A structural comparison of aliovalent analogues: K(Mg[sub 1/3]Nb[sub 2/3])PO[sub 5] and KTiOPO[sub 4]

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

DOI:https://doi.org/10.1006/jssc.1993.1045· OSTI ID:6486625

McCarron, III, E M; Calabrese, J C; Gier, T E; Cheng, L K; Foris, C M; Bierlein, J D ^[1]

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1. Du Pont Central Research, Wilmington, DE (United States)

K(Mg[sub 1/3]Nb[sub 2/3])PO[sub 5] (KMNP) is an aliovalent analogue of potassium titanyl phosphate, KTiOPO[sub 4] (KTP). Single crystals of KMNP were grown from a 3K[sub 2]O/2P[sub 2]O[sub 5] flux and their structure was determined. KMNP is not isostructural with KTP (noncentrosymmetric orthorhombic space group Pna2[sub 1]). Instead, it crystallizes in the noncentrosymmetric, enantiomorphic space groups P4[sub 1]22 and P4[sub 3]22 (tetragonal, a = 6.5366(3), c = 10.847(1) [Angstrom]). Unlike KTP, KMNP exhibits vanishingly small ([approximately]0) second harmonic generation (SHG). The main structural differences between KMNP and KTP are the lack of a (Mg, Nb)-O bond equivalent to the very short titanyl Ti[double bond]O bond found in KTP and a change in the connectivity of the MO[sub 6/2] octahedra - instead of the cis-trans arrangement of the TiO[sub 6/2] chains in KTP, the (Mg[sub 1/3]Nb[sub 2/3])O[sub 6/2] chains of KMNP are linked in an all-cis configuration. Phase evolution in and SHG data for the system K[Ti[sub 1[minus]x](Mg[sub 1/3]Nb[sub 2/3])[sub x]]PO[sub 5](K[T[sub 1[minus]x](MN)[sub x]]P) are also reported. The results of this study suggest that the aliovalent substitution of (Mg[sub 1/3]Nb[sub 2/3]) for Ti is primarily responsible for the dramatic loss of SHG and that the change in space group is only of minimal importance. 24 refs., 7 figs., 4 tabs.

• OSTI ID: 6486625
• Journal Information: Journal of Solid State Chemistry; (United States), Vol. 102:2; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MAGNESIUM OXIDES
CRYSTAL STRUCTURE
NIOBIUM OXIDES
PHOSPHORUS OXIDES
POTASSIUM COMPOUNDS
TITANIUM OXIDES
HARMONIC GENERATION
LATTICE PARAMETERS
ORTHORHOMBIC LATTICES
SPACE GROUPS
TETRAGONAL LATTICES
WAVEGUIDES
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
DIFFRACTION
FREQUENCY MIXING
MAGNESIUM COMPOUNDS
NIOBIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
REFRACTORY METAL COMPOUNDS
SCATTERING
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360602* - Other Materials- Structure & Phase Studies