Influence of nanoparticle seeding on the phase formation kinetics of sol-gel-derived Sr0.7Bi2.4Ta2O9 thin films

2003 ◽  
Vol 18 (2) ◽  
pp. 387-395 ◽  
Author(s):  
Yun-Mo Sung ◽  
Gopinathan M. Anilkumar ◽  
Seung-Joon Hwang
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Phase Formation ◽  
Volume Fraction ◽  
Sol Gel ◽  
Fluorite Phase ◽  
Microstructural Development ◽  
Aurivillius Phase ◽  
Si Substrates ◽  
Formation Kinetics

Sr0.7Bi2.4Ta2O9 (SBT) thin films were deposited on unseeded and SBT nanoparticle (approximately 60–80 nm) seeded Pt/Ti/SiO2Si substrates via sol-gel and spin-coating techniques. The SBT thin films were heated at 600 °C for 1 h to form the fluorite phase, and these fluorite films were further heated at 730–760 °C for fluorite-to-Aurivillius phase transformation. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction analyses showed highly enhanced kinetics in seeded SBT thin films. Johnson–Mehl–Avrami isothermal kinetic analyses were performed for the characterization of Aurivillius phase formation in unseeded and seeded SBT thin films using the volume fraction values. The Avrami exponents were determined as approximately 1.4 and approximately 0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius-type plots, the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be approximately 264 and approximately 168 kJ/mol, respectively. This gives a key reason for the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needlelike crystals, while those on seeded ones showed formation of domains comprising directionally grown wormlike crystals. On the basis of the phase formation kinetics and microstructural development, a model representing different nucleation and crystal growth mechanisms for the unseeded and seeded SBT thin films was proposed.

Enhancement of Aurivillius Phase Formation Kinetics in SBT Thin Films using Nanoparticle Seeding

2003 ◽  
Vol 784 ◽  
Author(s):  
Yun-Mo Sung ◽  
Woo-Chul Kwak ◽  
Se-Yon Jung ◽  
Seung-Joon Hwang
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Phase Transformation ◽  
Phase Formation ◽  
X Ray Diffraction ◽  
Aurivillius Phase ◽  
X Ray ◽  
Si Substrates ◽  
Formation Kinetics ◽  
Kinetics Of

ABSTRACTPt/Ti/SiO2/Si substrates seeded by SBT nanoparticles (∼60–80 nm) were used to enhance the phase formation kinetics of Sr0.7Bi2.4Ta2O9 (SBT) thin films. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction (Q-XRD) analyses showed highly enhanced kinetics in seeded SBT thin films. The Avrami exponents were determined as ∼1.4 and ∼0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius–type plots the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be ∼264 and ∼168 kJ/mol, respectively. This gives a key reason to the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needle-like crystals, while those on seeded ones showed formation of domains comprised of directionally grown worm-like crystals.

An Effective Way to Suppress the Pyrochlore Phase Formation in SBT Thin Films

2003 ◽  
Vol 784 ◽  
Author(s):  
Se-Yeon Jung ◽  
Woo-Chul Kwak ◽  
Seung-Joon Hwang ◽  
Yun-Mo Sung
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Seed Layer ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Energy Difference ◽  
Ion Diffusion ◽  
Aurivillius Phase ◽  
Si Substrates ◽  
Coating Methods

ABSTRACTSr0.7Bi2.4Ta2O9 (SBT) thin films were deposited on Pt/Ti/SiO2/Si substrates with and without a seed layer of ∼40 nm thickness using sol-gel and spin coating methods. The influence of seed layer on the phase formation characteristics of SBT thin films was investigated using x-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Formation of pyrochlore as well as Aurivillius phase was observed in both the unseeded and seeded SBT films heated at 740°C. However, it was revealed that Aurivillius phase formation was enhanced in seeded SBT thin films and pyrochlore phase formation was highly suppressed. In this study, two possible mechanisms for the suppression of pyrochlore phase formation were proposed from the perspectives of activation energy difference for Aurivillius and pyrochlore phase formation and Bi-ion diffusion to pyrochlore phase.

Suppression of pyrochlore phase formation in Sr0.7Bi2.4Ta2O9 thin films using nanoseed layer

2003 ◽  
Vol 18 (8) ◽  
pp. 1745-1748 ◽  
Author(s):  
Se-Yeon Jung ◽  
Seung-Joon Hwang ◽  
Yun-Mo Sung
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Seed Layer ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Energy Difference ◽  
Ion Diffusion ◽  
Aurivillius Phase ◽  
Si Substrates ◽  
Coating Methods

A Sr0.7Bi2.4Ta2O9 (SBT) seed layer approximately 40 nm thick was formed on Pt/Ti/SiO2/Si substrates, and SBT thin films with the same chemical composition were deposited on the substrates with and without seed layer using sol-gel and spin coating methods. The influence of seed layer on the phase formation characteristics of SBT thin films was investigated using x-ray diffraction and scanning electron microscopy analyses. Formation of pyrochlore as well as Aurivillius phase was observed in both the unseeded and seeded SBT films heated at 740 °C. However, it was revealed that Aurivillius phase formation was enhanced in seeded SBT thin films and pyrochlore phase formation was highly suppressed. In this study, two possible mechanisms for the suppression of pyrochlore phase formation were proposed from the perspectives of activation energy difference between Aurivillius and pyrochlore phase formation, and Bi-ion diffusion to pyrochlore phase.

Phase Formation Kinetics in Sol-Gel Derived Strontium Bismith Tantalate

2001 ◽  
Vol 666 ◽  
Author(s):  
Yun-Mo Sung ◽  
Woo-Chul Kwack
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Phase Formation ◽  
Sol Gel ◽  
Avrami Exponent ◽  
Fluorite Phase ◽  
X Ray Diffraction ◽  
Aurivillius Phases ◽  
Formation Kinetics ◽  
Isothermal Kinetic

ABSTRACTPhase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via sol-gel and pyrolysis process, was investigated by using thermal analysis. Each of the two exotherms, appearing in differential thermal analysis (DTA) scan curves, was identified as crystallization of fluorite phase and transformation of fluorite to aurivillius phase, respectively by using x-ray diffraction (XRD). By applying non-isothermal kinetic analyses to the DTA results, activation energy values for the formation of fluorite and aurivillius phases were determined as 192 and 375 kJ/mol, respectively and Avrami exponent values for each reaction were determined as 0.91 and 0.96, respectively. These activation energy and Avrami exponent values were discussed in detail to understand phase formation mechanism in SBT system.

Nonisothermal phase formation kinetics in sol-gel-derived strontium bismuth tantalate

2001 ◽  
Vol 16 (7) ◽  
pp. 2039-2044 ◽  
Author(s):  
Yun-Mo Sung
Keyword(s):  
Thermal Analysis ◽  
Phase Formation ◽  
Sol Gel ◽  
Fluorite Phase ◽  
X Ray Diffraction ◽  
Aurivillius Phases ◽  
Formation Kinetics ◽  
Analysis Technique ◽  
Dta Curve ◽  
Phase Formation Mechanism

Phase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via the sol-gel and pyrolysis processes, was investigated using the thermal analysis technique. The two exotherms, appearing in the differential thermal analysis (DTA) curve, were identified as crystallization of fluorite phase and transformation of fluorite to Aurivillius phase, respectively, using x-ray diffraction. Nonisothermal kinetic analysis of the DTA results shows activation energy values for the formation of fluorite and Aurivillius phases as 192 and 375 kJ/mol, respectively, and Avrami exponent values for each reaction as 0.91 and 0.96, respectively. The results of this investigation are presented and discussed in detail to understand the phase formation mechanism in the SBT system.

Effect of polyvinylpyrrolidone on the formation of perovskite phase and rosette-like structure in sol-gel–derived PLZT films

2007 ◽  
Vol 22 (8) ◽  
pp. 2195-2203 ◽  
Author(s):  
Z.H. Du ◽  
T.S. Zhang ◽  
J. Ma
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Phase Formation ◽  
Crystallization Behavior ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Microstructural Development ◽  
Electrical And Optical Properties ◽  
Molecular Weights ◽  
Gel Particles

Poly-vinylpyrrolidones (PVP) with different molecular weights were used to modify the sol-gel solutions for preparing Pb0.91La0.09(Zr0.65,Ti0.35)0.9775O3 (PLZT, 9/65/35) thin films. The crystallization behavior and microstructural development of the PLZT films with and without PVP addition were investigated. It was found that the addition of PVP significantly improved perovskite phase formation of the PLZT films, but the films exhibited rosette-like morphology. Further study on the PLZT films and the gel particles showed that a premature nucleation of PbO grains in the PVP modified sol-gel solution induced the Pb-rich domains in the films, which accelerated the growth of the grains and thus led to the rosette-like structure. In addition, the electrical and optical properties of the PLZT films with rosette-like structure were also studied and discussed.

Secondary Phase Formation and Microstructural Development in the Interaction Between SrBi2Ta2O9 Films and Pt/Ti/SiO2/Si Substrates

1997 ◽  
Vol 12 (8) ◽  
pp. 2104-2110 ◽  
Author(s):  
Chung-Hsin Lu ◽  
Buh-Kuan Fang
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Spin Coating ◽  
Pyrochlore Phase ◽  
Pyrochlore Structure ◽  
Secondary Phase ◽  
Microstructural Development ◽  
Titanium Layer ◽  
Si Substrates ◽  
Secondary Phase Formation

The phase formation and microstructural development of SrBi2Ta2O9 thin films prepared via spin-coating using metalorganic solution on Pt/Ti/SiO2/Si substrates have been investigated in this study. The spun-on films started to crystallize from above 550 °C and were well crystallized at 800 °C. At higher than 850 °C a secondary phase having a pyrochlore structure was formed in the films. The analysis of EDS and SIMS confirmed that the interaction between the films and the titanium species which diffused outward from the titanium layer on substrates was the origin for the occurrence of the pyrochlore phase. In addition, varying the thickness of the coated films and platinum layers had remarkable influence on the formation amount of the pyrochlore phase.

Enhanced Aurivillius phase formation kinetics in seeded SBT thin films

2003 ◽  
Vol 254 (1-2) ◽  
pp. 92-99 ◽  
Author(s):  
Se-Yeon Jung ◽  
Seung-Joon Hwang ◽  
Yun-Mo Sung
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Aurivillius Phase ◽  
Formation Kinetics

Phase transition and piezoelectricity of sol–gel-processed Sm-doped BiFeO3 thin films on Pt(111)/Ti/SiO2/Si substrates

2015 ◽  
Vol 3 (9) ◽  
pp. 2115-2122 ◽  
Author(s):  
Wei Sun ◽  
Jing-Feng Li ◽  
Qi Yu ◽  
Li-Qian Cheng
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Sol Gel ◽  
Orthorhombic Phase ◽  
High Quality ◽  
Si Substrates ◽  
Bifeo3 Thin Films ◽  
Gel Processing

We prepared high-quality Bi1−xSmxFeO3 films on Pt(111)/Ti/SiO2/Si substrates by sol–gel processing and found rhombohedral–orthorhombic phase transition with enhanced piezoelectricity.

Sign in / Sign up

Export Citation Format

Share Document