Orientation and Mg Incorporation of Calcite Grown on Functionalized Self-Assembled Monolayers: A Synchrotron X-ray Study

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Cryst. Growth Des.

DOI:https://doi.org/10.1021/cg050164x· OSTI ID:913945

Kwak, S; DiMasi, E; Han, Y; Aizenberg, J; Kuzmenko, I

Calcite crystals were nucleated from MgCl2/CaCl2 solutions onto functionalized self-assembled monolayers adsorbed onto E-beam evaporated Au films. Synchrotron X-ray scattering studies of the crystals reveal new information about preferred orientation and Mg incorporation. The Au [111] axis is distributed within 2.6 degrees of the film surface normal, but the oriented crystals may be tilted up to 6 degrees away from this axis. For low Mg{sup 2+} content, SO{sub 3}--functionalized films nucleated primarily near the (106) calcite face, odd-chain-length carboxylic acid terminated alkanethiol films nucleated near the (012) face, and even-chain-length carboxylic acid terminated alkanethiol films nucleated near the (113) face. [Mg{sup 2+}]/[Ca{sup 2+}] concentration ratios (n) of 2 and greater defeated this preferred orientation and created a powder texture. Diffraction patterns within the layer plane from the coarse calcite powders indicated a shift to higher 2 accompanied by peak broadening with increasing n. For 0.5 < n < 3.5, a double set of calcite peaks is observed, showing that two distinct Mg calcite phases form: one of comparatively lower Mg content, derived from the templated crystals, and a Mg-rich phase derived from amorphous precursor particles. According to the refinement of lattice parameters, Mg incorporation of up to 18 mol % occurs for n = 4, independent of film functionality. We discuss the differences between the differently functionalized monolayers and also introduce the hypothesis that two separate routes to Mg calcite formation occur in this system.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 913945
• Report Number(s): BNL--78513-2007-JA
• Journal Information: Cryst. Growth Des., Journal Name: Cryst. Growth Des. Journal Issue: 6 Vol. 5
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
CALCITE
CARBOXYLIC ACIDS
CONCENTRATION RATIO
GRAIN ORIENTATION
LATTICE PARAMETERS
NSLS
ORIENTATION
SYNCHROTRONS
national synchrotron light source