The Influence of the Precursor on the Formation of Bi₂O₃ Polymorphs in CSD‐Derived Thin Films

Abstract

This work examines the synthesis and characterization of crack‐free, β‐Bi2O3 thin films prepared on Pt/TiO2/SiO2/Si or corundum substrates using the sol‐gel method. We observed that the Bi‐based precursor has a pronounced influence on the β‐Bi2O3 phase formation. Well‐crystallized, single β‐Bi2O3 thin films were obtained from Bi‐2ethylhexanoate at a temperature of 400°C. In contrast, thin films deposited from Bi‐nitrate and Bi‐acetate resulted in non‐single Bi2O3 phase formation. TEOS was used for the stabilization of the β‐Bi2O3 phase. The phase composition of the thin films was characterized by means of X‐ray diffraction (XRD), whereas the morphology and thickness of the thin films were studied using scanning electron microscopy (SEM). The β‐Bi2O3 films' dielectric properties were characterized utilizing microwave‐frequency measurement techniques: (1) the split‐post dielectric resonator method (15 GHz) and (2) the planar capacitor configuration (1–5 GHz). The dielectric constant and dielectric loss measured at 15 GHz were 257 and 7.5 × 10−3, respectively.

Electrical characterization of sol–gel-derived (1−x)NBT–xNTa (0.05<x<0.3) thin films

“…Studies of bismuth-based compounds [14] have shown that a Bi-precursor with longer carboxylate chains, due to its low decomposition temperature, can expedite the formation of Bi-based compounds. Based on these reports [12][13][14], we have used the Bipropionate precursor for the preparation of NBT-NTa n thin films with sol-gel synthesis. Nevertheless, the focus of this study will be on an electrical characterization of NBTNTa thin films, in particular with compositions up to 30 mol% of NTa, which in bulk form show the greatest diversity in electrical responses.…”