Growth, spectral and thermal properties of KAP single crystals in the presence of DL-Alanine and L-Methionine amino acid dopants

Effect of divalent metal ion impurities (Ba²⁺, Ca²⁺ and Mg²⁺) on the growth, structural and physical properties of KAP crystals

Single crystals of potassium hydrogen phthalate (KAP), a semi-organic compound, have been grown by slow evaporation method at room temperature from aqueous solution in the presence of divalent metal ionic impurities Ba(2+), Ca(2+) and Mg(2+). Elemental analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES) proves the incorporation of these impurities into the grown crystals. Powder X-ray diffraction studies confirmed the phase formation and metal ions doping into KAP crystals. Thermogravimetric-differential thermal analysis (TG-DTA) shows the onset decomposition temperatures to be 255, 238, 251 and 250°C for pure, Ba(2+), Ca(2+) and Mg(2+) doped KAP crystals respectively. Microhardness studies revealed that all the three doped crystals have improved hardness values than that of undoped KAP crystal. Ca-KAP crystal exhibited the highest second harmonic generation (SHG) conversion efficiency of 16 mV with the output power of nearly half of the standard potassium dihydrogen phosphate (KDP) crystal. The grown crystals were also subjected to Fourier transform infrared (FTIR) spectroscopy, ultra violet-visible-near infrared (UV-NIR) spectroscopy studies and dielectric studies. Among the three investigated metal ion impurities, Ca(2+) ion seem to have positive influence on the growth, mechanical, thermal, dielectric and SHG characteristics of KAP which makes it suitable for applications.

Effect of amino acid additives on the growth and physical properties of potassium acid phthalate (KAP) crystals

Single crystals of potassium acid phthalate (KAP) have been grown from aqueous solution by slow evaporation technique by adding l-alanine (LA), glycine (Gly) and l-tyrosine (LT) as additives. Powder X-ray diffraction studies confirmed the phase formation and amino acids doping into KAP crystals. The optical absorption studies reveal that the LA doped crystals possess less absorption of visible ray than the pristine, Gly and LT doped KAP crystals. Optical transmission is found to be low in LT doped KAP than in all the other crystals. TG-DTA studies show the decomposition temperatures to be 255 °C, 232 °C, 258 °C and 264 °C for pure, LA, Gly and LT doped KAP crystals respectively. SHG efficiency of LA doped KAP crystal was found to be 1.1 times (31 mV for KDP and 34 mV for LA doped KAP) that of potassium dihydrogen phosphate (KDP) crystal. This is much higher when compared to that of undoped KAP crystal (12mV). The grown crystals were also subjected to FTIR, microhardness and dielectric studies.

Structural, spectral, optical and dielectric properties of copper and glycine doped LAHCl single crystals

Cu2+ and glycine doped L-arginine monohydrochloride monohydrate (LAHCl) single crystals were grown by slow solvent evaporation technique. The grown single crystals were confirmed by X-ray diffraction study and the interaction of dopants with LAHCl molecule was identified in Fourier transform infrared spectra. The crystalline perfection of pure and doped crystals was analyzed by high resolution X-ray diffraction studies. Vickers microhardness and UV-visible spectroscopy were carried out respectively to study the mechanical stability and optical transmittance of pure and doped LAHCl single crystals. He-Ne laser of wavelength 632.8 nm was used to measure refractive index and birefringence of grown crystals. The second harmonic generation efficiency was also measured for pure and doped LAHCl single crystals using Nd:YAG laser.