Direct observation can give hints for controlling crystals growth
Nanocrystals and nanowires of various types are an essential basic element in a wide range of domains including electronics and photonics where these nanomaterials represent a prerequisite for creating new and really groundbreaking electronic and electronic-optical devices. However, the precise knowledge on the details of the growth and decomposition of crystals at nanosize level is still unavailable as these processes represent a challenge for experimental observation and until recently the real-time tracking has not been achievable.
The authors of the new study have applied the electron microscopy of high resolution to observe the behavior of nanocrystals CuO upon changes in the pressure under a pure oxygen atmosphere.
Under high enough pressure, the copper ground has formed crystals of copper oxide. Under the decrease of pressure, the growth in the hermetically-sealed camera has stopped, while upon additional lowering pressure the process has undergone backward.
Using the microscope, the scientists have documented that the disappearance of nanocrystal layer begins with the cleavage of this layer to separate fragments. Moreover, finally, the whole layer but not its single components disappear. The cleavage facilitates the process of removing an excessive layer completely while all subjacent layers of the crystal stay untouched.
This observation concerns not only the copper oxide but all nanosized crystals in general. The growth of mono- and polycrystals of silicon, metal oxides, and other compounds warrant for electronics were conducted before basically by intuition without accurate comprehension on the details of the process at the atomic level. Applying the new data, one could additionally optimize the growth process.
The research article is published in the prominent journal Scientific Reports.
Previously, the researchers from several Russian institutions have developed a technique of assembling nanocrystals from nanoparticles. The suggested method has a benefit that for constructing crystals, only time-honored biocompatible materials are applied.