姓 名: 武海军
职 称: 教授
联系电话: 15829286473
个人主页: http://gr.xjtu.edu.cn/zh/web/wuhaijunnavy
E-MAIL: wuhaijunnavy@xjtu.edu.cn
专业方向: 球差扫描透射电镜,无铅压电,热电,功能氧化物薄膜
个人详情

一、学术成果概述

申请人于新加坡国立大学获得博士学位后任李光耀博士后研究员(Lee Kuan Yew Postdoctoral Fellow,新加坡国立大学每年仅1名),目前在西安交通大学工作。申请人围绕国家对于高效功能材料的战略需求,长期从事可实现力↔电↔热环境感知和能量转换的铁电/压电和热电材料的结构设计、机理分析及性能调控。电子功能材料的晶格和电荷等自由度共存并相互作用,产生丰富的物理效应,例如铁电/压电效应(晶格应变与极化电荷耦合)和热电效应(晶格简谐振动能量子即声子与载流子电荷耦合)。这些材料的序参量往往具有长程属性,这导致材料对外场的静态响应(例如极化强度)优异但是动态响应(例如压电系数d33)往往不佳。电偶极子因其强的各向异性而倾向长程排布,但是他们不易随外场变化而灵活响应,因此传统铁电材料的压电响应不理想;声子/载流子作为材料热/电传输的媒介倾向长程传导,但是对于要求低热传导和高电传导的热电材料,在保证电传导长程性的同时实现声子传导短程化是核心。如何将这些本征的长程序参量短程化是优化材料动态响应的关键挑战。

申请人通过调控点缺陷实现长程序参量的短程化,从而优化铁电/压电和热电材料动态响应,基于此思路开展了如下工作:(1)利用材料因元素挥发所产生的本征空位,在长程基体中形成短程有序的纳米畴,其短程有序的二维畴界有利于电偶极子在两相间灵活旋转,据此制备的无掺杂NaNbO3薄膜的压电系数是性能报道最高的无铅薄膜的四倍、是性能报道最高的铅基薄膜的两倍,为高性能无铅压电薄膜开辟了新途径,如图1A所示;(2)通过固溶置换原子来调控相的稳定性,彻底打破长程基体的束缚,形成多相共存的短程有序畴,电偶极子可在低能垒的共存相之间灵活旋转,实现了无铅压电陶瓷压电敏感性和热稳定性的协同提升,在Ca和Sn固溶的BaTiO3陶瓷中获得了室温附近30 oC的宽温域内压电系数d33>600 pC/N(之前文献记录,此性能只有一个温度点),如图1B所示;(3)通过点缺陷从局域上扰乱晶格的长程谐振性来散射声子,同时调控电子结构来优化载流子长程输运,从电子和原子层次解耦热电输运参数,协同优化了热电材料中强耦合的电声输运性能,获得了极宽温域的高热电性能,在K掺杂、S固溶的PbTe中实现了热电优值ZT>2的温域从50 oC提升到250 oC,创造了当时平均ZT值的最高记录1.56,如图1C所示。这些研究为提升功能材料动态响应提供了新思路。

图1. 研究问题、思路及成果概述

目前,申请人在上述领域共发表SCI收录论文107篇,其中以(共同)第一或通讯作者身份发表60篇(其中IF>10的文章44篇),包括Science (1), Nat. Commun. (3), Adv. Mater. (3), J. Am. Chem. Soc. (JACS, 8), PNAS (1), Energy Environ. Sci. (EES, 7), Adv. Energy/Funct. Mater./Adv. Sci. (7)等,其中ESI高被引论文20篇,SCI引用>100的文章21篇,SCI总被引>6500次,SCI他引4680次,H因子44 (WOS ResearcherID: B-8598-2016)。研究工作被Science的Insights专栏报道、Science以摘选图片的形式进行了亮点报道、Nature文章在摘要中高度评价等。被国际同行评价为:“通过多原子掺杂显著地抑制了长程有序(significantly suppress long-range ordering)获得了纳米级短程有序”、“通过固溶构建新型相界在优化压电综合性能方面取得巨大的成功(great success)”、“结构缺陷降低声子热导的代表作”、“点缺陷优化电子能带结构显著地提升(remarkably improved)电声传输”、“方法简单但是非常有效(simple yet highly effective)”、“低成本(low-cost)的制备方法具有实际应用的优势(practical advantages)”、“成分越简单性能反而越好(Less can be more)”、“毫无疑问地(little doubt)证明了材料具有高的热稳定性”、“达到应用水平(reached a level sufficient for use in applications)”等。

二、研究方向

1.各向同性热电材料

利用点缺陷调控载流子分布和声子传输,协同优化各向同性热电材料中强耦合的热电参数,提出了协同优化电声输运的新策略,在不同的热电体系中均实现了综合性能的新突破

热电材料是一类可实现热能和电能相互转换的新型功能材料,在温差发电和固态制冷方面具有广阔的应用前景,但是热电材料主要的应用瓶颈是低的转化效率(ZT=α2σκ-1T-1)。高效热电材料具有大的温差电动势α、高的电导率σ、以及低的热导率κ。然而热电材料这些电声输运参数相互依赖、此消彼长,如何协同优化这些相关联的参数以提升综合性能一直是热电材料领域的关键科学问题。

武海军通过在各向同性热电材料中引入以点缺陷为主导多尺度缺陷,协同优化了材料的电声输运行为。点缺陷在前期研究中无法被直接观察和表征,因此其对电声输运的作用往往被严重低估进而无法被充分利用。武海军运用球差矫正扫描透射电镜直接观察到热电体系中广泛存在着大量的间隙原子,并且发现相比纳米结构,点缺陷在电声输运中可以起到更加重要的作用。除了传统的异价置换原子掺杂以提高电导率和同价置换原子固溶以提高温差电动势外,武海军发现:间隙原子可填补材料本征的空位,提高载流子迁移率,进一步提高电导率;同时,高密度的间隙原子(或团簇)还可以作为有效的声子散射源,极大地降低晶格热导率。据此,武海军提出构建以点缺陷为主导的多尺度结构缺陷从电子、原子、晶格层次同步优化电声输运的方法,并在不同的热电体系(锡基和铅基硫族化合物)中获得成功应用。例如,在PbTe中,武海军通过掺杂钾和固溶硫,引入了原子级的点缺陷、纳米级析出相及亚微米级相界等,获得很高的综合热电性能:ZT>2的温度区间从50 oC提升到250 oC。该方法有望成为继纳米化后应用更广、效果更佳的同时优化电声输运的新策略。

武海军以一作/共一/通讯在该方向上发表IF>10文章15篇,包括Nat Commun (2014), Energ Environ Sci (2013, 2015, 2018, 2019), J Am Chem Soc (2017, 2020), PNAS (2019), Adv Energ Mater (2019, 2019),等。受邀撰写热电专著一章(Springer)。武海军的上述工作得到了业内专家的广泛好评:京都大学Kageyama教授在Nat Commun的关于材料化学和物理前沿综述中,以武海军的工作为代表介绍热电材料,肯定了我们的工作是降低声子热导的“effective means (有效方法)”;张清杰院士在发表于Nature的文章摘要中肯定武海军的工作为利用多尺度结构缺陷减低声子热导的两篇代表作之一。

2.各向异性热电材料

利用点缺陷调控载流子迁移,提高各向异性热电材料的晶体对称性,解决了其低热导且低电导的固有问题,维持其本征低热导的同时大幅提升了电传导,为开发新型热电材料提供了新思路

以硒化锡(SnSe)为代表的新型各向异性热电体系因具有环境友好且廉价的元素而极具潜力。这些材料因具有二维弹簧式(层内强健和层间弱键)的低对称性结构而呈现高的非谐振性,对声子传输具有强烈的散射,因此本征地具有极低的热传导,而且其电传输性能也非常差。因此如何保持或降低其低热导同时大幅度提升其电传导是本领域面临的挑战之一。

注意到传统的各向同性热电材料(如PbTe)因具有高的晶体对称性,其电子能带收敛或重叠,能带简并度高,本征地具有高的电输运性能,武海军提出引入置换原子来提高材料的晶体对称性,以大幅提升材料的电传输性能、同时进一步降低材料的晶格热导率、最终获得高的综合热电性能的思路。以SnSe为例,其高的热电性能只出现在很窄温度区的高温立方相,在很宽的低温区,其低对称性相的性能非常低。武海军通过引入置换原子Te,减小了Sn-Se强健和弱键的键长和键角的差异,提高了SnSe的晶体对称性,不仅增加了能带简并度,而且有利于载流子迁移,实现了材料的电导率和温差电动势的同时提升;同时Te置换原子也会引起局部晶格畸变,增加了声子散射,进一步降低了材料的晶格热导率。在室温--500 oC的宽温域范围内,材料的平均ZT从1.2提升到1.6,对应的能量转化效率从14%提升到19%,创造了该温域热电材料的新记录。

武海军以一作/共一/通讯在该方向上发表IF>10文章8篇,包括J Am Chem Soc (2014, 2019, ESI高引文章), Adv Energ/Funct Mater (2015, 2019), Mater Horiz (2019)等,合作发表一篇Science (2019)。武海军的上述工作,得到了业内专家的广泛好评:美国西北大学Kanatzidis教授(埃尼奖获得者)在发表于Chem Rev综述中肯定了武海军的工作“enables higher carrier mobility without deteriorating the Seebeck coefficient” (实现了温差电动势和迁移率的同时优化);张清杰院士以及国际热电协会主席Ctirad Uher教授在发表于Adv Mater综述中盛赞了武海军“The multiscale features ... were clearly resolved ... advanced electron microscopy techniques (运用先进电子显微镜非常清晰地展现了多尺度结构缺陷) ”。

3.无铅压电陶瓷

利用点缺陷调控相的稳定性,扩宽了纳米相共存(电偶极子可灵活响应)的温域,同步提高了无铅压电材料的压电敏感性和温度稳定性,为拓宽了无铅压电材料应用范围

以锆钛酸铅 (PZT) 为代表的铅基压电材料因其优异的性能而被广泛应用,然而PZT含有大量有毒元素铅,因此开发高性能无铅压电材料来替代PZT就显得很重要。钛酸钡 (BTO) 和铌酸钾钠 (KNN) 是最具潜力的无铅压电体系,但因其固有的多步相变特征导致其相界倾斜,其大压电性能的温度稳定性与PZT差距很大,因此如何协同提高压电敏感性和温度稳定性是本领域的难题。

武海军拟利用其多步相变的不利特性,通过固溶引入多种置换原子来调控相稳定性,设计了两种新的相界调控思路:(1)引入准四相点,在该点附近,两个铁电相界靠近形成一个宽温域的、三相共存的相界带,纳米级共存相之间具有很小的能垒,便于电偶极子在外场下灵活响应;同时宽温域的相界带有利于高的压电敏感性的温度敏感性。基于该思路,武海军在BTO体系中固溶Sn和Ca,获得具有准四相点的相图,使压电系数从600 pC/N提升到700 pC/N,并且在室温以上40 oC的宽温域内(之前记录:仅一个温度点)压电系数大于600 pC/N。(2)调控两步铁电相变,使其彼此靠近但没有完全汇聚,形成一个宽温域的、三相共存的相界带。基于该思路,武海军在KNN体系中固溶Sb、Bi、Zr、Fe和Ag,获得了宽温域、三相共存的相变带,使压电系数从550 pC/N提升到650 pC/N,并且在室温以上30 oC的宽温域内 (之前记录:仅一个温度点) 压电系数大于550 pC/N。

武海军以一作/共一/通讯在该方向上发表IF>10文章9篇:Energ Environ Sci (2017, ESI高引文章), J Am Chem Soc (2016, ESI高被引文章, 2018, 2019, 2020), Adv Mater (2018), Adv Funct Mater (2019), Nano Energy (2020), Adv Electron Mater (2019)。武海军的上述工作,得到了业内专家的广泛好评:卧龙岗大学张树君教授在Adv Mater中多次讨论并肯定了武海军的工作,“Of particular significance is that compositional tuning … has achieved great success in improving the piezoelectric properties by constructing a new … phase boundary (通过固溶构建新相界在优化压电综合性能方面取得巨大的成功)”。同济大学翟继卫教授在其MSE-R综述中认为武海军的工作“little doubt ... exhibited high temperature stability (充分证明具有高的温度稳定性) ”。

4.无铅压电薄膜

利用点缺陷诱发形成极化纳米畴,破解了薄膜合金化和外延性的矛盾,实现了无铅压电薄膜性能的突破,为高性能无铅压电薄膜的设计提供新思路

相对于无铅压电陶瓷的快速发展,其薄膜的发展却很滞后,主要源于薄膜的外延性随着合金化程度增加而明显变差,陶瓷体系中引入多种元素合金化的方式很难被应用到薄膜体系。因此如何化解薄膜合金化和外延性的矛盾,提升无铅压电薄膜的性能是该领域的极大挑战。

武海军通过去合金化,调控材料零维无序点缺陷,诱发形成三维有序结构,实现了简单的成分但极高的性能。在铌酸钠(NaNbO3)薄膜体系,Na空位往往对性能不利。武海军反常规地增加Na的缺失,形成Nb反位缺陷,使其在薄膜界面上有序化形成二维反位畴,再沿薄膜面外生长形成纳米细丝反向畴。在高密度的反位相界的界面处形成Nb原子偏聚,具有很大的畸变,促使整个薄膜的Nb原子沿面外方向偏移,继而形成大的面外极化。最终获得了巨大的压电系数约1098 pC/N,是性能最好的无铅薄膜的四倍,是性能最好的铅基薄膜的两倍;因为去合金化,维持了材料本身极高的居里温度约450℃,保证了极好的温度稳定性。另外,武海军将零维无序点缺陷诱发形成三维有序结构扩展到过渡金属氧化物SrFeOx薄膜体系,通过氧空位有序化来调控相变,获得纳米级导电相(SrFeO3)和绝缘相(SrFeO2.5)的共存,有望应用到高密度的电阻转换存储器。

武海军以(共同)一作或通讯在该方向上发表文章3篇,包括Science (2020), Nat. Commun. (2021), Adv Mater (2019)等。武海军的上述工作,得到了业内专家的广泛好评:研究工作被Science的同期Insights专栏报道,概括我们的工作为“Less can be more in functional materials (成分越简单性能越好)”,称赞我们方法为“simple yet highly effective self-assembly (简单但是非常有效的自组装)”。

三、代表性论文(一作、通讯或共一)

1. Huajun Liu,# Haijun Wu,# Khuong Phuong Ong, Tiannan Yang, Ping Yang, Pranab Kumar Das, Xiao Chi, Yang Zhang, Caozheng Diao, Wai Kong Alaric Wong, Eh Piew Chew, Yi Fan Chen, Chee Kiang Ivan Tan, Andrivo Rusydi, Mark B. H. Breese, David J. Singh, Long-Qing Chen, Stephen J. Pennycook, Kui Yao, Giant piezoelectricity in oxide thin films with nanopillar structure, Science, 369, 292-297 (2020). (#equal contribution)

Science Perspective: Less can be more in functional materials. Science, 368(2020) 1325.

https://science.sciencemag.org/content/369/6501/252.full

2. Haijun Wu,# Li-Dong Zhao,# Fengshan Zheng, Di Wu, Yanling Pei, Xiao Tong, Mercouri G. Kanatzidis, Jiaqing He, Broad temperature plateau for thermoelectric figure of merit ZT>2 in phase separated PbTe0.7S0.3, Nature Communications, 2014, 5, 4515. (IF=11.878) (ISI highly cited paper)

3. Haijun Wu,#,* Shoucong Ning,# Moaz Waqar,# Huajun Liu, Yang Zhang, Honghui Wu,* Ning Li, Yuan Wu, Kui Yao, Turab Lookman, Xiangdong Ding, Jun Sun, John Wang,* Stephen J. Pennycook*, Alkali-deficiency driven charged out-of-phase boundaries for giant electromechanical response, Nature Communications, 12, 2841 (2021). (IF=11.878) (*1st corresponding author)

4. Jie Yin,# Hongxiang Zong,# Hong Tao, Xuefei Tao, Haijun Wu,* Yang Zhang, Li-Dong Zhao, Xiangdong Ding, Jun Sun, Jianguo Zhu, Jiagang Wu,* Stephen J. Pennycook.* Nanoscale bubble domains with polar topologies in bulk ferroelectrics. Nature Communications 2021, 12 (1), 3632. (* corresponding author)

5. Haijun Wu, Cheng Chang, Dan Feng, Yu Xiao, Xiao Zhang, Yanling Pei, Shengkai Gong, Jiaqing He, Mercouri G. Kanatzidis, Li-Dong Zhao, Synergistically optimized electrical and thermal transport properties in SnTe via alloying high-solubility MnTe, Energy & Environmental Science, 2015, 8, 3298. (IF=33.25)

6. Chunlin Zhao,# Haijun Wu,#,* Fei Li, Yongqing Cai, Dongsheng Song, Yang Zhang, Jiagang Wu,* Dingquan Xiao, Jianguo Zhu, Stephen J. Pennycook,* Practical High Piezoelectricity in Barium Titanate Ceramics Utilizing Multiphase Convergence with Broad Structural Flexibility, Journal of the American Chemical Society, 2018, 140, 15252−15260. (#equal contribution and *1st corresponding author) (IF=14.695)

7. Bingchao Qin, Dongyang Wang, Wenke He, Yang Zhang, Haijun Wu,* Stephen J. Pennycook, Li-Dong Zhao,* Realizing high thermoelectric performance in p-type SnSe through crystal structure modification, Journal of the American Chemical Society, 2019, 141, 1141–1149. (*1st corresponding author) (IF=14.695) (ISI highly cited paper)

8. Yu Xiao, Dongyang Wang, Yang Zhang, Congrun Chen, Shuxuan Zhang, Kedong Wang, Guangtao Wang, Stephen John Pennycook, G Jeffrey Snyder, Haijun Wu,* Li-Dong Zhao,* Band sharpening and band alignment enable high quality factor to enhance thermoelectric performance in n-type PbS, Journal of the American Chemical Society, 2020, accepted. (*1st corresponding author)

9. Bingchao Qin, Yang Zhang, Dongyang Wang, Qian Zhao, Bingchuan Gu, Haijun Wu,* Hongjun Zhang,* Bangjiao Ye, Stephen J. Pennycook, Li-Dong Zhao*. Ultrahigh average ZT realized in p-type SnSe crystalline thermoelectrics through producing extrinsic vacancies, Journal of the American Chemical Society, 142 (2020) 5901-5909. (*1st corresponding author)

10. Xiaoying Liu, Dongyang Wang, Haijun Wu,* Jinfeng Wang, Guangtao Wang, Yang Zhang, Stephen J. Pennycook and Li-Dong Zhao,* Intrinsically low thermal conductivity in BiSbSe3: A promising thermoelectric material with multiple conduction bands, Advanced Functional Materials, 2019, 29, 1806558. (*1st corresponding author) (IF=15.621)

11. Haijun Wu, Xiaoxu Zhao, Li-Dong Zhao, Jiagang Wu, Dongsheng Song, Changjian Li, Thirumalai V. Venkatesan, John Wang, Kian Ping Loh, Stephen J. Pennycook, The Atomic Circus: Small Electron Beams Spotlight Advanced Materials Down To the Atomic Scale, Advanced Materials, 2018, 30, 1802402. (IF=25.809)

12. Haijun Wu, Yang Zhang, Jiagang Wu, John Wang, Stephen J. Pennycook, Microstructural origins of high piezoelectric performance: a pathway to practical lead-free materials, Advanced Functional Materials, 2019, 29, 1902911. (IF=15.621)

13. Haijun Wu, Yang Zhang, Li-Dong Zhao, Stephen J. Pennycook, Seeing atomic-scale structural origins and foreseeing new pathways to improved thermoelectric materials, Materials Horizons, 2019, 6, 1548-1570. (IF= 14.356)

14. Haijun Wu, Fengshan Zheng, Di Wu, Zhehua Ge, Xiaoye Liu and Jiaqing He, Advanced Electron Microscopy for Thermoelectric Materials, Nano Energy, 2015, 13, 626 (IF=15.548)

15. Haijun Wu, J. Montana, Z. Zhang, Y. Qu, Z. Wang, L.-D. Zhao, J. Q. He, Strong enhancement in phonon scattering through nanoscale grains in lead sulfide thermoelectrics, NPG Asia Materials, 2014, 6, e108. (IF=8.052)

16. Haijun Wu, Xiaoxu Zhao, Feng Tian, Dongsheng Song, Kian Ping Loh, and Stephen J. Pennycook, Progress and prospects of aberration-corrected STEM for functional materials, Ultramicroscopy, 2018, 194, 182-192. (IF=2.644)

17. Haijun Wu,* D. Xue,* D. Lv, J. Gao, S. Guo, Y. Zhou, X. Ding, C. Zhou, S. Yang, Y. Yang and X. Ren, Microstructure at morphotropic phase boundary in Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramic: Coexistence of nano-scaled {110}-type rhombohedral twin and {110}-type tetragonal twin, Journal of Applied Physics, 2012, 112, 052004 (invited). (*1st corresponding author) (IF=2.328)

18. Ting Zheng, Yang Zhang, Qingqing Ke, Haijun Wu,* LIEW Weng Heng, Dingquan Xiao, Jianguo Zhu, Stephen J Pennycook, Kui Yao, Jiagang Wu,* High-performance Potassium Sodium Niobate Piezoceramics for Ultrasonic Transducer, Nano Energy, 2020, accepted. (*1st corresponding author)

19. Haixu Qin, Jianbo Zhu, Ning Li, Haijun Wu,* Fengkai Guo, Sibo Sun, Dandan Qin, Stephen J. Pennycook, Qian Zhang, Wei Cai, Jiehe Sui,* Enhanced mechanical and thermoelectric properties enabled by hierarchical structure in medium-temperature Sb2Te3 based alloys. Nano Energy 78, 105228 (2020). (*1st corresponding author)

20. Cao Guan, Wen Xiao, Haijun Wu,* Ximeng Liu, Wenjie Zang, Hong Zhang, Jun Ding, Yuan Ping Feng, Stephen J. Pennycook, and John Wang,* Hollow Mo-doped CoP Nanoarrays for Water Splitting, Nano Energy 48 (2018) 73–80. (*1st corresponding author) (ISI highly cited paper and hot paper) (IF=15.548)

21. Fengkai Guo, Bo Cui, Yuan Liu, Xianfu Meng, Yang Zhang, Haijun Wu,* Stephen J. Pennycook, Wei Cai, and Jiehe Sui,* Thermoelectric SnTe with band convergence, dense dislocations and interstitials through Sn self-compensation and Mn alloying, Small, 2018, 14, 1802615. (*1st corresponding author) (IF=10.856)

22. Fengkai Guo, Muchun Guo, Yang Zhang, Bo Cui, Liangjun Xie, Haijun Wu,* Qian Zhang, Stephen J. Pennycook, Wei Cai, and Jiehe Sui*, Simultaneous Boost of Power Factor and Figure-of-Merit in In-Cu Codoped SnTe, Small, 2019, 15, 1902493. (*1st corresponding author) (IF=10.856)

23. Xin Qian, Dongyang Wang, Yang Zhang, Haijun Wu,* Stephen J. Pennycook, Lei Zheng,* Pierre F. P. Poudeu,* Li-Dong Zhao,* Contrasting roles of small metallic elements M (M = Cu, Zn, Ni) in enhancing the thermoelectric performance of n-type PbM0.01Se. Journal of Materials Chemistry A 8, 5699-5708 (2020). (*1st corresponding author) (IF=10.733)

24. Bingchao Qin, Xuegao Hu, Yang Zhang, Haijun Wu,* Stephen. J. Pennycook, Li-Dong Zhao*, Comprehensive investigation on the thermoelectric properties of p-type PbTe-PbSe-PbS alloys, Advanced Electronic Materials, 2019, 5, 1900609. (*1st corresponding author) (IF=6.312)

25. Zhiwei Huang, Yang Zhang, Haijun Wu,* Stephen J. Pennycook, and Li-Dong Zhao,* Enhancing Thermoelectric Performance of p‑Type PbSe through Suppressing Electronic Thermal Transports, ACS Applied Energy Materials, 2019, 2, 11, 8236-8243. (*1st corresponding author)

26. Dongyang Wang, Zhiwei Huang, Yang Zhang, Lijie Hao, Guangtao Wang, Sihao Deng, Hongliang Wang, Jie Chen, Lunhua He, Bao Xiao, Yadong Xu, Stephen J. Pennycook, Haijun Wu,* Li-Dong Zhao,* Extremely low thermal conductivity from bismuth selenohalides with 1D soft crystal structure. Science China Materials, 63 (2020) 1759-1768 (Cover). (*1st corresponding author)

Science Share: Simple structures to slow heating. Science, 368(2020) 1325.

https://science.sciencemag.org/content/368/6497/1325.1

27. Hong Tao, Jie Yin, Chunlin Zhao, Haijun Wu,* Jiagang Wu,* New Role of Relaxor Multiphase Coexistence in Potassium Sodium Niobate Ceramics: Reduced Electric Field Dependence of Strain Temperature Stability. ACS Applied Materials & Interfaces 12, 49822-49829 (2020). (*1st corresponding author)

28. Jun Wu, Nannan Han, Shoucong Ning, Tian Chen, Chunxu Pan, Haijun Wu,*, Stephen J. Pennycook*, Cao Guan*, Single Atom Tungsten Doped CoP Nanoarrays as a pH-universal catalyst for high-efficiency hydrogen evolution reaction, ACS Sustainable Chemistry & Engineering, accepted. (*1st corresponding author)

29. Ting Zheng,# Haijun Wu,# Yuan Yuan,# Xiang Lv, Qi Li, Dingquan Xiao, Jiagang Wu, Ke Wang, Jingfeng Li, Yueliang Gu, Jianguo Zhu, and Stephen J. Pennycook, The structural origin of enhanced piezoelectric performance and stability in lead free ceramics, Energy & Environmental Science, 2017, 10, 528-537. (#equal contribution) (ISI highly cited paper) (IF=33.25)

30. Bo Wu,# Haijun Wu,# Jiagang Wu, Dingquan Xiao, Jianguo Zhu, and Stephen John Pennycook, Giant Piezoelectricity in Nanostructured Alkali Niobate Lead-Free ceramics with Phase Coexistence, Journal of the American Chemical Society, 2016, 138, 47, 15459–15464. (#equal contribution) (IF=14.695) (ISI highly cited paper)

31. Yu Xiao,# Haijun Wu,# Juan Cui, Dongyang Wang, Liangwei Fu, Yang Zhang, Yue Chen, Jiaqing He, Stephen J. Pennycook, Li-Dong Zhao, Realizing high performance n-type PbTe by synergistically optimizing effective mass and carrier mobility and suppressing bipolar thermal conductivity, Energy & Environmental Science, 2018, 11, 2486-2495. (#equal contribution) (IF=33.25)

32. Yu Xiao,# Haijun Wu,# Wei Li, Meijie Yin, Yang Zhang, Liangwei Fu, Yuexing Chen, Stephen J. Pennycook, Li Huang,* Jiaqing He, Li-Dong Zhao,* Remarkable roles of Cu to synergistically optimize phonon and carrier transport in n-type PbTe-Cu2Te, Journal of the American Chemical Society, 2017, 139, 18732−18738. (#equal contribution) (IF=14.695) (ISI highly cited paper)

33. Y.-L. Pei,# Haijun Wu,# D. Wu, F. Zheng and J. Q. He, High thermoelectric performance realized in BiCuSeO system by improving carrier mobility through 3D modulation doping, Journal of the American Chemical Society, 2014, 136, 13902-13908. (#equal contribution) (IF=14.695)

34. Junjiang Tian,# Haijun Wu,# Zhen Fan,* Stephen J. Pennycook,*, Yang Zhang, Dongfeng Zheng, Zhengwei Tan, Haizhong Guo, Pu Yu, Xubing Lu, Guofu Zhou, Xingsen Gao, Jun-Ming Liu, High-density resistive switching memories based on nanoscale topotactic phase transformation in SrFeOx epitaxial thin films, Advanced Materials, 2019, 31, 1903679. (#equally contribution) (IF=25.809)

35. X. P. Wang,# Haijun Wu,# S. B. Xi, Z. G. Yu, W. S. V. Lee, J. Zhang, Z. H. Wu, J. O. Wang, T. D. Hu, L. M. Liu, Y. Han, S. W. Chee, U. Mirsaidov, Y.W. Zhang, A. Borgna, J. Wang, S. J. Pennycook*, Y. H. Du* and J. M. Xue*, Strain stabilized nickel hydroxide nanoribbons for efficient water splitting, Energy & Environmental Science, 2020, 13, 229-237. (#equally contribution) (IF=33.25)

36. Y.-L. Pei,# Haijun Wu,# J. Sui,# J. Li, D. Berardan, C. Barreteau, L. Pan, N. Dragoe, W.-S. Liu, J. Q. He and L.-D. Zhao, High thermoelectric performance in n-type BiAgSeS due to intrinsically low thermal conductivity, Energy & Environmental Science, 2013, 6, 1750-1755. (#equal contribution) (IF=33.25)

37. Xin Qian,# Haijun Wu,# Dongyang Wang,# Yang Zhang, JinFeng Wang, Guangtao Wang, Lei Zheng,* Stephen J. Pennycook, Li-Dong Zhao,* Synergistically optimizing interdependent thermoelectric parameters of n-type PbSe through alloying CdSe, Energy & Environmental Science, 2019, 12, 1969-1978. (#equally contribution) (IF=33.25)

38. Hong Tao,# Haijun Wu,# Yao Liu,# Yang Zhang, Jiagang Wu,* Fei Li,* Xiang Lyu,1 Chunlin Zhao, Dingquan Xiao, Jianguo Zhu, and Stephen J. Pennycook2,* Ultrahigh Performance in Lead-free Piezoceramics Utilizing a Relaxor Slush Polar State with Multiphase Coexistence, Journal of the American Chemical Society, 2019, 141, 13987-13994. (#equal contribution) (IF=14.695)

39. L.P. Hu,# Haijun Wu,# T.J. Zhu, C.G. Fu, J. Q. He, P.J. Ying, and X.B. Zhao, Tuning multi-scale microstructures to enhance thermoelectric performance of n-type bismuth telluride based solid solutions, Advanced Energy Materials. 2015, 5, 411. (#equal contribution) (IF=24.884)

40. Yu Xiao,# Haijun Wu,# Dongyang Wang, Changlei Niu, Yanling Pei, Yang Zhang, Ioannis Spanopoulos, Ian Thomas Witting, Xin Li, Stephen J. Pennycook, G. Jeffrey Snyder, Mercouri G. Kanatzidis, and Li-Dong Zhao, Amphoteric Indium Enables Carrier Engineering to Enhance the Power Factor and Thermoelectric Performance in n-Type AgnPb100InnTe100+2n (LIST), Advanced Energy Materials, 2019, 1900414. (#equal contribution) (IF=24.884)

41. Fengkai Guo,# Haijun Wu,# Jianbo Zhu, Muchun Guo, Yang Zhang, Qian Zhang, Stephen J. Pennycook, Wei Cai*, and Jiehe Sui*, Synergistic boost of output power density and efficiency in In-Li codoped SnTe, Proceedings of the National Academy of Sciences of the United States of America, 2019, 116, 21998-22003. (#equal contribution) (IF=9.580)

42. Dandan Qin,# Haijun Wu,# Songting Cai,# Jianbo Zhu, Bo Cui, Li Yin, Haixu Qin, Wenjing Shi, Yang Zhang, Qian Zhang, Weishu Liu, Jian Cao, Stephen J. Pennycook, Wei Cai,*, and Jiehe Sui,* Enhanced thermoelectric and mechanical properties in Yb0.3Co4Sb12 with in-situ formed CoSi nanoprecipitates, Advanced Energy Materials, 2019, 9, 1902435. (#equal contribution) (IF=24.884)

43. Xiao Zhang,# Dongyang Wang,# Haijun Wu,# Meijie Yin, Yanling Pei, Shengkai Gong, Li Huang, Jiaqing He, Stephen J. Pennycook, and Li-Dong Zhao, Simultaneously enhancing power factor and reducing thermal conductivity of SnTe via introducing its analogues, Energy & Environmental Science, 2017, 10, 2420--2431. (#equal contribution) (IF=33.25)

44. Guohua Dong#, Suzhi Li#, Tao Li#, Haijun Wu#, Tianxiang Nan, Haixia Liu, Yuxin Cheng, Yuqing Zhou, Wanbo Qu, Yifan Zhao, Bin Peng, Zhiguang Wang, Zhongqiang Hu, Zhenlin Luo, Wei Ren, Stephen J. Pennycook, Ju Li, Jun Sun, Zuo-Guang Ye, Tai Min, Zhuangde Jiang, Ziyao Zhou*, Xiangdong Ding*, Ming Liu*, Periodic wrinkle-patterned single-crystalline ferroelectric oxide membranes with enhanced piezoelectricity, Advanced Materials, 2020, 2004477. (#equal contribution)

45. Xin Li,# Haijun Wu,# Abdelnaby Mohamed Kotb Elshahawy, Ling Wang, Steve Stephen J. Pennycook, Cao Guan, and John Wang, Cactus-Like NiCoP/NiCo-OH 3D-Porous Structure with Tunable Compositional Ratio for High-Performance Electrochemical Capacitors. Advanced Functional Materials, 2018, 28, 1800036. (#equal contribution) (IF=15.621) (ISI highly cited paper)

46. S. Z. Zhi,a,b# J. B. Li,c,# L. P. Hu,a,b* J. Q. Li,a,b# Ning Li,e Haijun Wu,d,e* F. S. Liu,a,b X. B. Zhao,e H. P. Xie,b Stephen J. Pennycook,e and T. J. Zhuf*, Medium entropy GeTe: entropy driven synergy of phase, band and phonon engineering leading to state-of-the-art thermoelectric performance, Advanced Science 2021, 8 (12), 2100220. (* corresponding author)

47. Jiazhan Xin,# Haijun Wu,# Xiaohua Liu, Tiejun Zhu, Guanting Yu, Jiaqing He, Xinbing Zhao, Mg vacancy and dislocation strains as strong phonon scatterers in Mg2Si1-xSbx thermoelectric materials, Nano Energy, 2017, 34, 428–436. (#equal contribution) (IF=15.548)

48. Xiaoxi Chen,# Haijun Wu,# Juan Cui, Yang Zhang, Jiaqing He, Yue Chen, Wei Cai, Stephen J. Pennycook, Zihang Liu, Lidong Zhao and Jiehe Sui, Extraordinary thermoelectric performance in n-type manganese doped Mg3Sb2 Zintl: high band degeneracy, tuning carrier scattering mechanism and hierarchical microstructure, Nano Energy, 2018, 52, 246–255. (#equal contribution) (IF=15.548)

49. W. X. Zhou,# Haijun Wu,# S. W. Zeng, J. Zhou, C. J. Li, R. Guo, J. X. Xiao, Z. Huang, W. M. Lv, K. Han, P. Yang, C. G. Li, S. J. Chua, K. Y. Zeng, T. Venkatesan, J. S. Chen, Y. P. Feng, Stephen. J. Pennycook, Ariando, Artificial two-dimensional polar metal by charge transfer to a ferroelectric insulator, Communications Physics, 2, 125 (2019). (#equally contribution)

50. Yumei Wang,# Haijun Wu,# Xian Qin, Kui Yao*, Stephen J. Pennycook and Francis Eng Hock Tay, Outstanding Piezoelectric Performance in Lead-Free 0.95(K, Na)(Sb, Nb)O3-0.05(Bi, Na, K)ZrO3 Thick Films with Oriented Nanophase Coexistence, Advanced Electronic Materials, 2019, 1800691. (#equally contribution) (IF=6.312)

51. Cao Guan,* Ximeng Liu, Abdelnaby M. Elshahawy, Hong Zhang, Haijun Wu,* Stephen J. Pennycook, and John Wang,* Metal–Organic Framework Derived Hollow CoS2 Nanotube Arrays: an Efficient Bifunctional Electrocatalyst for Overall Water Splitting. Nanoscale Horizons, 2017, 2, 342-348. (*corresponding author) (IF=9.095) (ISI highly cited paper and hot paper)

52. Nan Zhang, Ting Zheng,* Ning Li, Chunlin Zhao, Jie Yin, Yang Zhang, Haijun Wu,* Stephen J. Pennycook, Jiagang Wu,* Symmetry of the Underlying Lattice in (K,Na)NbO3-Based Relaxor Ferroelectrics with Large Electromechanical Response. ACS Applied Materials & Interfaces 13, 7461-7469 (2021). (* corresponding author)

53. Xin Li,# Haijun Wu,# Cao Guan, Stephen J. Pennycook, and John Wang, (Ni,Co)Se2/NiCo-LDH core-shell structured electrode with cactus-like (Ni,Co)Se2 core for asymmetric supercapacitors. Small, 2018, 1803895. (#equally contribution) (IF=10.856)

54. Cao Guan,# Haijun Wu,# Weina Ren, Ximeng Liu, Afriyanti Sumboja, Zhaolin Liu, Chuanwei Cheng, Stephen J. Pennycook, and John Wang, Metal–Organic Framework-Derived Integrated Nanoarrays as Binder-free Catalyst for Overall Water Splitting, Journal of Materials Chemistry A, 2018, 6, 9009–9018. (#equal contribution) (IF=10.733)

55. Junjiang Tian,# Yang Zhang,# Zhen Fan,* Haijun Wu,* Lei Zhao, Jingjing Rao, Zuhuang Chen, Haizhong Guo, Xubing Lu, Guofu Zhou, Stephen J. Pennycook, Xingsen Gao, Jun-Ming Liu, Nanoscale phase mixture and multi-field-induced topotactic phase transformation in SrFeOx, ACS Applied Materials & Interfaces, 2020, accepted. (*corresponding author) (IF=8.456)

56. Yang Zhang, Dezhen Xue,* Haijun Wu,* Xiangdong Ding, Turab Lookman, Xiaobing Ren, Adaptive ferroelectric state at morphotropic phase boundary: Coexisting tetragonal and rhombohedral phases, Acta Materialia, 2014, 71, 176-184. (*corresponding author) (IF=7.293)

57. Yiming Zhou,# Haijun Wu,# Dongyang Wang,# Liangwei Fu, Yang Zhang, Stephen J. Pennycook, Jiaqing He, Li-Dong Zhao, Investigations on electrical and thermal transport properties of Cu2SnSe3 with unusual coexisting nanophases, Materials Today Physics, 2018, 7 77-88. (#equally contribution)

58. Xin Qian,# Haijun Wu,# Xiang Gao,# Dongyang Wang, Yang Zhang, Stephen J. Pennycook, Lei Zheng,* Li-Dong Zhao*, Synergistically optimizing interdependent thermoelectric parameters of n-type PbSe through introducing a small amount of Zn, Materials Today Physics, 9 (2019) 100102. (#equally contribution)

59. Y.M. Zhou,# Haijun Wu,# Y.L. Pei, C. Chang, Y. Xiao, X. Zhang, S.K. Gong, J.Q. He, L.D. Zhao, Strategy to optimize the overall thermoelectric properties of SnTe via compositing with its property-counter CuInTe2, Acta Materialia, 2017, 125, 542-549. (#equal contribution) (IF=7.293)

60. Xiaoxuan Zhang,# Haijun Wu,# Yanling Pei, Bolun Zhao, Yiming Zhou, Shengkai Gong, Jiaqing He, Li-Dong Zhao, Investigation on thermal transport and structural properties of InFeO3(ZnO)m with modulated layer structures, Acta Materialia, 136 (2017) 235e241. (#equal contribution) (IF=7.293)

61. Peng Zheng,# Haijun Wu,# Jialin Guo, Jianhui Dong, Suping Jia, Zhenping Zhu, P–N co-doping induced structural recovery of TiO2 for overall water splitting under visible light irradiation, Journal of Alloys and Compounds, 615 (2014) 79–83. (#equal contribution) (IF=4.175)

62. Wenke He, Dongyang Wang, Haijun Wu, Yu Xiao, Yang Zhang, Dongsheng He, Yue Feng, Yu-jie Hao, Jin-Feng Dong, Lijie Hao, Dongfeng Chen, Jianfei Qin, Xin Li, Jian-Ming Song, Yingcai Zhu, Wei Xu, Changlei Niu, Xin Li, Guangtao Wang, Xugui Xia, Shengqiang Bai, Chang Liu, Stephen J. Pennycook, Jiaqing He, Lidong Chen, Jing-Feng Li, Li-Dong Zhao,* High thermoelectric performance in low-cost SnS0.91Se0.09 crystals, Science, 365, 1418-1424 (2019). (IF=41.037)

63. L. D. Zhao, Haijun Wu, S. Q. Hao, C. I. Wu, X. Y. Zhou, K. Biswas, J. Q. He, T. P. Hogan, C. Uher, C. Wolverton, V. P. Dravid and M. G. Kanatzidis, All-scale hierarchical thermoelectrics: MgTe in PbTe facilitates valence band convergence and suppresses bipolar thermal transport for high performance, Energy & Environmental Science, 2013, 6, 3346-3355. (IF=33.25) (ISI highly cited paper)

64. Cao Guan, Afriyanti Sumboja, Haijun Wu, Weina Ren, Ximeng Liu, Hong Zhang, Stephen J. Pennycook, Zhaolin Liu, Chuanwei Cheng, and John Wang, Hollow Co3O4 nanospheres embedded Nitrogen-doped Carbon Nanoarrays as Flexible Cathode for Zn-Air battery, Advanced Materials, 2017, 29, 1704117. (IF=21.95) (ISI highly cited paper)

65. L.-D. Zhao, Y. Xiao, Haijun Wu, X. Zhang, C. Chang, D. Wu, G. Tan, H. Chi, Y. Pei, S. Gong, C. Uher, J. Q. He, M. G. Kanatzidis, Enhanced Thermoelectric Properties in the Counter-Doped SnTe System with Strained Endotaxial SrTe, Journal of the American Chemical Society 2016, 138, 2366. (IF=14.695) (ISI highly cited paper)

66. Hongxiang Zong, Haijun Wu, Xuefei Tao, Deqing Xue, Jun Sun, Stephen J. Pennycook, Tai Min, Zhenyu Zhang, Xiangdong Ding, Percolated strain networks and universal properties of ferroelastic glasses, Physical Review Letters, 2019, 123, 015701. (IF= 9.227)

67. J. Sui, J. Li, J. Q. He, Y.-L. Pei, D. Berardan, H. J. Wu, N. Dragoe, W. Cai and L.-D. Zhao, Texturation boosts the thermoelectric performance of BiCuSeO oxyselenides, Energy & Environmental Science, 2013, 6, 2916-2920. (IF=33.25) (ISI highly cited paper)


Book chapter:

H. J. Wu, J. Q. He, Electron Microscopy for Characterization of Thermoelectric Nanomaterials. In: CSSR Kumar (Ed.) Transmission Electron Microscopy Characterization of Nanomaterials. Springer Heidelberg New York Dordrecht London, 2014, pp.428-531.

http://link.springer.com/chapter/10.1007%2F978-3-642-38934-4_10