Calculation of chemical bond parameters in La1?xCaxCrO3 (0.0?x?0.3)

Abstract

ABSTRACT:The chemical bond parameters, that is, bond covalency, bond Ž susceptibility, and macroscopic linear susceptibility of La Ca CrO x s 0.0, 0.1, 0.2, 1yx x 3 . 0.3 has been calculated using a semiempirical method. This method is the generalization of the dielectric description theory proposed by Phillips, Van Vechten, Levine, and Ž . Tanaka PVLT . In the calculation of bond valence, two schemes were adopted. One is the Ž . bond valence sums BVS scheme, and the other is the equal-valence scheme. Both schemes suggest that for the title compounds bond covalency and bond susceptibility are mainly influenced by bond valence and are insensitive to the Ca doping level or structural change. Larger bond valences usually result in higher bond covalency and Ž bond susceptibility. The macroscopic linear susceptibility increases only slightly for BVS . scheme with the increasing Ca doping level.

Lattice Energy Estimation for Inorganic Ionic Crystals

“…The definition of ionicity f i and covalency f c can be found in diverse literature both for binary crystals 12-16 and for complex crystals. − Therefore, only a brief discussion is given in this paper. Usually there are two ways to calculate f i and f c depending on the availability of dielectric constant or index of refraction.…”

“…(ii) Complex Ionic Crystals. From our previous study, it is known that complex crystals can be decomposed into the binary crystals. − On the basis of this idea, the total lattice energy U cal of a complex crystal can be written as …”

“…( 2) Complex Crystal LaCrO 3 . For LaCrO 3 , the bond parameters, including bond ionicity , bond length d μ , etc., are taken from our previous study . The compound can be decomposed into many binary crystals as follows: For the La 1/3 O 2/3 (1) bond, = 0.9753. d μ = 2.765 Å, = 3.0, and = 1.5.…”

The correlations among bond ionicity, lattice energy and microwave dielectric properties of (Nd1−xLax)NbO4ceramics

“…As we all know, we can deal with many binary crystals especially the A N B 8ÀN type by using the PV theory. 6,7,17 Then Levine et al 18,19 successfully dealt with complex crystals such as ABC 2 , ABC 3 and ABC 4 and more complex crystals. However, an explicit expression is not given for decomposing the complex multiband crystals into the sum of binary crystals.…”

The relationship between bond ionicity, lattice energy, coefficient of thermal expansion and microwave dielectric properties of Nd(Nb1−xSbx)O4ceramics

“…As we all know, we could deal with many binary crystals particularly of the A N B 8-N by using the PV theory. 6,7,17 Then Levine et al 18,19 successfully dealt with complex crystals such as ABC 2 , ABC 3 and ABC 4 and more complex crystals. However an explicit expression was not given for decomposing the complex multibond crystals into the sum of binary crystals.…”