Effect of dopants on the low temperature microwave dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics

The dominance of paramagnetic loss in microwave dielectric ceramics at cryogenic temperatures

“…16 Recent reports have found a variety of behavior ranging from a strong increase to a significant drop in the loss tangent at low temperatures, [17][18][19][20][21] although the mechanism for this has not been unambiguously identified. It is also appealing to consider using materials with very low loss at cryogenic temperatures in practical communication and radar systems.…”

Microwave dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics doped with Nb2O5, MnO2 or V2O3

“…As a conclusion, BZT samples with a good compactness and a high dielectric constant were obtained by using more than 0.25% Varma et al [9,10] made a detailed investigation on the effect of dopants addition in BZT. They added several dopants of varying valence, ionic size and concentration and studied the variations in densification and microwave dielectric properties.…”

“…As a consequence, many investigations have been carried out in ordered to reduce the sintering parameters of BZT ceramic without affecting the microwave dielectric properties. Several authors reported improvements in sinterability by using sintering aids or dopants or by adding glasses [1,[8][9][10]. In order to overcome the disadvantages of solid-state reaction method, soft chemistry techniques have been also used, but, in most cases, the researchers had to compromise on the microwave dielectric properties [11,12].…”

Doped Ca(Ca1/4A2/4Ti1/4)O3 (A=Nb, Ta) Dielectrics for Microwave Telecommunication Applications

“…But we found that doping of V 2 O 5 in Ca(Ca 1/4 A 2/4 Ti 1/4 )O 3 (A=Nb, Ta) ceramics led to deterioration of the density and dielectric properties. It is understood that 23 dopant addition is to aid the densification process during sintering when added in small quantities. This occurs either (i) due to the formation of liquid phases at low temperatures if the dopants are low melting or (ii) due to the formation of vacancies of cations or anions because of the substitution of dopants in the lattice sites or their segregation in the grain boundaries.…”

“…Moreover, Ca 5 Nb 2 TiO 12 ceramics have found application in broadband DR‐loaded microstrip patch antennas 16 and also in the fabrication of rectangular 17 and cylindrical 18,19 dielectric resonator antennas. Doping of ceramics 20–24 has been established as an effective tool for tuning the properties of microwave dielectric materials. Hence, to explore the possibility of improving the densification and microwave dielectric properties, aliovalent and isovalent dopants were added to calcined Ca 5 Nb 2 TiO 12 and Ca 5 Ta 2 TiO 12 powders.…”