Studies on some ternary alkali lead bromide crystals

Abstract

Crystal growth is an important area of research in Materials Science in which emphasis is given on the synthesis, growth and characterization of crystalline materials. Alkali lead bromide mixed crystals (pure and rare earth -doped) are found to very good properties. They are not only the potential laser host materials but also promising low phonon energy value materials, expected to be useful in the acousto-optic industry. However, in all the reports, the growth of single crystals has been done by the melt method. It would be better if we are able to grow the crystals at room temperature, may be, by the solution method. Although it is a challenging task, it is interesting to grow such single crystals by the solution method. The present study is an attempt in this direction. The materials chosen for the present investigation as per the expected composition are KPb2Br5, KPbBr3, K2PbBr4 ,K3PbBr5 , NaPb2Br5, NaPbBr3, Na2PbBr4, and Na3PbBr5. These are expected to possess the required properties to demonstrate their use in several applications. The main objectives of the present work are to grow good quality crystals by the solution method and to study the structural, chemical, optical, thermal, and dielectrical properties of the crystals. Details of the present study are reported in this thesis. In our present work, we have grown all the eight samples by the slow evaporation method. The grown samples were characterized by single crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), UV-Vis-NIR spectral, atomic absorption spectroscopic (AAS), scanning electron microscopic (SEM), energy dispersive X-ray spectral (EDAS), thermogravimetric (TG/DTA) and electrical (AC and DC) measurements. Vii The results obtained in the present study indicate that even though the crystals grown are not properly mixed they exhibit superior optical characteristics required for acousto-optical (AO) devices.