State Key Laboratory of Coal Resources and Safe Mining Department of Materials Science and Engineering China University of Mining&Technology(Beijing) Beijing 100083 China;
State Key Laboratory of Coal Resources and Safe Mining Department of Materials Science and Engineering China University of Mining&Technology(Beijing) Beijing 100083 China;
State Key Laboratory of Coal Resources and Safe Mining Department of Materials Science and Engineering China University of Mining&Technology(Beijing) Beijing 100083 China;
State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China;
State Key Laboratory of Coal Resources and Safe Mining Department of Materials Science and Engineering China University of Mining&Technology(Beijing) Beijing 100083 China;
(K,Na)NbO3(KNN); lead-free; two-dimensional(2D)structure; piezoelectric property;