Synthesis and characterizations of calcium germanatenanowires

Abstract

Crystalline calcium germanate nanowires with a diameter of 50–200 nm and length of several dozens of micrometres have been synthesized by a simple and facile hydrothermal process. X-ray diffraction and high-resolution transmission electron microscopy results show that the crystalline calcium germanate nanowires are mainly composed of tetragonal Ca₂GeO₄, orthorhombic Ca₂Ge₇O₁₆ and triclinic CaGe₂O₅ phases. The role of different growth conditions demonstrates that the hydrothemral temperature, reaction time, compactness, Ca source materials and surfactants play an essential role in the formation and size of the calcium germanate nanowires. The nucleation and crystalline growth mechanism are proposed to explain the formation and growth of the calcium germanate nanowires. The photoluminescence spectrum of the calcium germanate nanowires shows three fluorescence emission peaks centered at 421 nm, 488 nm and 529 nm, exhibiting a promising potential for optical applications.