The effect of ionic radius carbon dot on Ti⁴⁺ in lattice parameters of Ba_0.2Sr_0.8TiO₃ thin films

¹ Doctoral Program, Department of Physics, IPB University, Bogor, Indonesia
² Research Center for Climate and Atmosphere, National Research and Innovation Agency (BRIN), Bandung, Indonesia
³ Computer Engineering Technology, IPB University Vocational School, Bogor, Indonesia
⁴ Physics Education, Universitas Muhammadiyah Prof. DR. HAMKA, Jakarta, Indonesia
⁵ Research Center for Sustainable Production System and Life Cycle Assessment, National Research and Innovation Agency (BRIN), Tangerang Selatan, Indonesia
⁶ Department of Chemistry, Faculty of Mathematics and Natural Sciences, IPB University, Bogor, Indonesia
⁷ Organic Electronics Research Center, Ming Chi University of Technology, New Taipei City, 243303, Taiwan
⁸ Department of Physics, Faculty of Mathematics and Natural Sciences, IPB University, Bogor, Indonesia

^* Corresponding author: ahmadripai@apps.ipb.ac.id

Abstract

Barium Strontium Titanate (Ba₀.₂Sr₀.₈TiO₃) thin films doped with carbon dots at varying concentrations (0%, 2%, 4%, and 6%) were successfully synthesized using the Chemical Solution Deposition (CSD) method. The films were deposited on p-type (100) silicon substrates via spin coating at 8000 rpm, followed by annealing at 850 °C for 8 hours. Structural characterization using X-ray Diffraction (XRD) confirmed a cubic lattice structure for all samples, with lattice parameters (a = b = c) measured as 3.306 Å, 3.324 Å, 3.336 Å, and 3.311 Å for the 0%, 2%, 4%, and 6% doping levels. The observed increase in lattice parameters with higher carbon dot concentrations is attributed to the larger ionic radius of carbon dots (10 Å) compared to Ti⁴⁺ (0.61 Å). These results indicate that carbon dot incorporation modulates the structural properties of Ba₀.₂Sr₀.₈TiO₃ films, which could have significant implications for their functional applications.