Programme

P.22 -- Posters, VCTP-51

Date: Tuesday, 4 August 2026

Time: 09:30 - 10:30

Synergistic multi-doping effect on thermal-electrical properties of Ce0.8−x(La1/3Sm1/3Gd1/3)0.2MxO2−y (M = Ca, Sr) electrolytes for intermediate temperature solid oxide fuel cells

Le Thu Lam1,2, Hua Xuan Dat3, Nguyen Thi Hong4, Tran Quoc Cuong1, Do Viet Thuc1, Tran Minh Tien2

1Faculty of Natural Sciences and Technology, Tay Bac University, Sonla, Vietnam, Email: lethulam@utb.edu.vn 2Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam 3Hung Vuong High School for the Gifted, Viet Tri, Phutho, Vietnam 4Hong Duc University, 565 Quang Trung, Hac Thanh, Thanh Hoa 441430, Viet Nam

The simultaneous incorporation of rare-earth (La3+, Sm3+, Gd3+) and alkaline-earth (Ca2+ or Sr2+) multi-dopants breaks the local lattice symmetry, suppresses the vacancy ordering into defect clusters, and increases the unit-cell free volume, thereby leading to a marked improvement in ionic conductivity relative to single-doped ceria. A combined effect of weakened interionic electrostatic attraction and a more flexible lattice structure enhances the thermal expansion coefficient within the range of 12.70 - 13.25 × 10-6 ◦C-1. The non-linear dependence of vacancy activation energy and ionic conductivity on the multi-dopant content is driven by the competition between the enhanced vacancy mobility via the expanded free volume and elastic relaxation at low doping levels and suppressed vacancy hopping due to defect clustering and cation blocking at higher fractions. We find that Ce0.75(La1/3Sm1/3Gd1/3)0.2Ca0.05O1.85 and Ce0.77(La1/3Sm1/3Gd1/3)0.2Ca0.03O1.87 reach the lowest activation energy and the highest bulk ionic conductivity.

Presenter: Le Thu Lam