## 2 Experimental Section  
The specimens were manufactured using a conventional mixed oxide process. The compositions used in this study were as follows.  
Pb\({}_{0.88}\)(La\({}_{0.6}\) Sm\({}_{0.4}\))\({}_{0.08}\)(Mn\({}_{1/3}\) Sb\({}_{2/3}\))\({}_{0.02}\) Ti\({}_{0.98}\)O\({}_{3+}\) sintering aids (0.25 wt% CuO) were used. The raw materials above 99% purity such as PbO, La\({}_{2}\)O\({}_{3}\), Sm\({}_{2}\)O\({}_{3}\), MnO\({}_{2}\), Sb\({}_{2}\)O\({}_{5}\), and TiO\({}_{2}\) for the given composition were weighted by mole ratio, and the powders were ball-milled for 24 h. After drying, they were calcined at 850 \({}^{\circ}\)C for 2 h. Thereafter, 0.25 wt% CuO was added, ball-milled, and dried again. A polyvinyl alcohol (PVA: 5%) was added to the dried powders. The powders were molded by the pressure of 1000 kg/cm\({}^{2}\) in a mold, which has a diameter of 17 mm, burned out at 600 \({}^{\circ}\)C for 3 h, and then sintered at 1200 \({}^{\circ}\)C and 1230 \({}^{\circ}\)C for 2 h. Density was measured using the Archimedes method. For measuring the piezoelectric and dielectric characteristics, the specimens were polished to 1 mm thickness and then electrodeposited with Ag paste. Poling was carried out at 120 \({}^{\circ}\)C in a silicon oil bath by applying DC fields of 40 kV/cm for 30 min. All samples were aged for 24 h prior to measuring the piezoelectric and dielectric properties. The microstructure and crystal structure of specimens were investigated with the aids of a scanning electron microscope (SEM: Model Hitachi, S-2400, Hitachi High-Technologies Corporation, Tokyo, Japan) and X-ray diffractometer (XRD: BRUKER D8 ADVANCE, Bruker, Billerica, MA, USA), respectively. The operation conditions for the X-ray diffractometer are as follows: 0.25 sec time/step (step size: 0.019443897\({}^{\circ}\)), scan mode: continuous scan. For investigating the dielectric properties, capacitance was measured at 1 kHz using an LCR meter (ANDO AG-4034, Yokogawa, Japan), and dielectric constant was calculated. For investigating the piezoelectric properties, the resonant and anti-resonant frequencies were measured by an Impedance Analyzer (Agilent 4294A, Keysight Technologies, Santa Rosa, CA, USA) according to the IRE standard [26], and then the electromechanical coupling factor and mechanical quality factor were calculated. Dynamic range (D.R.) was calculated as 20 Log (\(\text{Z}\text{a}/\text{Z}\text{r}\)). Here, \(\text{Z}\text{r}\) is the impedance at the anti-resonant frequency, and \(\text{Z}\text{a}\) is the impedance at the resonant frequency. Using the ceramics sintered at 1200 \({}^{\circ}\)C and 1230 \({}^{\circ}\)C for 2 h, ultrasonic piezoelectric devices were manufactured by circular type (14 \(\O\)\(\times\) 0.7 mm), using the ceramics sintered at 1200 \({}^{\circ}\)C for 2 h. Ultrasonic piezoelectric devices a the fixed thickness of 0.7 mm were manufactured by square type (length \(\times\) width, length = width). The ultrasonic piezoelectric devices were fabricated by varying the length of the piezoelectric device to 3.5, 4.9, 6.3, 7.7 and 9.1 mm, respectively. Resonant and piezoelectric characteristics were analyzed. Figure 1 show a photograph of the fabricated ultrasonic piezoelectric samples where the side length of each piezoelectric device is apparent against the length scale.  
Figure 1: A photograph of the fabricated ultrasonic piezoelectric samples.