npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041


Review Paper

New Phys.: Sae Mulli 2020; 70: 220-225

Published online March 31, 2020

Copyright © New Physics: Sae Mulli.

Large Piezoelectric Coefficient of high Quality Mn-doped (K$ _{0.5}$Na$ _{0.5}$)NbO$ _{3}$ Thick film by Using a Laser Doppler Vibrometer

Hae Jin SEOG1, Bong Chan PARK1, Shinuk CHO1, Tae Heon KIM1, Ill Won KIM1*, Aman ULLAH2,3

1Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Korea

2Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Korea
3Department of Physics, University of Science and Technology, Bannu 28100, KPK, Pakistan


Received: February 18, 2020; Revised: February 19, 2020; Accepted: February 19, 2020

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


The development of lead-free ferroelectric and piezoelectric materials is required from the viewpoint of environmental preservation. Among various lead-free materials, (K$ _{0.5}$Na$ _{0.5}$)NbO$ _{3}$ (KNN) has attracted much attention due to its excellent ferroelectric and piezoelectric properties. In this study, high-quality Mn-doped (K$ _{0.5}$Na$ _{0.5}$)NbO$ _{3}$ (KNMN) films were deposited on Pt/TiO$ _{2}$/SiO$ _{2}$/Si substrates by using the sol-gel method. For various numbers of coating cycles; the KNMN films have thicknesses of around 0.8, 1.0, 1.5 and 2.0 $\mu$m, respectively. The effective piezoelectric coefficient ($d_{33,\text{eff}}$) of the KNMN films was analyzed using a home-made laser Doppler vibrometer that could measure large millimeter-scale areas. The average $d_{33,\text{eff}}$ of a 2-$\mu$m-thick KNMN film was measured to be around 120 pm/V, which is comparable to those of lead-based materials and higher than those of other lead-free piezoelectric film alternatives.

Keywords: Effective piezoelectric coefficient, Laser Doppler vibrometer, (K,Na)NbO$ _{3}$, Thick film, Lead-free


Fig. 1. (a) Metal/Ferroelectric/Metal (MFM) capacitor structure for measuring device using the laser Doppler vibrometer (LDV) system. (b) Effective piezoelectric coefficient ($d_{33,\text{eff}}$) of the KNMN 2.0 $\upmu$m-thick film. The inset shows the P-E hysteresis loop of the KNMN film.

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