A doubling of the post-perovskite phase boundary and structure of the Earth's lowermost mantle

Nature ◽  
2005 ◽  
Vol 434 (7035) ◽  
pp. 882-886 ◽  
Author(s):  
John W. Hernlund ◽  
Christine Thomas ◽  
Paul J. Tackley
Keyword(s):  
Phase Boundary ◽  
Perovskite Phase ◽  
Lowermost Mantle

Efficacy of the post-perovskite phase as an explanation for lowermost-mantle seismic properties

Nature ◽  
2005 ◽  
Vol 438 (7070) ◽  
pp. 1004-1007 ◽  
Author(s):  
James Wookey ◽  
Stephen Stackhouse ◽  
J-Michael Kendall ◽  
John Brodholt ◽  
G. David Price
Keyword(s):  
Perovskite Phase ◽  
Seismic Properties ◽  
Lowermost Mantle

Effects of Zr/Ti Ratio on the Structure and Ferroelectric Properties in PZT-PZN-PMN Ceramics near the Morphotropic Phase Boundary

2008 ◽  
Vol 55-57 ◽  
pp. 125-128 ◽  
Author(s):  
R. Muanghlua ◽  
S. Niemchareon ◽  
Wanwilai C. Vittayakorn ◽  
Naratip Vittayakorn
Keyword(s):  
Transition Temperature ◽  
Phase Boundary ◽  
Coercive Field ◽  
Phase Structure ◽  
Remanent Polarization ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Piezoelectric Ceramics ◽  
Pure Perovskite Phase ◽  
All Ceramic

The piezoelectric ceramics of Pb(ZrxTi1−x)O3 – Pb(Zn1/3Nb2/3)O3 – Pb(Mn1/3Nb2/3)O3; PZT-PZN-PMN with Zr/Ti ratios of 48/52, 50/50 and 52/48 were fabricated in order to investigate the effect of compositional modifications on the ferroelectric properties of PZT-PZN-PMN ceramics. The phase structure of ceramics sintered at 1,150°C was analyzed. Results show that the pure perovskite phase was in all ceramic specimens, and the phase structure of PZT-PZN-PMN piezoelectric ceramics transformed from tetragonal to rhombohedral, with the Zr/Ti ratios increased in the system. The PZT-PZN-PMN ceramics with a Zr/Ti ratio of 50/50 exhibited the most promising properties including high remanent polarization and low coercive field of 25.95 µC cm−2 and 12.5 kV cm−1, respectively. Furthermore, the transition temperature decreased when the Zr/Ti ratio increased in the system.

scholarly journals Structure and Physical Properties of PZT-PMnN-PSN Ceramics Near the Morphological Phase Boundary

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Nguyen Dinh Tung Luan ◽  
Le Dai Vuong ◽  
Truong Van Chuong ◽  
Nguyen Truong Tho
Keyword(s):  
Physical Properties ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Coercive Field ◽  
Phase Structure ◽  
Remanent Polarization ◽  
Perovskite Phase ◽  
Electromechanical Properties ◽  
Ceramic Samples ◽  
Pure Perovskite Phase

The 0.9Pb(ZrxTi1−x)O3-0.07Pb(Mn1/3Nb2/3)O3-0.03Pb(Sb1/2Nb1/2)O3(PZT-PMnN-PSN) ceramics were prepared by columbite method. The phase structure of the ceramic samples was analyzed. Results show that the pure perovskite phase is in all ceramics specimens. The effect of the Zr/Ti ratio on the region of morphotropic phase boundary for PZT-PMnN-PSN ceramics was studied. Experimental results show that the phase structure of ceramics changes from tetragonal to rhombohedral with the increase of the content of Zr/Ti ratio in the system. The composition of PZT-PMnN-PSN ceramics near the morphotropic phase boundary obtained is the ratio of Zr/Ti: 49/51. At this ratio, the ceramic has the optimal electromechanical properties: thekp=0.61, theεmax=29520, thed31=-236 pC/N, theQm=2400, high remanent polarization (Pr=49.2 μC·cm−2), and low coercive fieldEc=10.28 kV·cm−1.

The elasticity of the MgSiO3 post-perovskite phase in the Earth's lowermost mantle

Nature ◽  
2004 ◽  
Vol 430 (6998) ◽  
pp. 442-445 ◽  
Author(s):  
T. Iitaka ◽  
K. Hirose ◽  
K. Kawamura ◽  
M. Murakami
Keyword(s):  
Perovskite Phase ◽  
Lowermost Mantle

Processing and Properties of PSZN-PZT Quaternary Piezoelectric Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 205-208
Author(s):  
Li Feng Wang ◽  
Qingchi Sun
Keyword(s):  
Electric Field ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Sintering Temperature ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
High Electric Field ◽  
Sintering Behavior ◽  
Synthesis Methods ◽  
Xrd Patterns

Piezoelectric Pb(Sn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3-PbZrO3 (PSZN-PZT) quarternary ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared by the conventional calcination route. The conventional and twice synthesis methods were compared. XRD patterns indicated the more complete perovskite phase was formed by the twice synthesis methods. The sintering behavior was investigated. The microstructure was studied and the piezoelectric and ferroelectric properties and the properties under high electric field were determined. The optimized results were obtained when the ratio of Zr/Ti is 43/45 and the sintering temperature is 1260°C.

Post‐Perovskite Phase Transition in the Pyrolitic Lowermost Mantle: Implications for Ubiquitous Occurrence of Post‐Perovskite Above CMB

2021 ◽  
Author(s):  
Yasuhiro Kuwayama ◽  
Kei Hirose ◽  
Laura Cobden ◽  
Mayu Kusakabe ◽  
Shigehiko Tateno ◽  
...  
Keyword(s):  
Phase Transition ◽  
Perovskite Phase ◽  
Lowermost Mantle

Morphotropic Phase Boundary of Lead-Free Piezoelectric Ceramics from BNT- KN System

2008 ◽  
Vol 55-57 ◽  
pp. 225-228 ◽  
Author(s):  
N. Pisitpipathsin ◽  
W. Koontasing ◽  
Sukum Eitssayeam ◽  
Uraiwan Intatha ◽  
Gobwute Rujijanagul ◽  
...  
Keyword(s):  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Niobium Oxide ◽  
Perovskite Phase ◽  
Piezoelectric Materials ◽  
Research Work ◽  
Lead Free ◽  
Ceramic System ◽  
Dielectric Data ◽  
Ferroelectric Perovskite

In this research work, the investigation of the morphotropic phase boundary, physical properties and electrical properties of lead- free piezoelectric materials of bismuth sodium titanium oxide: (Bi0.5Na0.5)TiO3 (BNT) and potassium niobium oxide : KNbO3 (KN) in the ceramic system of (1-x)BNT- xKN where x= 0.00, 0.03, 0.05, 0.08, 0.10 and 0.15 by modified mixed oxide method was carried out. The BNT and KN powders were prepared separately using calcination technique with optimum calcination temperature for producing both BNT and KN powders of about 800°C. XRD results revealed that the BNT-KN ceramics with low KN content of x less than 0.05 contain ferroelectric perovskite phase with rhombohedral symmetries while the higher KN content ceramics have mixed symmetries between rhombohedral and orthorhombic. From the evidences including phases, microstructures and dielectric data of the BNT-KN ceramics, it may be assumed that the morphotropic phase boundary may be at around the composition of x = 0.05.

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