Phase Decomposition and Dielectric Properties of Reactively Sputtered Bismuth Zinc Niobate Pyrochlore Thin Films Deposited from Monoclinic Zirconolite Target

Abstract

Thin films of Bi 2 O 3 -ZnO-Nb 2 O 5 system with cubic pyrochlore structure can be deposited using both cubic and monoclinic (zirconolite) targets. When monoclinic target was used, the as-deposited phase was nonequilibrium cubic monophase. After post-annealing in the 600-800 • C range, phase decomposition occurred, resulting in more thermodynamically stable cubic pyrochlore and monoclinic zirconolite phases. The dielectric properties, such as dielectric constant and electric field dependent tunability, showed a steep increase along with phase separation. However, dielectric loss had a reverse tendency. The maximum tunability was about 38%, which exceeds that of cubic pyrochlore monophase films deposited from cubic target.

Effects of substrate on the crystalline structure and microwave dielectric properties of Bi1.5Mg1.0Nb1.5O7 sol–gel thin films

“…Note that significant dispersion in the dielectric constant is observed in the BMN thin film on ceramic substrate in the microwave frequency region, and the dielectric constant abrupt decrease with the frequency increasing. According to Kamba et al [48], the appearance of dielectric dispersion is a signature of partially disordered, where the main lattice periodicity is preserved, and only some of the sublattices exhibit disorder [46]. This result is in agreement with the XRD analysis above.…”

“…The XRD and SEM measurements exhibit that the crystallinity increases gradually in the films deposited on the glass, the ceramic and the Si(1 0 0). Secondly, It is demonstrated that cubic pyrochlore structure with preferred (2 2 2) orientation is regarded to be a positive factor for large dielectric constant [7,[44][45][46]. The XRD results reveal that the film on Si(1 0 0) substrate shows strong (2 2 2)-oriented texture, and that of the glass and ceramic substrate samples exhibit slightly (2 2 2) and (4 0 0) orientations, respectively.…”

Tunable Coplanar Waveguide (Cpw) Line Integrating Bismuth Zinc Niobate (Bzn) Thin Films

“…Using tunable dielectric materials such as ferro-and para-electrics, several tunable circuits have been widely applied to beam-steering antenna systems or reconfigurable RF applications because of low loss, low power consumption, and low cost, compared with other technologies as semiconductor and microelectromechanical system (MEMS) technology [1]. Therefore, various materials as Ba x Sr 1−x TiO 3 (BST), Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 (BZN) [2,3], PbO-ZnO-Nb 2 O 5 (PZN) [4], lead zirconate titanate (PZT) [5], etc. have been developed and used for design of several tunable circuits (capacitors, matching networks, filters, and phase shifters).…”