Dielectric relaxations in pure, La-doped, and (La, Co)-codoped BiFeO3: Post-sintering annealing studies

Wang, Q.Q.; Wang, C.C.; Zhang, N.; Wang, H.; Li, Y.D.; Li, Q.J.; Huang, Shouguo; Yu, Yi; Guo, Youmin; Lin, Zhongqin

doi:10.1016/j.jallcom.2018.02.014

Cited by 18 publications

(10 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, it can be considered that the relaxation behavior of oxides at high temperatures is mainly dominated by oxygen vacancies. In addition, the activation energy (0.66 eV) of R2 is within the activation energy range of 0.3∼1.2 eV in the relaxation caused by oxygen vacancies [36,37]. Therefore, it is reasonable to believe that R2 at high-temperature segments is related to oxygen vacancies.…”

Section: Resultsmentioning

confidence: 74%

“…The concentration of oxygen vacancy in CuMoO 4 increases (decreases) at high temperatures when annealing in N 2 (O 2 ). Generally, the intensity of dielectric-relaxation peak caused by point defect is proportional to the defect concentration [27,36,38]. In other words, the peak value is higher (lower) with increasing (decreasing) the oxygen-vacancy concentration.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Cao

et al. 2020

Mater. Res. Express

View full text Add to dashboard Cite

Tungsten (W)-doped copper molybdate (CuMo 1−x W x O 4 , x=0∼0.12) compounds were prepared by the sol-gel method. The effects of doping content on the phase transition behavior and dielectric properties of CuMo 1−x W x O 4 (x=0∼0.12) were investigated. X-ray diffraction and UV-vis diffuse reflectance spectroscopy clarified that W doping facilitated the transition of green α-phase to brown γ-phase. The chemical composition and structure of the CuMo 1−x W x O 4 (x=0∼0.12) were investigated by Fourier transform infrared (FT-IR) spectroscopy and Raman spectra. The dielectric spectra of CuMo 1−x W x O 4 at −130°C∼150°C and the color-change of CuMo 0.94 W 0.06 O 4 at 20°C∼50°C illustrated that the phasetransition temperature moves toward high temperature with increasing W. The functional relationship between the electrical modulus M' and the frequency (1 Hz∼10 MHz) indicated that there are two dielectric relaxation mechanisms for CuMo 1−x W x O 4 , which correspond to the polarization relaxation caused by hopping motion of polaron at low-temperature region (R1) and the relaxation dominated by oxygen vacancies at high temperatures (R2). It has also been confirmed that the phase transition of relaxation type exists in CuMo 1−x W x O 4 , and that R1 occurs in γ-phase and R2 occurs in α-phase. It is of great significance to establish the dielectric relationship between phase transition and relaxation. With the content of W, the intensity of relaxation peak and activation energy of R1 did not change too much, but the relaxation behavior of R2 was inhibited and the activation energy increased gradually. The above results show that dielectric spectra are an important discovery as a new method to study the phase transition of materials, and is conducive to exploring the motion state of micro-particles. The control of phasetransition temperature is of great significance for this thermochromic material as a temperature sensor.

show abstract

Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Cao

et al. 2020

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…From the Arrhenius plot of the Cd 0.40 Li 0.60 Ga 2.66 O y sample, activation energies of 0.83 and 0.70 eV have been calculated at high- and low-temperature regions, respectively (Figure d). Activation energy in the ranges of 0.3–0.5 and 0.6–1.2 eV have been reported to be associated with singly and doubly ionized oxygen vacancies, respectively. ,− Therefore, the activation energy estimated in the current system might be due to doubly ionized oxygen vacancies. From the PL spectrum, where the oxygen vacancies caused emission, the band gap was estimated to be 2.35 eV, and half of it more or less matched the activation energy estimated .…”

Section: Resultsmentioning

confidence: 77%

“…These two values also strongly supported the role of doubly ionized oxygen vacancies in the ionic conductivity of Li + -substituted samples. 44,50…”

Section: Resultsmentioning

confidence: 99%

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior

2018

View full text Add to dashboard Cite

Stoichiometric and nonstoichiometric cadmium gallate (gallium-rich) samples have been synthesized by a modified epoxide gel method. Cubic spinel arrangement was inferred for stoichiometric and gallium-rich compositions from powder X-ray diffraction analysis. Complete structural analysis employing Raman spectroscopy has been carried out to find the intricate differences between these two samples. Additional evidence for the cubic symmetry and elemental ratio of these samples has been gathered using microscopy techniques and energy-dispersive X-ray analysis. Li+ substitution for Cd2+ in gallium-rich spinel was examined, and up to 60 mol % of Cd2+ could be substituted with Li+, retaining the spinel arrangement. The introduction of lithium led to a decrease in cubic lattice parameter. Changes in the vibration modes upon lithium substitution were analyzed by Fourier transform infrared and Raman spectral measurements. The band gap value was found to increase with increase in lithium content, indicative of the Burstein–Moss effect in this system. Oxygen vacancies created as a result of lithium substitution was further examined by oxygen-ion conductivity (493–773 K) and dielectric spectroscopic measurements (100–400 K). The estimated activation energy, from these measurements, suggested major contribution of doubly ionized oxygen vacancies to the conductivity in addition to lithium-ion mobility in Li+-substituted samples. A possible defect structure operative in this system has been proposed. The catalytic role of oxygen vacancies as defect centers has been favorably utilized for the photodegradation of aqueous methylene blue dye solution.

show abstract

“…Compared with the undoped sample, all the other ceramics exhibit a dielectric relaxation character. [39,42] In addition to the broaden peak of the ε r -T peak, the dielectric constant values are slightly decreased and the peak position of ε r also changed toward the high temperature with the frequency increasing. [43] It is evident from Fig.…”

Section: Ferroelectric Propertiesmentioning

confidence: 99%

Structure, Dielectric and Multiferroic Properties of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping

Zeng

Zhang

et al. 2021

Preprint

View full text Add to dashboard Cite

Multiferroic (1- x)Bi0.85Nd0.15Fe0.98Zr0.02O3- xBaTiO3 (x = 0, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4) ceramics were synthesized by the conventional solid state reaction method. X-ray diffraction studies confirm the phase transition from rhombohedral perovskite structure to pseudocubic structure with the introduction of BaTiO3. The results of the refinement indicate the BaTiO3 is successfully doped into the crystal lattice. The microstructure analysis shows that the average grain size increases with the introduction of BaTiO3. An increase in remanant polarization has been achieved at room temperature as the BaTiO3 concentration increasing. A greatly reduced leakage current density of about two orders of magnitude is observed in x = 0.375 (J = 2.4×10− 7 A/cm2) ceramic. The dielectric properties have been enhanced by the addition of BaTiO3, which is attributed to the reduction in Fe2+ ions and oxygen vacancies. Due to the grain effect and structure transition caused by the doping of BaTiO3, the magnetization reveals a slight decrease while the coercive field for x = 0.325 (Hc = 1785.8 Oe) increases to 6.4 times of the undoped ceramic.

show abstract

Dielectric relaxations in pure, La-doped, and (La, Co)-codoped BiFeO3: Post-sintering annealing studies

Cited by 18 publications

References 45 publications

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior

Structure, Dielectric and Multiferroic Properties of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping

Contact Info

Product

Resources

About

Dielectric relaxations in pure, La-doped, and (La, Co)-codoped BiFeO3: Post-sintering annealing studies

Cited by 18 publications

References 45 publications

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO4 obtained by a modified sol-gel method

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO4 obtained by a modified sol-gel method

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa2O4 Leading to Multifunctional Behavior

Structure, Dielectric and Multiferroic Properties&nbsp;of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping

Contact Info

Product

Resources

About

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Effect of W doping on phase transition behavior and dielectric relaxation of CuMoO₄ obtained by a modified sol-gel method

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior

Structure, Dielectric and Multiferroic Properties of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping