Lanthanum Doping into A-sites of BaBiO3 via Thin Film Synthesis

• Published in: Journal of the Korean Physical Society 2020, 76(3), , pp.215-220
• Main Authors: Talha, M., Jeong, Y. H.
• Format: Article
• Language: English
• Subjects: Buffer layers; Chemical synthesis; Doping; Image analysis; Lanthanum; Lanthanum oxides; Lattice vacancies; Mathematical and Computational Physics; Monolayers; Particle and Nuclear Physics; Perovskite structure; Perovskites; Physics; Physics and Astronomy; Substitutes; Substrates; Theoretical; Thin films; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.76.215

BaBiO 3 is an insulator with perovskite structure. While the hole doping of BaBiO 3 has been achieved long ago, its electron doping has not been realized yet because trivalent La ions, for example, tend to substitute for tetravalent Bi ions in B sites rather than divalent Ba ions in A-sites. We have used thin film synthesis to substitute La ions for Ba ions in BaBiO 3 ; we first deposit, on a substrate, a buffer layer of BaBiO 3 to overcome the lattice mismatch and then deposit a triple unit of a monolayer of Ba-deficit BaBiO 3 , the necessary amount of La 2 O 3 to fill in the A-site vacancies, and lastly a monolayer of pure BaBiO 3 . This triple unit of Ba-deficit Ba 1− x BiO 3 /La 2 O 3 /pure BaBiO 3 is repeated several times for a certain thickness sample, and then the whole structure is treated thermally at 550 °C. Scanning TEM image analysis confirms that La ions go indeed to the A-sites and La doped BaBiO 3 remains in perovskite structure. It is found that La substitution for Ba in BaBiO 3 causes the Raman peak related to the breathing mode of BaBiO 3 to decrease in intensity as a function of the doping level. Dielectric measurements of La doped BaBiO 3 also reveal an upward shift in temperature and associated relaxation behaviors for the octahedral tilt-driven structural transition which occurs at T c ∼ 140 K for pure BaBiO 3 .