Uncovering piezoelectric effect in polycrystalline diamond membranes

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Diamonds have historically been considered nonpiezoelectric for over 100 years.
• Piezoelectricity is the ability of certain materials to generate an electric charge in response to applied mechanical stress.

Purpose of the Study:

• To investigate the piezoelectric effect in ultrathin and ultraflexible polycrystalline diamond membranes.
• To understand the origin of this unexpected piezoelectricity and its dependence on membrane characteristics.

Main Methods:

• Fabrication of ultrathin and ultraflexible polycrystalline diamond membranes.
• Experimental measurement of the piezoelectric voltage coefficient.
• First-principles calculations to model the underlying physical mechanisms.

Main Results:

• A notable piezoelectric effect was observed in polycrystalline diamond membranes.
• The piezoelectric response peaked in ~5-micrometer-thick membranes, with a voltage coefficient of ~82.2 mV·m/N.
• First-principles calculations attributed the piezoelectricity to local asymmetry induced by grain boundaries.

Conclusions:

• Polycrystalline diamond membranes exhibit significant piezoelectric properties, challenging previous assumptions.
• Grain boundary asymmetry is the key mechanism driving the observed piezoelectricity.
• These findings pave the way for novel diamond-based applications in energy harvesting, sensing, and wearable electronics.