Lattice dynamics and phonon characteristics of complex perovskite microwave ceramics

• Published in: IET Nanodielectrics 2019-03, Vol.2 (1), p.11-26
• Main Authors: Shi, Feng, Dong, He-Lei, Zhou, Di, Wang, Chun-Hai, Tan, Qiu-Lin, Xiong, Ji-Jun, Wang, Qing
• Format: Article
• Language: English
• Subjects: atomic thermal vibrational properties; barium compounds; Ceramics; complex perovskite microwave dielectric ceramics; crsytal structures; Crystal structure; dielectric losses; Dielectric properties; Far infrared radiation; four-parameter semiquantum model; FTIR; Infrared spectra; intrinsic properties; Kramers-Kronig relations; lattice dynamics; Lattice vibration; Lorentz three-parameter classical model; Microwave communications; microwave materials; Millimeter waves; millimetre wave devices; neodymium compounds; Parameter identification; permittivity; Perovskites; phonon characteristics; Phonons; Raman spectra; Review Article; sintering; Superstructures; Symmetry; Vibration mode; vibrational modes; Vibrational spectra
• ISSN: 2514-3255; 2514-3255
• DOI: 10.1049/iet-nde.2018.0016

Complex perovskite microwave dielectric ceramics (MWDCs) of $A\lpar {B}^{\prime}_{1/3}{B}^{\prime \prime}_{2/3}\rpar {\rm O}_3$A(B1/3′B2/3′′)O3-type (A = Ba, Sr,…; B′ = Mg, Zn,…; B″ = Nb, Ta), which exhibit excellent dielectric properties, have currently been widely used in microwave and millimetre wave devices. Vibrational spectra, including both Raman and far-infrared (FIR) spectra, are powerful tools to investigate the atomic thermal vibrational properties of MWDCs and reveal the intrinsic origin of dielectric properties. In this review, lattice dynamics and phonon characteristics of the $A\lpar {B}^{\prime}_{1/3}{B}^{\prime \prime}_{2/3}\rpar {\rm O}_3$A(B1/3′B2/3′′)O3-type MWDCs are summarised and presented in detail to introduce remarkable progress in this field and make a guide for the design of novel advanced MWDCs. The atomic sites and the corresponding modes in Raman and FIR spectra are identified and illuminated. The effects of the processing conditions and the ordered superstructures in the nanoscale region on vibrational modes are summarised systemically. Intrinsic properties can be extrapolated from the fitting results of FIR spectroscopy, which were also discussed based on the Kramers–Krönig relations, Lorentz three-parameter classical model and four-parameter semi-quantum model. The correlations between vibrational modes (phonons), crystal structures, and dielectric properties are created, which can help to build the mathematical models so as to understand the structure–property relationship of MWDCs better.