Ferroelectricity in Gly · H3PO3 crystal

A new Gly · H₃PO₃ crystal was grown and its physical properties were investigated. DSC measurements revealed a phase transition at about 224 K. Dielectric investigations showed a large anomaly of dielectric permittivity at 224.7 K along the b-axis. The appearance of spontaneous polarization (along the b-axis) observed by means of a Sawyer-Tower circuit gives evidence for a para-ferroelectric phase transition in this material.     

Defects,phase transitions and dynamical disorder in superionic protonic conductors H3OUO2PO4 · 3H2O and CsHSO4

Specific properties of the hydrogen bond and protons appear to be responsible for the formation of the quasi-liquid state of conducting ions and the resulting superionic behaviour. This state is reached by successive phase transitions involving the mobile species and their interactions with a more or less rigid framework. H₃OUO₂PO₄ · 3H₂O (HUP) and CsHSO₄ can be considered as models of wet and dry superionic conduction, respectively. Interactions between static effects and dynamical disorder as well as the coupling between sublattices are discussed in relation to results obtained by calorimetry, impedance spectroscopy (up to 10 GHz), vibrational spectroscopy and quasi-elastic neutron scattering.     

Mn5(PO3(OH))2(PO4)2(H2O)4的水热合成和光谱研究

在水热反应条件下合成出具有红磷锰矿结构的Mn5(PO3(OH) ) 2 (PO4 ) 2 (H2 O) 4单晶 ,在X ray单晶结构分析的基础上 ,对其固体紫外可见漫反射光谱、红外光谱、荧光光谱和热重光谱进行了研究。结果表明 ,构成该化合物的PO4 四面体及MnO6 八面体通过共顶点或共棱方式相连接 ,与P ,Mn配位的氧分为 3类 :即端基氧 (Od)、二桥氧 (Ob)和三桥氧 (Oc)。因而在 2 10和 2 5 0nm左右出现了Od→Mn和Ob ,c→Mn的荷移跃迁吸收谱带 ;在 10 0 0～ 110 0cm- 1 处 ,P—O的伸缩振动峰分裂为 3个 ;70 0～ 980cm- 1 处存在 3类Mn—O的伸缩振动。对标题化合物分别采用 2 18和 310nm的光激发 ,分别在 35 4和 4 13nm产生强而尖锐的荧光光谱发射峰 ,表现了很强的光学效应。热重分析表明该化合物在 2 70℃以下结构保持稳定 ,在 2 70～36 0℃范围内失去配位水。量化计算得单点能为 - 4 5 5 8 6 5 95 5 5 1a u ;前线轨道能量HOMO(Alpha) =- 0 2 80 80a u ,LOMO(Alpha) =0 0 15 2 7a u ,能隙为 0 2 96 0 7a u ;HOMO(Beta) =- 0 2 5 919a u ,LOMO(Beta)=0 0 0 10 8a u ,能隙为 0 2 6 0 72a u ;偶极矩为 4 2 0 82Debye。     

超分子化合物C11H6N2O·H3PO4·H2O的合成与晶体结构

采用水热反应法合成超分子化合物C11H6N2O·H3PO4·H2O,通过元素分析、红外光谱和X射线单晶衍射对其组成、结构进行分析.该化合物属于三斜晶系,空间群P-1,晶胞参数a=0.73350(6)nm,b=0.74191(7)nm,c=1.15692(14)nm,α=96.395(2)°,β=92.9940(10)°,γ=90.3440(10)°,V=0.62477(11)nm3,Z=2,F(000)=308,Dc=1.585g·cm-3,最终偏差因子R1=0.0521,wR2=0.1282.该化合物的不对称单元由3个独立的分子4,5-二氮芴-9-酮、磷酸和水分子构成,氢键连接分子形成三维超分子化合物.     

H3PO4-RhB-H2O2体系催化分光光度法测定痕量锡的研究

基于稀磷酸介质中存在活化剂氯离子时,痕量锡催化过氧化氢氧化罗丹明Ｂ的褪色反应,建立了测定痕量锡的催化分光光度法,了影响催化反应的动力学条件。方法的检出限为５．２×１０＾－１２ｇ／ｍＬ,线性范围为０－９ｎｇ／２５ｍＬ。用于人发及水样中痕量锡测定,结果令人满意。     

一种新型钼磷酸盐杂多化合物(NH3CH2CH2NH3)7H2[NaMo12O30(PO4)2(HPO4)5(H2PO4)]·7H2O的合成和光谱研究

本文采用水热反应条件 ,合成得到一种新型的含五价钼原子的杂多化合物 :(NH3CH2 CH2 NH3) 7H2[NaMo1 2 O30 (PO4 ) 2 (HPO4 ) 5(H2 PO4 ) ]·7H2 O ,在晶体结构测定的基础上对其进行红外、拉曼和紫外 可见漫反射光谱研究。结果表明 :较长的Mo(Ⅴ )—O键键长和分子内大量的氢键造成化合物红外光谱特征的红移。     

Ionic conductivity in the system Li9−4xZrx〈PO4〉3

Lithium ion conductors of composition Li_9−4xZr_x〈PO₄〉₃ (0.0 < x < 2.0) have been prepared by the conventional solid state reaction and also by a wet chemical method. X-ray diffraction patterns reveal identical crystallographic morphology for the compounds prepared by the two methods. However, they can be prepared and sintered at much lower temperatures by the wet chemical method. Their conductivities are also higher. Compared to pure Li₃PO₄, one of the end member of the series, the conductivity increases sharply with substitution of lithium by zirconium. The highest conductivity has been obtained in the composition Li_1.8Zr_1.8〈PO₄〉₃ (x = 1.8), prepared by the wet chemical method. The conductivity value of 10⁻³ ω⁻¹ cm⁻¹ is obtained at around 225°C with an activation energy of about 0.5 eV.     

Proton conductivity,structural and thermal properties of (1–x) CsH2PO4−xBa(H2PO4)2

Physics of the Solid State - The structural, electrotransport, and thermodynamic properties of the (1–x)CsH2PO4−xBa(H2PO4)2 system in a wide range of compositions (x = 0.1–0.4)...     

Sr3Gd(PO4)3:Tm3+的真空紫外光谱特性

研究了Sr3Gd(PO4)3 : Tm3 和GdPO4 : Tm3 样品的结构特性、光谱特性.GdPO4 : Tm3 为单斜晶系,基质掺入铥离子后结构没有明显变化.GdPO4:Tm3 在164和210 nm附近有强烈的吸收峰.位于164 nm附近的强烈的吸收峰是归因于基质的吸收引起,210 nm附近的吸收峰则归因于Gd 的8S7/2-6GJ的能级跃迁.在164 nm真空紫外光激发下,样品于453及363 nm处有较强的发射峰,发射主峰位于453nm,属于Tm3 的1D2→3H4(22,123 cm-1)跃迁的典型发射.由于阳离子质量的不同,Sr3Gd(PO4)3:Tm3 在166 nm附近的激发峰高于GdPO4: Tm3 的同位置的激发峰,其在363 nm处的发射有明显减弱,而在453 nm处的蓝色发射有显著的增强.     

NiL(ClO4)2催化NaBrO3-MA-H3PO4体系振荡反应的研究

报道了一种反式Ｃｕｒｔｉｓ环的镍（Ⅱ）的配合物ＮｉＬ（ＣｌＯ４）２（Ｌ为２,４,４,９,１１,１１－六甲基－１,５,８,１２－四氮杂环十四－１,５,８,１２－四烯）催化ＮａＢｒＯ３－ＣＨ２（ＣＯＯＨ）２（ＭＡ）－Ｈ３ＰＯ４体系的化学振荡反应。测得该体系的振荡范围,研究、分析了各物种浓度、自由基抑制剂和还原剂、Ａｇ＾＋、Ｈｇ＾２＋以及温度对振荡反应的影响。结果表明Ｂｒ＾－起重要动力学控制作用,在反应     

Characteristics of xLiFePO4·y Li3V2(PO4)3 electrodes for lithium batteries

A series of mechanical mixture of lithium–iron–vanadium–phosphate compositions that can be represented in two-component notation, xLiFePO₄·y Li₃V₂(PO₄)₃ (LFVP), has been evaluated as electrodes in lithium cells for x:y = 0:1, 1:1, 5:1, 10:1, and 1:0, in which an olivine component, LiFePO₄ (LFP), and a monoclinic component, Li₃V₂(PO₄)₃ (LVP), coexisted. Powder X-ray diffraction (XRD) patterns show that the end members and the electrochemical profiles of cells with these electrodes are consistent with those expected for the olivine LiFePO₄(x = 1, y = 0) and for monoclinic Li₃V₂(PO₄)₃ (x = 0, y = 1). XRD data and the changes of cell parameters indicate that there existed some V- and Fe-doping in the composite xLiFePO₄·y Li₃V₂(PO₄)₃, resulting with a good performance compared with single LiFePO₄ and Li₃V₂(PO₄)₃. Electrochemical characteristics were evaluated by using cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the electron transfer activity and the lithium ion diffusion rate in LFVP are better than single LFP and LVP.     

Hydrothermal synthesis of Fe5(PO4)4(OH)3·2H2O microflowers for fabricating high-performance LiFePO4/C composites

Hierarchical Fe₅(PO₄)₄(OH)₃·2H₂O microflower was synthesized by a hydrothermal reaction with self-prepared β-FeOOH nanorod as raw material. The microflowers were self-assemblies of symmetric building blocks with deep grooves. The possible morphology evolution process was proposed. The microflowers morphology was retained when they were lithiated to prepare LiFePO₄/C composites through a carbothermal reduction method with citric acid as both reducing agent and carbonaceous coating conductor source. As cathode materials for lithium ion batteries, the as-obtained LiFePO₄/C composites deliver a high discharge capacity of 156 mAh g^?1 at 0.1 C rate and exhibit excellent cycling stability, which may be ascribed to the homogeneous coated carbon and the unique microflower structure with grooves.     

原子吸收法间接测定水中可溶性PO3-4的研究

研究并建立了测定水中PO3-4的方法，用草酸钙将PO3-4转化为磷酸钙，加醋酸溶解磷酸钙，离心沉降未反应的试剂，用AAS法测定清液中的Ca2+，即可间接测定PO3-4的含量。     

原子吸收法间接测定水中可溶性PO4^3—的研究

研究并建立了测定水中PO4^3-的方法,用草酸钙将PO4^3-转化为磷酸钙,加醋酸溶解磷酸钙,离心沉降未反应的试剂,用AAS法测定清液中的Ca^2 ,即可间接测定PO4^3-的含量。     

H3正三角形和H4正四面体结构的变分计算

采用改进排列通道量子力学(Modified Arrangement Channel Quantum Mechanics,简称MACQM)方法和变分法,计算了H₃体系正三角形和H₄体系的正四面体结构的能量曲线.当H₃体系原子核的间距R=1.74a₀,波函数变分参数α=1.03时,体系能量有最低值-1.58161 a.u.;当H₄体系原子核的间距R=1.60a₀,波函数变分参数α=1.07时,体系能量有最低值-2.28097 a.u.,这表明H₃体系的正三角形构型和H₄的正四面体结构是可以稳定存在的.     

用多核固体核磁共振研究CsH2PO4 和CsH5(PO4)2的制备

探讨可能用作燃料电池固体酸电解质的化合物CsH₂PO₄ (CDP)和CsH₅(PO₄)₂(CPDP)的制备. CDP和CPDP混合物由摩尔比1∶4的Cs₂CO₃∶H₃PO₄水溶液结晶而成,而CDP和Cs₂HPO₄·1.5H₂O (H-DCHP)混合物依其摩尔比1∶2的水溶液制备. 甲醇清洗能最有效地将CDP从其混合物中分离出来. CDP、CPDP以及H-DCHP的¹³³Cs 和³¹P 魔角旋转谱以及CPDP和H-DCHP的¹H魔角旋转谱均为首次报道,对各化合物的谱峰做了指认. 说明,透过确认合成的电解质以及合成过程所产生的副产物,多核固体核磁共振对于控制固体酸电解质合成的品质是一个非常有用的工具.     

H+5团簇离子及其中性团簇产物H3和H4

报道了H+5的实验结果.分析讨论了H+5的形成和分解途径.根据理论分析,以稳定的H+3为核心与一个或多个氢分子结合可能形成稳定的H+n氢团簇离子.另一方面,在高频离子源中, 有发生H+3与H2反应的条件.实验中,从高频离子源引出的离子束被静电加速器加速,然后用90°磁分析器选择质量数为5的离子,再将这些离子偏转20°,最后在20°方向测量它们的能谱.从能谱发现,在高频离子源中可能通过H+3与H2的离子-分子反应形成了H+5团簇离子;并且在H+5的分解产物中还发现可能存在H3和H4等中性团簇产物.     

Electrochemical behavior of Mg-doped 7LiFePO4–Li3V2(PO4)3 composite cathode material for lithium-ion batteries

Mg-doping effects on the electrochemical property of LiFePO₄–Li₃V₂(PO₄)₃ composite materials, a mutual-doping system, are investigated. X-ray diffraction study indicates that Mg doping decreases the cell volume of LiFePO₄ in the composite. The cyclic voltammograms reveal that the reversibility of the electrode reaction and the diffusion of lithium ion is enhanced by Mg doping. Mg doping also improves the conductivity and rate capacity of 7LiFePO₄–Li₃V₂(PO₄)₃ composite material and decreases the polarization of the electrode reaction. The discharge capacity of the Mg-doped composite was 93 mAh?g^?1 at the current density of 1,500 mA?g^?1, and Mg-doped composite has better discharge performance than the original 7LiFePO₄–Li₃V₂(PO₄)₃ composite at low temperature, too. At ?30 °C, the discharge capacity of Mg-doped LFVP is 89 mAh?g^?1, higher than that of the original composite. Electrochemical impedance spectroscopy study shows that Mg²⁺ doping could enhance the electrochemical activity of 7LiFePO₄–Li₃V₂(PO₄)₃ composite. Mg doping has a positive influence on the electrochemical performance of the LiFePO₄–Li₃V₂(PO₄)₃ composite material.     

Conductivity studies and ion transport mechanism in LiI–Li3PO4 solid electrolyte

Mixtures of LiI–Li₃PO₄ were sintered at low temperature. It was observed that the conductivity improved up to 10⁻³ S cm⁻¹ with the addition of LiI. Infrared technique (Fourier transform infrared spectroscopy [FTIR]) was employed to detect the presence of polyhedral structures. From the FTIR spectra of the binary samples with various weight percents of LiI, the PO₄ ³⁻ bands and the PO bending experienced small shifting which indicates that interaction has occurred. Alternating current conductivity versus frequency shows a linear variation suggesting that the behavior follows Jonsher power law. The conduction mechanism of LiI–Li₃PO₄ solid electrolyte follows the quantum mechanical tunneling model.