arXiv subjects

Barnik Mandal

Publications and source records attributed to Barnik Mandal.

3 recordsLinked to original sources

arXiv2025

Highly Transparent Lead-Free Piezoelectric Haptic Device

Acoustic haptic technology adds touch sensations to human-machine interfaces by integrating piezoelectric actuators onto touchscreens. Traditional piezoelectric haptic technologies use opaque lead-containing ceramics that are both toxic and visible. We have developed a highly transparent lead-free piezoelectric haptic device using potassium sodium niobate (KNN) and transparent conductive oxide thin films. The KNN film, grown on glass, exhibits a pure perovskite phase and a dense microstructure. This device achieves up to 80% transmittance, surpassing lead zirconate titanate (PZT) thin films. It generates an acoustic resonance at 16.5 kHz and produces a peak-to-peak displacement of 1.0 um at 28 V unipolar, making it suitable for surface rendering applications. This demonstrates the potential of transparent lead-free piezoelectric actuators as an effective alternative to conventional PZT haptic actuators.

cond-mat.mtrl-sci↗

arXiv2025

Ferroelectric HfO$_2$-ZrO$_2$ multilayers with reduced wake-up

Since the discovery of ferroelectricity in HfO$_2$ thin films, significant research has focused on Zr-doped HfO$_2$ and solid solution (Hf,Zr)O$_2$ thin films. Functional properties can be further tuned via multilayering, however, this approach has not yet been fully explored in HfO$_2$-ZrO$_2$ films. This work demonstrates ferroelectricity in a 50 nm thick, solution-processed HfO$_2$-ZrO$_2$ multilayer film, marking it as the thickest multilayer film to date exhibiting ferroelectric properties. The multilayer structure was confirmed through transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy, with high-resolution TEM revealing grain continuity across multiple layers. This finding indicates that a polar phase in the originally paraelectric ZrO$_2$ layer, can be stabilized by the HfO$_2$ layer. The film attains a remanent polarization of 9 uC/cm$^2$ and exhibits accelerated wake-up behavior, attributed to its higher breakdown strength resulting from the incorporation of multiple interfaces. These results offer a faster wake-up mechanism for thick ferroelectric hafnia films.

cond-mat.mtrl-sci↗

arXiv2025

Solution-Based Fabrication of High-Performance K$_{0.5}$Na$_{0.5}$NbO$_3$ Thin Films for Surface Haptics

K$_{0.5}$Na$_{0.5}$NbO$_3$ is among the most promising lead-free piezoelectrics. While its sputtered films match the performance of the champion piezoelectric Pb(Zr,Ti)O$_3$, reproducible processing of high-quality and time-stable solution-processed K$_{0.5}$Na$_{0.5}$NbO$_3$ films remains challenging. Here, we report 1 $\mu$m-thick Mn-doped K$_{0.5}$Na$_{0.5}$NbO$_3$ films prepared through a chemical solution deposition process, which have perfectly dense microstructure and uniform composition across their thickness. The films exhibit a high transverse piezoelectric coefficient ($e_{31,f} = -15.4$ C/m$^2$), high dielectric permittivity ($\varepsilon_r \approx 920$), low dielectric losses ($\tan\delta = 0.05$) and can withstand electric fields up to at least 1 MV/cm. The functional properties show excellent stability over time, and the synthesis process is reproducible. Furthermore, a surface acoustic haptic device is demonstrated by using K$_{0.5}$Na$_{0.5}$NbO$_3$ thin-film actuators. The results demonstrate the high potential of Mn-doped K$_{0.5}$Na$_{0.5}$NbO$_3$ films to become a replacement for lead-based Pb(Zr,Ti)O$_3$ films in piezoelectric applications.

cond-mat.mtrl-sci↗