Phase transitions and relaxor properties of doped quantum paraelectrics

✍ Scribed by W Kleemann; J Dec; Y.G Wang; P Lehnen; S.A Prosandeev

• Book ID: 104152164
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 367 KB
• Volume: 61
• Category: Article
• ISSN: 0022-3697
• DOI: 10.1016/s0022-3697(99)00278-4

✦ Synopsis

Scaling properties of the paraelectric susceptibility with respect to temperature T and electric field E have been evidenced on solid solutions Sr 1Ϫx Ca x TiO 3 , x Ӷ 1; and are explained within the framework of both the transverse Ising model (TIM) and an anharmonic oscillator model (AOM). The impurity-induced ferroelectric phase transitions occurring at x Ͼ x c Ϸ 0:002 are modeled using a heterogeneous TIM, which is solved numerically. Alternatively, we present a coupled mode model involving a TIM and an AOM for the impurity and the host lattice subsystems, respectively. Relaxor properties such as dielectric polydispersivity, quasi-first-order Raman scattering, bilinear coupling of optic and acoustic phonon modes and hyper-Rayleigh light scattering in the paraelectric regime are attributed to polar nanodomains due to fluctuations of defect-induced quenched random fields (RFs). Some of these features are modeled within the framework of the heterogeneous TIM including RF interactions.