镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用

本文研究了镧石型碳酸镨钕[（PrNd）₂（CO₃）₃·8H₂O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图,证明所得样品为碱式碳酸镨钕[（PrNd）（OH）（CO₃）,BPN]。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明：LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。     

碳酸镨的结晶活性、外观形貌及结晶生长机制

采用原位pH值测定法确定了碳酸镨的结晶活性区域,并用扫描电镜观测了不同结晶区域结晶碳酸镨的外观形貌.结果表明在低配比区域(NH4HCO3/PrCl3的摩尔比小于3)为碳酸镨的易结晶区域,结晶产物为交叉层叠的花瓣形颗粒;在高配比区域(NH4HCO3/PrCl3的摩尔比大于3)为碳酸镨的可结晶区域,延长陈化时间可以得到鱼鳞片状的亮晶产物;所有结晶碳酸镨都具有镧石型结构,其基本构筑单元为片状结晶,这与镧石的层状结构相关.影响结晶的主要因素是加料比,其它因素象温度,加料方式和搅拌强度等对结晶过程也有影响.     

碳酸铈的相态转变及其对物性化学指标的调谐

为了获得同时具有高堆密度、低氯根和细颗粒特征的CeO_2,研究了在碱性热水溶液中镧石型碳酸铈向碱式碳酸铈相态转变的条件和特点。结果表明:在95℃下,随着溶液pH值的提高和反应时间的延长,相态转化越彻底,所得产物的颗粒大小和分布范围均减小,堆密度增大,氯根含量降低。当溶液pH在12～13时,经4 h的陈化可以得到纯的碱式碳酸铈。原始碳酸铈的颗粒度为22.3μm,氯根含量为1814 mg·kg~(-1),堆密度为0.55 kg·L~(-1),相态转化后的颗粒度下降到1～2μm,氯根含量降低到100 mg·kg~(-1)以下,堆密度上升到1 kg·L~(-1)以上。与此同时,碱的加入可以促进相态转化速度和程度,减少气泡产生。据此,确定了碱的加量。工业应用结果证明,采用该方法可以制备D_(50)为1～2μm,氯根含量小于100 mg·kg~(-1),堆密度介于1.1～1.2 kg·L~(-1)的CeO_2产品。     

熔盐电解法制备镨钕钆合金的研究

本工艺采用熔融氟化锂-氟化镨钕-氟化钆熔盐三元体系为电解质,通过电解氧化钆与氧化镨钕混合物的方法,制备了成分稳定的镨钕钆合金,同时就电解质组元、温度、阴极电流密度、加料速度对电解过程的影响进行了试验研究。结果表明:在试验条件下可以生产钆含量(10~15)%±0.5%(质量分数)的镨钕钆合金,金属直收率大于98%,电流效率大于78%;产品含碳小于0.05%,含铁小于0.3%,含Ca,W均小于0.01%,同时具有成本低、工艺稳定、产品质量好等优点。     

CL-P507萃取色层分离镨、钕的研究

报道了P507萃淋树脂分离镨钕的双峰现象及其原因,料液中加入(CH_2)_6N_4可有效地消除双峰现象,且镨钕分离的最佳温度为～40℃。     

三价镨钕与α-羟基羧酸配合物的理论模拟

在实验工作的基础上, 探索稀土配合物结构理论计算的可能性, 并利用分子模型（ＭＭ＋ ）、ＩＮＤＯ等理论方法计算了α羟基羟酸配体对三价镨钕离子的分离作用, 得到三价镨钕配合物分子的势能差与三价镨钕离子分离因数之间存在同步升降的变化趋势; 计算了配位键的特性以及配体的空间位阴效应; 指出了用分子模型来确定和设计对三价镨钕离子具有高分离因数配体结构的可能性。在实验工作的基础上, 探索稀土配合物结构理论计算的可能性, 并利用分子模型（ＭＭ＋ ）、ＩＮＤＯ等理论方法计算了α羟基羟酸配体对三价镨钕离子的分离作用, 得到三价镨钕配合物分子的势能差与三价镨钕离子分离因数之间存在同步升降的变化趋势; 计算了配位键的特性以及配体的空间位阴效应; 指出了用分子模型来确定和设计对三价镨钕离子具有高分离因数配体结构的可能性。     

电感耦合等离子体发射光谱法同时测定镨钕氧化物中氯和硫含量

建立了一种电感耦合等离子体发射光谱(ICP-OES)同时测定镨钕氧化物中氯(Cl)和硫(以SO₄^2-形式存在)含量的方法。读取真空紫外波段129～190 nm谱线信号，优化了测试参数。使用硝酸低温溶解样品，选择分析谱线为Cl(134.724 nm)和S(180.731 nm)，标准曲线法测定。在优化条件下，Cl和S在0～10 mg/L范围内线性相关系数均为0.9999, Cl回收率为93.1%～107.2%，相对标准偏差(RSD)为4.8%; S回收率为89.9%～94.9%, RSD为3.8%。该方法可以检测镨钕氧化物材料中含量大于0.014%的Cl和含量大于0.003%的S。     

镨钕掺杂对γ-Ce2S3红颜料性能的影响

以镨钕氧化物富集物和无水碳酸钠作为添加剂掺杂到氧化铈中制得的混合物为原料,在1000℃经硫化氢气体硫化合成了一种新颖的γ型五元稀土倍半硫化物γ-Na-Ce-Pr-Nd-S红色环保颜料.使用X射线粉末衍射、固体可见漫反射光谱、热重-差示扫描量热分析及扫描电镜表征等测试手段对产物进行了表征.与未掺杂镨钕的产品对比,发现适量掺杂镨钕可降低硫化产物的烧结程度、增加产品亮度及增强产品的热稳定性.     

离子色谱法测定一些金属材料中镧、铈、镨,钕

本文叙述了用离子色谱法测定稀土元素,选用0.002mol/l乙二胺—0.006mol/l柠檬酸为淋洗液,用本所改装的光度检测器,在无梯度淋洗装置条件下,不需预分离共存元素,可测定多种金属材料中镧、铈、镨和钕。     

惰气熔融-红外光谱法测定镨钕镝中的氧

研究了惰性气体-红外光谱法测定镨钕镝合金中的氧,采用石墨套坩埚和高纯镍篮,在4500W的分析功率下,对0.1g实际样品进行分析,取得了满意的效果。实验结果表明,样品释放完全,测定结果相对标准偏差(RSD,n=5)为1.9%,以GSBH40104—1996标准样品(ω(O)/%=0.00943)进行加标回收实验,回收率测量结果为95%～108%。     

La2(CO3)3纳米线的微乳液法制备与表征

La₂(CO₃)₃ nanowires were prepared in the nonionic surfactant microemulsion(Triton X-100/cyclohexane/water)system. Transmission electron microscopy (TEM) and selected area electronic diffraction (SAED) were used to characterize the shape and size of the products. The results showed that the pH value and concentration of mother solution, temperature and aging time all could affect the morphology and size of the La₂(CO₃)₃ nanowires. The lengths of the nanowires were more than 10 μm and the diameters were in the range of 30～200 nm.     

Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。     

Fe(0)(CO)3(Ph2Ppy)2Mn+Cln中金属-金属成键的光谱研究

本文研究了七个以反式二（二苯基膦吡啶）－三羰基铁为三齿配体的过渡金属双核配合物，将Ｊｏｒｇｅｎｓｅｎ建议的处理电荷转移光谱的方法推广处理ＭＭＣＴ跃迁，通过光学电负性的计算取得金属－金属成键的证据。由Ｒａｍａｎ光谱羰基伸缩振动频率的蓝移进一步支持这类化合物中存在金属－金属成键相互作用的推断。     

Synthesis, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

Phenoxide-assisted P-C bond cleavage in PdCl2(PPh3)2 under very mild conditions

PdCl₂(PPh₃)₂ reacted with NaOAr (Ar = Ph, p-tolyl) at 0 °C to afford PdCl(Ph)(PPh₃)₂, instead of PdCl(OAr)(PPh₃)₂, in 12-16% isolated yields based on Pd. The structure was confirmed by NMR and X-ray crystallography. GC-MS analysis of the reaction solution revealed that OPPh₂(OAr), OPPh(OAr)₂, and OP(OAr)₃ are formed, while NMR studies indicated that PdCl(Ph)(PPh₃)₂ is produced when PdCl(OAr)(PPh₃)₂ decomposes. The reaction of PdCl₂(PPh₃)₂ with Bu₃Sn(OC₆H₄-p-OMe) also gave PdCl(Ph)(PPh₃)₂ in 8% isolated yield. These results suggest that PdCl(OAr)(PPh₃)₂ is highly labile and the aryloxy ligand exchanges with the phenyl groups in triphenylphosphine even under very mild conditions.     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

Syntheses and characterization of two oxoborates, (Pb3O)2(BO3)2MO4 (M=Cr, Mo)

Two oxoborates, (Pb₃O)₂(BO₃)₂MO₄ (M=Cr, Mo), have been prepared by solid-state reactions below 700 °C. Single-crystal XRD analyses showed that the Cr compound crystallizes in the orthorhombic group Pnma with a=6.4160(13) Å, b=11.635(2) Å, c=18.164(4) Å, Z=4 and the Mo analog in the group Cmcm with a=18.446(4) Å, b=6.3557(13) Å, c=11.657(2) Å, Z=4. Both compounds are characterized by one-dimensional chains formed by corner-sharing OPb₄ tetrahedra. BO₃ and CrO₄ (MoO₄) groups are located around the chains to hold them together via Pb–O bonds. The IR spectra further confirmed the presence of BO₃ groups in both structures and UV–vis diffuse reflectance spectra showed band gaps of about 1.8 and 2.9 eV for the Cr and Mo compounds, respectively. Band structure calculations indicated that (Pb₃O)₂(BO₃)₂MoO₄ is a direct semiconductor with the calculated energy gap of about 2.4 eV.     

Spectroscopic properties of guanidinium zinc sulphate [C(NH2)3]2Zn(SO4)2 and ab initio calculations of [C(NH2)3]2 and HC(NH2)3

Raman and FTIR spectra of guanidinium zinc sulphate [C(NH₂)₃]₂Zn(SO₄)₂ are recorded and the spectral bands assignment is carried out in terms of the fundamental modes of vibration of the guanidinium cations and sulphate anions. The analysis of the spectrum reveals distorted SO₄²⁻ tetrahedra with distinct S–O bonds. The distortion of the sulphate tetrahedra is attributed to Zn–O–S–O–Zn bridging in the structure as well as hydrogen bonding. The CN₃ group is planar which is expressed in the twofold symmetry along the C–N (1) vector. Spectral studies also reveal the presence of hydrogen bonds in the sample. The vibrational frequencies of [C(NH₂)₃]₂ and HC(NH₂)₃ are computed using Gaussian 03 with HF/6-31G* as basis set.     

CuO/Cu2(OH)2CO3梭型中空颗粒的制备及其气敏性能

以Cu₂(OH)₃NO₃为前驱体,采用无模板溶剂热法成功合成了大小为1~2μm的CuO/Cu₂(OH)₂CO₃中空梭型微粒。高倍电镜显示其外壳层由高度弥散的CuO和Cu₂(OH)₂CO₃纳米颗粒组成。通过控制反应时间证明了该中空梭型粒子的形成过程是由自组装和奥斯特瓦尔德熟化过程控制。该纳米材料的特殊结构使其对乙醇、丙酮等有机气体有良好的气敏性能。