Crystal growth of KCl:CuO single crystal starting from inhomogeneous solid-melt phase using the Czochralski method

Abstract

In this work the Czochralski technique was employed to grow a pure KCl and KCl:CuO single crystals, these crystals were grown starting from homogeneous and heterogeneous phases, respectively. The heterogeneous phase consists two different phases which are KCl as melting phase and CuO nano-crystals (NCs) as a solid state phase. Due to the high temperature of the crystal growth environment this approach has a big challenge to keep NCs in the solid state phase during the crystal growth process. To control and analyze the obtained crystals, several techniques of characterization were used to investigate the structural and optical properties of CuO NCs dispersed in a crystalline medium (KCl). The main structural results of X ray diffraction (XRD), Raman, and IR spectroscopy prove the presence of nanocrystallites with monoclinic phase of CuO, where the estimated average size is aproxmetly 30 nm. Quantitative analyzes of elements using the energy-dispersive X-ray spectroscopy (EDX) demonstrates the high purity of samples. Moreover, the optical properties were investigated using UV–Vis spectroscopy and photoluminescence (PL), where CuO crystallites exhibit three bands located at 450 nm, 557 nm, and 594 nm with blue shift as a comparison of bulk CuO, this blue shift is a result of nanoscale of CuO. The presence of CuO NCs in the crystalline medium (KCl) enhances the PL properties; this feature makes the obtained crystal an excellent candidate for integration into optical devices that operate within the visible range, particularly between 450 and 600 nm.