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

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衍射图证明了LPN向碱式碳酸镨钕[(PrNd)(OH)(CO3),BPN]的相态转变。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。     

结晶碳酸钕的水热合成、外观形貌及其组成

Crystalline neodymium carbonates were prepared by treating the amorphous precipitate formed from the reaction between neodymium chloride and ammonium bicarbonate under hydrothermal condition. Their composition, morphology and crystal phase were identified by means of elemental analysis, SEM and XRD. It was found that Nd₂(CO₃)₃·2.5H₂O with tengerite-type structure and sheet morphology was obtained when the feed molar ratio(FMR=n_(NH4)2CO2/n_NdCl3)was 2 or 1.8 and hydrothermally treated at 150 ℃ for 12h. However, orthogonal NdOHCO₃ particles agglomerated with long rod crystals were formed when lowering FMR to 1.5 under the same hydrothermal condition. Phase transformation from tengerite-type Nd₂(CO₃)₃·2.5H₂O to orthogonal NdOHCO₃ was occurred when increasing hydrothermal temperature or prolonging hydrothermal time, which is beneficial to the preparation of neodymium hydroxyl-carbonate with neodymium oxide content higher than 70%.     

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.     

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。     

镧石型碳酸钕的形成及晶种对结晶的促进作用

The characteristics of pH value variation during aging process of amorphous neodymium carbonate formed by three different feeding manners have been investigated. The promotion action of seeding on the crystallization of neodymium carbonate is discussed. X-ray diffraction pattern and the elemental analysis results show that neodymium carbonate can transfer from amorphous to crystalline normal neodymium carbonate Nd₂(CO₃)₃·8H₂O with lanthanide structure at room temperature. Its crystallization activity zone lies in lower feeding ratio area expressed by n_NH4HCO3/n_NdCl3 between 2～3. The existing of seeds can shorten crystalline time, from more than 15 h without seed to 2 h with seeds under normal feeding manner. And the spontaneity nucleation time can be shortened further when feeding with multi-steps normal manner. However, whether multi-steps normal or synchronously and continuously feeding manner, the precipitate formed can transfer to crystalline neodymium carbonate directly under seeding. At the same time, it is observed that the variation of pH value reduces with the decrease of feeding amount and the shortening of aging period, indicating that with synchronously and continuously feeding manner can not only realize fast crystallization, but also control pH value within a narrow range, which is beneficial for the producing of neodymium carbonate crystal with narrow-distributed particle size and monitoring of its crystallization process.     

以草酸、碳酸根构筑的一个钕(Ⅲ)配位聚合物的晶体结构和荧光性质

水热条件下采用Nd₂(CO3)3和草酸钠作为反应物合成出一个新的三维钕(Ⅲ)配位聚合物{[Nd₂(ox)(cb)₂(H₂O)₂]·3H₂O}_n (1)(ox=草酸,cb=碳酸),并分别用元素分析、红外光谱、差热分析、X-射线粉末衍射和X-射线单晶衍射等表征了该结构。晶体结构分析结果表明:μ₂桥联的草酸根离子与μ₄桥联的碳酸根离子将钕离子连接成三维微孔结构,沿b轴和c轴方向分别具有孔径大小为0.53 nm×0.41 nm和0.59 nm×0.84 nm的通道。拓扑分析结果表明化合物1为(4,5)连接类型。荧光分析表明常温固态下配合物1发射近红外荧光。     

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。     

钕的氢氧化物和氧化物纳米线的制备及表征

以金属钕为起始原料，采用简单的碱性溶液下水热法制备出氢氧化钕纳米线。所得到的水热产物采用X-射线衍射、扫描电镜和透射电镜等进行了结构与形态表征。研究发现，水热处理的温度、碱液浓度和碱的种类等对水热产物的形貌、长径比和结晶状态有较大影响，提高水热温度和增加碱液浓度有利于氢氧化钕纳米线的生长。在相同水热反应温度(180 ℃)、水热时间(45 h)和碱浓度下，5 mol·L^-1 NaOH溶液体系制备的氢氧化钕纳米线具有较高纯度和较长的长径比，其直径为20～40 nm，长度为2～10 μm。该氢氧化钕纳米线在空气气氛下500 ℃烧结后形成具有体心立方结构的C型Nd₂O₃，该Nd₂O₃仍具有一维纳米线形貌。升高焙烧温度时产物的形貌和相结构都发生了明显变化。     

分光光度法测定氯化稀土和轻稀土氧化物中的镨,钕,钐

本文提出在１０％盐酸介质，用紫外－可见分光光度法测定氯化稀土、轻稀土氧化物中的镨、钕、钐，测定波长分别为４４４ｎｍ、５７５ｎｍ、４０１ｎｍ，钐对镨的干扰和镨对钕的干扰均可用校正系数加以消除。方法回收率为９７．５％～１０２．９％，检出下限分别为５０×１０￣（－６）ｇ／ｍＬ，１０×１０￣（－６）ｇ／ｍＬ，１００×１０￣（－６）ｇ／ｍＬ。     

制备条件影响碳酸羟基磷灰石晶格的计算分析

在碳酸羟基磷灰石(CHA)结构分析中,对A型取代(CO₃^2-取代OH^-)和B型取代(CO₃^2-取代PO₄^3-)2种取代的稳定性仍存有争议。为了研究碳酸取代的可能位置和2种取代稳定性,本文利用计算机辅助手段详细研究了不同反应顺序和不同反应试剂对碳酸羟基磷灰石晶体结构的影响。本实验分别采用含Na和不含Na 2种不同的反应试剂,分别在HA生成过程中和HA生成以后加入CO₃^2-,通过离子共沉淀法制备了4种碳酸羟基磷灰石。通过X射线衍射(XRD)、红外光谱(IR)对他们的结构和基团进行了表征,并用Jade 6.5, Materials Studio 4.0以及Origin 7.0进行了精修、计算和拟合。结果表明,无论工艺过程如何变化,均主要生成晶体能量较低、晶格结构稳定的B型取代碳酸羟基磷灰石;与普通磷灰石相比,由于存在晶格畸变,因此碳酸取代磷灰石的结晶度下降;碳酸根在反应溶液中的浓度影响CHA的晶格畸变程度,较高游离碳酸浓度引起的晶格畸变大;Na⁺的引入,可以降低碳酸羟基磷灰石中的晶格畸变,从而提高结晶度;含Na的B型取代主要是取代Ca(Ⅱ)位置的Ca离子。IR分析结果表明四种碳酸羟基磷灰石中的CO₃^2-均以B型取代为主,通过对870 cm^-1附近峰的拟合,计算出材料中A型取代和B型取代的比值。     

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。     

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.     

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。     

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.     

(ZrO2)0.92(Gd2O3)0.08纳米晶的水热合成及其烧结体的电性能

用新制备的(Gd，Zr)(OH)_x·yH₂O共沉淀作前驱体，在强碱性介质中用水热法合成了(ZrO₂)_0.92(Gd₂O₃)_0.08纳米立方晶，考察了反应温度、pH值等水热反应条件对纳米晶粒大小的影响。将(ZrO₂)_0.92(Gd₂O₃)_0.08