Lateral deformations of a crystal of potassium acid phthalate in an external electric field

The anisotropy of deformations in potassium acid phthalate crystals arising under the action of an external electric field up to 1 kV mm−1 applied along the [001] polar axis was studied using X-ray diffraction methods at room temperature. Electrical conductivity was measured and rocking curves for reflections 400, 070 and 004 were obtained by time-resolved X-ray diffractometry in Laue and Bragg geometries. Two saturation processes were observed from the time dependences of the electrical conductivity. A shift in the diffraction peaks and a change in their intensity were found, which indicated a deformation of the crystal structure. Rapid piezoelectric deformation and reversible relaxation-like deformation, kinetically similar to the electrical conductivity of a crystal, were revealed. The deformation depended on the polarity and strength of the applied field. The deformation was more noticeable in the [100] direction and was practically absent in the [001] direction of the applied field. X-ray diffraction analysis revealed a disordered arrangement of potassium atoms, i.e. additional positions and vacancies. The heights of potential barriers between the positions of K+ ions and the paths of their possible migration in the crystal structure of potassium acid phthalate were determined. The data obtained by time-resolved X-ray diffractometry and X-ray structure analysis, along with additional electrophysical measurements, allow the conclusion that the migration of charge carriers (potassium cations) leads to lateral deformation of the crystal structure of potassium phthalate in an external electric field.

Effect of trytophan as dopant on potassium acid phthalate single crystals

Optically transparent single crystals of potassium acid phthalate (KAP, 0.5 g) 0.05 g and 0.1 g (1 and 2 mol %) trytophan were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X- ray diffraction analysis confirmed the changes in the lattice parameters of the doped crystals. The presence of functional groups in the crystal lattice has been determined qualitatively by FTIR analysis. Optical absorption studies revealed that the doped crystals possess very low absorption in the entire visible region. The dielectric constant has been studied as a function of frequency for the doped crystals. The thermal stability was evaluated by TG-DSC analysis.

Linear and Nonlinear Optical Constants of Potassium Acid Phthalate crystal

Single crystals of potassium hydrogen phthalate (KAP) are grown by solution growth technique. Linear optical constants are evaluated from UV/VIS/NIR spectrum. The Z scan technique is used to elucidate the third order nonlinearity in the material. The results indicate that the compound exhibits reverse saturable absorption (RSA) and self-defocusing performance. The second harmonic generation (SHG) efficiency of the crystal evaluated by Kurtz and Perry technique is compared with that of the standard KDP crystal. Attempt is made to correlate the SHG efficiency with the crystalline perfection in the material. Full Text: PDF ReferencesMiniewicz.A, Barkiewics.S, "On the electro‐optic properties of single crystals of sodium, potassium and rubidium acid phthalates", Adv.Mat.Opt.Elect,2,157(1993). CrossRef Comeretto.D, Rosy.L, "Optical properties of potassium acid phthalate", J.Mat.Res, 12, 1262(1997). CrossRef Krajewski.T, Breczewski.T, "Dielectric and pyroelectric properties of TGS crystals doped with nitroaniline molecules", Ferroelectrics, 25, 547 (1980). CrossRef N. Kejalakshmy, K. Srinivasan, "Growth, optical and electro-optical characterisations of potassium hydrogen phthalate crystals doped with Fe3+ and Cr3+ ions", Opt. Mater. 27,389–394A, (2004). [5] CrossRef Ester. G.R, Price.R, Halfpenny. P.J, "An atomic force microscopic investigation of surface degradation of potassium hydrogen phthalate (KAP) crystals caused by removal from solution", J.Cryst.Growth, 182, 95(1998). CrossRef Hiroyuki Toda, Carl M. Verber "Simple technique to reveal a slow nonlinear mechanism in a z-scanlike n2 measurement", Opt. Lett. 17(19) 1379(1992). CrossRef K.J. Arun, S.Jayalekshmi, "Investigations on the nonlinear optical properties of glycinium oxalate single crystals", Optoelectron. Lett. 7(2), 136, (2011). CrossRef K.J.Arun, S.Jayalekshmi, "Third order nonlinear optical constants of L-alaninium oxalate", Phot. Lett. Poland 7(3), 81-83 (2015) CrossRef