Tracing microscopic atomic displacements using polarized Raman spectroscopy: a case study on BaTiO₃

Abstract

Here, we demonstrate the power of polarized Raman spectroscopy (PRS) in tracing microscopic atomic displacements in a single crystalline material. Crystalline materials often show extremely small microscopic atomic displacements as a function of temperature, pressure, electric and magnetic field or across phase transition which can be traced by our defined method using routinely available Raman spectrometers and with the knowledge of Raman tensors and phonon deformation potentials. Importantly, the information is directional and provides a vital information about the root cause of polarization in ferroelectrics, multiferroics. In this article, the method is demonstrated by carrying out the temperature and directional dependent PRS study on BaTiO 3 single crystal, where the Ti ion displacement across the various phase transitions is well documented. The value of the ferroelectric polarization and its component along different crystallographic axes as well as their temperature variations calculated from the Ti displacement obtained by our defined method matches well with the reported results obtained from other techniques. This method thus can be applied to obtain quantitative information of atomic displacements in a crystalline solid.

Amorphous Boron Nitride Memristive Device for High-Density Memory and Neuromorphic Computing Applications

“…35 In the present study, the highest Raman peak observed at 1444 cm −1 was attributed to Raman active phonon mode E 2g , which was the result of planar atomic displacement of the boron and nitrogen atoms caused by an inherent increase in their vibrational motion. 27,36 The UV−visible spectrum of the a-BN sample exhibited a sharp peak at 279.95 nm, suggesting that it is highly transparent within the visibleto-infrared region (Figure S2a). 37 The optical band gap (E gap ) of a-BN was calculated using a Tauc plot as approximately 4.37 eV, as shown in Figure S2b (Supporting Information).…”