ac conductivity relaxation processes in CaCu3Ti4O12 ceramics: Grain boundary and domain boundary effects

2006 ◽  
Vol 89 (24) ◽  
pp. 242906 ◽  
Author(s):  
Wei Li ◽  
Robert W. Schwartz
Keyword(s):  
Grain Boundary ◽  
Ac Conductivity ◽  
Domain Boundary ◽  
Boundary Effects ◽  
Relaxation Processes ◽  
Conductivity Relaxation

scholarly journals Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5822
Author(s):  
Hicham Mahfoz Kotb ◽  
Mohamad M. Ahmad ◽  
Adil Alshoaibi ◽  
Koji Yamada
Keyword(s):  
Grain Boundary ◽  
Relative Permittivity ◽  
Domain Boundary ◽  
Secondary Phase ◽  
High Energy ◽  
Relaxation Processes ◽  
Heterogeneous Structure ◽  
Reactive Sintering ◽  
Domain Boundaries ◽  
A Minor

CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε’ = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell–Wagner polarization effect at the blocking grain boundaries and domain boundaries. The higher tanδ of the cosubstituted samples was correlated with their lower grain boundary’s resistivity, as confirmed by IS analysis. Modulus-spectrum analysis revealed two relaxation processes for the pure and (Bi3+, Nb5+) cosubstituted CCTO samples. Dissimilar behavior was observed for the (Al3+, Nb5+) cosubstituted CCTO, where three relaxation mechanisms were observed and attributed to the grain, domain-boundary, and grain-boundary responses.

Grain boundary effects on dielectric, infrared and Raman response of SrTiO3 nanograin ceramics

2006 ◽  
Vol 26 (14) ◽  
pp. 2855-2859 ◽  
Author(s):  
Jan Petzelt ◽  
Tetyana Ostapchuk ◽  
Ivan Gregora ◽  
Maxim Savinov ◽  
Dagmar Chvostova ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Effects ◽  
Grain Boundary Effects ◽  
Raman Response

Studies on grain boundary effects in spray deposited BICOVOX 0.1 films on platinum-coated stainless steel substrate

Ionics ◽  
2010 ◽  
Vol 17 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Rajeev Joshi ◽  
Ratikant Mishra ◽  
C. A. Betty ◽  
Shilpa Sawant ◽  
S. H. Pawar
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Boundary Effects ◽  
Grain Boundary Effects

scholarly journals OXYGEN SELF-DIFFUSION IN YBa2Cu3O7-x : GRAIN-BOUNDARY EFFECTS

1990 ◽  
Vol 51 (C1) ◽  
pp. C1-1035-C1-1042 ◽  
Author(s):  
J. SABRAS ◽  
C. DOLIN ◽  
J. AYACHE ◽  
C. MONTY ◽  
R. MAURY ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Effects ◽  
Self Diffusion ◽  
Grain Boundary Effects

Inelastic Behavior and Grain-Boundary Effects in Polycrystalline Materials

2006 ◽  
Vol 978 ◽  
Author(s):  
Jibin Shi ◽  
Mohammed Zikry ◽  
Tarek Moustafa Hatem
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Boundary Effects ◽  
Polycrystalline Materials ◽  
Inelastic Behavior ◽  
Multiple Slip ◽  
Computational Schemes ◽  
Grain Boundary Effects ◽  
Polycrystalline Aggregates

AbstractDislocation-density based multiple-slip constitutive formulations and specialized computational schemes are introduced to account for grain-boundary (GB) effects in polycrystalline aggregates. New kinematically based interfacial grain-boundary regions and formulations are introduced to account for dislocation-density transmission, absorption, and pile-ups that may occur due to CSL grain-boundary misorientations.

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