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Lijia Liu

Lijia Liu

Contact Information

Title: Assistant Professor
Office: ChB 066
Phone (Office): ext 84456
E-mail: lijia.liu@uwo.ca

Physical & Analytical Teaching Division

Materials: Design, Function and Characterization Synthesis, Catalysis and Molecular Materials

Luminescent nanomaterials, Synchrotron X-ray spectroscopy

Group Website

Education

B.Sc. University of Science and Technology of China
Ph.D. Western University

Research

My research group studies the fundamental properties of advanced light-emitting materials. These materials are commonly used in optoelectronics, bioimaging, and sensing. We use modern spectroscopy techniques, such as steady-state photoluminescence, time-resolved photoluminescence, absorption spectroscopy to analyze the luminescence mechanism of the materials. The information obtained provides a guideline toward designing new synthesis strategies in order to precisely control the luminescence property of the material and ultimately achieve performance enhancement in practical applications. Synchrotron-based spectroscopy is another major tool which will be regularly utilized to gain in-depth information on the correlation between the observed luminescence and the electronic structure of the material. We also work on developing new synchrotron radiation-based spectroscopy techniques for their use in material analysis. Techniques based on X-ray absorption fine structure (XAFS) and X-ray excited optical luminescence (XEOL) will be advanced in both time-domain (i.e., in situ study) and space domain (i.e., nanoscale imaging).

Current ongoing projects are:

Lead halide perovskite. Lead halide perovskite ABX3 has recently become an attractive material in research fields like solar cells, light-emitting diodes, optical detectors, and even catalysis. It contains a large family of compounds of similar structure: A monovalent cation (Cs+, or organic CH3NH3+), a divalent Pb2+, and three halide ions (Cl-, Br-, or I-). The color of the luminescence can also be tuned throughout the visible wavelength by composition tuning. Research along this direction involves (1) synthesis of ABX3 nanocrystals of stable, bright and color-tunable luminescence, and (2) spectroscopy characterization using PL, XAFS and XEOL. We aim to discover the key factors that control the luminescence properties of ABX3 nanocrystals and to develop synthesis strategies of ABX3 for practical applications.

Calcium hydroxyapatite. Calcium hydroxyapatite (HAp) is the main component in human calcified tissue (i.e. bones and teeth). Synthetic HAp plays an extremely important role in tissue engineering, such as bioimplant and coating. Other than HAp, the calcium orthophosphate family contains several stable species of different chemical formula, which either co-exists with HAp, or transforms to HAp reversibly under controlled environment. We have found that different calcium phosphate species have their unique contributions to the bioactivity of an implant coating. Research along this direction aims to study (1) the crystallization process of synthetic HAp and its interaction with biomolecules, (2) the structure transformation among calcium orthophosphate species under various conditions, (3) dissolution of synthetic HAp in simulated body fluid. Our approach is to develop a strategy which is able to track the evolvement of structure and composition of calcium phosphate implant by monitoring its luminescence.

Collaborative projects. We are collaborating with several research groups in China and Canada who are specialising in material synthesis. We use these materials as test candidates to develop novel in situ, in operando spectroscopy/microscopy techniques at synchrotron research facilities in Canada, Taiwan, and US.

Students in the group will have opportunity to develop skills in both material synthesis and spectroscopy analysis. Training includes wet-chemical synthesis (mostly inorganic), standard characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence, UV-visible spectroscopy. Students will also visit synchrotron radiation research facilities to perform hands-on experiments. The three mostly visited facilities are the Canadian Light Source (CLS, Canada), Advanced Photon Source (APS, US), and Taiwan Photon Source (TPS, Taiwan).

Teaching

Selected Publications