Chemical bonding in titanium-metalloid compounds

Abstract

First-principles molecular-orbital calculations for titanium-metalloid compounds TiB, TiB 2 , TiC, Ti 2 N, TiN, TiO, TiO 2 , TiSi, TiSi 2 , TiP, TiS, and TiS 2 have been made by the use of discrete-variational X␣ method with model clusters composed of about 100 atoms. In order to compare the covalent bonding quantitatively among these compounds with different crystal structures, we used covalent bond density in which both the strength and the number of each type of the bonds in the compounds are taken into account. The covalent bond density represents the strength of the covalent bonding per unit volume irrespective of crystal structures. The dominant covalent bonding in the titanium compounds except for TiO is found to be the Ti-X bonding, which mainly arises from the interaction between Ti-3d-X-np and Ti-4p-X-np orbitals. Each compound exhibits a wide variety of chemical bondings depending upon its crystal structure and local coordinations. However, their total covalent bond density simply decreases and the ionic character increases with rising the atomic number of X atoms. The trend agrees with a simple expectation from the electronegativity differences between Ti and X.

R dependence of electronic structure in perovskite type structure compounds, RBRh3 (R: Sc, Y and La)

“…This is consistent with observed metallic resistivity and Pauli paramagnetism [13,14]. The similar presence of pseudo gap between the Ti-3d and C-2p (or N-2p) band were reported in TiC and TiN [4]. The PDOS above E F are antibonding states of Rh 4d, B 2p and Sc 3d.…”

Characteristics of niobium hydrogen solid solution

“…7 shows the change in the total bond orders in the clusters for the Nb-Nb and Nb-H interactions. The bond order is the population of electrons participating in the covalent bonding [21]. As the Nb-Nb bond order decreases, the Nb-H bond order starts and increases due to the presence of the interstitial hydrogen atoms.…”

Characteristics of titanium–hydrogen solid solution

“…6 shows change of total bond order between all of Ti pairs. Bond order is a criterion of covalent binding [15]. The bond order between Ti atoms decreased with the increasing of hydrogen content.…”