Publication近日，广东以色列理工学院材料科学与工程系谭启教授（共同通讯作者）与四川大学合作在国际顶级期刊《自然-通讯》上发表题为“Excellent Hardening Effect in Lead-Free Piezoceramics by Embedding Local Cu-doped Defect Dipoles in Phase Boundary Engineering”的高水平论文，采用新策略实现无铅压电陶瓷的优异硬化效果，有望推动其在高功率应用中的发展。该研究获MATEC重点实验室开放研究项目资助，彰显了广以学者在国际材料研究领域的前沿地位。《自然-通讯》是国际顶尖学术期刊《自然》旗下的子刊，也是材料化学等领域公认的高水平期刊，以严格的同行评审和学术影响力著称。该期刊在JCR分区中常年位列Q1， 2024年影响因子为14.7。研究背景与问题压电陶瓷是一种特殊的陶瓷材料，它可以实现机械能与电能的相互转换，在工业和科技领域有着广泛应用，包括声波传感器、声波发生器、电子点火器、压力传感器等。传统含铅压电陶瓷（如PZT）因性能优异且大规模工业化生产，在市场中占据主导地位。然而，铅的毒性对环境有害，因此开发无铅压电陶瓷以替代含铅材料成为研究的重要趋势。其中，基于钾钠铌酸盐（KNN）的无铅压电陶瓷因其在相界工程、织构化、缺陷工程和复合陶瓷等方面取得的显著进展而备受关注，展现出较高的压电系数（d₃₃）、电致应变和温度稳定性。
谭启教授发表、联合发表超过120篇期刊文章、2本大学教材、3本书籍章节及50份企业内部报告。作为一个创新者，他在陶瓷、聚合物、储能和电子器件领域拥有60项专利及商业秘密。作为企业及美国政府科技项目的首席科学家，率先开发了纳米绝缘介电复合材料、高温高能量密度电容器。谭启教授获得多个奖项，包括中国科学院自然科学奖一等奖，通用电气全球研究中心创新奖，2022年广东以色列理工学院最佳教学奖，2023年中国创新创业成果交易会最具投资价值科技成果奖等奖项。他同时还是MRS, ACERS, SPIE, iMAPS and IEEE等学术机构的成员及多家期刊的评审人。
PublicationRecently, Professor Daniel Q. Tan from the Department of Materials Science and Engineering at Guangdong Technion-Israel Institute of Technology (GTIIT) co-published a high-impact paper as a corresponding author in the top journal Nature Communications by collaborating with Sichuan University. The study, titled "Excellent Hardening Effect in Lead-Free Piezoceramics by Embedding Local Cu-doped Defect Dipoles in Phase Boundary Engineering," proposed a new strategy to achieve excellent hardening effect in lead-free piezoceramics, paving the way for their application in high-power devices. The study was supported by the MATEC open research program, reinforcing GTIIT scholars’ leading role in international materials research.Nature Communications is a sub-journal of the renowned and international journal Nature, widely recognized as a high-impact publication in fields such as materials science and chemistry. Known for its rigorous peer-review process and strong academic influence, it consistently ranks in the JCR Q1 category, with a 2024 impact factor of 14.7.Research backgroundPiezoelectric ceramics are a type of ceramic materials capable of interconverting mechanical and electrical energy, with extensive industrial applications such as ultrasonic transducers, acoustic generators, electronic igniters, and pressure sensors. Piezoceramics, represented by lead zirconate titanate (Pb(Zr, Ti)O₃, PZT) family, dominate the piezoelectric market due to excellent electrical properties and large-scale industrial production. Considering the toxicity of lead (Pb) and the need for environmental protection, research on lead-free piezoceramics to replace Pb-based ones is imperative. Among these, potassium sodium niobate ((K, Na)NbO₃, KNN)-based lead-free piezoceramics stand out due to the significant progress in their piezoelectric coefficient (d₃₃), electro-strain, and temperature stability achieved through phase boundary engineering (PBE), texturing, defect engineering, and composite ceramics.
To make KNN achieve the industrial-scale production of high-power applications, piezoceramics are expected to have both high d₃₃ and mechanical quality factor (Qₘ) (also known as hard piezoceramics) as they operate in resonant mode. High d₃₃ ensures the good electromechanical properties, while high Qₘ reduces the heat generation caused by dissipated energy. However, achieving a balance between d₃₃ and Qₘ is highly challenging because they have different preferences for extrinsic contributions. This imbalance is more pronounced in KNN-based piezoceramics. Traditional acceptor doping (i.e., copper Cu and manganese Mn) and the newly-proposed isolatedoxygen-vacancy strategy greatly improve Qₘ but fail to ensure high d₃₃, which compromises the mechanical properties, rendering mass production unfeasible. Additionally, traditional acceptor doping is mainly implemented on pristine KNN ceramics with low d₃₃ values (e.g., <150 pC/N), resulting in even worse d₃₃ after acceptor doping as expected.
Solutions and resultsThis study proposed a new strategy to study potassium sodium niobate (KNN)-based lead-free piezoelectric ceramics and achieved important results in many aspects. By embedding local copper acceptor defect dipoles in orthogonal-tetragonal phase boundary engineering (O-T PBE), the d₃₃ and Qₘ balance of KNN-based ceramics was achieved. This strategy retains the room temperature O-T phase boundary and introduces dimer (CuNb′′′-Vo••)' and trimer (Vo••-CuNb′′′-Vo••)• defects. The existence of trimer defects was confirmed by X-ray absorption fine structure (XAFS) spectroscopy and first-principles calculations. The retained O-T phase boundary and the local structural inhomogeneity caused by the defects ensure high d33, and the defect dipoles formed by the dimer defects polarize the PD pinning domain wall motion and improve Qₘ. The KNN-BNH-1Cu sample was made better than other typical KNN-based piezoelectric ceramics.
Mesoscopic ferroelectric domain structure
and polarization hysteresis behavior
Electromechanical properties
and domain evolution model
ConclusionBased on O-T PBE, by introducing copper acceptor doping, dimer (𝐶𝑢𝑁𝑎′′′−𝑉𝑁••)′ and trimer (𝑉𝑁••−𝐶𝑢𝑁𝑎′′′−𝑉𝑁••)• defects are formed. Dimer defects form defect dipole polarization and pin domain wall motion; trimer defects introduce local structural heterogeneity, resulting in nanoscale multiphase coexistence and rich nanodomains. Experimental results show that when the copper doping amount x=1, Qₘ increases by 4 times, while d₃₃ only decreases by 1/5 (reaching 340 pC/N, Qₘ is 256). This strategy provides a new paradigm for the balance between d₃₃ and Qₘ in lead-free piezoelectric ceramics, which is expected to promote their development in high-power applications and promote the practical application of lead-free piezoelectric ceramics in more fields.Paper linkhttps://www.nature.com/articles/s41467-025-58269-5PROFILE谭启(Daniel Tan)Professor and Deputy Head
of Materials Science
and Engineering Program
Daniel Tan was recruited and appointed by Technion - Israel Institute of Technology as the professor of Guangdong Technion - Israel Institute of Technology in August 2018. Dr. Tan received a Ph. D. in Materials Science and Engineering from University of Illinois at Urbana-Champaign (UIUC) in 1998, and a Ph.D in Solid State Physics from Chinese Academy of Science in 1989 following Academician T.S.Ke. He used to teach at the University of Science and Technology of China. In 1994, he moved to the United States as a visiting scientist (Argonne National Laboratory and UIUC). He joined Honeywell Corp. in 1998 as a Sr. Scientist to develop high-K ferroelectric materials for semiconductor industry. In 2000, he was recruited to CTS Corp. as a Sr. Staff Engineer to develop high performance piezoelectric transducers and cell phone antenna materials. In the following 12 years, he dedicated his passion, innovation and pioneering efforts in Nanodielectrics and Energy Storage to General Electric. In 2016, he joined W.L. Gore as a Sr. Polymer Dielectric Scientist to further the high performance polymer investigations for capacitor and membrane technology.
Dr. Tan has authored/co-authored over 120 journal papers, 2 college teaching textbooks, 3 book chapters, and 50 corporate internal reports. As an innovator, he holds 60 patents and trade secrets in the field of ceramics, polymers, energy storage and electronic components. He has pioneered development in nanodielectric composites, high temperature and high energy density capacitors as a principal scientist for industry and US government. He is the recipient of various awards including the First Place Prize of Natural Science Award of Chinese Academy of Science, GE Global Research Innovation Award, 2022 Best Teaching Award of Guangdong Technion - Israel Institute of Technology, and The Most Worthy Technology Investment Award from the China Innovation and Entrepreneurship Fair 2023. He is a member of MRS, ACERS, SPIE, iMAPS and IEEE and reviewers of several journals.
