Phase transition temperature and electrical properties of (Bi1∕2Na1∕2)TiO3–(Bi1∕2A1∕2)TiO3 (A=Li and K) lead-free ferroelectric ceramics

2008 ◽  
Vol 103 (8) ◽  
pp. 084121 ◽  
Author(s):  
Yuji Hiruma ◽  
Kazushige Yoshii ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Electrical Properties ◽  
Phase Transition Temperature ◽  
Lead Free ◽  
Ferroelectric Ceramics

Dielectric, Piezoelectric, Pyroelectric Properties and Polymorphic Phase Transition of 0.95 (KXNa1-X) NbO3-0.05LiSbO3 Lead-Free Ferroelectric Ceramics

2013 ◽  
Vol 377 ◽  
pp. 161-165
Author(s):  
Yang Yang Zhang ◽  
Jin Ping Zhang ◽  
Er Ping Wang ◽  
Sheng Lin Jiang ◽  
Lin Lu
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Electrical Properties ◽  
Room Temperature ◽  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Polymorphic Phase Transition ◽  
Lead Free Ceramics ◽  
Enhanced Properties ◽  
Tetragonal Phase Transition

0.95 (KXNa1-X) NbO3-0.05 LiSbO3(KNN-LS-X) (X=0.4-0.5) lead-free ceramics were prepared by conventional solid method. The effect of K/Na ratio on the dielectric, piezoelectric, pyroelectric and polymorphic phase transition was studied. The results show that the electrical properties strongly depend on the K/Na ratio. The KNN-LS-X(X=0.45) ceramics exhibit enhanced properties (εr=891.267,d33=222pC/N,Kp=0.43517,Qm=64.72,p=15×10-4C/m2K). Enhanced electrical properties of the KNN-LS-X (X=0.45) ceramics could be attributed to the effect of K/Na ratio modifying the polymorphic orthorhombic-tetragonal phase transition temperature to room temperature, which could make KNN-LS-X (X=0.45) ceramics use as a new ferroelectric sensor.

scholarly journals Synthesis, Structural, Electrical, and Thermal Studies of ( and ) Ferroelectric Ceramics

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Shiv K. Barbar ◽  
M. Roy
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Thermal Studies ◽  
Activation Energies ◽  
Ferroelectric Ceramics ◽  
Scanning Calorimetry ◽  
Conventional Solid State Reaction ◽  
Modulated Differential Scanning Calorimetry ◽  
Orthorhombic Crystal Structure

The polycrystalline ceramic samples of lead barium niobate with general formula ( and 0.4) were prepared by conventional solid state reaction method. The room temperature X-ray diffraction patterns reveal that both of the samples have orthorhombic crystal structure with space group Cm2m. The dielectric constant and dissipation factor were measured as a function of frequency (100 Hz-2 MHz) and temperature (RT-660K). The DC electrical conductivity of both the samples was measured from RT to 660 K. The activation energies calculated from log σ versus 1000/T curves in ferroelectric phase of the compounds are 1.09 eV for pure () sample and 1.36 eV for Ba-substituted () sample. The values of activation energies show that the substitution of Ba2+ ion on Pb2+ ion site increases the resistivity of pure PbNb2O6 () ceramic. The modulated differential scanning calorimetry (MDSC) has been used to investigate the phase transition temperature of both the compounds and also to see the effect of Ba2+ ion substitution on the phase transition temperature, specific heat, and other thermal parameters of the compound.

Large electrostrictive effect in Sn-doped NBT–BT lead-free relaxor ceramics

2020 ◽  
Vol 34 (11) ◽  
pp. 2050100
Author(s):  
W. P. Cao ◽  
J. Sheng ◽  
Z. Liu ◽  
C. Gao ◽  
Z. H. Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Relaxor Ferroelectrics ◽  
Lead Free ◽  
Ferroelectric Relaxor ◽  
Pseudocubic Phase ◽  
Further Development ◽  
Electrostrictive Effect

In this work, we design and adjust the composition in [Formula: see text]–[Formula: see text] lead-free relaxor ferroelectrics by doping SnO2 to introduce a relaxor phase and accordingly obtain prominent lead-free electrostrictors. It was found that all the samples exhibited ideal features of relaxor ferroelectrics and the ferroelectric-relaxor phase transition temperature of the ceramics was adjusted to near or below room temperature after doping with a handful of [Formula: see text]. A relatively high electrostrictive coefficient [Formula: see text] of 0.0293 m4/C2 was achieved for the composition with [Formula: see text], which was attributed to the formation of relaxor pseudocubic phase developed by the [Formula: see text] substitution. These results provide some instructive thoughts for the further development of [Formula: see text]-based electrostrictive materials by B-site doping.

Large electrostrain near the phase transition temperature of (Bi0.5Na0.5)TiO3–SrTiO3 ferroelectric ceramics

2008 ◽  
Vol 92 (26) ◽  
pp. 262904 ◽  
Author(s):  
Yuji Hiruma ◽  
Yoshitaka Imai ◽  
Yoshinori Watanabe ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ferroelectric Ceramics

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

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