1. Unique Nanoscale Physical Effects
Surface effect: As the size decreases, the number of surface atoms of nanodiamonds increases sharply, leading to a rapid increase in specific surface area and surface binding energy
. This lack of atomic coordination causes many defects on the surface, giving nanodiamonds extremely high surface activity and instability, making them very easy to combine with other atoms (such as adsorbing functional groups like -COOH, -OH, etc.).

Quantum size effect: When the particle size decreases to a certain value, the electronic energy levels near the Fermi level change from quasi-continuous to discrete, and the absorption spectrum threshold shifts towards shorter wavelengthsThis effect gives nanomaterials high optical nonlinearity, specific catalytic properties, and strong oxidizing and reducing capabilities.

Small size effect: When the particle size is comparable to or smaller than physical characteristic dimensions like light wavelength and de Broglie wavelength, the periodic boundary conditions of the crystal are destroyed, leading to significant changes in macroscopic properties such as acoustic, optical, electrical, magnetic, and thermal characteristics.

Macroscopic quantum tunneling effect: Macroscopic quantities of nanoparticles (such as magnetization) exhibit a tunneling effect through thermal barriersThis physical effect defines the time limit for information storage in magnetic media and is the foundation of future miniaturized electronic devices.

2. Significantly Altered Physical and Structural Parameters

Larger lattice constant and lattice distortion: The lattice constant of ordinary natural cubic diamonds is relatively small, while that of nanodiamonds is about 0.360–0.365 nm, slightly larger than natural diamonds.Due to the combined action of the size effect and lattice distortion, the lattice distortion of nanodiamonds (0.2%–1%) is about twice as large as that of ordinary diamonds synthesized by the static pressure method.

Extremely low Debye characteristic temperature: The Debye temperature is an important physical quantity reflecting the bonding force between atoms.The Debye temperature of ordinary large-particle diamond single crystals is as high as 1800–2242K, whereas that of nanodiamonds is only about 364K.This means the bonding force between atoms in nanodiamonds has been greatly weakened, and the amplitude of atoms deviating from their equilibrium positions has increased by 2.4 times, leading to a substantial increase in their activity.

Decreased thermal stability (low initial oxidation temperature): Ordinary diamonds usually start oxidizing at 800°C.In contrast, due to their super chemical activity and severe crystal structure incompleteness, the initial oxidation temperature of nanodiamonds in the air is lowered to 500–530°C, which is significantly lower than that of macroscopic large-sized diamonds

Huge specific surface area: Nanodiamonds have a huge specific surface area of 200–420 m²/g.Compared to ordinary diamonds, this allows them to adsorb a large number of impurity atoms or functional groups.