Spherulitic and rotational crystal growth of Quartz thin films

Nick R Lutjes,Beatriz Noheda,Jordi Antoja-Lleonart,Silang Zhou,Václav Ocelík

doi:10.1038/s41598-021-94147-y

Abstract

To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth. Thus, understanding the mechanisms that give rise to spherulitic growth can help regulate the growth process. Here the spherulitic type of 2D crystal growth in thin amorphous Quartz films was analyzed by electron back-scatter diffraction (EBSD). EBSD was used to measure the size, orientation, and rotation of crystallographic grains in polycrystalline SiO2 and GeO2 thin films with high spatial resolution. Individual spherulitic Quartz crystal colonies contain primary and secondary single crystal fibers, which grow radially from the colony center towards its edge, and fill a near circular crystalline area completely. During their growth, individual fibers form so-called rotational crystals, when some lattice planes are continuously bent. The directions of the lattice rotation axes in the fibers were determined by an enhanced analysis of EBSD data. A possible mechanism, including the generation of the particular type of dislocation(s), is suggested.

Highlights

To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth
Besides non-crystallographic branching leading to the formation of individual fibers in Quartz thin film crystallization[1], a gradual crystal lattice rotation inside each fiber is observed through Electron Back-Scatter Diffraction (EBSD)
We use EBSD analysis to understand the spherulitic growth of crystalline Quartz from an amorphous thin film with unprecedented detail

Summary

Introduction

To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth. Individual spherulitic Quartz crystal colonies contain primary and secondary single crystal fibers, which grow radially from the colony center towards its edge, and fill a near circular crystalline area completely During their growth, individual fibers form so-called rotational crystals, when some lattice planes are continuously bent. Besides non-crystallographic branching leading to the formation of individual fibers in Quartz thin film crystallization[1], a gradual crystal lattice rotation inside each fiber is observed through EBSD. This kind of crystal growth has already been reported as micron-sized trans-rotational 2D crystals of FeO7 and SbTe8, formed by thermally-induced crystallization of amorphous thin films during in-situ experiments in a transmission electron microscope. The authors in that study used EBSD to determine crystal lattice orientation, combined with scanning X-ray micro-diffraction, which has Scientific Reports | (2021) 11:14888

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