Dongyun Guo

Effect of Ce doping on the microstructure and electrical properties of BiFeO3 thin films prepared by chemical solution deposition

Ce-doped Bi1−xCexFeO3 (BCFOx) thin films with x = 0–0.12 were successfully prepared on SnO2 : F(FTO)/glass substrates by chemical solution deposition. The BCFOx films showed a gradual phase transition from a rhombohedral to a pseudotetragonal structure with increase in the Ce content. The substitution of Bi with Ce greatly reduced the leakage current and the dielectric loss of the BCFOx films, which showed an Ohmic conduction mechanism. The BCFOx films with x = 0.06 exhibited a well squared-shaped P–E hysteresis loop with a remanent polarization (2Pr) of 92.3 µC cm−2 and an improved anti-fatigue characteristic after 1010 read/write polarization cycles.

High-speed preparation and dielectric properties of BaTi4O9 film by laser chemical vapor deposition

BaTi4O9 film was prepared on Pt/Ti/SiO2/Si substrate by laser chemical vapor deposition. The microstructure and dielectric properties were investigated. The single-phase BaTi4O9 film with random orientation was obtained. The surface consisted of round and rectangular grains, and the cross-section was columnar microstructure. The deposition rate (Rdep) was 135xa0μmxa0h−1. The dielectric constant (εr) and loss (tanδ) were 35 and 0.01, respectively, at 1xa0MHz. With increasing temperature, εr increased and showed a broad peak around 736xa0K, which indicated there might be a phase transition.

Microstructure and dielectric response of (1 1 1)-oriented tetragonal BaTiO3 thick films prepared by laser chemical vapor deposition

Abstract (1 1 1)-oriented barium titanate (BaTiO3) thick films were prepared on Pt-coated Si substrates by laser chemical vapor deposition. The effects of deposition temperature on the orientation, microstructure, and dielectric response of the BaTiO3 films were investigated. BaTiO3 films exhibited a significant (1 1 1) orientation at deposition temperatures from 930 to 1010 K. With increasing deposition temperature from 875 to 1010 K, the surface microstructure changed from cauliflower-like to columnar structures with pyramidal caps. The permittivity of a (1 1 1)-oriented tetragonal BaTiO3 film prepared at 980 K was 1890 at room temperature and 2600 at the Curie temperature of the film (395 K).

Preparation of rutile TiO2 thin films by laser chemical vapor deposition method

TiO2 thin films were prepared on Pt/Ti/SiO2/Si substrate by laser chemical vapor deposition (LCVD) method. The effects of laser power (PL) and total pressure (ptot) on the microstructure of TiO2 thin films were investigated. The deposition temperature (Tdep) was mainly affected by PL, increasing with PL increasing. The single-phase rutile TiO2 thin films with different morphologies were obtained. The morphologies of TiO2 thin films were classified into three typical types, including the powdery, Wulff-shaped and granular microstructures. ptot and Tdep were the two critical factors that could be effectively used for controlling the morphology of the films.

Dielectric properties of Ba4Ti13O30 film prepared by laser chemical vapor deposition

Compounds in the BaO–TiO2 system have attracted great attention due to their excellent dielectric properties, which can be applied to microwave devices [1–6]. Among them, Ba4Ti13O30 ceramics were prepared 60 years ago [7]. However, Rase and Roy reported the improper stoichiometry, BaTi3O7. The correct structure of Ba4Ti13O30 was later solved by Tillmanns and Negas et al. [8, 9]. Since, Ba4Ti13O30 compound has low dielectric constant (er) and high-quality factor (Q), it is often used to improve microwave dielectric property of the other compounds as additive [10, 11]. To the best of our knowledge, there was no literature reported on preparation and dielectric property of single-phase Ba4Ti13O30 ceramics and film. Laser chemical vapor deposition (LCVD) is considered to be a promising process to prepare high-quality films at high deposition rate (Rdep) [12–15]. In this study, Ba4Ti13O30 film was prepared on Pt/Ti/SiO2/Si substrate by LCVD. The effect of frequency and temperature on dielectric properties of Ba4Ti13O30 film was investigated. Experimental

Effect of Mo substitution on ferroelectric properties of Bi3.6Ho0.4Ti3O12 thin films prepared by sol-gel method

The series of (Bi0.9Ho0.1)4−2x/3Ti3−xMoxO12 (BHTM) (x=0, 0.9%, 1.5%, 3.0%, and 6.0%) thin films on Pt/Ti/SiO2/Si substrates is prepared by sol-gel method, and the effect of Mo content on the microstructure and ferroelectric properties of these films are investigated. When the Mo content is not excessive, the BHTM films consisted of the single phase of Bi-layered Aurivillius phase. The B-site substitution with high-valent cation of Mo6+, in Bi3.6Ho0.4Ti3O12 films, enhanced the 2Pr (remanent polarization) and reduced the 2Ec (coercive field) of these films. The BHTM thin film with x=1.5% exhibited the best electrical properties with 2Pr of 48.4u2002μC/cm2, 2Ec of 263.5 kV/cm, dielectric constant of 391 (at 1 MHz), good insulting behavior, as well as the fatigue-free characteristic.

Impedance Spectroscopy of Dielectric BaTi 5 O 11 Film Prepared by Laser Chemical Vapor Deposition Method

BaTi5O11 film was prepared on Pt/Ti/SiO2/Si substrate by the laser chemical vapor deposition method. A single-phase BaTi5O11 film with

Ferroelectric and dielectric properties of Bi4-xNdxTi3O12 thin films prepared by sol–gel method

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