scholarly journals Observation of Spin Reorientation Transitions in Lead and Titanium-Modified BiFeO3 Multiferroics

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ashwini Kumar ◽  
Poorva Sharma ◽  
Qi Li ◽  
Fujun Qiu ◽  
Jianhui Yan ◽  
...  
Keyword(s):  
Magnetic Measurement ◽  
Spin Reorientation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spintronic Devices ◽  
Solid State Route ◽  
Multiferroic Bifeo3 ◽  
Measurement Results ◽  
X Ray Absorption ◽  
Conventional Solid State Route

We report the synthesis and basic characterization details of bulk Bi1 − xPbxFe1 − xTixO3 (x = 0.05 and 0.1) polycrystalline samples, which have been synthesized using the conventional solid-state route. We studied the effects of partially doping of Pb and Ti ion on structural, vibrational, and magnetic properties of multiferroic BiFeO3. X-ray diffraction (XRD) was used for crystallographic studies, followed by Rietveld refinement, and phase formation of the compounds was confirmed, which indicates that the sample has rhombohedral (R3c, 100%) symmetry for x = 0.05 and R3c (98%) + P4mm (2%) symmetry for x = 0.1. X-ray absorption spectroscopy has been probed at Fe L2,3 and O K edges to determine the valence (charge) state of Fe in BiFeO3. Interestingly, the magnetic measurement results revealed the existence of spin reorientation transition in Pb and Ti-modified BiFeO3, which indicates that the BiFeO3 samples studied may find promising applications in memory and spintronic devices.

IMPROVEMENT OF COERCIVITY IN COBALT-DOPED ANATASE TiO2 NANOPARTICLES HYDROTHERMALLY PREPARED

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2550-2555
Author(s):  
MINGZAI WU ◽  
YING XIONG ◽  
NAN JIANG ◽  
HAI PING QI ◽  
QIANWANG CHEN
Keyword(s):  
Room Temperature ◽  
Magnetic Measurement ◽  
Hydrothermal Process ◽  
Hysteresis Loops ◽  
Anatase Tio2 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Measurement Results ◽  
Ferromagnetic Hysteresis

Anatase Ti 1-x Co x O 2 nanoparticles were prepared by a hydrothermal process at 180 °C. Ferromagnetic hysteresis loops of the as-prepared samples were measured at room temperature. The Ti 1-x Co x O 2 ( x = 0.0376) powder shows coercivity up to 700 Oe, which is the highest value reported for anatase Ti 1-x Co x O 2. X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurement results provided evidence that Co was incorporated into TiO 2 lattice. Combined with the fact that the preparation was carried out in an oxidized environment starting from cobalt (II) in the oxidized state, it is suggested that the homogeneous doping of Co into the lattice of anatase should be responsible for the improvement of coercivity in anatase Ti 1-x Co x O 2 nanoparticles.

Effects of Nano-Sized BN Doping on the Phase Formation, Tc and Critical Current Density of MgB2 Superconductor

2005 ◽  
Vol 23 ◽  
pp. 113-116 ◽  
Author(s):  
S. Soltanian ◽  
M. Delfany ◽  
X.L. Wang ◽  
M.J. Qin ◽  
H.K. Liu ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Magnetic Measurements ◽  
Magnetic Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Measurement Results ◽  
Diffraction Patterns ◽  
Synthesized Materials

MgB2 polycrystalline bulk samples with additions of 0, 5, 10 and 20% wt.% nano-sized BN powders were prepared using the reaction in-situ method. All the samples were sintered at 850°C for 1h in Ar. All the samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) and magnetic measurements. The X-ray diffraction patterns show that the BN does not react with Mg and B during the heat treatment and remains as a separate phase. The synthesized materials thus contain two separate BN and MgB2 phases. In addition, the samples contain a small, almost constant amount of MgO. SEM shows that the samples contain MgB2 grains with average grain sizes of about 250 nm. Magnetic measurement results show that the critical current density and irreversibility fields decrease slightly as the BN level increases. The Tc drops slightly from 38.9 to 38.2 K and has a sharp transition with a transition width of less than 1 K. The field dependence of Jc for all the samples is also presented.

Microstructure Properties of Bi0.5Na0.5TiO3-BaZrO3 Piezoelectric Ceramics

2012 ◽  
Vol 151 ◽  
pp. 310-313
Author(s):  
Jenn Sen Lin ◽  
Teng Chin Yu ◽  
Cheng Hsing Hsu ◽  
Ci Jie Huang ◽  
His Wen Yang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solid State ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Diffraction Patterns ◽  
Conventional Solid State Route ◽  
Scanning Electron

The microstructure properties of the perovskite Bi0.5Na0.5TiO3-BaZrO3 ceramics were prepared with the conventional solid-state route have been investigated. The resultant microstructure properties were analyzed based upon the densification, the X-ray diffraction patterns and scanning electron microscopy. The correlation between the microstructures and the sintering temperature was also examined.

Influences of Pressure Conditions on Synthesis of Mg(Zr0.05Ti0.95)O3 Dielectric Ceramics

2012 ◽  
Vol 430-432 ◽  
pp. 692-695
Author(s):  
Ching Fang Tseng ◽  
Cheng Hsing Hsu ◽  
Ci Jie Huang ◽  
Chun Hung Lai
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Microscopy Techniques ◽  
Structure And Microstructure ◽  
Conventional Solid State Route

The microwave dielectric properties and microstructures of an Mg(Zr0.05Ti0.95)O3 ceramic system have been investigated. The compounds were prepared by the conventional solid-state route with various pressure conditions from 25 to 100 Kg/cm2 and sintered at 1420oC for 4 h. The structure and microstructure were analyzed using X-ray diffraction and scanning electron microscopy techniques. The Mg(Zr0.05Ti0.95)O3 had excellent dielectric properties: Q×f ~ 194,000 (GHz), εr ~ 17.9, and τf ~ -43 ppm/oC for the sample at 90 Kg/cm2.

Effect of Sintering Behaviors on Microwave Dielectric Properties of (Ca0.3Sr0.1)Sm0.4TiO3 Ceramics

2014 ◽  
Vol 602-603 ◽  
pp. 738-741
Author(s):  
Cheng Hsing Hsu ◽  
Shang Hung Tsai ◽  
Wen Shiush Chen ◽  
Chun Hung Lai ◽  
Jenn Sen Lin
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Sintering Conditions ◽  
Diffraction Patterns ◽  
Conventional Solid State Route

The microstructure and dielectric properties of the (Ca0.3Sr0.1)Sm0.4TiO3 ceramics with various sintering conditions have been investigated. The compounds were prepared by the conventional solid-state route with various sintering temperatures from 1340 to 1400°C and sintering duration from 3 h. The resultant microwave dielectric properties were analyzed based upon the densification, the X-ray diffraction patterns and the microstructures of the ceramics. The correlation between the microstructures, the microwave dielectric properties and sintering behaviors was also examined. The εr value of 96.7 and Q×f value of 11,600 GHz were obtained for (Ca0.3Sr0.1)Sm0.4TiO3 ceramics sintering at 1370°C for 3 h. The (Ca0.3Sr0.1)Sm0.4TiO3 ceramics had suitable dielectric properties can find applications in microwave devices such as resonator, filter and antenna.

Effect of Pressure Conditions on Characteristics of (Ca0.2Sr0.8)3Ti2O7 Dielectric Ceramics

2013 ◽  
Vol 278-280 ◽  
pp. 377-380
Author(s):  
Hsin Han Tung ◽  
Yu Chuan Chen ◽  
Wen Shiush Chen ◽  
Cheng Hsing Hsu ◽  
Jenn Sen Lin
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Microscopy Techniques ◽  
Structure And Microstructure ◽  
Conventional Solid State Route

The microwave dielectric properties of (Ca0.2Sr0.8)3Ti2O7 ceramic system have been investigated with various pressure conditions. The compounds were prepared by the conventional solid-state route with various pressure conditions from 60 to 80 Kg/cm2 and sintered at 1450oC for 4 h. The structure and microstructure were analyzed using X-ray diffraction and scanning electron microscopy techniques. The (Ca0.2Sr0.8)3Ti2O7 had excellent dielectric properties: Q×f ~ 50,000 (GHz) and εr ~ 63.2 for the sample at 70 Kg/cm2.

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

The Relative Merits of Oxides of Hafnium, Cerium and Thorium as Surrogates for Plutonium Oxide in Calcium Phosphate Ceramics

2009 ◽  
Vol 1193 ◽  
Author(s):  
B. L. Metcalfe ◽  
S. K. Fong ◽  
L. A. Gerrard ◽  
I. W. Donald ◽  
E. S. Welch ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcination Temperature ◽  
Cerium Oxide ◽  
Absorption Spectroscopy ◽  
Hafnium Oxide ◽  
Intermediate Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption ◽  
Additional Phase

AbstractThe choice of surrogate for plutonium oxide for use during the initial stages of research into the immobilization of intermediate level pyrochemical wastes containing plutonium andamericium oxides in a calcium phosphate host has been investigated by powder X-ray diffraction and X-ray absorption spectroscopy. Two non-radioactive surrogates, hafnium oxide and cerium oxide, together with radioactive thorium oxide were compared. Similarities in behaviour were observed for all three surrogates when calcined at the lowest temperature, 750°C but differences became more pronounced as the calcination temperature was increased to 950°C. Although some reaction occurred between all the surrogates and the host to form a substituted whitlockite phase, increasing the temperature led to a significant increase in the cerium reaction and the formation of an additional phase, monazite. Additionally it was observed that the cerium became increasingly trivalent at higher temperatures.

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