1. Full name:     Le Thi Anh Thu                                      2. Sex: Female

3. Date of birth: 05/10/1982                                            4. Place of birth: Hanoi – Viet Nam

5. Admission decision number: Decision 4982/QĐ-ĐHKHTN, date on 27/11/2013 by Rector of VNU University of Science.

6. Changes in academic process: Extended time by decision No 1033/QD-DHKHTN dated on 25/4/2017 and 2303/QD-DHKHTN dated on 03/7/2018, by Rector of Rector of VNU University of Science.

7. Official thesis title: Synthesis of materials, research of some magnetic-electric phase transitions in perovskite: La0,7Sr0,3MnO3: Ni và La2NiO4+: BaTiO3

8. Major:           Solid State Physics                                           9. Code: 9440130.02

10. Supervisors:            Prof.Dr. Bach Thanh Cong

Dr. Nguyen Ngoc Dinh

11. Summary of the new findings of the thesis:

-  The perovskite La0,7Sr0,3Mn1-xNixO3 (x = 0; 0.02; 0.04; 0.06; 0.08; 0.1) and (La2NiO4+ δ)1-x (BaTiO3)x with x = 0.0; 0.05; 0.1, 0.2; 0.3; 0.5 systems have been produced by traditional ceramic and  sol-gel methods and their structure have been investigated, respectively.

- Basing on the analyzing of the critical indexes and comparison with other’s results, we show the change of spin order in the Ni-doped disordered ferromagnetic La0,7Sr0,3Mn1-xNixO3 system is related with long-range exchange interactions.

- It was experimentally shown that the conductivity of (La2NiO4+δ)1-x (BaTiO3)x (x ≤0.3) is enhanced comparing with that of the pristine La2NiO4+δ in the temperature region near the metal-insulator transition temperature TMI. The sample (La2NiO4)0.9(BaTiO3)0.1 has lowest TMI =700 K (427 oC) and resistivity   at this temperature.

- The high temperature MIT in the composite (La2NiO4+δ)1-x(BaTiO3)x is explained well using the conducting model containing small polaron (SP) and large polaron (LP) carriers. At TM the concentrations of two carrier types are equal. The resistivity and the phase transition temperature changes relate with the La2NiO4+δ relative unit cell ratio   variation. The MIT in (La2NiO4+δ)1-x(BaTiO3)x satisfies approximately Mott’s criterion.

- Content of the thesis was published in: i/ 02 ISI publications: 1 paper in Journal of Electronic Materials and the other in Bulletine of Materials Science (accepted); ii/ 02 paper in the national scientific journal: Journal of Science Technology, VNU Journal of Science: Mathematics-Physics; iii/ 02 reports at International Conference ICAMN 2014 and The 10th National Conference on Solid State Physics & Materials Science.

12. Practical applicability: (La2NiO4)0.9(BaTiO3)0.1 is potentially applied as cathode material in SOFC and La0.7Sr0.3Mn1-xNixO3 may be applied in spintronic area.

13. Further research directions: To investigate on electrodes for solid oxide fuel cells operating at the middle temperatures and to measure its Volt-Ampere characteristics.

14. Thesis-related publications:

1. Le Thi Anh Thu, H.D. Chinh, N.N. Dinh, H.D. Chinh, N.T. Hue, N.D. Dung, M. Kurisu, K. Konishi, B.T. Cong (2014) “Magnetic properties of nano-sized La2NiO4 and (La2NiO4)1-x(BaTiO3)x composites” in the book Advanced Materials and Nanotechnology ICAMN 2014, Bach Khoa Publishing House,  pp. 511-514, ISBN: 978-604-911-946-0.

2. Le Thi Anh Thu, N.N. Dinh, B.T. Cong (2015), “Study on properties of core - shell composites (La2NiO4)1-x(BaTiO3)x”, VNU Journal of Science: Mathematics-Physics  31, pp. 24-30.

3. Le Thi Anh Thu, H.T. Huong, H.D. Chinh, N.N. Dinh, H.D. Chinh, N.T. Hue, N.D. Dung, M. Kurisu, K. Konishi, B.T. Cong (2016) “Structure, electrical properties, and application possibility as solid oxid fuel cells cathode materials of (La2NiO4)1-x(BaTiO3)x (x=0.0-0.5) composites”, Journal of Science Technology  54 (1A), pp.66-71

4. Le Thi Anh Thu, N.N. Dinh, B.T Cong (2017) “The enhancement of the La2NiO4 materials when doped by dielectric BaTiO3”. Oral report of the 10th Conference of Physics & Materials Science, 19-2/10/2017, Hue City, Conference Proceedings, E-16, p.132.

5. T.D. Thanh, P.D.H. Yen, K.X. Hau, N.T. Dung, L.V. Nhan, L.T. Huong, L.V. Bau, Le Thi Anh Thu, B.T. Cong, N.X. Nghia, L.H. Khiem, and S.C. Yu (2019), “Critical Behavior of Ni-doped La0.7Sr0.3MnO3 Ceramics”, Journal of Electronic Materials 48 (3), pp. 1353-1362 (Tạp chí ISI).

6. L T  Thu, N N Dinh, N Viet Tuyen AND B T Cong  ” Metal-Insulator Transition and Small to Large Polarons Crossover in La2NiO4+δ/BaTiO3 Composites”, Bulletine of Materials Science (Indian Academy of Sciences, Tạp chí ISI). Accepted by 21/01/2020.