Effect of potassium for cesium replacement in atomic level structure of potassium cobalt hexacyanoferrate(II)

Potassium cobalt hexacyanoferrate(II) [K2CoFe(CN)6] is an extremely selective ion exchanger for cesium ions. To examine the atomic level background for the selectivity a computational structural study using DFT modelling was carried out for K2CoFe(CN)6 and for products where Cs has replaced K in the elemental cube cages closest to the surface. In the K-form compound the potassium ions are not in the center of the Co–Fe–CN elementary cube cages closest to the surface but locate about 140 pm from the cube center towards the surface. When cesium ions are exchanged to these potassium ions they locate much deeper from the surface, being only about 70 pm upwards from the cube center. This apparently leads to much stronger bonding of cesium compared to potassium. Once taken up into the outermost cube cages on the surface of the crystallites cesium ions are not able to penetrate further since they are much larger than the electron window between the cubes. Furthermore, they are not able to return to the solution phase either leading to a practically irreversible sorption.

Analysis of molecular bonds by the spectrum of nitrogen atoms in order to optimize the synthesis of mineral fertilizers

The model of the structure of the crystal cubic lattice proposed by the authors takes into account the presence of short and long diagonal bonds passing along the faces and through the center of the elementary cube. The mechanism of energy distribution between two and three valence electrons of the N atom in the ground and excited states is described. It is shown that the optical spectrum of the N atom is mirrored on the set of energies of the 2p2 term, called the spectral memory of the nitrogen atom by the authors. The mechanism of “trigger of excitation” of N atoms is described for the first time. The optical spectrum of N atoms determines the energies of the FCC → HCP phase transitions; solid → liquid phase of the hcp; boiling and melting points. The error in calculating the temperatures of phase transitions is ± 3.3%, and the density at the boiling and melting points is not more than 1%.

HIMPUNAN KUBIK ASIKLIK DAN KUBUS DASAR

Given a topological space X. Then define an algebra object H∗ (X) whichis called the homology group of X. H∗ (X) is the collection the kth homology group ofX which is denoted by Hk(X). An elementary cube Q is a finite product of elementaryintervals I = [l, l + 1] or I = [l, l], for some l ∈ Z. In this paper, it is proved that allelementary cubes are acyclic, which means that Hk(Q) is isomorphic to Z if k = 0, andHk(Q) is isomorphic to 0 if k > 0.

NEW SOLUTION OF VERTEX TYPE TETRAHEDRON EQUATIONS

In this letter we formulate a new N-state spin integrable model on a three-dimensional lattice with spins interacting round each elementary cube of the lattice. This model can also be reformulated as a vertex type model. Weight functions of the model satisfy tetrahedron equations.

Gitterdeformationen um Zwischengitteratome, Leerstellen, Zwischengitteratom-Paare und Frenkel-Paare in Kupfer

The distortions of the lattice around a number of different point defects in copper are calculated with the help of the electronic digital computer Z 22 using a general method developed by TEWORDT 3. In the case of an interstitial which is sited at the center of an elementary cube about 500 atoms and in the case of a vacancy about 50 atoms are treated as discrete particles. The elastic solutions which are joined to the displacements of the discrete particles are determined for an anisotropic continuum. The changes in volume of the crystal arising from the interstitial are found to be 0.911, 1.219 and 1.441 atomic volumes respectively for the MORSE potential VM and the two BORN-MAYER potentials V1, V2 we have used [see Eqs. (25) — (27)]. The corresponding values for the vacancy are —0.441, — 0.378 and —0.321 atomic volumes. Further we caluclate the relaxation of the lattice around three configurations of interstitial pairs with axes in the (1,0,0), (1,1,0) and (1,1,1) directions considering about 100 atoms as movable in each case. The contributions to the binding energies arising from the potential V1 turn out to be 0.81, —0.18 and —0.26 eV respectively. This strongly indicates that interstitial pairs can attract one another. Finally the stability of the 10 closest interstitial-vacancy pairs (FRENKEL pairs) is examined. All pairs smaller than 1.5 lattice constants in diameter are found to be instable, the other pairs are stable and give a discrete spectrum of BORN-MAYER energies. The results are discussed in connection with recent experiments in the field of radiation damage.