Synthesis, Crystal Structure and NLO Properties of a Mixed Crystal K_1−x(NH₄)_xH₂PO₄ (x = 0.5)

Author： Parthiban S. Meenakshisundaram Subbiah

ISSN： 1074-1542

Source： Journal of Chemical Crystallography, Vol.41, Iss.2, 2011-02, pp. : 111-114

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Abstract

A new mixed crystal K_1−x(NH₄)_xH₂PO₄ (KADP) of ammonium dihydrogen phosphate (ADP) of ADP–KCl system has been synthesized with x = 0.5 by slow evaporation of the mixture of equimolar aqueous solution at room temperature. Crystal composition determined by single crystal X-ray diffraction analysis reveals that it belongs to the tetragonal system with noncentrosymmetric space group I-42d and it is structurally similar to ADP crystals with the following parameters: a = 7.418(3) Å; c = 7.2284(6) Å; v = 404.63(4) Å³; z = 4. The substitution results in defect centers which influence the physical properties. Mixed crystal has a superior NLO activity, twice that of KH₂PO₄ (KDP), a well known NLO material and the enhanced NLO activity is rationalized. The structural analysis of KADP and the influence of partial cationic substitution in ADP by K⁺ ions on the NLO properties are reported.The synthesis and crystal structure of a new mixed crystal K_0.5(NH₄)_0.5H₂PO₄ (KADP) have been presented. The structural analysis of KADP reveals that K⁺ and NH₄⁺ cations coexist in the same crystal of KADP.