On the Lead Determination in Alkali Halides by Spectroscopic Method

The octahedral complex [PbX₆]^4- (X=Cl, Br) in natrium/potassium chloride or bromide monocrystals as well as in the concentrated solutions of these alkali halides, impurified by lead, shows a characteristic absorption in the region 250-300 nm. Using the height of this absorption band, a quantitative method for determination of lead in the range 8x10¹⁴ - 3.2x10¹⁶ atoms/cm³ of halide monocrystals or 0.5 - 20 mg/ml of solutions respectively, was elaborated. Standard graphs of the peak extinction of [PbX₆]^4- in natrium/potassium chloride and bromide as function of the lead concentration have been obtained.     

Dynamics of Intercalated Water Molecules in Synthetic Layered Silicates

Abstract

Diffusional motions of water molecules in a synthetic fluorinated layered silicate have been studied by neutron scattering. Motions in a one-water-layer hydration state are slower than in those in a two-water-layer hydration state. Good fits to the data were obtained with the Kohlrausch-Williams-Watt lineshape that is often applied to disordered systems.     

Spectral Studies of Divalent Copper in Antlerite Mineral

Electron paramagnetic resonance (EPR) spectra on antlerite mineral are recorded both at RT & LNT. Optical absorption spectra are recorded from 200 – 2500 nm at RT. The chemical analysis of antlerite reveals that the concentration of CuO in the mineral is 67.30 wt%. Optical absorption spectrum of antlerite shows four bands, which are mainly due to Cu(II). EPR and optical results of the antlerite sample confirmed that Cu(II) is in rhombically distorted (D_2h) octahedral symmetry with g₁ = 2.36, g₂ = 2.16 and g₃ = 2.07. The NIR spectra of antlerite are attributed to water fundamentals.     

二价阳离子掺入KDP晶体能力的研究

本文旨在寻找影响杂质阳离子进入KDP晶体能力的因素,我们使用分析纯的KH2PO4和超纯水(电阻率≥18.2MΩ·cm)为原料,分别加入BaCl2·2H2O,CuCl2·2H2O和MgCl2·6H2O,通过降温方式快速生长出KDP晶体.结果表明,cu2+及Mg2+在晶体中的含量基本保持不变,不随其在生长溶液中量的增大而增大,cu2+在晶体中的含量大于Mg2+在晶体中的含量;不同的是,Ba2+在晶体中的含量随着其在生长溶液中量增大而增大.从实验结果我们推断出离子半径和离子水合热是影响二价杂质阳离子在水溶液晶体生长过程中进入KDP晶体能力的重要因素.     

Theoretical Approach to the Deformation-induced Luminescence in Metals

The present paper reports the mechanoluminescence (ML) produced during fracture of metals. The mechanism of ML in metals is based on the generation of holes during the decay of mobile dislocations on the surface and subsequent electron-hole radiative recombination. The following equation is derived for the transient ML intensity of the fracto-induced ML in metals . The above equation shows that I should be maximum for a particular value of time t. For β 〉 α, . This equation shows that I should decrease exponentially with time. For the fracto-induced ML in metals, t_M and I_m may be expressed by the following equations . The spectroscopy of ML in metals is also discussed. A good correlation is found between the theoretical and experimentals results.     

Crystal-Chemical Features of Apatite in Carbonatites of the Tomtor Deposit (The Republic of Sakha (Yakutia), Russia): X-Ray Diffraction and Vibrational Spectroscopy Data

Crystallography Reports - An analysis of a number of samples from the Tomtor deposit of Nb and rare-earth elements (Republic of Saha (Yakutia)) by X-ray diffractometry, IR spectroscopy, and Raman...     

铌镁酸铅陶瓷的稀土元素及钛酸铅互掺改性研究

本文采用了铌铁矿法,研究了稀土元素及钛酸铅(PT)的掺入对铌镁酸铅(PMN)铁电陶瓷的介电性能及拉曼行为的影响.分别掺入Y2O3 、Sin2O3、La2O3稀土氧化物后,PMN的介电常数峰值(εm)有所下降,而掺人PT后εm有所上升.稀土元素的掺人使相转变温度(Tm)朝远离居里点的低温方向移动,室温下的介电损耗值减小,介电常数频率稳定性得到增强.PT的掺入使Tm朝接近居里点的高温方向移动.拉曼光谱研究表明稀土元素、PT的掺人影响了PMN陶瓷的B位有序度,导致其介电性变化.     

Mesomorphic Complexes of the Lanthanide Elements

Abstract

Mesomorphic lanthanide(III) complexes of salicylaldimine ligands have been synthesised. The effect upon the mesomorphic behaviour is discussed with variation of the counter-anion, number of alkoxy chains and the nature of the ligand framework. Complexes displaying either smectic or columnar mesophases have been realised.     

Quasi-Atomistic Approach to Modeling of Liposomes

Crystallography Reports - Small-angle X-ray scattering is an important structural tool for studying biological membranes; however, interpretation of scattering data remains a challenging problem....     

Erratum to:Influence of Chlorides of Mono- and Divalent Metals on the Oligomeric Composition of Lysozyme Crystallization Solutions and Further Crystal Growth

Crystallography Reports - An Erratum to this paper has been published: https://doi.org/10.1134/S1063774521340046     

An Introduction to the Solid State Polymerization of Transition-metal Complexes: A Comparative Study

Preliminary studies in this laboratory^' of topochemical and topotactic polyreactions of NiBr₂[P(CH₂CH₂CN)₃]₂ have shown that the reactions are in many cases characterized by a) product specificity, b) stereospecificity, c) “crystallographic specificity” and d) highly anisotropic “front motion” through individual single crystals. The polymerization reaction under investigation here is     

提高掺铒硅基纳米材料发光效率的探索

本文中,我们以SiO2介质镶嵌的纳米晶Si薄膜(nc-Si/SiO2)作为基质,将稀土离子Er掺入其中所形成的nc-Si:Er3+/SiO2薄膜材料为主,介绍了nc-Si→Er3+之间的能量转移过程,探讨了实现各类掺Er的Si基纳米材料高效率发光的可能途径.这些方法主要包括:增强nc-Si→Er3+的能转移效率,提高有效Er的掺杂浓度,选择最佳的退火温度,增加Er-O发光复合体的浓度和制备新的Er掺杂Si基纳米结构等.这些方法对制备具有高发光效率的掺铒硅基纳米材料具有重要的实际意义.     

Quantum-chemical Approach to the Dependence of Oxygen Charge on Bond Angle in SiO2

A recently published review on the effective oxygen charge in SiO₂ and its dependence on the bond angle of oxygen has shown that, as a rule, solid-state theoretical calculations lead to the conclusion that the oxygen charge increases with increasing bond angle, whereas quantum-chemical calculations for limited clusters yield an opposite result, i.e. a decrease of the oxygen charge with increasing oxygen angle. In the present paper it is shown that also a quantum-chemical approach to the problem, namely a molecular-orbital calculation for an Si O Si bridge, reveals an increase of the charge of oxygen with its bonding angle, which is, however, relatively weak.     

A New Approach to Estimation of the Thermal Conductivity of Titanium Alloys

Crystallography Reports - The thermal conductivities of seven titanium alloys (VT1-0, VT18U, VT20, IMI834, Ti6242S, Ti6Al4V, and Ti6Al7Nb) have been measured. According to the data obtained, the...     

The Electron Microscopic Approach to the Structure and Reactivities of Organic Solids

In this paper we continue investigations started in Refs. 1 and 2 studying the effect of a magnetic field on electrohydrodynamics of liquid crystalling complex ethers with dielectric constant anisotropy close to zero. The investigations were made with 100 μm thick layers having initial planar “first” structure of B and C mixtures described in Ref. 2.

Figure 1 shows dependences of optical layer transmittance on the intensity of the magnetic field (H) directed normal to bearing surfaces, and in the absence of an electric field in the absence of an electric field (curves I and II). For some threshold values H = H_th all the samples showed an increased transmission arising due to Fredericks transition.³     

Crystal Growth and Physico-Chemical Properties of Lead Molybdate in the Homogeneity Region

From data of both X-ray phase analysis and differential thermal analysis, as well from measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85–50.50 mole% MoO₃, has been determined. It was also established that the compound was a daltonide phase. The results obtained explain the Pb/Mo ratio changes along the crystal.     

Complexes in the vapour phase and their implications for vapour growth

The significance of polymeric molecules (Cu₃Cl₃, Pt₆Cl₁₂, Ag₃I₃) for chemical transport and the direction of transport in temperature gradients is described. A survey of the large number of dimeric chloride molecules discovered so far, and the corresponding enthalpies of dimerization, is given. 1 : 1 Heterocomplexes such as LiCsCl₂, NaAlCl₄, KThCl₅, CdPbCl₄, AIUCl₈, ThUCl₈, and their enthalpies of reaction for the formation of such complexes from the dimers of the components (e.g., Na₂Cl₂ + Al₂Cl₆ or Th₂Cl₈ + U₂Cl₈) are reported. The stability of larger heterocomplexes (e.g., MeAl₂Cl₈, MeAl₃Cl₁₂, CoGa₂Cl₈, Tl₂ThCl₆) is also reported. The deposition of crystals of compounds, such as CuCl₂, CrCl₂,HgCr₂Se₄, Pd₂A l, by means of gas complexes as reactants, is described.     

Provenance Study of the Lead Detected in the Antique Ceramic Sculpture from the Kerch Bay

Crystallography Reports - When studying the ceramic sculpture (bearded male head) found in the Kerch Bay during underwater excavations of the Institute of Archaeology of the Russian Academy of...