Colossal permittivity of (Tm+Nb) co-doped rutile-TiO2 ceramics with ultralow dielectric loss and excellent thermal stability

Ultralow dielectric loss in Tb + Ta‐modified TiO2 giant dielectric ceramics via designing defect chemistry

“…As x increases from 0 to 0.02, the 2 θ of all peaks decreases as shown in Figure 1B, meaning that the lattice parameters increase with increasing Tb and Ta content. As the ionic radii of Ta 5+ (0.069 nm) and Tb 3+ (0.098 nm) are bigger than Ti 4+ (0.065 nm), the lattice parameter should increase with x based on the size of the ionic radii 6,12 . However, for x = 0.04, 2 θ increases, which may be due to the generation of impurity phases.…”

“…As the ionic radii of Ta 5+ (0.069 nm) and Tb 3+ (0.098 nm) are bigger than Ti 4+ (0.065 nm), the lattice parameter should increase with x based on the size of the ionic radii. 6,12 However, for x = 0.04, 2θ increases, which may be due to the generation of impurity phases. This is in-line with the variation of lattice parameters, as shown in Table 1.…”

“…They are entangled and combined to form defect clusters, which localize the delocalized electrons and reduce the loss due to electron conduction. 1,6 The short-range hopping of electron around point defect or between defect clusters in the grain (EPDD effect) is more easily activated at low temperature (<50 K). This local motion of elections can fully keep up with the fluctuation of applied electric field and lead to the excellent dielectric properties.…”

“…Moreover, its reaction to the applied electric field causes the interesting CP phenomenon, named electron pinning defect dipoles (EPDDs) mechanism 1 . Inspired by this pioneering research, a giant dielectric response was also observed in other rutile TiO 2 ceramics with defect clusters prepared by the researchers, such as Lu 3+ + Nb 5+ , 10 Tm 3+ + Nb 5+ , 6 Gd 3+ + Nb 5+ , 11 Ga 3+ + Sb 5+ , 12 and Eu 3+ + Ta 5+ , 13 which have further enhanced dielectric properties. However, scholars have presented a disputed explanation of the CP mechanism of TiO 2, involving internal barrier layer capacitor (IBLC), hopping conductivity, and electrode effects 13–18 .…”

“…Materials with large dielectric constants ( ε r > 10 3 ) are receiving increasing focus, due to their use in manufacturing capacitors, thermoelectric, and photoelectric sensors 1–3 . However, the high tan δ and sensitivity temperature/frequency stability of CP materials limit their widespread use in industry, and there is controversy over the origin and mechanism of CP 4–6 . Therefore, CP materials have been a hot topic of focus for researchers.…”