Ab initio study of Al(III) adsorption on stepped {100} surfaces of KDP crystals

Journal Article · Thu Apr 01 04:00:00 EST 2004 · Structural Chemistry

OSTI ID:862209

Salter, E A; Wierzbicki, A; Land, T A

Crystals of potassium dihydrogen phosphate (KH{sub 2}PO{sub 4}, KDP) are grown in large scale for use as nonlinear material in laser components. Traces of trivalent metal impurities are often added to the supernatant to achieve habit control during crystal growth, selectively inhibiting the growth of the {l_brace}100{r_brace} face. Model systems representing AlPO{sub 4}-doped KDP {l_brace}100{r_brace} stepped surfaces are prepared and studied using ab initio quantum methods. Results of Hartree-Fock partial optimizations are presented, including estimated energies of ion pair binding to the steps. We find that the PO{sub 4}{sup 3-} ion takes a position not unlike that of a standard phosphate in the crystal lattice, while the aluminum atom is displaced far from a K{sup +} ion position to establish coordinations with the PO{sub 4}{sup 3-} ion and to bind with another lattice-bound phosphate. Our optimized structures suggest that it is the formation of a fourth coordination of Al(III) to a third phosphate ion from solution, or perhaps from a nearby position in the lattice, that disrupts further deposition, pinning the steps.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 862209
• Report Number(s): UCRL-JRNL-203527
• Journal Information: Structural Chemistry, Journal Name: Structural Chemistry Journal Issue: 2 Vol. 16
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
42 ENGINEERING
ADSORPTION
ALUMINIUM
ATOMS
CRYSTAL GROWTH
CRYSTAL LATTICES
DEPOSITION
IMPURITIES
ION PAIRS
LASERS
PHOSPHATES
POTASSIUM