The Principles Determining the Structure of Complex Ionic Crystals

Abstract

The calculated heats of ionization, which are in calories per mole, refer, of course, to the ionization at infinite dilution.The values of pKs calculated are insufficiently accurate for the heat effect of the third ionization step to be calculated. Heat, however, is evolved in this ionization. SummaryWith the quinhydrone electrode measurements of the Ph values of phosphate mixtures have been made which lead to the following values for the ionization constants of phosphoric acid pK, (25°) = 2.10, pKi (37.5°) = 2.16 pKi (25°) = 7.13, pKi (37.5°) = 7.06These figures are compared with those derived from other data. From the data of Britton pK3 at 20°is calculated to be about 12.1.

Average and Local Structure, Debye Temperature, and Structural Rigidity in Some Oxide Compounds Related to Phosphor Hosts

“…Based on Pauling's rules for ionic crystal structures, 42 we would expect that structures containing polyhedra of lower charge cations (Al 3+ instead of Si 4+ ) and oxygen would be better connected and therefore more rigid, and this is indeed borne out by the DFT calculations. Refinements of low temperature neutron power diffraction data collected at 15 K were conducted to extract atomic displacement parameters (U iso ) to experimentally determine Figure 3 shows excellent agreement between the structural models and the data.…”

Ionization Energy as a Stability Criterion for Halide Perovskites

“…The value of the tolerance factor for CH 3 NH 3 PbI 3 is t = 0.91 20 , which is within the range of acceptable values t = 0.8 − 0.95 19 . Li et al 19 pointed out that the tolerance factor alone does not fully capture formability of perovkite structures and proposed to add Pauling's octahedral factor 21 r B /r X (r B and r X are the ionic radii of cation B and anion X, respectively) as an additional geometrical criterion. In the case of CH 3 NH 3 PbI 3 the octahedral factor r Pb /r I = 0.54 is within the allowable range of 0.414 − 0.732 21 .…”

Quantum topology phase diagrams for molecules, clusters, and solids

“…The final suggestion for future work is to understand Linus Pauling's [26]* rules for determining the crystal structures of complex ionic crystals specifically in terms of the EulerPoincare relation for solids, see Eq. (2), within the quantum topology framework.…”

“…(2), within the quantum topology framework. In particular of the five rules, [26] first, third, fourth, and fifth rules could be considered, the second rule being the exception as it requires the calculation of both the charge of the anion integrated over the atomic basin and the strength of electrostatic bonds reaching the anion, which is outside of the scope of this approach. However, we can apply the Euler-Poincare relation within the quantum topology framework to the remaining four rules by developing quantum topology analogs.…”