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How to use PFM technology to explore the internal microstructure of materials? Learn the secret of high resolution!
With the rapid development of modern science and technology, in-depth understanding of the internal microstructure of materials has become one of the focuses of many research fields. Piezoresponse Force Microscopy (PFM) is an innovative variant of the atomic force microscope capable of imaging and manipulating the field of piezoelectric/ferroelectric materials at high resolution. This article will delve into the operating principles and applications of PFM and reveal the secrets of its high resolution.
Basic principles of PFM technology
PFM technology has gradually attracted widespread attention since it was first implemented, mainly due to its advantages in different fields of ferroelectric materials, semiconductors and even biology.
PFM enables researchers to identify areas of varying sizes, ranging from 100 × 100 μm2, to the nanoscale, while simultaneously imaging sample surface topography.
In a typical PFM operation, researchers use a sharp conductive probe to contact the piezoelectric material and apply an AC voltage to the probe to stimulate deformation of the sample. The deflection of the probe is detected by standard split photodiode detection methods and demodulated by a lock-in amplifier to achieve high-resolution imaging.
Basic knowledge of piezoelectric effect
The piezoelectric effect describes the strain produced by a material when an electric field is applied. This effect enables PFM to detect electrical and mechanical changes in materials. Taking BaTiO3 as an example, when a voltage of 1V is applied, a tiny displacement will occur, only 0.0856 nanometers. Such small displacements are difficult to capture for traditional detection systems, so PFM uses phase-locking technology to separate the target signal from random noise.
PFM’s multiple imaging modes
PFM technology can be distinguished into vertical and lateral imaging modes. By splitting the photodiode detector, PFM can obtain in-plane and out-of-plane piezoelectric response signals to analyze the polarization direction of the material.
In vertical PFM mode, the direction of polarization can be identified with phase information, while in lateral PFM mode, in-plane polarization components can be determined.
Application of PFM in biomaterials
The application of PFM technology in biomaterials has also shown its broad potential, such as in the study of teeth, bones, lungs, and single collagen fibers. The endogenous piezoelectricity of these materials may play an important role in their mechanical biology. play a key role in learning.
Introduction to advanced PFM mode
With the advancement of technology, PFM has also launched a variety of advanced modes, significantly improving the flexibility of detecting nanoscale features. For example, time-sequential PFM technology allows instantaneous imaging of material switching by applying voltage pulses above a critical voltage to the sample and subsequently imaging, capturing the instantaneous switching process.
In addition, contact resonance PFM technology improves the signal-to-noise ratio of the signal by adjusting the applied frequency, thereby achieving higher measurement accuracy. The switching spectrum (SS) PFM technology further expands the application range of PFM and provides detection of material properties under different electric fields.
Conclusion
The development of PFM technology is rapidly promoting research in materials science, electronics and even biomedicine. This technology can reveal the mysteries of the internal structure of various materials with high resolution, and as the technology continues to advance, it will bring more sophisticated observation and research methods. In the future, in what new fields or technologies can PFM continue to exert its strong potential?
