Pb(Zr,Ti)O3 (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. (K,Na)NbO3 (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, (Na,K)NbO3-Ba(Cu,Nb)O3 (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKNBCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan δ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and 20 μC/cm2.

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• 임지호(인하대학교 신소재공학과) | Ji-Ho Lim (Department of Materials Science and Engineering, Inha University)
• 이주승(인하대학교 신소재공학과) | Ju-Seung Lee (Department of Materials Science and Engineering, Inha University)
• 이승희(인하대학교 신소재공학과) | SeungHee Lee (Department of Materials Science and Engineering, Inha University)
• 정한보(인하대학교 신소재공학과) | Han-Bo Jung (Department of Materials Science and Engineering, Inha University)
• 박춘길(인하대학교 신소재공학과) | Chun-kil Park (Department of Materials Science and Engineering, Inha University)
• 안철우(한국기계연구원 부설 재료연구소) | Cheol-Woo Ahn (Functional Ceramics Department, Powder & Ceramics Division, Korea Institute of Materials Science (KIMS))
• 유일열(금오공과대학교 신소재공학과) | Il-Ryeol Yoo (School of Materials Science and Engineering, Kumoh National Institute of Technology)
• 조경훈(금오공과대학교 신소재공학과) | Kyung-Hoon Cho (School of Materials Science and Engineering, Kumoh National Institute of Technology)
• 정대용(인하대학교 신소재공학과) | Dae-Yong Jeong (Department of Materials Science and Engineering, Inha University) Corresponding author