What are Nanocrystals?

Nanocrystals refer to crystalline materials on the nanometer scale, or nanoparticles with a crystalline structure. Nanocrystals have very important research value. The electrical and thermodynamic properties of nanocrystals exhibit strong size dependence, allowing them to be controlled through careful fabrication processes. Nanocrystals can provide the crystal structure of monomers, and the study of the crystal structure of these monomers can provide information to explain the behavior of macroscopic samples of similar materials, regardless of complex grain boundaries and other crystal defects. Semiconductor nanocrystals with dimensions smaller than 10 nanometers are commonly referred to as quantum dots.

definition:

Nanocrystals refer to single-phase or multi-phase polycrystals composed of grains with a size of 1–10 nm [1].

Crystal structure

The structural feature of this crystal is that the atoms on the grain boundary account for 50% of the total number of atoms in the crystal. The number of grain boundaries in the nanocrystal is about 10 grain boundaries/cm.

principle:

In such a huge number of grain boundaries (or phase boundaries), the atoms at the core are constrained by adjacent lattices to form a certain arrangement configuration, which is different from crystals (atomic arrangement in crystal grains) and Different from the amorphous state, but hooked into a new configuration, it is a three-dimensional ordered structure with its own periodicity and atomic spacing, and different grain boundaries are different from each other. There are 10 atomic configurations in 10 grain boundaries in a 1cm nanocrystal. This is because the orientation of each grain is different, and the grains with different orientations exert different constraints on the atoms at the core of the surrounding grain boundaries in different sizes and directions. , resulting in different configurations of atomic arrangements [2].

Grain boundary phase:

The atoms on the grain boundary (or phase boundary) are also called grain boundary phase (or phase boundary phase). The new properties of nanocrystals mainly come from the special arrangement of atoms on the grain boundary phase (or phase boundary phase). The new configuration of the atomic arrangement of the core part on the phase boundary brings new properties to nanocrystals, which are usually prepared by gas-phase shock condensation [3].