Influence of iso-valent ‘Sm’ double substitution on the ionic conductivity of La0.9Sr0.1Al0.9Mg0.1O3-δ ceramic system

• Published in: Materials chemistry and physics 2020-02, Vol.241, p.122345, Article 122345
• Main Authors: Verma, Onkar Nath, Jha, Priyanka A., Singh, Pragati, Jha, Pardeep K., Singh, Prabhakar
• Format: Article
• Language: English
• Subjects: Electrical resistivity; Hopping conduction; Ion currents; Ionic conductivity; Ions; LaAlO3; Oxygen content; Perovskite electrolyte; Perovskites; Samarium; Solid oxide fuel cell; Solid oxide fuel cells; Substitutes; Thermogravimetric analysis
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2019.122345

The La0.9-xSr0.1Al0.9Mg0.1O3-δ is considered as a promising perovskite to be used as electrolyte in Solid Oxide Fuel Cell due to good ionic conductivity (~10−3 S/cm) with high transference number ~ 0.99. The oxide ionic conductivity can be altered with the critical triangle area which is affected by size and nature of substituent. In the lack of comprehensive study on influence of double-substitution, we have synthesized substituted systems A″xLa0.9-xSr0.1Al0.9Mg0.1O3-δ with x = 0.01, 0.03 and 0.05, here A″ = Ba (aliovalent) and Sm (isovalent) having R3‾c symmetry. The electrical conductivity data is analyzed using Rice – Roth's free-ion like model for ionic conduction and hopping transport mechanism (Arrhenius model). The defect chemistry suggests that Ba substituted compositions have concentration dependent oxygen content. Whereas, Sm substituted compositions have concentration independent oxygen content. This is verified using thermogravimetric analysis in N2 and O2 atmospheres. Our results also revealed that the aliovalent substitution of Ba effectively increases the ionic conductivity with high transference number, while isovalent substitution of Sm increases the electronic contribution to the total conductivity. •Structure-property correlation is investigated in SmxLa0.9-xSr0.1Al0.9Mg0.1O3-δ.•Compared with aliovalent (Ba2+) double substitution for ionic conduction.•Oxygen vacancies in Ba2+ substituted system are composition dependent.•Oxygen vacancies in Sm3+ substituted system are composition independent.•Ba2+ substituted system is Type I and Sm3+ substituted system is type II conductor.