An electron and X-ray diffraction study of the compositely modulated barium nickel hollandite Ba _x (Ni _x Ti_{8— x} )O₁₆, 1.16 < x < 1.32, solid solution

Abstract

Hollandite samples, Ba x (NixTi 8Àx )O 16 (1.1 < x < 1.40) made by ceramic techniques, have been studied by electron and X-ray diffraction. As a result, the barium nickel hollandite system is described as a composite modulated single phase solid solution made up of mutually incommensurable (along b) framework and Ba ion sub-structures. The magnitude of the incommensurate primary modulation wave-vector when defined with respect to the framework sub-structure q ¼ b Ba * (measured directly from electron diffraction patterns (EDPs)) acts as a chemical ruler in that it is directly related to composition and given by x = 2 . The superspace group symmetry was found to be I 0 2/ m(0, x = 2 , 0)1. Both the framework and the Ba sub-structures have the same I2/m average structure space group symmetry. The solid solution limits for Ba x (Ni x Ti 8Àx )O 16 were found to correspond to 1.16 < x < 1.32 . These limits were found by calculating the lattice parameters of both the frame work and sub-lattice from the powder X-ray diffraction patterns.

High-Temperature Electrochemical Crystal Growth of Hollandite-Type CsxTi8O16 with Controlled Electronic Properties

“…Some peaks are still unknown (marked with inverted triangles), assignable to neither the hollandite-related structures nor the starting materials. Carter and Withers reported the appearance of extra reflections originating from an incommensurate sublattice in barium titanium oxide hollandites Ba x M y Ti 8– y O 16 ( M = Mg, Mn, Fe, Co, Ni, and Zn). , While the possibility that the extra reflections come from the Cs sublattice cannot be ruled out, we tentatively conclude that this possibility is rather unlikely. The reasons are as follows: (1) There are no satellite reflections in the single-crystalline XRD pattern for the V = −1.0 V crystal.…”

Aperiodic mineral structures

“…19) surrounding individual parent Bragg reflections, with the satellites at the high-angle side showing much higher intensity than those of the low-angle side, which are scarcely discernible. Several authors (Carter and Withers, 2004;Norén et al, 2005) have provided conclusive proof of the incompatibility of this observation with a conventional incommensurate modulation and suggested, instead, a composite modulated structure. Bindi et al (2013) have studied by means of transmission electron microscopy the low-(90 K) and ultra-low-(4.2 K) temperature behaviour of the Cu-rich members of the pearceiteÀpolybasite group, i.e.…”

The composite modulated structure of cupropearceite and cupropolybasite and its behavior toward low temperature

“…5b) surrounding individual parent Bragg reflections, with the satellites at the high-angle side showing much higher intensity than those of the low-angle side, which are hardly discernible. Carter and Withers (2004) and Norén et al (2005) have provided conclusive proof of the incompatibility of this observation with a conventional incommensurate modulation and suggested, instead, a composite modulated structure in which the Ag + ions of the B layer partially occupy a mesh whose lattice parameters are quite incommensurate with those of the A module, and are additionally displaced due to interaction between the modules.…”