排序方式: 共有11条查询结果,搜索用时 46 毫秒
1.
2.
R. Yimnirun A. Ngamjarurojana R. Wongmaneerung S. Wongsaenmai S. Ananta Y. Laosiritaworn 《Applied Physics A: Materials Science & Processing》2007,89(3):737-741
The temperature scaling of the ferroelectric hysteresis was investigated in hard lead zirconate titanate (PZT) bulk ceramic.
The power-law temperature scaling relations were obtained for hystersis area 〈A〉, remnant polarization Pr, and coercivity EC in the forms of 〈A〉∝T-0.9650, Pr∝T-0.0261, and EC∝T-0.8823, respectively, which are mostly comparable to those of its soft counterpart. The observation that Pr decayed more slowly with temperature than in soft PZT was attributed to the presence of the complex defects in hard PZT.
However, the product of Pr and EC still provided the similar scaling law on the T dependence in comparison with 〈A〉.
PACS 77.80.-e; 77.80.Fm; 77.84.-s; 77.84.Dy 相似文献
3.
In this study, the potential of recycled poly(ethylene terepthalate) (rPET) as a well‐defined reinforcing material for the in situ microfibrillar‐reinforced composite (iMFC) was investigated in comparison with that of liquid crystalline polymer (LCP). Each dispersed phase (LCP or rPET) was melt blended with high density polyethylene (PE) by using extrusion process. The rheological behavior, morphology, and the thermal stability of LCP/PE and rPET/PE blends containing various dispersed phase contents were investigated. All blends and LCP exhibited shear thinning behavior, whereas Newtonian fluid behavior was observed for rPET. The incorporation of LCP or rPET into PE significantly improved the processability. A potential of rPET as a processing lubricant by bringing down the melt viscosity of the blend system was as good as LCP. The elongated LCP domains were clearly observed in as‐extruded strand. Although the viscosity ratio of the rPET/PE system was lower than that of the LCP/PE blend system, most rPET domains appeared as small droplets. An addition of LCP and rPET into the PE matrix improved the thermal resistance significantly in air but not in nitrogen. The obtained results suggested the high potential of rPET as a processing aid and good thermally resistant material similar to LCP. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
4.
S. Wongsaenmai K. Kanchiang S. ChandarakY. Laosiritaworn S. RujirawatR. Yimnirun 《Current Applied Physics》2012,12(2):418-421
In this study, ceramics in Mn-doped ((Ka0.5Na0.5)0.935Li0.065)NbO3 ceramics (Mn content = 0.25, 0.50, 1.00 and 1.50 mol%) were successfully prepared by the conventional mixed-oxide technique. The crystal structure was identified by XRD as a single-phase perovskite structure with tetragonal symmetry. The valence of Mn ions, characterized by the synchrotron XAS technique, was seen to change from Mn4+ to Mn3+ during the formation of the crystal. The valence state of Mn strongly affected the crystal structure and ferroelectric properties of the ceramics. The ferroelectric parameters show the decrease of remnant polarization and the increase of the coercive field with increasing MnO2 content. The results confirm the Mn3+ in KNNL perovskite lattices, leading to the formation of oxygen vacancies and hardening effects. 相似文献
5.
R. Yimnirun X. Tan S. Ananta S. Wongsaenmai 《Applied Physics A: Materials Science & Processing》2007,88(2):323-328
In this study, lead indium niobate (Pb(In1/2Nb1/2)O3 or PIN) ceramics were prepared by a wolframite precursor method via a vibro-milling technique. Fine-grain ceramics were achieved
with average grain size of 1–2 μm, indicating advantage of the vibro-milling technique used. The dielectric and ferroelectric
properties were measured by means of an automated dielectric measurement set-up and a standardized ferroelectric tester, respectively.
The dielectric properties of PIN ceramic were measured as functions of both temperature and frequency. The results indicated
that the dielectric properties of the PIN ceramic were of relaxor ferroelectric behavior with temperature of dielectric maximum
(Tm)∼53 °C and dielectric constant (εr)∼4300 (at 1 kHz). The P–E hysteresis loop measurements at various temperatures showed that the ferroelectric properties of
the PIN ceramic changed from the paraelectric behavior at temperature above Tm to slim-loop type relaxor behavior at temperature slightly below Tm. Moreover, the P–E loop became more open at temperatures much lower than Tm.
PACS 77.22.Ch; 77.84.Dy 相似文献
6.
Supattra Somsri Naoto Kuwamura Tatsuhiro Kojima Nobuto Yoshinari Takumi Konno 《Chemical science》2020,11(34):9246
Cyclodextrins are widely used cyclic oligosaccharides of d-glucose whose hydrophilic exterior is covered by hydroxyl groups and whose hydrophobic interior is surrounded by lipophilic moieties. Because of this structural feature, cyclodextrin molecules commonly aggregate into dimensional structures via intermolecular hydrogen bonds, and their aggregation into closed oligomeric architectures has been achieved only via the attachment of functional substituent groups to the cyclodextrin rings. Here, we report the first structurally characterized self-assembly of non-substituted γ-cyclodextrin molecules into cyclic hexamers, which was realized in a chiral coordination framework composed of complex-anions with d-penicillamine rather than l- or dl-penicillamine. The self-assembly is accompanied by the 3D-to-2D structural transformation of porous coordination frameworks to form helical hexagonal cavities that accommodate helical γ-cyclodextrin hexamers. This finding provides new insight into the development of cyclodextrin chemistry and host–guest chemistry based on chiral recognition and crystal engineering processes.The complex anions with d-penicillamine are organized into a 3D porous framework that allows the inclusion of γ-CD. The inclusion is accompanied by the 3D-to-2D transformation of porous frameworks so as to accept cyclic hexamers of γ-CD. 相似文献
7.
R. Yimnirun S. Ananta A. Ngamjarurojana S. Wongsaenmai 《Applied Physics A: Materials Science & Processing》2005,81(6):1227-1231
Effects of uniaxial compressive pre-stress on the ferroelectric properties of ceramics in the PMN-PZT system are investigated. The ceramics with a formula xPb(Mg1/3Nb2/3)O3-(1-x)Pb(Zr0.52Ti0.48)O3 or xPMN-(1-x)PZT when x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0 are prepared by a conventional mixed-oxide method. The ferroelectric properties under the uniaxial compressive pre-stress of the PMN-PZT ceramics are observed at the stress levels up to 13 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It is found that with increasing compressive pre-stress levels the area of the ferroelectric hysteresis (P–E) loops, the saturation polarization (Psat), the remanent polarization (Pr), and the coercive field (Ec) decrease. These results are interpreted through the non-180° ferroelastic domain-switching processes. Finally, the calculated differential permittivity for all the xPMN-(1-x)PZT ceramics, except for 0.5 PMN-0.5 PZT, decreases with increasing applied stress. PACS 77.22.Ch; 77.84.Dy 相似文献
8.
Muangjai Unruan Supattra Wongsaenmai Yongyut Laosiritaworn Ruyan Guo Rattikorn Yimnirun 《Physics letters. A》2010,374(9):1147-1153
The influences of perpendicular compressive stress on the ferroelectric properties of (1−x)Pb(In1/2Nb1/2)O3-xPbTiO3 (x=0.1-0.4) ceramics were investigated in this study. In general, with increasing compressive stress the coercive field and the dissipation energy of the ceramics were seen to increase. The stress-induced changes in the polarization, however, depended significantly on ceramic compositions. The observations were mainly interpreted in terms of competing influence of the domain switching through non-180° domain walls, clamping of domain walls, and the stress-induced decrease in the switchable part of spontaneous polarization. 相似文献
9.
Busaraporn Samran Supattra Aungkutranont Timothy J. White Sujitra Wongkasemjit 《Journal of Sol-Gel Science and Technology》2011,57(2):221-228
A novel room temperature sol–gel synthesis of Ti-SBA-15 is described using moisture stable silatrane and titanium glycolate
precursors, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (EO20PO70EO20) as the structure directing agent. Catalyst performance was optimized by systematically investigating the influence of acidity,
reaction time and temperature, and titanium loading. Small angle X-ray scattering (SAXS) and transmission electron microscopy
(TEM) showed well-ordered 2D mesoporous hexagonal structures, while N2 adsorption/desorption measurements yielded high surface areas (up to 670 m2/g), with large pore diameters (5.79 nm) and volumes (0.83 cm3/g). Diffuse reflectance UV–visible spectroscopy (DRUV) was found that tetravalent titanium as Ti4+O4 tetrahedra were incorporated in the framework through displacement of Si4+O4 after calcination (550°C/6 h) to loadings of 7 mol% Ti without perturbation of the ordered mesoporous structure, or decoration
by extra-framework anatase containing Ti4+O6 octahedra. The catalytic activity and selectivity of styrene epoxidation using hydrogen peroxide (H2O2) showed that the conversion of styrene increases significantly at higher titanium contents. The only products of this reaction
were styrene oxide and benzaldehyde, with selectivity of 34.2 and 65.8%, respectively, at a styrene conversion of 25.8% over
the 7 mol% Ti-SBA-15 catalyst. Beyond this titanium loading, anatase is deposited on the framework and catalytic activity
degrades. The performance of the new catalyst is also shown to be superior to conventional materials produced by incipient
wetness impregnation where Ti resides on the surface of SBA-15, giving a styrene conversion of 11.9% under identical reaction
conditions. 相似文献
10.
S. Wongsaenmai W. Qu S. Ananta R. Yimnirun X. Tan 《Applied Physics A: Materials Science & Processing》2007,88(4):757-761
Ferroelectric ceramics with formula Pb0.8Ba0.2[(In1/2Nb1/2)1-xTix]O3 (PBINT) (x=0.0,0.1,0.2,0.3,0.4 and 0.5) were prepared via a two-step solid state reaction method. It was found that ceramics
with compositions in the range of x=0.0∼0.3 showed a pseudo-cubic structure, whereas the ceramic with x=0.5 displayed a tetragonal
structure. All compositions showed significant frequency dispersion in their dielectric properties. The remanent polarization
Pr as well as the coercive field Ec, measured at room temperature, increases with the Ti content. The experimental results obtained in this system are summarized
into a phase diagram, with the morphotropic phase boundary (MPB) located at x=0.4. Compared with the Pb[(In1/2Nb1/2)1-xTix]O3 solid solution system, incorporating Ba in the A-site leads to a significant decrease in the dielectric maximum temperature
Tmax, a suppression of the dielectric relaxation parameter γ, and a shift of the MPB composition to a higher Ti content.
PACS 77.84.Dy; 77.80.Bh; 77.22.Ch 相似文献