料的硬度等性能得到提高.     

表面活性修饰沉淀法制备纳米铌钪酸铅

采用一种表面活性修饰沉淀法,成功地在700℃的低温下合成钙钛矿相Pb(Sc1/2Nb1/2)O3(PSN)纳米粉体。通过X射线衍射、扫描电镜、透射电镜等现代测试手段对纳米粉体进行表征。结果表明,PSN纳米粉体的晶粒尺寸在80nm左右。分析认为,纳米粉体的获得是由其前驱体的高分散性决定的,其原因在于四甲基氢氧化铵(TMAH)和十六烷基三甲基溴化铵(CTAB)的复合作用。对纳米PSN粉体的形成机制进行了详细讨论。本实验提出的表面修饰沉淀法为合成含铌钙钛矿多元化合物提供了一种新的低成本路径。     

A new sol-gel process for preparing Ba(Mg_(1/3)Nb_(2/3))O_3 nanopowders

Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2-4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders. At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na ions. The as-prepared colloidal Nb2O5-nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃for 1 h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.     

超重力对燃烧合成Al_2O_3/ZrO_2(4Y)的影响

基于超重力下燃烧合成Al_2O_3/ZrO_2(4Y),通过调整超重力大小,研究超重力对复合陶瓷凝固组织与性能的影响.结果表明:随着超重力增加,陶瓷共晶团从胞状结构转化为棒状结构,且棒状共晶团得以细化,其体积分数与长径比增加.性能显示:随着超重力增加,陶瓷相对密度显著提高,陶瓷硬度与弯曲强度因棒状共晶团细化、内部缺陷尺寸减小而得以增大,同时因棒状共晶团细化及分布于共晶团边界上ZrO_2四方相细化、球化,陶瓷断裂韧性也随之升高.     

ZrO_2对超重力下燃烧合成Al_2O_3/ZrO_2(4Y)的影响

基于超重力下燃烧合成Al_2O_3/ZrO_2(4Y),通过改变ZrO_2(4Y)含量,研究材料成分、结构与性能之间的关系.结果表明:当ZrO_2(4Y)体积分数低于37%,复合陶瓷是以ZrO_2四方相纳微米纤维镶嵌其上且取向各异的棒状共晶团为基体;当ZrO_2(4Y)体积分数高于40%,则获得ZrO_2四方相微米类球晶为基的复合陶瓷.力学性能显示,Al_2O_3/33%ZrO_2(4Y)以低的凝固温度,达到了最高的相对密度与硬度值,且也因低的缺陷尺寸及裂纹偏转与桥接增韧所带来的高断裂韧性,具有最高的弯曲强度值.     

Cu在熔融（Li,K）2CO3中的热腐蚀行为研究

采用电化学阻抗谱技术研究了Ｃｕ在６５０℃熔融（Ｌｉ,Ｋ）２ＣＯ２中的腐蚀行为,在腐蚀初期,Ｃｕ的腐蚀的电化学阻抗谱呈典型的腐蚀反应受氧化剂粒子扩散控制的特征,随着腐蚀的进行,在Ｃｕ的表在逐渐形成了Ｃｕ２Ｏ膜,但同时,生成的Ｃｕ２Ｏ也发生溶解,使Ｃｕ局部遭受较快腐蚀,其电化学阻抗谱呈双抗弧特征,提出了相应的等效电路,并求取了相关电化学参数。     

Structure and transport properties of （La1-x-yYy）2/3Cal/3MnO3 with La-site vacancies

Several samples of manganese oxides La（1-x）2/3Cal/3MnO3 （V-LCMO） and （La0.7-xY0.3）2/3Cal/3MnO3 （x〈0.15） （V-LYCMO） with vacancies at La-site （La-vacancy） were prepared by solid-state reaction method. The X-ray diffraction（XRD） patterns refined by Rietveld confirm that these compounds exhibit single phase structure with orthorhombic symmetry （Pnma）. The lattice parameters, Mn-O bond length and Mn—O—Mn bond angle vary with La-vacancy concentration, as an indication of the occurrence of the local Jahn-Teller effect. The measurement result of V-LCMO compounds shows that the maximum magnetoresistance（MR） is about 220% at TIM=268 K and La-vacancy content x=0.04. For V-LYCMO compounds, there exists metal-insulator transition at about 50 K, and a very large MR （over 106%） is observed at the temperature ranging from 40 K to 50 K.     

Comparative magnetic studies of (Sm, Nd) trichloroacetates and their heteronuclear CuLn2(CCl3COO)8·6H2O systems: structure and spectroscopy of a new type of Eu trichloroacetate

Two series of compounds: heteronuclear CuLn₂(CCl₃COO)₈·6H₂O (Ln = Nd and Sm) and their simple analogues Ln(CCl₃COO)₃·2H₂O (Ln = Eu, Nd, Sm) were synthesized. New Eu(III) trichloroacetate; Eu(CCl₃COO)₃·3H₂O·CH₃OH was obtained, its molecular structure was determined by X-ray diffraction and compared with the data of respective systems reported earlier. Magnetization was measured and the susceptibility was derived in the limit of low field. Magnetic susceptibilities were calculated and discussed for series of homo- and hetero-nuclear chloroacetates.

Untypical hysteresis was found (two loops) in samarium trichloroacetate. This phenomenon is most probably the effect of flops of spins in magnetic fields of 30,000 Oe and very weak (if any) interaction intermediated by weak hydrogen bonding between the chains. A similar magnetic behavior was observed in neodymium carboxylate where the magnetic ordering was observed as a result of Nd–Nd interaction at low temperature (1.6 K). For this system, the magnetic moment depends on magnitude of the magnetic field and ferromagnetic ordering appears at low temperatures. The strongest interactions of coupled ions and antiferromagnetic ordering with T_N=6.5 K were found in CuSm₂(CCl₃COO)₈·6H₂O single crystals.

Heisenberg model was applied in the calculations for three interacting ions located linearly. The following relation was derived:

and applied in calculations of the exchange integrals. Mechanism of the exchange interaction was discussed on the basis of the obtained results.