Bi2o3

Regioregular poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) of 4002‐EE grade with four different molecular weights (25, 37, 46, 55 kDa) was purchased from Rieke Metals. [6,6]‐phenyl C71 butyric acid methyl ester (PC₇₀BM) of purity >99% was purchased from Solenne. Bismuth oxide nanoparticles (Bi₂O₃) (with a β phase, tetragonal crystal structure; 38 nm diameter; surface area 18 m² g⁻¹) were purchased from Alfa Aesar. X‐ray detectors with different P3HT molecular weighs were fabricated by preparing the P3HT: PC₇₀BM: Bi₂O₃ solution where 80 mg of each P3HT sample was mixed with 80 mg of PC₇₀BM, 80 mg of Bi₂O₃ in 1 mL dichlorobenzene (DCB; 1 mL; anhydrous; Sigma‐Aldrich). The solution was stirred overnight followed by preheating at 60°C for 30 min before deposition of the films. The solution preparation was carried out in a N₂ glove box (MBraun MB20G).

Pellets with 10% bismuth excess were synthesized by mixing Bi₂O₃ (99.9%), CaO (99.995%) and Fe₂O₃ (99.9%) powders (Sigma-Aldrich) with different x_Cas. The pellets were pressurized to form 1-inch-diameter button-shaped targets. They were calcinated at 800 °C for 8 h in ambient conditions. After the calcination, the pellets were ground into fine powders, and formed into the same shape as the previous targets. Then, they were sintered at 850 °C for 8.5 h under ambient conditions. The epitaxial BCFO thin films (x_Ca = 0.1–0.6) were deposited on a SrTiO₃ (001) substrate (CrysTec GmbH) using pulsed laser deposition with a KrF excimer laser (λ = 248 nm). The heater T during film growth was 665 °C in an oxygen environment of 0.07 Torr. Laser fluence and repetition rate were set to be ~1 J cm⁻² and 10 Hz. All the films were in-situ cooled down to room T at a rate of 10 °C min⁻¹ under an oxygen environment of 500 Torr. The c-axis lattice parameters of the as-grown BCFO thin films were characterized using a four-circle X-ray diffractometer (PANalytical X’Pert PRO MRD) with Cu K_α1 radiation. We measured 2θ−ω X-ray scans from 10° to 60° at an interval of 0.1°. We also performed reciprocal space maps and line scans using a synchrotron source (Beamline 3A, PLS II) in Pohang Accelerator Laboratory.

The reactants used in this study were K₂CO₃ (≥99.0%, ~150 μm, Sigma-Aldrich), Na₂CO₃ (≥99.5%, ~10 μm, Sigma-Aldrich), Li₂CO₃ (99.997%, ~20 μm, Sigma-Aldrich), Nb₂O₅ (99.9%, ~2 μm, Sigma-Aldrich), Bi₂O₃ (99.9%, ~10 μm, Sigma-Aldrich), ZrO₂ (99.0%, ~5 μm, Sigma-Aldrich), and TiO₂ (≥99.9%, ~1 μm, Sigma-Aldrich), which are typically used in a conventional synthetic process. The carbonate powders of K₂CO₃, Na₂CO₃ and Li₂CO₃ were dried at 120 °C for 24 h before use owing to their hygroscopic characteristics. Also, all treatments of these powders, including weighing and drying, were carefully performed within a glove box filled with an Ar gas atmosphere. Stoichiometric Bi₂O₃-Na₂CO₃-TiO₂ and K₂CO₃-Na₂CO₃-Nb₂O₅ powder mixtures were used for the syntheses of pure BNT and KNN, respectively. The general chemical reactions of the reactants for the formation of BNT and KNN are as follows:


Additionally, their respective modified compositions were used as templates to assess the feasibility of preparing more complex compositions, specifically, 0.76BNT-0.04BLT-0.2BKT and 0.955KNN-0.03BNKLZ-0.015BNT, which were recently discovered to possess excellent piezoelectric properties35 36 . These modified oxides were prepared using the stoichiometric Bi₂O₃-Na₂CO₃-TiO₂-Li₂CO₃-K₂CO₃ and K₂CO₃-Na₂CO₃-Nb₂O₅-Bi₂O₃-Li₂CO₃-ZrO₂-TiO₂ powder mixtures, respectively.