Ferroelectric and Magnetic Properties of Co Doping Bi6Fe2Ti3O18 Ceramics

2013 ◽  
Vol 745-746 ◽  
pp. 142-145 ◽  
Author(s):  
Chun Yan Chen ◽  
Song Hou ◽  
Xiang Yu Mao ◽  
Xiao Bing Chen
Keyword(s):  
Room Temperature ◽  
Ferroelectric Properties ◽  
Magnetic Behavior ◽  
Solid State Reaction Method ◽  
Stoichiometric Ratio ◽  
Aurivillius Phase ◽  
Co Doping ◽  
Maximum Value ◽  
Crystallographic Structures ◽  
Heavy Doping

In this paper, for the purpose of enhancement in the magnetic behavior, the five-layer Aurivillius phase structure Bi6Fe2-xCoxTi3O18 (BFCT-x, x = 0.0 ~ 2.0) ceramics were synthesized using the solid-state reaction method from a mixture of Bi2O3, Co2O3, Fe2O3, and TiO2 powders with different stoichiometric ratio. The microstructure, ferromagnetic and ferroelectric properties are investigated. The crystallographic structures of BFCT-x are determined to be the typical five-layer Aurivillius phase with a suggested structural transformation at heavy doping of Co ions. At room temperature, the remnant magnetization (2Mr) of BFCT-0.0, BFCT-0.6, BFCT-1.0 and BFCT-2.0 samples are 0.043 memu/g, 0.59 emu/g, 0.81 emu/g and 1.75 memu/g, respectively. The 2Mr, at first, gradually enhance and reach a greatest value of 0.81 emu/g at x = 1.0 then degrade again with the increasing of the ratio x. At room temperature, the samples have ferroelectricity, which the remnant polarization (2Pr) of the BFCT-0.0 , BFCT-0.6, BFCT-1.0 and BFCT-2.0 samples are 2.8 μC/cm2, 8.0 μC/cm2, 3.0 μC/cm2 and 7.2 μC/cm2 respectively. The 2Pr first increases, then decreases and increases again with Co doping. When x = 0.6, the 2Pr reaches a maximum value of 8.0 μC/cm2.

Effects of (Li, Ce) Co-Doping on Microstructure, Dielectric and Ferroelectric Properties of Strontium Niobate Ceramics

2014 ◽  
Vol 787 ◽  
pp. 236-241 ◽  
Author(s):  
Gang Chen ◽  
Jie Hao Wei ◽  
Xiao Dong Peng ◽  
Chun Lin Fu ◽  
Wei Cai
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Remnant Polarization ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Co Doping ◽  
Maximum Value ◽  
Coercive Electric Field

Sr2-x(Li2/3, Ce1/3)x Nb2O7 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) (SLCN) ceramics were prepared by solid-state reaction method. The microstructure, dielectric and ferroelectric properties were investigated. The results show that all ceramics have high relative densities. Li+ and Ce4+ co-doping can promote the grains growing, and improve the dielectric and ferroelectric properties of strontium niobate ceramics. The dielectric constant decreases firstly, and then increases with the increasing of x in Sr2-x(Li2/3, Ce1/3)x Nb2O7, and the sample with x = 0.5 exhibits enhanced dielectric properties (εr ≈ 250, tanδ ≈ 0.02). The remnant polarization (Pr) and coercive electric field (Ec) of SLCN ceramics increase firstly, and then decrease with the increasing of Li+ and Ce4+ content, finally reach the maximum value of remnant polarization (Pr ≈ 0.058μC/cm2, Ec ≈ 6.87 kV/cm ) for x = 0.2.

Dielectric and Ferroelectric Properties of (Pb0.9Ba0.1) ZrO3 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 247-250
Author(s):  
Jun Bo Wu ◽  
Xin Gui Tang ◽  
Qiu Xiang Liu ◽  
Yan Ping Jiang
Keyword(s):  
Phase Transition ◽  
Room Temperature ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Ferroelectric Hysteresis Loop ◽  
Dielectric Measurements ◽  
Reaction Method ◽  
Maximum Value ◽  
Ferroelectric Hysteresis ◽  
Maximum Permittivity

(Pb1-xBax)ZrO3(PBZ) ceramics forx= 0.10 were synthesized by the mixed oxide solid state reaction method. Phase transition was investigated by dielectric measurements in the temperature range from 27 to 350 °C at various frequencies. The permittivity of the solids corresponding to (Pb1-xBax) ZrO3showed the maximum value of 10220 atx= 0.10 at the phase transition temperature. The maximum permittivity gradually increasing concentration up tox= 0.10. The ferroelectric hysteresis loop of the PBZ ceramics forx= 0.10 is displayed at room temperature and 0.2 Hz.

Study on Dielectric and Ferroelectric Properties of Gd-Doped Sr2Bi4Ti5O18 Ceramics

2011 ◽  
Vol 328-330 ◽  
pp. 1131-1134
Author(s):  
Qian Chen ◽  
Zhi Jun Xu ◽  
Rui Qing Chu ◽  
Yong Liu ◽  
Ming Li Chen ◽  
...  
Keyword(s):  
Piezoelectric Properties ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Structural Ceramics ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Maximum Value ◽  
Pure Bismuth ◽  
Ferroelectric And Piezoelectric Properties

Lead-free piezoelectric ceramics Sr2Bi4-xGdxTi5O18 were prepared by conventional solid-state reaction method. Pure bismuth layered structural ceramics with uniform gain size were obtained in all samples. The effect of Gd-doping on the dielectric, ferroelectric and piezoelectric properties of Sr2Bi4Ti5O18 ceramics were also investigated. It was found that that Gd3+ dopant gradually decreased the Curie temperature (Tc) with the lower dielectric loss (tand) of SBTi ceramics. In addition, Gd-doping with appropriate content improved the ferroelectric and piezoelectric properties of the SBTi ceramics. The piezoelectric constant (d33) of the Sr2Bi3.9Gd0.1Ti5O18 ceramic reached the maximum value, which is 22 pC/N. The results showed that the Sr2Bi4-xGdxTi5O18 ceramic was a promising lead-free piezoelectric material.

Effect of Ce-Mn Codoping on the Structural, Morphological and Electrical Properties of the BaTiO3 Based Ceramics

2021 ◽  
Vol 11 (4) ◽  
pp. 12215-12226
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Doping Concentration ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Stoichiometric Ratio ◽  
Co Doping ◽  
Mn Doped ◽  
Co Doped

Undoped, Cerium (Ce) doped, Manganese (Mn) doped and Ce-Mn co-doped Barium Titanate (BaTiO3) with the general formula Ba1-xCexMnyTi1-yO3 (where x = 0.00, 0.01, 0.02, 0.03, y = 0.00; x = 0.00, y =0.01, 0.02, 0.03; and x = y = 0.01, 0.02,0.03) were synthesized by solid-state reaction method and sintered at 1200 C for 4 hr with an aim to study their structural and electrical properties. The grain size of the samples has been estimated using the Scanning Electron Microscopy (SEM). The X-ray Diffraction (XRD) analysis indicates that the structure of the Ce-doped and Ce-Mn co-doped BaTiO3 is cubic. However, the undoped BaTiO3 and Mn-doped BaTiO3 confirmed the tetragonal-cubic mixed phases. With the change of doping concentrations, the positions of different peaks shifted slightly. The lattice parameter varied irregularly with increasing doping concentration because of Mn's changeable valency. EDX spectra confirmed the presence of Ba, Ti, Ce, and Mn contents in the co-doped samples with stoichiometric ratio. Crystallinity is observed to be clearly increased when Ce-Mn is co-doped in BaTiO3. J-V characteristic curves indicate transition from conducting to semiconducting nature for the doped and co-doped samples with the increase in temperature. The dielectric constant of the samples increases up to 4500 with the doping concentration. The higher values of dielectric constant are observed for the 2% Mn-doped and 1% Ce-Mn co-doped samples compared to the other undoped samples. For the undoped and Mn-doped samples, constant dielectric values increase with temperature but decrease for the Ce-doped and Ce-Mn co-doped samples. It is inferred that co-doping of BaTiO3 with Ce and Mn would be beneficial and economical for its applications.

Influence of Co-Doping on Magnetic Properties and Magnetocaloric Effect of Fe–Co–Zr–Cu–B Melt-Spun Ribbons

2021 ◽  
Vol 21 (4) ◽  
pp. 2552-2557
Author(s):  
Nguyen Hai Yen ◽  
Nguyen Hoang Ha ◽  
Pham Thi Thanh ◽  
Nguyen Huy Ngoc ◽  
Tran Dang Thanh ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetocaloric Effect ◽  
Melt Spinning ◽  
Room Temperature ◽  
Tangential Velocity ◽  
Magnetic Behavior ◽  
Entropy Change ◽  
Co Doping ◽  
Melt Spun ◽  
Melt Spun Ribbons

In this work, we investigated magnetic properties and magnetocaloric effect in Fe90−xCoxZr7Cu1B2 (x = 0, 1, 2, 3 and 4) melt-spun ribbons. The ribbons were prepared by using a melt-spinning method with a tangential velocity of a copper wheel of 40 m·s-1. The obtained ribbons are almost amorphous. The alloys exhibit typical soft magnetic behavior with low coercivity at room temperature. A minor replacement of Fe by Co gives an increment in Curie temperature (TC) of the alloys to higher temperatures. The TC of the alloys increases from 242 to 342 K with an increase of x from 0 to 4. Maximum magnetic entropy change, ΔSm max, of the alloys, was found to be larger than 0.7 J·kg-1·K-1 in a magnetic field change ΔH of 12 kOe for all the concentrations of Co. High refrigerant capacitys (RC >100 J ·kg-1 with ΔH = 12 kOe) at room temperature region have been obtained for the alloys. The large magnetocaloric effect near room temperature suggests that the alloys can be considered as magnetic refrigerants in the range of 250–350 K.

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

2021 ◽  
Author(s):  
Lizhu Zeng ◽  
Yuming Lu ◽  
Lujia Zhang ◽  
Xin Gong ◽  
Jianfeng Tang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Oxygen Vacancies ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Structure Transition ◽  
X Ray ◽  
Co Doping ◽  
Average Grain Size ◽  
Rhombohedral Perovskite Structure

Abstract 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.

scholarly journals Dielectric, ferroelectric and magnetic properties of Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 ceramics prepared at different sintering conditions

2018 ◽  
Vol 12 (4) ◽  
pp. 394-402 ◽  
Author(s):  
Zhengxin Li ◽  
Zhenhua Wang ◽  
Rongli Gao ◽  
Wei Cai ◽  
Gang Chen ◽  
...  
Keyword(s):  
Structural Changes ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Grain Morphology ◽  
Solid State Reaction Method ◽  
Secondary Phases ◽  
Conventional Solid State Reaction ◽  
Multiferroic Properties ◽  
Co Doping ◽  
Sintering Time

Although BiFeO3 (BFO) has attracted great attention due to its special physical properties as a typical single phase multiferroic material, the application is limited due to the formation of impurities, defects and so forth. Herein, we report improved multiferroic properties of Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 (BLSFTO) ceramics by combination of co-doping and sintering schedule. BLSFTO multiferroic ceramics were prepared by using the conventional solid state reaction method and the effect of sintering time (2, 5, 10, 20 and 30 h) on the structural, dielectric and multiferroic properties was investigated systematically. The result indicates that stable BLSFTO phase with perovskite structure was formed for all the samples. Only some impurities such as Bi2O4 can be observed when the sintering time is longer than 20 h, indicating that the sintering time can induce structural changes in BLSFTO and too long sintering time can remarkably increase the secondary phases. In addition, the frequency dependent dielectric properties show that sintering time has distinct effect on the frequency stability and the relaxation process. The result demonstrates that the enhanced magnetization, improved dielectric and ferroelectric properties may be correlated with the structural transformation, impurities, oxygen vacancies and grain morphology.

Upconversion Luminescence and Temperature Sensing of InNbO4:Er3+/Yb3+ Phosphors

2021 ◽  
Vol 13 (4) ◽  
pp. 563-568
Author(s):  
Xingbang Dong ◽  
Huanjun Zhang ◽  
Yi Li ◽  
Zheng Wang ◽  
Yang Yang ◽  
...  
Keyword(s):  
Upconversion Luminescence ◽  
Solid State Reaction Method ◽  
Temperature Sensing ◽  
Fluorescence Intensity Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
Two Photon ◽  
Maximum Value ◽  
Optical Thermometry

Er3+/Yb3+ co-doped InNbO4 phosphors were synthesized using solid state reaction method. Crystal structure was characterized using X-ray diffraction (XRD), which confirm all obtained phosphors had a monoclinic-wolframite structure and no impurity phase was introduced upon doping. Upon 980 nm excitation, upconversion (UC) emission from Er3+ ions was observed in green and red range. UC emission was obviously enhanced after co-doping Yb3+ ions and reached the maximum for 10 mol% Yb3+ ions. The relation between emission intensity and pump power was performed, revealing that the UC emission result from two-photon processes. Optical temperature sensing property was investigated by exploiting fluorescence intensity ratio (FIR) between 2H11/2 and 4S3/2 levels of Er3+ ions. Its maximum value of absolute sensitivity obtained was 0.0091 K-1, suggesting InNbO4:Er3+/Yb3+ phosphors show potential application in optical thermometry.

scholarly journals Structural, Morphological and Magnetic Properties of Nd and Co co-doped BiFeO3 Ceramics at Room temperature

2017 ◽  
Vol 41 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Tamanna Mariam ◽  
Shamima Choudhury
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Average Grain Size ◽  
Co Doped ◽  
Simultaneous Substitution

Synthesis and characterization of BiFeO3 samples, co-doped with rare earth Nd and Co in place of Bi and Fe respectively were investigated at room temperature (RT). The formula of the four samples are Co-doped BiFe1–xCoxO3 (x = 0.05-0.10) and Nd and Co co-substituted Bi0.95Nd0.05Fe0.95Co0.05O3 and Bi0.90Nd0.10Fe0.90Co0.10O3. These ceramic samples were synthesized by conventional solid state reaction method. The X-ray diffraction patterns clearly reveal that the secondary impurity phases were eliminated significantly due to the simultaneous substitution of Nd and Co in place of Bi and Fe respectively of BiFeO3 ceramics. The surface morphology of the synthesized samples was found to improve due to the simultaneous substitution of Nd and Co in place of Bi and Fe in BiFeO3. The average grain size of the first sample with 5% doping of Co in place of Fe was 1.5?m. In the second sample with 10% Co doping in place of Fe, the average grain size became 1.25 ?m. In presence of 5% Nd in place of Bi as well as with 5% doping of Co in place of Fe , grain size reduced to 0.75?m. The sample with 10% doping of Nd and Co in place of Bi and Fe respectively, average grain size decreased to 0.5?m. The EDX spectroscpoy ensured the presence of Bi, Nd, Fe, Co and O in these samples and their percentage of mass and atoms. Magnetic properties of the samples were also investigated at room temperature by measuring magnetization versus magnetic field (M-H) hysteresis loops. The wider loop clearly demonstrates the significant improvement of the magnetic behavior in 10% Nd and Co doped Bi0.90Nd0.10Fe0.90Co0.10O3 sample. The enhanced magnetic properties might be attributed to the substitution induced suppression of spiral spin structure of BiFeO3. The outcome of this investigation suggests the potentiality of the simultaneous doping of Nd and Co in BiFeO3 ceramics to improve their structural, morphological and magnetic characteristics.Journal of Bangladesh Academy of Sciences, Vol. 41, No. 1, 85-93, 2017

scholarly journals Up-conversion luminescence of Er3+ and Yb3+ co-doped CaBi2Ta2O9 multifunctional ferroelectrics

2014 ◽  
Vol 04 (03) ◽  
pp. 1450018 ◽  
Author(s):  
Qiufeng Cao ◽  
Dengfeng Peng ◽  
Hua Zou ◽  
Jun Li ◽  
Xusheng Wang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ferroelectric Properties ◽  
Green Emission ◽  
Solid State Reaction Method ◽  
Fluorescence Intensity Ratio ◽  
Promising Candidate ◽  
Radiative Relaxation ◽  
High Temperature Sensor ◽  
Simple Solid State Reaction ◽  
Co Doped

Er 3+ and Yb 3+ co-doped CaBi 2 Ta 2 O 9 (CBT)-based bismuth layered-structure oxides were synthesized by a simple solid-state reaction method. Their up-conversion (UC) luminescence, dielectric and ferroelectric properties were investigated. Two strong green emission bands centered at 526 and 547 nm and a weak red emission band centered at 658 nm were obtained under a 980 nm laser excitation at room temperature. These emission bands originated from the radiative relaxation of Er 3+ from 2 H 11/2, 4 S 3/2, and 4 F 9/2 levels to the ground state 4 I 15/2, respectively. At the meantime, the fluorescence intensity ratio (FIR) variation of two green UC emissions at 526 and 547 nm has been studied as a function of temperature in the range of 153–603 K. The maximum sensor sensitivity obtained was 39 × 10-4 K-1 at 590 K, which indicated that Er 3+/ Yb 3+ co-doped CBT ceramic is a promising candidate for applications in optical high temperature sensor.

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