Zn₂GeO₄/SnO₂ Nanowire Heterostructures Driven by Plateau–Rayleigh Instability

Abstract

Herein, we report the formation of a particular core–shell structure, with a zinc germanate (Zn2GeO4) nanowire core and a discontinuous shell of SnO2 nanocrystals, obtained in a single-step process. We propose a growth model that combines the Plateau–Rayleigh mechanism to produce a pattern of amorphous germanium oxide (a-GeO2) particles along the Zn2GeO4 nanowire and the subsequent growth of well-faceted SnO2 crystals when the nanowire orientation meets good lattice matching conditions. In this latter case, the linear array of a-GeO2 particles acts as nucleation sites for the SnO2 crystallites, leading to a skewer-like morphology that retains the periodicity of the Plateau–Rayleigh process. Otherwise, nanowires with different orientations appear decorated with a pattern of a-GeO2 beads mimicking a necklace. Atomic resolution electron microscopy has been used to characterize the Zn2GeO4/SnO2 nanoheterostructures. In addition, optical confinement effects have been observed in the luminescence maps and spectra, which have potential for further exploitation in the design of optical microcavities.

Understanding the UV luminescence of zinc germanate: The role of native defects

“…The microstructural analysis of the microwires has been assessed by Raman spectroscopy and X-ray diffraction measurements and it has been already reported. 18,22 This procedure allows us to grow material of high crystalline quality. Figure 1 Reported RT PL results also show that the maximum wavelength of the visible band varies from blue to green depending on the synthesis conditions, which is consistent with the interplay of several intrinsic defects in the luminescence mechanisms.…”

“…The microstructural analysis of the microwires has been assessed by Raman spectroscopy and X-ray diffraction measurements and it has been already reported. 18,22 This procedure allows us to grow material of high crystalline quality. 370 − 380 nm, and another broad band peaked at 500 − 540 nm.…”

Controllable Synthesis and Luminescence Properties of Zn2GeO4 : Mn2+ Nanorod Phosphors

“…As the reaction time increases, Zn 2 GeO 4 :Mn 2+ nanorods will gather together to form a nanorod‐like array structure. Two doping mechanisms of Mn 2+ in the Zn 2 GeO 4 host crystal should be considered: (i) thermal migration and (ii) ion exchange reaction by repeated dissolution and precipitation of the host crystal [39] . The experimental conditions such as reaction temperature and time change show that the product is prepared under short reaction time or low reaction temperature usually include hexagonal Zn(OH) 2 and GeO 2 impurity phases.…”

The role of surface properties in the cathodoluminescence of Zn2GeO4/SnO2 nanowire heterostructures

“…The synthesis of the Zn 2 GeO 4 nanowires and heterostructures was carried out by thermal evaporation. A mixture of ZnO:Ge:C powders (2:1:2 wt %) and SnO 2 in 10% wt of Zn:Ge was conducted during 8 h at 800 o C under an Ar flow of 1.5 l/min [4]. Samples were transferred to a silicon wafer for characterization.…”