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Research Fields

1. Novel Ferro/Piezoelectric Ceramics and Devices

1.1 High Performance Lead-free Piezoelectric Ceramics

With the increasingly stringent environmental regulations around the world, replacing lead-based components by the lead-free ones is required. Piezoelectric ceramics is an important material in electronic and information industries. It is necessary and imperative to develop high performance lead-free piezoelectric ceramics and devices. We mainly focus on: design of high performance lead-free piezoelectric material systems; study of phase transition behavior and structure-composition relationship at the morphotropic phaseboundary (MPB); microstructure regulation and performance optimization of perovskite-type lead-free piezoelectric ceramics; controllable preparation and performance optimization of layer structured perovskite-type lead-free piezoelectric ceramics. The main material systems include: perovskite structure materials (KNN, BNT, BT), bismuth layer-structured materials, tungsten bronze type materials.

Materials design of intergrowth bismuth layer-structured ferroelectrics


Phase structure and piezoelectric properties of lead-free ceramics (1-x)(K0.48Na0.52)NbO3-(x/5.15)K2.9Li1.95Nb5.15O15.3 

Representative Achievements:

1.   Yiqing Lu, Yongxiang Li, Dong Wang, Tianbao Wang, Qingrui Yin, Lead-free Piezoelectric Ceramics of (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-(Bi1/2Ag1/2)TiO3 System, Journal of Electroceramics, 21, 309–313 (2008).

2.   Zhiguo Yi, Yongxiang Li, Yun Liu, Ferroelectric and Piezoelectric Properties of Aurivillius Phase Intergrowth Ferroelectrics and the Underlying Materials Design, Phys. Status Solidi A-Appl. Mat.,208, 1035-1040(2011).

3.   Youliang Wang, Yiqing Lu, Mengjia Wu, Dong Wang, Yongxiang Li, Phase Structure and Enhanced Piezoelectric Properties of Lead-Free Ceramics (1-x)(K0.48Na0.52)NbO3-(x/5.15)K2.9Li1.95Nb5.15O15.3 with High Curie Temperature, International Journal of Applied Ceramic Technology, 9, 221 (2012).

4.   Faqiang Zhang, Yongxiang Li, Hui Gu, Xiang Gao, Local orderings in long-range-disordered bismuth-layered intergrowth structure, Journal of Solid State Chemistry, 212, 165-170 (2014).

5.   Feng Liu, Olivia Wahyudi, and Yongxiang Li, A new Bi0.5Na0.5TiO3 based lead-free piezoelectric system with calculated end-member Bi(Zn0.5Hf0.5)O3, Journal of Applied Physics, 115, 114101 (2014).

1.2 Textured Lead-free Piezoelectric Ceramics

Texture control of piezoelectric ceramics is a convenient and effective approach to improve the piezoelectric and mechanical properties by tailoring the microstructure of ceramics without drastically changing the composition of the materials. The main research directions include: preparation of the anisotropic template grains by hydrothermal method or molten salt method and selection of template; study on the process of screen-printing and tape casting; mechanism of grain oriented growth; optimization design and tailoring of anisotropic functional ceramics; solid-state growth of lead-free piezoelectric single crystal based on grain oriented growth.

The schematic diagram of screen-printing texturing process

      LNT+2LiCl 1000-6h-1副本.jpg

 Template grains for textured ceramics


Textured ceramics: KNBT and (Bi0.5Na0.5)0.94Ba0.06TiO3

KNN single crystal grown by solid-state crystal growth (SSCG) method

Representative Achievements:

1.   Mengjia Wu, Yongxiang Li, Dong Wang, Qingrui Yin, Highly textured (Na1/2Bi1/2)0.94Ba0.06TiO3 ceramics prepared by the screen-printing multilayer grain growth technique, Ceramics International, 34, 753–756 (2008).

2.   Zhiyuan Lu, Yali Li, Yilin Wang, Wenjun Wu, Yongxiang Li, Anisotropic Dielectric Properties of LiNb0.6Ti0.5O3 Microwave Ceramics by Screen-Printing Templated Grain Growth, Journal of American Ceramic Society, 94, 4364-4370 (2011).

3.   Yali Li, Chun Hui, Yongxiang Li, Youliang Wang, Preparation of textured K2BiNb5O15 ceramics with rod-like templates by the screen-printing technique, Journal of Alloys and Compounds, 509, L203-L207 (2011).

4.   Zhiqiang Zhang, Jie Yang, Zhifu Liu, Yongxiang Li, Evolution of textured microstructure of Li-doped (K,Na)NbO3 ceramics prepared by reactive templated grain growth, Journal of Alloys and Compounds, 624, 158-164 (2015).

5.   Jie Yang, Qunbao Yang, Yongxiang Li, Yun Liu, Growth mechanism and enhanced electrical properties of K0.5Na0.5NbO3-based lead-free piezoelectric single crystals grown by a solid-state crystal growth method, Journal of the European Ceramic Society, 36, 541-550 (2016).


1.3 Piezoelectric Devices and Smart Structures

Piezoelectric ceramics have many functions and coupling effects, such as mechanical, electrical, acoustic, optical, thermal and elastic, which can be used as pressure, temperature, light and other various sensors. Piezoelectric ceramics, which have the three basic elements of perception, drive and control for intelligent materials, will be one of the core materials for the design and development of smart ceramics and related devices. The main research directions include: preparation process and technology of new generation high performance piezoelectric ceramic multilayer, design and manufacture high performance, miniaturized, intelligent and green piezoelectric transducers and their prototype devices, providing scientific and technological basis for device design and integration in intelligent structures.

Ultrasonic transducer based on lead-free piezoelectric ceramic

Medical ultrasonic probe based on KNLN lead-free piezoelectric ceramic

Representative Achievements:

1.   Zhiqiang Zhang, Zhifu Liu, Yongxiang Li, Preparation of 0.84(K0.48Na0.52)NbO3 -0.16K0.56Li0.38NbO2.97 Lead-free Piezoelectric Ceramics by Multi-layer Process, Journal of Inorganic Materials, 29, 23-27 (2014).

2.   Benpeng Zhu, Zhiqiang Zhang, Teng Ma, Xiaofei Yang, Yongxiang Li, K. Kirk Shung, and Qifa Zhou, (100)-Textured KNN-based thick film with enhanced piezoelectric property for intravascular ultrasound imaging, Applied physics letters, 106, 173504 (2015).

3.   李永祥,张志强,刘志甫,杨群保,一种织构化无铅压电陶瓷多层驱动器及其制备方法,中国发明专利号:ZL 201510816013.0


2. Advanced Dielectric Materials and Multilayer Devices

Advanced dielectric materials are the key materials for the development of electronic components, and the cornerstone of passive components and electronic packaging. In order to meet the needs of developing electronic components and system integration technology, the research of new dielectric materials is facing new challenges constantly. Low temperature co-fired ceramic (LTCC) technology is an important technology of passive integration. Due to its excellent electrical, mechanical, thermal and technological characteristics, it is widely used in military, aerospace, automobile, wireless communication, electronic information and other fields. We aim at the development of new high-performance dielectric materials and new devices for future applications, combined with LTCC passive integration technology.


2.1 High Performance LTCC Microwave Dielectric Materials

Different component applications have different requirements for dielectric constant. For example, package substrates and chip inductors need low dielectric ceramics. Most of Bluetooth modules and dielectric antennas use dielectric materials with medium suitable dielectric constant. Capacitors require high dielectric constant to reduce the volume of devices. In order to meet the needs of microwave, millimeter wave and terahertz wave applications, all kinds of dielectric materials are required to have low dielectric loss. On the other hand, the embedment of various passive devices in the substrate to achieve high-density integration requires the matching of different technological properties, which is one of the challenges to LTCC research. Therefore, the main research directions include: the development of series of high-performance LTCC microwave dielectric materials with high/medium/low-k, the adjustment mechanism of dielectric constant and dielectric loss, the exploration of new LTCC microwave and millimeter wave dielectric materials, the research on the co-fireability adjustment of dielectric materials and metal electrodes and the material reliability in the application of LTCC devices. A variety of LTCC microwave dielectric materials with dielectric constant of 5 ~ 90 have been successfully developed, and some of them have been used in the production of LTCC devices.

Li–Nb–Ti–O high-k LTCC dielectric materials

The interface of self-developed LTCC material co-fired with silver electrode and the LTCC multilayer substrate (100×100×0.5 mm3) 

Representative Achievements:

1.   Yanping Long, Yilin Wang, Wenjun Wu, Dong Wang, Yongxiang Li, Sintering and Microwave Dielectric Properties of the LiNb0.63Ti0.4625O3 Ceramics with the B2O3–SiO2 Liquid-Phase Additives, Journal of American Ceramic Society, 92, 2630–2633 (2009).

2.   Zhiyuan Lu, Yali Li, Yilin Wang, Wenjun Wu, Yongxiang Li, Anisotropic Dielectric Properties of LiNb0.6Ti0.5O3 Microwave Ceramics by Screen-Printing Templated Grain Growth, Journal of American Ceramic Society, 94, 4364-4370(2011).

3.   Zhifu Liu, Yilin Wang, Wenjun Wu, Yongxiang Li, Li–Nb–Ti–O microwave dielectric ceramics, Journal of Asian Ceramic Societies, 1, 2-8 (2013).

4.   Mingsheng Ma, Zhifu Liu, Faqiang Zhang, Feng Liu and Yongxiang Li, Suppression of silver diffusion in borosilicate glass-based low-temperature co-fired ceramics by copper oxide additionJournal of the American Ceramic Society, 99, 2402-2407 (2016).

5.   刘志甫,李永祥,一种低温共烧陶瓷材料及其制备方法,申请号:ZL 201510109370.3 / US 15066203 / JP 2016-38076


2.2 Research of LTCC technology

LTCC technology is an interdisciplinary technology involving electromagnetic simulation and device design technology, ceramic powder preparation technology, tape-casting technology, multilayer technology (hole punching, printing, lamination, cutting, etc.), ceramic sintering technology, etc. In order to meet with the more stringent requirements of cost control and environmental protection, environmentally friendly slurries will gradually replace the slurry containing toluene and other toxic solvents, and the base metal electrodes are gradually applied to LTCC passive devices. These requirements broaden the research field of LTCC technology. The main research directions are focused on: preparation technology of high-quality LTCC powder; tape casting technology of LTCC materials; LTCC process technology such as drilling, printing, lamination, etc.; co-firing of multilayer heterogeneous materials and other related scientific and technological problems.

(a)   d50~10μm       (b) d50 <3μmd90 <6μm   (c) d50<0.4μmd90<1μm

Particle size control of LTCC powders

Rheological characteristics of LTCC tape-casting slurries and green tapes fabricated by the slurries

Representative Achievements:

1.   Zhifu Liu, Yilin Wang, Yongxiang Li, Combinatorial study of ceramic tape-casting slurries, ACS Combinatorial Science, 14, 205-210 (2012).

2.   刘志甫,马名生,李永祥等,一种低温共烧陶瓷生带材料及其制备方法和应用,中国发明专利号:ZL201310422945.8

3.   刘志甫,李永祥,陶瓷流延浆料及其制备方法,中国发明专利申请号:201110319794.4


2.3 LTCC Multilayer Devices

LTCC multilayer components and packaging substrates have the advantages of high frequency performance, high reliability, low thermal expansion coefficient, high thermal stability and chemical stability. The relevant components include microwave / millimeter wave filter, coupler, power divider, inductor, antenna and other passive components, and they are widely used in the fields of integrated circuit, multi-chip packaging substrate and so on. With the increasing density of integrated packaging and the emergence of new packaging technologies, new research results in the field of structural design, thermal management, electromagnetic compatibility, integration technology, etc. have been reported. According to the application requirements of LTCC technology in high-frequency passive components and packaging substrate, we mainly focus on: the design and preparation of high-performance LTCC passive components based on self-developed materials; the exploration of new technology and new process of LTCC passive component integration.

Filters and couplers based on SICCAS-K5F3

Filters based on SICCAS-K5F3 and their measured performance


SIW duplexers based on SICCAS-K70 and their performance


2.4 Dielectric Materials for Energy Storage and Their Applications

Capacitors with high energy storage density are widely used in modern industry and military, such as pulse power system, petroleum exploration, hybrid vehicles, solar energy and other new energy power generation systems, etc. Ceramic electrostatic capacitors have attracted more and more attention in the field of energy storage because of their all-solid-state characteristics, wide working temperature range, high working voltage and rapid discharging. The energy storage density is proportional to the dielectric constant and the square of the applied electric field, so the development of dielectric ceramics with large dielectric constant and high breakdown field strength becomes the key to realize the miniaturization of high-power pulse devices. The main research directions include: research on new dielectric ceramics with high energy storage density and high temperature resistant; research on ways to improve the energy storage density and related mechanisms; research on preparation technology and properties of novel ceramic capacitors; research on integration and modularization technology of energy storage ceramic capacitors; reliability assessment of energy storage dielectric materials and capacitors.



The dielectric and energy storage properties of surface coating modified ceramics

Ba1-xCaxTiO3 dielectric ceramics with large breaking-strength and high permittivity

TDSC results of BaTiO3 single crystals under different heat treatment

Representative Achievements:

1.Zhifu Liu, Zhiqiang Zhang, Faqiang Zhang and Yongxiang Li, Enhanced energy storage properties of barium titanate ceramics made from surface modified particles, Journal of Advanced Dielectrics, 3, 1350023 (2013).

2.Jiyuan Miao, Zhiqiang Zhang, Zhifu Liu, Yongxiang Li, Investigation on the dielectric properties of Mg-doped (Ba0.95Ca0.05)(Ti0.85Zr0.15)O3 ceramics, Ceramics International, 41, S487-491 (2015).

3.Wanghua Wu, Zhifu Liu, Yan Gu, Zhenxing Yue, Yongxiang Li, Thermally stimulated depolarization current study on barium titanate single crystals, AIP Advances, 8, 045005 (2018).

4.顾燕,刘志甫,李永祥,一种高耐压陶瓷电介质材料及其制备方法,中国发明专利号:ZL 201610040913.5

5.李永祥,苗纪远,刘志甫,一种高介电常数的多层陶瓷电容器介质材料及其制备方法,中国发明专利号:ZL 201510174215.X


3. Sensitive Materials and Devices

3.1 Nanostructured Sensitive Materials and Integrated Devices

Sensitive materials can make light, electricity, magnetism, heat, gas, humidity and other signals convert to each other, which are widely used in the fields of environment, new energy, information display, safety, chemical industry and biology. The combination of nano sensitive materials with advanced device preparation and integration technology can not only give full play to the performance advantages of nano sensitive materials, but also enable devices to be miniaturized and multifunctional, and even develop new devices and systems to obtain new functions and new applications. Based on the previous work, this research aims to combine nano sensitive materials and various sensitive elements with LTCC passive integration technology to research and develop new functional devices. The main research directions include: preparation and properties of nano sensitive materials; wireless gas, pressure and temperature sensors based on LTCC technology; LTCC microcavity structure and ceramic microsystem, etc.

2D SnS2 nano materials synthesized by high temperature chemical bath method

Gas sensing properties of wireless gas sensors integrated with 2D SnS2 nanoflakes through LTCC technology

Performance of wireless LC pressure sensors through LTCC technology

Representative Achievements:

1.   X. F. Yu, Y. X. Li, W. Y. Ge, Q. B. Yang, N. F. Zhu, K. Kalantar-Zadeh, Formation of nanoporous titanium oxide films on silicon substrates using an anodization process, Nanotechnology, 17, 1–7(2006).

2.   X. F. Yu, Y. X. Li, W. Wlodarski, S. Kandasamy, K. Kalantar-Zadeh, Fabrication of nanostructured TiO2 by anodization: A comparison between electrolytes and substrates, Sens. Actuator B,130, 25–31(2008).

3.   Hao Wen, Zhifu Liu, Jiao Wang, Qunbao Yang, Yongxiang Li, Jerry Yu, Facile Synthesis of Nb2O5 Nanorod Array Films and Their Electrochemical Properties, Appl. Surf. Sci,.257, 10084-10088 (2011).

4.    Mingsheng MaHareem KhanWei ShanYichao WangJian Zhen OuZhifu LiuKourosh Kalantar-zadehYongxiang Li, A novel wireless gas sensor based on LTCC technology, Sensors and Actuators B: Chemical, 239, 711-717 (2017).

5.   Lin Lin, Mingsheng Ma, Faqiang Zhang, Feng Liu, Zhifu Liu, Yongxiang Li, Fabrications and Performance of Wireless LC Pressure Sensors through LTCC Technology, Sensors, 18, 340 (2018).


3.2 PTC Thermosensitive Materials and Devices

Positive Temperature Coefficient (PTC) thermistor ceramics have been widely used in temperature sensing, temperature compensation, over-current protection, constant temperature heating, motor switch, delay start and other fields due to its unique resistance-temperature, time-current and volt-ampere characteristics. PTC ceramics are one of the most frequently contacted functional ceramics in daily life. The components made by PTC ceramics are widely used in various kinds of household appliances. The main research directions are focused on the application of  PTC ceramics in anti-icing and deicing system for aircraft. Through the composition optimization of PTC ceramics and design of a unique electrical insulation and packaging structure, the heating efficiency of PTC thermistor is greatly improved. We have taken the lead in developing high performance PTC ceramic heater element for aviation applications in China.

PTC ceramic heater element