Refinement of the structures of the layer silicates MCuSi[sub 4]O[sub 10] (M = Ca, Sr, Ba) by Rietveld analysis of neutron powder diffraction data

Journal Article · Mon Mar 01 00:00:00 EST 1993 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1006/jssc.1993.1083· OSTI ID:6135130

Chakoumakos, B C; Fernandez-Baca, J A; Boatner, L A ^[1]

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1. Oak Ridge National Lab., TN (United States)

The MCuSi[sub 4]O[sub 10] (M = Ca, Sr, Ba) compounds possess the gillespite (BaFeSi[sub 4]O[sub 10]) structure, which is tetragonal, P4/ncc, Z = 4. Data sets of 2365 step intensities were recorded for the tital compounds with [lambda] = 1.400 [Angstrom] at T = 295 K. For M = Ca, a = 7.3017 (3) [Angstrom], c = 15.1303 (6) [Angstrom], V[sub cell] = 806.66 (9) [Angstrom][sup 3], R[sub exp] = 0.0453, R[sub wp] = 0.0515, for 487 reflections. For M = Sr, a = 7.3707 (2) [Angstrom], c = 15.5904 (6) [Angstrom], V[sub cell] = 846.9 (1) [Angstrom][sup 3], R[sub exp] = 0.0433, R[sub wp] = 0.0489, for 521 reflections. For M = Ba, a = 7.4409 (3) [Angstrom], c = 16.1367 (8) [Angstrom], V[sub cell] = 893.4 (1) [Angstrom][sup 3], R[sub exp] = 0.0466, R[sub wp] = 0.0522, for 546 reflections. The gillespite structure contains an unbranched single silicate layer, which can be viewed as a tesselation of corner-linked Si[sub 4]O[sub 10] rings. The Cu in MCuSi[sub 4]O[sub 10] is in square-planar coordination with the nonbridging oxygens of the corrugations of the silicate layer. The alkaline-earth atom, in distorted cubic coordination, joins together adjacent [CuSi[sub 4]O[sub 10]][sup 2[minus]] slabs. Increasing the size of the alkaline-earth atom increases the cell dimensions anisotropically (i.e., [Delta]c > [Delta]a) due to the inflexibility of the silicate anion. Room-pressure experiments show no evidence for oxygen intercalation or polytypism. The lattice mismatch between the [CuSi[sub 4]O[sub 10]][sup 2[minus]] slabs of the gillespite structure type and the square-planar CuO[sub 2] layers of the superconducting cuprates is small, which suggests possible applications of these materials as exotic thin-film substrates for the high [Tc] cuprates or other novel structures having cuprate and silicate layers. 20 refs., 2 figs., 4 tabs.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6135130
• Journal Information: Journal of Solid State Chemistry; (United States), Vol. 103:1; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM SILICATES
CRYSTAL STRUCTURE
CALCIUM SILICATES
COPPER SILICATES
STRONTIUM SILICATES
LATTICE PARAMETERS
OXYGEN
TETRAGONAL LATTICES
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
COPPER COMPOUNDS
CRYSTAL LATTICES
ELEMENTS
NONMETALS
OXYGEN COMPOUNDS
SILICATES
SILICON COMPOUNDS
STRONTIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies