scholarly journals BiFeO3 codoping with Ba, La and Ti: Magnetic and structural studies

2015 ◽  
Vol 05 (04) ◽  
pp. 1550034 ◽  
Author(s):  
O. García-Zaldívar ◽  
S. Díaz-Castañón ◽  
F. J. Espinoza-Beltran ◽  
M. A. Hernández-Landaverde ◽  
G. López ◽  
...  
Keyword(s):  
Room Temperature ◽  
Family System ◽  
Spontaneous Magnetization ◽  
Solid State Reaction Method ◽  
Ferromagnetic Behavior ◽  
Conventional Solid State Reaction ◽  
Dopant Incorporation ◽  
Calorimetric Measurements ◽  
Different Temperatures ◽  
Rhombohedral Perovskite Structure

Conventional solid state reaction method, from oxides and carbonates, was employed to prepare bismuth (Bi)-based multiferroic systems. The undoped BiFeO3 (BFO) and the codoped system with Ba, La and Ti (Bi[Formula: see text]BaxFe[Formula: see text]TiyO3, Bi[Formula: see text]BaxLazFe[Formula: see text]TiyO3) with x,y,[Formula: see text] were prepared stoichiometrically and sintered at two different temperatures. The structural and magnetic properties were investigated at room temperature. XRD measurements confirm the obtaining of the rhombohedral perovskite structure of the BFO family system. For the undoped system, some reflections of undesired phases are present for two different sintering temperatures, while for the doped system only one phase is present for both temperatures. The magnetic characterization at room temperature revealed remarkable differences between the ceramic samples. The results show that for undoped BFO system, spontaneous magnetization is not observed at room temperature. Nevertheless, in doped one, a well-defined ferromagnetic behavior is observed at room temperature, possible, due to the suppression of the spatially modulated spin structure of BFO promoted by the reduction of the rhombohedral distortion and the weakening of the Bi–O bonds. The XPS results confirm the presence of oxygen vacancies and the coexistence of Fe[Formula: see text] and Fe[Formula: see text] in all the studied samples. Calorimetric measurements reveal that the dopant incorporation has not a direct effect in Néel temperature but possibly yes in ferroelectric-paraelectric transition.

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.

Investigations of PbxSr1-xTiO3 Thin Films and Ceramics for Microelectronic Applications

2004 ◽  
Vol 811 ◽  
Author(s):  
M. Jain ◽  
Yu.I. Yuzyuk ◽  
R.S. Katiyar ◽  
Y. Somiya ◽  
A.S. Bhalla ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Room Temperature ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
Phase Shifters ◽  
Conventional Solid State Reaction ◽  
Mode Behavior ◽  
Dielectric Devices ◽  
Pst System

ABSTRACTWe have investigated electrical and optical properties of the lead strontium titanate {(PbxSr1-x)TiO3 or PST} ceramic and dielectric properties of the thin films of PST at low and high frequencies. (PbxSr1-x)TiO3 compositions with × ≤ 0.4 are paraelectric at room temperature and exhibit ferroelectric phase transition below room temperature. Only one phase transition in the PST system (compared to three in BaxSr1-xTiO3) was recorded. The studies indicated that PST has potential for tunable microwave devices in the paraelectric phase. In the present studies, Pb0.3Sr0.7TiO3 (PST30) ceramic was prepared by the conventional solid-state reaction method and thin films of PST were prepared by sol-gel technique. Structural, microstructural, dielectric, and Raman measurements were performed on these samples. Sharp phase transition was observed in case of the ceramic by dielectric and Raman measurements at 283 K. Raman measurements revealed well-pronounced soft-mode behavior below the Curie temperature in PST ceramic. The thin film of PST deposited on lanthanum aluminate substrate was highly (100) oriented and showed dielectric maxima at ∼280 K, which was close to that in case of the bulk. Eight element coupled micro-strip phase shifters (CMPS) was fabricated on the PST film and tested in the frequency range of 15-17 GHz. The average figure of merit of 49 °/dB for PST30 film in the Ku band at 533 kV/cm suggests the potentiality of these films for high frequency tunable dielectric devices.

Effect of Gd Substitution on the Dielectric Properties and Magnetoelectric Effect of BiFeO3

2010 ◽  
Vol 150-151 ◽  
pp. 1470-1475
Author(s):  
Gui Lin Song ◽  
Tian Xing Wang ◽  
Cun Jun Xia ◽  
Chao Li ◽  
Fang Gao Chang
Keyword(s):  
Dielectric Constant ◽  
Rare Earth ◽  
Dielectric Loss ◽  
Room Temperature ◽  
Magnetoelectric Effect ◽  
Solid State Reaction Method ◽  
Impurity Phase ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Dielectric Relaxation Process

Multiferroic Bi1-xGdxFeO3(x=0, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. For all the samples prepared, they exhibit magnetoelectric effect at room temperature, and the dielectric constant and dielectric loss decrease with increasing frequency in the range from 10000Hz to 1 MHz from a typical orientational dielectric relaxation process. It has been found that both dielectric constant and dielectric loss are strongly dependent on the Gd3+ content. And substitution of Bi with rare earth Gd helps to eliminate the impurity phase in BiFeO3 ceramics.,

Cluster Glass Behavior of Doped Cobaltite Nd0.80Sr0.20CoO3

2011 ◽  
Vol 413 ◽  
pp. 524-528
Author(s):  
Yi Yun Yang
Keyword(s):  
Glass Transition ◽  
Rare Earth ◽  
Transition Temperature ◽  
Spontaneous Magnetization ◽  
Ac Susceptibility ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Dc Magnetization ◽  
Glass Behavior

In this paper, the rare earth cobaltite Nd0.80Sr0.20CoO3sample was prepared using conventional solid state reaction method. The dc magnetization, ac susceptibility, hysteresis loop of polycrystalline Nd0.80Sr0.20CoO3sample was carried out using the physical properties measurement system of Quantum Design. A dynamic analysis of ac susceptibility implies cluster glass transition temperatureTSG=72.06 K which occurs much higher by 25 K than that point at which the dc magnetization reaches a maximum. The cluster glass behavior of polycrystalline Nd0.80Sr0.20CoO3sample, which originates from the phase separation at low temperature, was systematically investigated in this paper. It was found that the sample has a small spontaneous magnetization and the weak frequency dependent peak so that we assume that the sample is cluster-glass.

Electrical Properties of Nb-Doped and Nb-Mn-Codoped BaTiO3-(Bi0.5Na0.5)TiO3 Lead-Free PTCR Ceramics

2010 ◽  
Vol 67 ◽  
pp. 134-142
Author(s):  
Guo Rong Li ◽  
Sen Lin Leng ◽  
Liao Ying Zheng ◽  
Jiang Tao Zeng ◽  
Zhi Jun Xu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
High Resistivity ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
Xrd Patterns ◽  
Temperature Resistivity

Nb-doped and Nb-Mn-codoped (1-xmol%)BaTiO3-xmol%(Bi0.5Na0.5)TiO3 (BBNTx) lead-free positive temperature coefficient of resistivity (PTCR) ceramics were prepared by the conventional solid state reaction method. The XRD patterns indicated that all BBNTx samples formed a single perovskite structure with tetragonal phase. 0.25 mol% Nb doped BBNT1 ceramic, sintered at 1330°C for 1h in air, had low room-temperature resistivity (ρ25) of 80 Ω•cm and a high resistivity jump (maximum resistivity [ρmax]/minimum resistivity [ρmin]) of 4.2 orders of magnitude with Tc about 152°C. The Nb-doped BBNTx (10≤x≤60) ceramics also showed distinct PTC effect with Tc between 185 and 232°C by sintering in N2, which was shut off when samples were cooled to a low temperature. In addition, The Nb-Mn-codoped BBNT1 ceramics exhibited higher resistivity jump than the single Nb-doped ones, with increasing the room-temperature resistivity.

Magneto-Opto Electronic Applications of Conductive and Room Temperature Ferromagnetic (Al, Mn) Co-Doped ZnO Particles with Visible Emission

2020 ◽  
Vol 20 (6) ◽  
pp. 3913-3918 ◽  
Author(s):  
Divya Rehani ◽  
Swati Bishnoi ◽  
Manish Saxena ◽  
Shailesh Narain Sharma
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Magnetic Measurements ◽  
Hexagonal Wurtzite Structure ◽  
Solid State Reaction Method ◽  
Ferromagnetic Behavior ◽  
Maximum Conductivity ◽  
Doped Zno ◽  
Mn Doped ◽  
Co Doped

The Mn, Al co-doped ZnO samples were synthesized using solid-state reaction method and were annealed in furnace at 300 °C, 600 °C and 900°C temperature. All the samples prepared were investigated in detail for analysis of their structural, morphological, optical, magnetic and electrical behavior. The XRD data confirmed the hexagonal wurtzite structure of pristine, Mn doped and Al, Mn co-doped ZnO. For morphological investigation SEM and TEM techniques were employed. The PL properties of the ZnO:Mn, Al sample revealed emission in the blue region (415–438 nm). Furthermore, IV studies were carried out to examine the conductivity of the ZnO:Mn, Al samples and maximum conductivity was found in the sample with 5% Al doping and annealing temperature 600 °C. The magnetic measurements revealed room temperature ferromagnetic behavior in the optimized ZnO:Mn, Al sample annealed at 600 °C which indicates its suitability for Magneto-Opto Electronic Applications.

Room Temperature Magnetoelectric Coupling in Bi5Ti3FeO15 Ceramics

2013 ◽  
Vol 668 ◽  
pp. 762-766 ◽  
Author(s):  
X.Q. Chen ◽  
Xiang Bin Zeng ◽  
F.J. Yang ◽  
X.P. Kong ◽  
C. Wei ◽  
...  
Keyword(s):  
Electric Field ◽  
Room Temperature ◽  
Magnetic Measurement ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Solid State Reaction Method ◽  
Layered Perovskite ◽  
Conventional Solid State Reaction ◽  
Magnetic Dipoles ◽  
Ferroelectric Hysteresis

Magnetoelectric(ME) coupling at room temperature(RT) in four-layered perovskite Bi5Ti3FeO15(BTFO) ceramics prepared by conventional solid state reaction method was observed. Unsaturated ferroelectric hysteresis loop with 2Pr=0.464 μC/cm2 and 2Ec=25 kV/cm at an applied electric field 58 kV/cm was obtained because of lower breakdown voltage which maybe induced by lower relative density of the sample. A weak ferromagnetic (Mr=0.122 memu/g, Hc=69 Oe) rather than an antiferromagnetic property was observed at RT by magnetic measurement. Significantly, the ME coupling between the electric dipoles and magnetic dipoles at RT was demonstrated by measuring the effect of magnetic and DC electric poling on ferroelectric and magnetic hysteresis loops, respectively. Both Pr and Mr decreased after magnetic and DC electric poling. And the rate of Pr change decreased with increasing measuring electric field.

Electrical Properties of a High-Tc Superconductor-Polymer Compersite

2007 ◽  
Vol 546-549 ◽  
pp. 1989-1992
Author(s):  
Fang Gao Chang ◽  
Kun Fang ◽  
Gui Lin Song
Keyword(s):  
Annealing Temperature ◽  
Solid State Reaction Method ◽  
Gravimetric Analysis ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Different Temperatures ◽  
Zero Resistance ◽  
Composite Samples

A superconductor-polymer composite of Bi1.8Pb0.4Sr2Ca2Cu3Oy and ethylene propylene rubber (EPR) was prepared by conventional solid-state reaction method. The phase structure of the composite was characterized by using x-ray diffraction technique. The resistivity of composite samples annealed at different temperatures was measured between 40K and 300K. The results indicate that the resistivity of the as-prepared composite increases with increasing EPR content and shows essentially a semiconducting behavior above Tc. For fixed EPR content, the resistivity of composite samples decreases with increasing annealing temperature. The composite begins to show some signs of superconducting transition at an annealing temperature of 700 °C and zero resistance is reached for samples sintered at 800°C. Thermal gravimetric analysis (TGA) on the composite confirmed that 65% of the EPR content still present in the superconducting composite samples. SEM was used to investigate the surface morphology of the composites. Preliminary results show that the mechanical properties of the composite have been much improved compared with its parent superconductor ceramics.

Structural and Dielectric Properties of Na0.5Bi0.5TiO3 Ferroelectric Ceramics

2012 ◽  
Vol 585 ◽  
pp. 219-223
Author(s):  
Rekha Kumari ◽  
N. Ahlawat ◽  
Ashish Agarwal ◽  
M. Sindhu ◽  
N.N. Ahlawat
Keyword(s):  
Dielectric Properties ◽  
Solid State Reaction Method ◽  
Wide Frequency Range ◽  
Ferroelectric Ceramics ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
X Ray ◽  
Different Temperatures

Na0.5Bi0.5TiO3 (NBT) ceramics were synthesized by conventional solid state reaction method. Structural and dielectric properties of these ceramics were investigated. Crystalline phase of sintered ceramics was investigated by X-ray diffraction (XRD). The Rietveld refinement of powder X-ray diffraction revealed that the prepared ceramics exhibit the rhombohedral space group R3c. Dielectric properties of Na0.5Bi0. analyzer.5TiO3 (NBT) ceramics were studied at different temperatures in a wide frequency range using impedance

Influence of Sintering Temperatures on Microstructures and the Thermal Conductivity of CuAlO2 Ceramics

2016 ◽  
Vol 848 ◽  
pp. 222-227 ◽  
Author(s):  
Zi Jun Song ◽  
Lian Jun Wang ◽  
Wan Jiang ◽  
Wei Luo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Solid State ◽  
Room Temperature ◽  
Solid State Reaction Method ◽  
Oxide Ceramic ◽  
Synthetic Process ◽  
Reaction Method ◽  
Environmental Friendly ◽  
Different Temperatures

Oxide ceramic is a kind of environmental friendly materials, which has attracted more and more interests for its bunch of advantages such as sound chemical, thermal stability, simple synthetic process, cheap price, harmless and safety. Therefore, Oxide ceramic will be a promising material in the future. In this work, polycrystalline samples of CuAlO2 were prepared by a solid state reaction method. The mixture of pure CuO and Al2O3 powders was firstly pressed under the pressure of 60 MPa, and then 200 MPa to prepare pellets of 5 mm thick and 10 mm in diameter. The green compacts were sintered at five different temperatures (1273 K, 1323 K, 1373 K, 1423 K, 1473 K) for various holding times (5 h, 10 h and 15 h) in the air and then the furnace cooled. The crystalline and microstructures of the sintered CuAlO2 bodies were detected by XRD and SEM. The properties of density, thermal conductivity were also investigated in detail. The experimental results show that CuAlO2 bodies were rhombohedral, belonging to R3m space group. It is found that the density and the thermal conductivity of CuAlO2 ceramics were significantly dependent on the sintering temperatures. The density and thermal conductivity increased with increasing the sintering temperatures. The thermal conductivity of samples sintered at 1273 and 1473 K with the same holding time (10 h) were 9.70 and 35.53 W/mk at the room temperature, 3.41 and 8.29 W/mk at 1100 K, respectively.

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