Thermal, optical and electrical properties of pure and L-cysteine doped KDP crystals

Abstract

KDP (Potassium Dihydrogen Phosphate) is a well-known ferroelectric crystal with the most promising NLO properties. Pure and L-Cysteine doped (1mol% and 2mol%) KDP crystals were grown at room temperature using slow evaporation technique. The crystals have been characterized using Thermo Gravimetric Analysis (TGA), Dielectric analysis, Photoluminescence (PL) and Second Hamonic Generation (SHG). Thermal behavior of the pure and doped crystals has been investigated in the temperature range room temperature to 500 °C. The dielectric behavior of the crystals has been studied in the frequency range of 100Hz to 100 kHz. Variation of dielectric constant (εr), dielectric loss (tan δ) and a.c. conductivity with frequency was studied. The Photoluminescence study suggests increase of active defects in the crystals due to doping. The second harmonic generation (SHG) efficiency of doped KDP crystals were found to be increasing with the increase in doping concentration of L-Cysteine. The results are reported and discussed.