Origins of Giant Dielectric Properties with Low Loss Tangent in Rutile (Mg1/3Ta2/3)0.01Ti0.99O2 Ceramic

Abstract

The Mg2+/Ta5+ codoped rutile TiO2 ceramic with a nominal composition (Mg1/3Ta2/3)0.01Ti0.99O2 was synthesized using a conventional solid-state reaction method and sintered at 1400 °C for 2 h. The pure phase of the rutile TiO2 structure with a highly dense microstructure was obtained. A high dielectric permittivity (2.9 × 104 at 103 Hz) with a low loss tangent (<0.025) was achieved in the as-sintered ceramic. After removing the outer surface, the dielectric permittivity of the polished ceramic increased from 2.9 × 104 to 6.0 × 104, while the loss tangent also increased (~0.11). The dielectric permittivity and loss tangent could be recovered to the initial value of the as-sintered ceramic by annealing the polished ceramic in air. Notably, in the temperature range of −60–200 °C, the dielectric permittivity (103 Hz) of the annealed ceramic was slightly dependent (<±4.4%), while the loss tangent was very low (0.015–0.036). The giant dielectric properties were likely contributed by the insulating grain boundaries and insulative surface layer effects.

Colossal Permittivity Characteristics of (Nb, Si) Co-Doped TiO2 Ceramics

“…Among these ceramics, the sample with x = 0.025 showed the minimum tanδ of ~0.11 and colossal permittivity (ε ~4.8 × 10 4 ) at 10 kHz and room temperature. This dielectric performance is close to that of (Nb, La) [25], (Ta, In) [6] and (Nb, Eu) [28] co-doped TiO 2 but lower than (Ta, Mg) [29], (Ta, Y) [30] (Ta, Ho) [31] (Nb, Zr) [14] co-doped TiO 2 . Figure 5 depicts the room temperature complex impedance (Z* = Z + iZ ) plots for the four ceramic samples.…”

DFT calculations and giant dielectric responses in (Ni1/3Nb2/3)xTi1−xO2

“…8(c). 12,15,23,24,45,[48][49][50] The comparative results reveal that 2.5% NiNTO, with its high 3 ′ and tan d values, shows promise for applications in capacitors. It should be noted that while a high 3 ′ can be achieved in 5%Nb 5+ -doped TiO 2 , the tan d was significantly large, approximately 0.5.…”

“…Subsequently, a series of acceptor/donor co-doped TiO 2 materials were widely investigated, involving trivalent acceptors and other acceptors. For instance, acceptor dopants (A + , B 2+ , C 3+ ), isovalent dopant (I 4+ ), and donor dopants (D 5+ ) (A = Ag or Li, 10,11 B = Mg, Zn, Sr, Cu or Ca, 12–15 C = Al, Sm, Bi, Fe, In, Dy, Ga, Gd, Yb, or Sc, 16–20 I = Zr, 21 and D = Nb 5+ , Sb 5+ , and Ta 5+ (ref. 1 and 22–26)).…”

Origin of Temperature Coefficient of Resonance Frequency in Rutile Ti1−xZrxO2 Microwave Ceramics

“…Among these phases, the thermodynamically stable phase is the rutile, as brookite and anatase phase can transform irreversibly to the rutile phase in the temperature range of 700-920 °C [5]. In several studies, colossal permi ivity was found for (Mg 2+ + Ta 5+ ) co-doped TiO2 [6], (Tb 3+/4+ and Sb 5+ ) co-doped TiO2 [7], (Zr and Ta) co-doped TiO2 [8], (Lu 3+ /Nb 5+ ) co-doped TiO2 [9], and (Nb and Mn) co-doped TiO2 [10]. Cohn et al [2] reported MW properties of TiO2 for dielectric resonators, which gained significant a ention [11].…”