Development of high quality large size direction controlled ADP single crystals and the effect of impurities on their growth

Abstract

Most of the extraordinary achievements in modern technology have been accomplished through the development of microelectronic, optoelectronic and optical devices made of artificial crystals. The growth of high quality single crystals remains a challenging endeavor of materials science. The present thesis discusses the growth and properties of ammonium dihydrogen phosphate (ADP) single crystals in the presence of various impurities. The thesis begins with brief introduction of crystal growth. The existing methods of low temperature solution growth are also presented. The necessary instrumentation details of the characterization techniques are discussed. Effect of ammonium malate on the growth and properties of ammonium dihydrogen phosphate single crystals grown by slow cooling along with seed rotation method has been investigated. The HRXRD studies show that the crystalline perfection of the crystals is good. The relation between the crystalline perfection and the SHG efficiency is explicated using HRXRD results. The significant results of the addition of semi-organic material L-Lysine monohydrochloride dihydrate on the growth and various properties of ADP single crystal grown by slow cooling method have been presented. The growth setup and the reason for the higher crystalline perfection are discussed elaborately. Though we got such results, naturally, in the case of ADP and KDP single crystals the growth of prismatic face is hard to control. The most dangerous impurities are trivalent metals Cr3+, Fe3+, Al3+, which make also important habit distortions. Explanations for higher growth rate are given. Comparison of all the results indicated that the presence of ammonium chloride in the mother solutions of ADP greatly increases the piezoelectric and SHG efficiencies and using the additive, crystal of size 7 cm in length and diameter was grown successfully. Summary of the present investigation and suggestions for the future work are presented. newline