Study of the structure and dielectric relaxation behavior of Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric ceramics

1999 ◽  
Vol 14 (12) ◽  
pp. 4581-4586 ◽  
Author(s):  
Xiaowen Zhang ◽  
Fei Fang
Keyword(s):  
Phase Boundary ◽  
Phase Region ◽  
Dielectric Behavior ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
Two Phase ◽  
X Ray ◽  
Dielectric Relaxation Behavior ◽  
Columbite Precursor

(1–x)PMN–xPT[PMN, Pb(Mg1/3Nb2/3)O3; PT, PbTiO3] system ferroelectric ceramics with x = 0.30, 0.33, 0.35, and 0.38 were synthesized by the columbite precursor method. Their structure and dielectric behavior were investigated. X-ray diffraction results demonstrate that no two-phase region is presented, but a quasi-cubic to tetragonal phase boundary lies between x = 0.30 and 0.33. Examination of the dielectric behavior reveals that the transformation from relaxor to normal ferroelectric behavior across the morphotropic phase boundary (MPB) is successive and continuous. It is suggested that x 4 0.30 to 0.33 is the composition of MPB for the PMN–PT system. The MPB is also a boundary for the PMN–PT system to transform from relaxor to normal ferroelectrics.

Electrical Properties of (1–x)(0.8PMN-0.2PNN)-xPT Ceramics near the Morphotropic Phase Boundary

2007 ◽  
Vol 336-338 ◽  
pp. 18-20
Author(s):  
Guo Yuan Zhou ◽  
Jin Song Pan ◽  
Xiao Wen Zhang
Keyword(s):  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Piezoelectric Properties ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
High Dielectric ◽  
Columbite Precursor

Ferroelectric ceramics of (1x)(0.8PMN0.2PNN)xPT (x = 0.280.43) were synthesized by the columbite precursor method. Their phase structures as well as the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) results demonstrate that the morphotropic phase boundary (MPB) of this system lies in the composition range of x = 0.31–0.37. Examination of the dielectric behavior indicates that the ceramics exhibit high dielectric constants near the MPB compositions. In addition, the piezoelectric properties of the ceramics were found quite well around the MPB. The interrelated mechanism was also discussed.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

scholarly journals Phase diagram and dielectric properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

2015 ◽  
Vol 05 (02) ◽  
pp. 1550014 ◽  
Author(s):  
Dabin Lin ◽  
Haohua Chen ◽  
Zhenrong Li ◽  
Zhuo Xu
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
X Ray ◽  
Pbtio3 Ceramics ◽  
Curie Temperatures ◽  
Columbite Precursor ◽  
Tetragonal Phase Transition

x Pb ( In 1/2 Nb 1/2) O 3- Pb ( Mg 1/3 Nb 2/3) O 3- PbTiO 3(x PIN –y PMN –z PT ) ternary ceramics with morphotropic phase boundary (MPB) composition were synthesized by columbite precursor method. x PIN –y PMN –z PT phase diagram was investigated by x-ray diffraction and dielectric measurements. According to the results of dielectric measurements, the Curie temperatures (Tc) and rhombohedral to tetragonal phase transition temperature (Tr−t) were found to be in the range of 173–212°C and 114–155°C, respectively, indicating that the Tr-t was increased with adding PIN component. In the MPB region, the highest Tr-t = 155° C was found in 0.32PIN–0.38PMN–0.30PT ceramic, that greatly expanded temperature usage range.

Stability of the Perovskite Structure in BSPT-Based Ferroelectric Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 231-234
Author(s):  
Yi Chen ◽  
De Jun Lan ◽  
Qiang Chen ◽  
Ding Quan Xiao ◽  
Xi Yue ◽  
...  
Keyword(s):  
Solid State ◽  
Diffraction Analysis ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Perovskite Structure ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
State Process ◽  
The Stability

(1-x)BiScO3-xPbTiO3 (BSPT) based ferroelectric ceramics were prepared by conventional solid state process. X-ray diffraction analysis revealed that the morphotropic phase boundary (MPB) separating the rhombohedral and tetragonal phases for the BSPT system exited near x=0.62. It was found that the stability of perovskite structure of the BSPT system was improved with the increase of PbTiO3 content. For the 0.36BiScO3-0.64Pb1-ySryTiO3 (BSPST) system, because of higher amount of ionic bonding, the stability of perovskite structure for BSPT compounds containing strontium is larger than that of non-strontium compound.

Crystal Structure Refinements of Ge(tP12), Physical Properties and Pressure-induced Phase Transformation Ge(tP12) ↔ Ge(tI4)

2008 ◽  
Vol 63 (6) ◽  
pp. 608-614 ◽  
Author(s):  
Aron Wosylus ◽  
Yurii Prots ◽  
Walter Schnelle ◽  
Michael Hanfland ◽  
Ulrich Schwarz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Theoretical Calculations ◽  
Structural Similarity ◽  
Phase Region ◽  
Maximum Pressure ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray

Single crystals of the modification Ge(tP12) are prepared by compressing semiconductor-grade germanium to pressures above 11(1) GPa and heating to temperatures between 1200(100) and 1500(150) K before a stepwise cooling precedes a complete pressure release. The tetragonal crystal structure of Ge(tP12) is refined by means of single crystal X-ray diffraction data collected at ambient conditions (a = 592.81(2), c = 698.03(3) pm, space group P43212). The atomic arrangement comprising interconnected spiral chains of fourfold symmetry bears a structural similarity to the high-pressure modification S(t I16). High-pressure ambient-temperature powder X-ray diffraction measurements reveal a significant anisotropy of the compressibility compatible with the selected crystal structure description. The determined bulk modulus of Ge(tP12) amounts to 70(1) GPa which is in good agreement with theoretical calculations and similar to experimental values of other four-coordinated germanium allotropes. Ge(tP12) is a diamagnetic semiconductor with χ0 = −3.1(3) ·10−7 emu g−1 and ρ300 K ≈ 6 Ωm at 300 K. At 10.1(3) GPa, the beginning of the formation of Ge(t I 4) indicates the onset of a structural transition. The two-phase region extends up to a maximum pressure of 13.0(5) GPa in the direction of increasing pressures. Upon stepwise decompression, the phase Ge(t P12) is reformed from Ge(t I4) at 9(1) GPa.

Pb VOLATILIZATION EFFECT ON DIELECTRIC AND PIEZOELECTRIC PROPERTIES IN A Ta-DOPED PMN-PT CERAMIC THICK DISK

2005 ◽  
Vol 19 (01n03) ◽  
pp. 549-552 ◽  
Author(s):  
C. ZHANG ◽  
J. T. WANG ◽  
S. X. SHEN ◽  
Y. FENG ◽  
I. AKUJOBI ◽  
...  
Keyword(s):  
Piezoelectric Properties ◽  
Dielectric Constants ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
X Ray ◽  
Ceramic Disk ◽  
Different Depths ◽  
Columbite Precursor ◽  
Dielectric And Piezoelectric Properties

A thick ceramic disk of 0.7 Pb ( Mg 1/3( Nb 0.9 Ta 0.1)2/3) O 3-0.3 PbTiO 3 ( PMNT - PT ) was prepared by columbite precursor method with PbO powder buffer surrounding the disk during the sintering process. The dielectric and piezoelectric properties and the microstructure of PMNT - PT samples cut from the different depths of the disk are studied. The phase purity is homogenous in the whole disk within our x-ray diffraction resolution. The dielectric constants, and the piezoelectric effect, d 33, vary with different samples. The samples cut from the middle parts of the disk have the higher d 33. It is believed that the sample processes, especially the Pb volatilization is responsible for these results.

Pressure buffering in a diamond anvil cell

2000 ◽  
Vol 64 (2) ◽  
pp. 241-245 ◽  
Author(s):  
T. Arlt ◽  
R. J. Angel
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
First Order ◽  
Diamond Anvil ◽  
First Order Phase

AbstractThe clinopyroxenes kanoite and spodumene were studied by single-crystal X-ray diffraction in a diamond anvil cell (DAC) at room temperature. At the displacive phase transitions between the C2/c and P21/c polymorphs both phases coexist within the same crystal. In this two-phase region the pressure in the DAC remains constant. The experimental results demonstrate that pressure buffering at first-order phase transitions can occur in the DAC.

scholarly journals Revisiting the Bøggild Intergrowth in Iridescent Labradorite Feldspars: Ordering, Kinetics, and Phase Equilibria

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 727
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Seungyeol Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Phase Region ◽  
Two Phase ◽  
Subsolidus Phase ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.

Nanostructured TiO2-Based Composites for Light Absorption

2014 ◽  
Vol 975 ◽  
pp. 207-212
Author(s):  
Dayse I. dos Santos ◽  
Olayr Modesto Jr. ◽  
Luis Vicente A. Scalvi ◽  
Americo S. Tabata
Keyword(s):  
Metal Oxide ◽  
Light Absorption ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Oxide Powders

Metal oxide nanocomposites were prepared by two different routes: polyol and sol-gel. Characterization by X ray diffraction showed that the first process produces directly a two-phase material, while the sol-gel powder never showed second phase below 600°C. Light spectroscopy of the treated powders indicated similarities for the processed materials. Although the overall material compositions are about the same, different structural characteristics are found for each processing. With the exception of Ti-Zn materials, all the double metal oxide powders showed higher absorbance than either TiO2 powder.

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

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