On the Binding Energy of Clusters with a Small Number of Lithium Atoms and Varying Scope of Interaction Between the Atoms. Hückel Molecular Orbital Approximation

The effect of the scope of interaction between the atoms in two-dimensional and threedimensional clusters containing 6, 7, 9, 10, 15 and 16 lithium atoms, upon the binding energy (BE) of the clusters has been investigated. BE of the clusters was calcuated by the HÜCKEL Molecular Orbital (HMO) method. It has been established that for clusters with the same number of atoms BE has its maximum value when the interaction of each atom of the cluster with the atoms of its first and second coordination spheres in the lithium lattice are taken into account. After the maximum BE decreases and tends to a constant value which is attained when the interaction of each atom of the cluster with the atoms of its six coordination spheres is taken into account. The reasons for the above result should be looked for in the limits of applicability of the calculation procedure based on the HMO method to the study of properties of various models of clusters containing a small number of metal (e.g. lithium) atoms.     

Condis Crystals of Small Molecules II. The Polymorphs of N,N'-bis(4-n-octyloxybenzal)-1,4-phenylenediamine (OOBPD)

The high temperature transitions between 300 and 500 K of N,N'-bis(4-n-octyloxybenzal)-1,4-phenylenediamine are analyzed by scanning calorimetry, optical microscopy, light transmission measurement, thermomechanical analysis and X-ray diffraction. The prior assignment of mesophase structure K3/385.2/K2/388.2/K1/415.3/H'/422.2/G'/426.9/I/436.6/C/475.4/N/505.4/Melt (temperatures in K) has been extended by the suggestion that K1 to K3 are conformationally disordered crystals.     

A model study of the growth of crystals consisting of a small number of metal atoms by the Hückel molecular orbital method (I). Addition of One atom to small crystals

The paper deals 1) with the regularities of the formation of (N + 1)-atomic clusters during the growth of N-atomic one-, two-, and three-dimensional crystals and 2) with the distribution with respect to stability of the (N + 1)-atomic clusters. The N-atomic crystals have the structure of a hypothetical metal with a simple cubic lattice and a small number of one-electron atoms. The binding energy (BE) of the clusters calculated by the Hückel molecular orbital method was assumed to be a measure of their stability. Interactions between nearest-neighbours only were taken into account. The most stable (N + 1)-atomic cluster formed from a one-dimensional crystal is that in which the N + 1-st atom is bonded to the end atom of the N-atomic one-dimensional crystal. For two-dimensional crystals, the N + 1st atom forms the strongest bond with an atom from the diagonal of the square. With three-dimensional crystals, the N + 1st atom is most strongly bonded to a corner atom of the small crystal. The inhomogeneity in the bond energy of the N + 1st atom to a surface atom of the small N-atomic crystal decreases with increasing N. According to earlier studies of ours, the BE per atom increases, whereas the mean energy of a nearest-neighbour bond decreases with increasing N.     

Growth of Ge1—xSix (x= 0 to 0.5) Single Crystals by a Zone Melting Method

Ge_1—xSi_x graded crystals with 0 < x < 0.66 were grown by a zone melting method in a double ellipsoid mirror furnace. They have a diameter of 9 mm and grown lengths between 27 and 80 mm. Single crystalline regions reached a maximum Si concentration of 50 at%, determined by EDX and ECP measurements. Starting with a Ge seed, a defined concentration profile was obtained by a wedge-shaped arrangement of the feed material. The concentration profiles could be predicted by a simulation program.     

Growth Mechanism in Atomic Layer Epitaxy (II). A Model of the Growth Process of CdTe on CdTe (111) Substrates

A realistic model of CdTe growth by atomic layer epitaxy (ALE) has been proposed. This model is based on experimental studies concerning the isothermal re-evaporation rates of elemental Cd and Te deposits on the (lll)A and (lll)B surfaces of CdTe substrates, on a study of surface morphology and crystal structure of CdTe single crystal overlayers grown by ALE on CdTe(lll)B substrates under various crystallization conditions as well as on the existing theories related to the interaction of thermally activated atoms or molecules with hot solid surfaces. This model includes: (i) an existence of transition layers of both Cd and Te₂ species, intermediate between a chemisorbed and a bulk-like film, which create reaction zones 3–4 monolayers thick near the substrate surface, and (ii) partial re-evaporation of the first, chemisorbed monolayer of the deposited constituent elements.     

具有准同型相界(MPB)组成的化合物(Sr1-x Bax)2NaNb5O15的晶体生长及性质研究

用Czochralski方法生长出铁电钨青铜型单晶(Sr1-xBax)2NaNb5O15(简称SBNN),晶体沿c轴方向生长.正交-四方相的准同型相界(简称为MPB)存在于x=0.45～0.50之间;SBNN晶体是不一致熔融的化合物,在晶体成长过程中,Sr2+的分凝系数比Ba2+的大,因此具有高浓度Ba2+的SBNN晶体很难生长.晶体的居里温度是243℃,在此温度下的相变是弥散的,随频率的增加,介电常数降低.     

Influence of Gravitation on the Processes of Heat and Mass Transfer in Solution Crystal Growth by the Travelling Heater Method (THM) (II)

The two-dimensional quasi-stationary thermodiffusive hydrodynamic problem of the crystal PbTe growth from solution by the travelling heater method has been solved. Computation is given for the temperature field distribution in crystal and solution. The picture of fluxes in solution was obtained under free convection for different lengths of solvent zone. It is shown that in the absence of absence of gravitation at the growing interface in solution there occurs a constitutional supercooling, whereas the free convection removes it, which leads to greater morphological stability of a growing crystal face.     

On the Iso‐Diameter Growth of β ‐BaB2O4 (BBO) Crystals by Flux Pulling Method

The iso‐diameter growth of β ‐BaB₂O₄ (BBO) crystals by the flux pulling method have been studied based on the phase equilibrium diagram in the BaB₂O₄‐Na₂O pseudo‐binary system and from the interface stability. The mathematical expressions for the cooling rate in the growth of the crystals with constant diameter under stable growth conditions are derived, the experimental phenomena such as diameter contraction and difficulty to grow a lengthy crystal by the flux pulling method are explained, the prerequisite for iso‐diameter BBO crystal growth from the flux is suggested; a new continuous charging flux pulling method is introduced to grow large‐sized high quality crystals with a relative high growth rate.     

X-ray Molecular and Crystal Structure Study of the Fe(II) Complex Containing 1,10-Phenanthroline and Saccharin: [Fe(C12H8N2)3] (C6H4COSO2N)2 · 4 H2O

X-ray molecular and crystal structure of the [Fe(C₁₂H₈N₂)₃] (C₆H₄COSO₂N)₂ · 4 H₂O is reported. In the complex, the Fe atom is bonded to the six nitrogen atoms with a distorted octahedral stereochemistry.     

Crystallization of the $${\text{Mn}}^{{\text{II}}}[12{\text{-MC}}_{{\text{Mn}}^{{\text{III}}}{\text{(N)shi}}}{\text{-}}4]^{2+}$$ Mn II [ 12 -MC Mn III (N)shi - 4 ] 2 + Structure with 1,2,4-Triazolate from Methanol

Journal of Chemical Crystallography - The metallacrown (MC) dimer complex {MnII(OAc)(1,2,4-trz) $$[12{\text{-MC}}_{{\text{Mn}}^{{\text{III}}}{\text{(N)shi}}}{\text{-}}4]$$...     

Growth of $${\text{N}}{{{\text{d}}}_{{{\text{1}}\; - \;y}}}{\text{Eu}}_{y}^{{{\text{2}} + }}{{{\text{F}}}_{{{\text{3}}\; - \;y}}}$$ Single Crystals with Tysonite-Type (LaF3) Structure and Investigation of the Concentration Dependence of Some Their Properties

Crystallography Reports - Nd1&nbsp;–&nbsp;yEuyF3&nbsp;–&nbsp;y crystals (y is the molar fraction of EuF2; 0 ≤ y ≤ 0.15) with a tysonite (LaF3) structure have...