Dielectric Properties of Amorphous (Ba _2/3 ,Sr _1/3 )TiO ₃ Films

ABSTRACT This study investigates the dielectric relaxation and electrical conduction mechanisms in Au/ a ‐(Ba 2/3 ,Sr 1/3 )TiO 3 (850 nm)/Pt structures across a wide temperature range. A high relative permittivity of 100 was measured. Analysis of Arrhenius plots reveals two distinct relaxation processes and multiple conduction regimes. At low temperatures, a first relaxation and bulk conductivity coexist with a common activation energy of 0.50 eV, attributed to the thermally activated reorientation of polar defect complexes. A second relaxation emerges, marked by a significant decrease in activation energy from 0.87 to 0.56 eV at 210°C. Combined with the observation of depressed Nyquist arcs and broadened tanδ(ω) peaks, this transition provides quantitative evidence for the formation and cooperative diffusion of oxygen vacancy clusters. Above 160°C, the bulk conduction arises from the thermally activated hopping of free charge carriers between trapping sites (Ti 4+ in reduced TiO 6 octahedra) by overcoming an energetic barrier of 1.16 eV. The interfacial conduction is thermally activated with an energy that varies from 1.75 to 0.64 eV when the temperature exceeds 275°C. It is expected that this mechanism is ascribed to the catalytic activity identified at the BST/Pt interface and to the electronic detrapping from oxygen vacancies, respectively. These results highlight that the complex interplay between structural disorder, vacancy clustering, and catalytic activity of the electrode is governing the functional performance of amorphous titanate‐based capacitors.