PHASE STRUCTURE, PIEZOELECTRIC AND MULTIFERRIOC BEHAVIOR OF (K0.48Na0.52)NbO3-Co2O3 PIEZOELECTRIC CERAMICS

2011 ◽  
Vol 04 (03) ◽  
pp. 225-229 ◽  
Author(s):  
WENJUAN WU ◽  
DINGQUAN XIAO ◽  
JIAGANG WU ◽  
JING LI ◽  
JIANGUO ZHU
Keyword(s):  
Room Temperature ◽  
Sintering Temperature ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
Piezoelectric Ceramics ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Solid State Sintering ◽  
Sintering Method

( K 0.48 Na 0.52) NbO 3-x% Co 2 O 3 (x = 0, 0.03 and 0.05) (KNN-x% Co2O3 ) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. An orthorhombic phase was observed for all KNN-x% Co2O3 ceramics at room temperature, and two phase transitions were confirmed by the high temperature X-ray diffraction and the temperature dependence of the dielectric constant. The Co2O3 greatly improves the density and decreases the sintering temperature of KNN ceramics. The KNN-0.05 mol%Co2O3 ceramic exhibits good properties (d33 = 120 pC/N , k p = 0.41, Q m = 213 and T c = 407°C) and a good age stability. The multiferroic behavior was also observed at room temperature for the KNN-0.05 mol%Co2O3 ceramic, as confirmed by P–E loops and magnetic behavior.

The Synthesis of Ultrafine Ba/Sr Titanate Powders

1991 ◽  
Vol 249 ◽  
Author(s):  
C.H. Lin ◽  
T.S. Yan ◽  
T.S. Chin
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Solid State ◽  
Solid Solutions ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Solid State Sintering ◽  
Sintering Method

ABSTRACTBa/Sr titanate powders were obtained by reacting TiO2.xH2O gel in Ba(OH)2 and/or Sr(OH)2 aqueous solution. Different reaction temperatures between 68°C and 98°C and different mole ratios of Ba(OH)2 and Sr(OH)2 were used.X-ray diffraction analysis showed that the titanate powders are cubic, and they are solid solutions of barium and strontium. The lattace spaces of the titanates are affected by the Ba(OH)g/ Sr(OH)g, mole ratio. TEM analysis showed that the titanate powders were spherical, ultrafine, and almost monodispersed. The particle size of the powders is about from 41 to 50 nm depending on the reaction temperature.The titanate powders were compacted and sintered at various temperatures. The best sintering temperature of the powders is about 150°C lower than that of powders made by solid state sintering method.

scholarly journals Формирование и трансформация моноклинной и орторомбической фаз в реакторных порошках сверхвысокомолекулярного полиэтилена

2018 ◽  
Vol 60 (9) ◽  
pp. 1847
Author(s):  
М.В. Байдакова ◽  
П.В. Дороватовский ◽  
Я.В. Зубавичус ◽  
Е.М. Иванькова ◽  
С.С. Иванчев ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polymer Synthesis ◽  
X Ray Diffraction ◽  
Reactor Powder ◽  
X Ray ◽  
The One

AbstractUsing powerful synchrotron X-ray radiation of the beamline “Belok” operated by the National Research Center “Kurchatov Institute,” we perform X-ray diffraction (XRD) study of an intact, virgin (not subjected to any external mechanical loads) particle isolated from reactor powder of ultrahigh molecular weight polyethylene. Along with the peaks originating from the orthorhombic phase, we detect the peaks characteristic of the monoclinic phase that is stable only under mechanical stress, suggesting that the mechanical stress that leads to the formation of the monoclinic phase and persists at room temperature develops during the polymer synthesis. The monoclinic phase gradually disappears when the particle is heated stepwise in increments of 5 K, and its peaks become undetectable when the temperature reaches 340 K. We contrast the results obtained for the phase composition of the virgin particle to those for a tablet prepared by compaction of the same reactor powder at room temperature. XRD analyses of the tablet were performed on D2 Phaser (Bruker) instrument. The monoclinic phase that originates during the polymer synthesis and the one that forms in the tablet during compaction have different parameters. We discuss the mechanisms by which these two different monoclinic phases originate during the processes involved.

Preparation and Microstructure of Pressureless Sintered Si2ON2-SiC Ceramic

2011 ◽  
Vol 335-336 ◽  
pp. 699-703
Author(s):  
Hui Hui Tan ◽  
Zhu Xing Tang ◽  
Xia Zhao ◽  
He Zhang
Keyword(s):  
Bulk Density ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Nitriding Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effect Of Additives ◽  
Sic Ceramic ◽  
Sintering Method ◽  
Scanning Electron

This paper introduces Si2ON2-SiC ceramic fabricated by pressureless sintering method and studies the effect of additives, nitriding temperatures on bulk density, porosity, phase composition and microstructure. It is discovered that additives MgO, CeO2 can increase the densities of Si2ON2-SiC ceramic apparently, and MgO additive has a better effect than CeO2. Nitriding temperature also is an important factor. The bulk density of the specimen with MgO additive reaches maximum at 1.91 g/cm3 when sintered at 1450 °C, and the bulk density of specimen with CeO2 additive is 1.86 g/cm3 at the same condition while the bulk density of the specimen without additive is only 1.75 g/cSuperscript textm3. The X-ray diffraction and scanning electron microscopy of the specimens show that the amount of Si2ON2 increase with the sintering temperature increase. But when the temperature is higher than 1500 °C the Si2ON2 grains will decompose into Si3N4, and Si2ON2 will vanish at 1550 °C

scholarly journals Effect of Sintering Temperature on Property of Low-Density Ceramic Proppant Adding Coal Gangue

2019 ◽  
Vol 26 (1) ◽  
pp. 94-98
Author(s):  
Jianying HAO ◽  
Huilan HAO ◽  
Yunfeng GAO ◽  
Xianjun LI ◽  
Mei QIN ◽  
...  
Keyword(s):  
Solid Waste ◽  
Bulk Density ◽  
Apparent Density ◽  
Sintering Temperature ◽  
Coal Gangue ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Method ◽  
Waste Coal

Calcined flint clay (45.6 wt.% Al2O3) and solid waste coal gangue were used to prepare low-density ceramic proppant by solid state sintering method. The density and breakage ratio of the ceramic proppant were systematically investigated as a function of sintering temperature. The morphology and phase composition of the ceramic proppant were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the ceramic proppant is composed of rod-like mullite and granular cristobalite. Bulk density and apparent density of the proppant first rise and then slightly decrease with increasing the sintering temperature, while breakage ratios under 35 MPa and 52 MPa pressure gradually decrease and then increase. As the sintering temperature increases up to 1400 °C, the ceramic proppant shows denser microstructure. The proppant sintered at 1400 °C have the best performance with 1.27 g/cm3 of bulk density, 2.79 g/cm3 of apparent density, 3.27 % of breakage ratio under 35 MPa closed pressure and 8.36 % of breakage ratio under 52 MPa closed pressure, which conform to the requirement of low-density ceramic proppant. The addition of solid waste can greatly reduce the preparation cost of the ceramic proppant.

Structural Characterization of Co70-xNixGa30 Ferromagnetic Shape Memory Alloys

2008 ◽  
Vol 52 ◽  
pp. 103-108 ◽  
Author(s):  
Sidananda Sarma ◽  
A. Srinivasan
Keyword(s):  
Magnetic Susceptibility ◽  
Shape Memory ◽  
Room Temperature ◽  
Structural Parameters ◽  
Ac Magnetic Susceptibility ◽  
X Ray Diffraction ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
X Ray ◽  
Ferromagnetic Shape Memory

Polycrystalline ingots of Co70–xNixGa30 (20 ≤ x ≤ 26) ferromagnetic shape memory alloy (FSMA) were prepared by arc melting elemental powders followed by homogenization at 1230 °C for 24 hrs and quenching in liquid nitrogen. Room temperature X-Ray diffraction (XRD) patterns of as-quenched samples exhibited single-phase tetragonal structure for alloy compositions with x = 21 to 26, and a two-phase structure (cubic A2-phase along with weak tetragonal phase) for the alloy with x = 20. Rietveld refinement was performed on the X-ray diffraction patterns to obtain the refined structural parameters. Differential Scanning Calorimeter (DSC) curves recorded from 30 °C to 250 °C revealed martensite-austenite and austenite-martensite transformations in all alloys except the alloy with composition x = 20. Low temperature ac magnetic susceptibility measurements confirmed the existence of martensitic transformations in the alloy with x = 20. The structural transformation temperatures show a linear variation with e/a ratio. All the alloys were ferromagnetic at room temperature. Curie temperature was determined using a high temperature ac magnetic susceptibility measurement set-up.

Effect of Iron Substitution on the High-temperature Properties of Sm(Co,Cu,Ti)z Permanent Magnets

2001 ◽  
Vol 674 ◽  
Author(s):  
Jian Zhou ◽  
Ralph Skomski ◽  
David J. Sellmyer ◽  
Wei Tang ◽  
George C. Hadjipanayis
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Permanent Magnets ◽  
Site Occupancy ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Iron Substitution

ABSTRACTRecently, Ti-substituted Sm-Co permanent magnets have attracted renewed attention due to their interesting high-temperature coercivity. Our presentation deals with the effect of iron substitutions on the magnetic properties of the materials. X-ray diffraction shows that the investigated Sm(Co,Fe,Cu,Ti)z materials (z = 7.0 - 7.6) are two-phase magnets, consisting of 1:5 and 2:17 regions. The iron content affects both the coercivity and the magnetization. Depending on composition and heat treatment, some samples show a positive temperature coefficient of the coercivity in the temperature range from 22 °C to 550 °C. Moderate amounts of iron enhance the room-temperature coercivity. For example, the room-temperature coercivity of Sm(Co6.0Fe0.4Cu0.6Ti0.3) is 9.6 kOe, as compared to 7.6 kOe for Sm(Co6.4Cu0.6Ti0.3). At high temperatures, the addition of Fe has a deteriorating effect on the coercivity, which is as high as 10.0 kOe at 500 °C for Sm(Co6.4Cu0.6Ti0.3). The room-temperature magnetization increases on iron substitution, from 73 emu/g for Sm(Co6.4Cu0.6Ti0.3) to 78 emu/g for Sm(Co6.0Fe0.4Cu0.6Ti0.3). The observed temperature dependence is ascribed to the preferential dumbbell-site occupancy of the Fe atoms.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

Sinterbility of (Bi4-xLax)Ti3O12 Ceramics

2008 ◽  
Vol 55-57 ◽  
pp. 841-844 ◽  
Author(s):  
Pasinee Siriprapa ◽  
Anucha Watcharapasorn ◽  
Sukanda Jiansirisomboon
Keyword(s):  
Grain Orientation ◽  
Sintering Temperature ◽  
Orthorhombic Phase ◽  
Preferred Orientation ◽  
Doping Content ◽  
X Ray Diffraction ◽  
Microstructural Investigation ◽  
X Ray ◽  
Lanthanum Titanate ◽  
Diffraction Patterns

This research studied the effects of sintering temperature and La3+ doping content on phase, microstructure and densification of bismuth lanthanum titanate (Bi4-xLaxTi3O12; BLT) ceramics when x = 0, 0.25, 0.5, 0.75 and 1.0, respectively. The BLT powders were prepared using a mixed-oxide method. The mixtures were calcined at 750°C for 4 h before being pressed and sintered at 1000-1150°C for 4 h. The result of phase analysis by X–ray diffraction (XRD) indicated the existence of orthorhombic phase for all sintering temperatures. The XRD peak intensities of the ceramics showed preferred orientation of a particular set of {00l}-type planes. The ceramics mainly composed of plate-like grains. Increasing the sintering temperature increased grain size and increased preferred grain orientation. The present of La3+ in BLT ceramics reduced preferred orientation especially at higher sintering temperature. Results of microstructural investigation agreed well with X-ray diffraction patterns.

Fabrication of Ti-Based Biodegradable Material Composites Prepared by Spark Plasma Sintering Method

2010 ◽  
Vol 654-656 ◽  
pp. 2158-2161 ◽  
Author(s):  
Eri Miura-Fujiwara ◽  
Takeshi Teramoto ◽  
Hisashi Sato ◽  
Equo Kobayashi ◽  
Yoshimi Watanabe
Keyword(s):  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Holding Time ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Porous Ti ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method

This study aims at producing porous Ti filled with biodegradable materials for biomedical implants by means of spark plasma sintering method (SPS). To improve bone fixation and to obtain appropriate Young’s modulus as a medical implant material, we applied -tri calcium phosphate (-TCP) to the Ti-based composite. Ti/-TCP powder mixtures were sintered by SPS under applied stress of 45MPa with various temperatures and holding time. Vickers hardness (Hv) of obtained composite increased with increasing the holding time up to 10 min, and saturated hardness was approximately 750 Hv, which is extremely higher than that of bulk Ti. Hardness also increased as sintering temperature increased up to 1473 K. From the results of microstructure observations by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDXS), O- and P- containing Ti surrounded around Ti particle, and O diffused into Ti particle to a certain extent. X-ray diffraction results indicated several kinds of Ti-O and/or Ti-P formed in the specimen. Results indicated that it is the brittle phases formed during sintering that increased the hardness.

scholarly journals Czochralski Growth, Magnetic Properties and Faraday Characteristics of CeAlO3 Crystals

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 245 ◽  
Author(s):  
Feiyun Guo ◽  
Qiyuan Li ◽  
Huaimin Zhang ◽  
Xiongsheng Yang ◽  
Zhen Tao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Circular Dichroism ◽  
Structure Refinement ◽  
Magnetic Behavior ◽  
Czochralski Method ◽  
Czochralski Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Van Vleck ◽  
Abnormal Magnetic Behavior

CeAlO3 crystals were grown in different growth atmospheres by the Czochralski method. The lattice parameters and space group of CeAlO3 crystal were determined by Rietveld structure refinement of X-ray diffraction (XRD) data. The influence of Ce4+ ions in the crystal on the transmittance and crystal color was confirmed by XPS analysis. Magnetization curve at room temperature and temperature dependencies of the magnetic susceptibility in two different directions were measured, indicating that CeAlO3 crystal has remarkable magnetic anisotropy and there is an abnormal magnetic behavior in the vertical <001> direction in the temperature range of 50–150 K. Faraday characteristics of CeAlO3 crystal were investigated at room temperature. Verdet constants of CeAlO3 at 532, 635 and 1064 nm are about 2.1 times as large as those of CeF3. The reason of large Verdet constants was analyzed based on the Van Vleck–Hebb theory and the magnetic circular dichroism (MCD) spectrum.

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