17 research outputs found
Colossal dielectric constants in transition-metal oxides
Many transition-metal oxides show very large ("colossal") magnitudes of the
dielectric constant and thus have immense potential for applications in modern
microelectronics and for the development of new capacitance-based
energy-storage devices. In the present work, we thoroughly discuss the
mechanisms that can lead to colossal values of the dielectric constant,
especially emphasising effects generated by external and internal interfaces,
including electronic phase separation. In addition, we provide a detailed
overview and discussion of the dielectric properties of CaCu3Ti4O12 and related
systems, which is today's most investigated material with colossal dielectric
constant. Also a variety of further transition-metal oxides with large
dielectric constants are treated in detail, among them the system La2-xSrxNiO4
where electronic phase separation may play a role in the generation of a
colossal dielectric constant.Comment: 31 pages, 18 figures, submitted to Eur. Phys. J. for publication in
the Special Topics volume "Cooperative Phenomena in Solids: Metal-Insulator
Transitions and Ordering of Microscopic Degrees of Freedom
Structural, dielectric and magnetic properties of (Pb1âCa )(Fe0.5Nb0.5)O3 solid solution ceramics
Studies of Ferroelectric and Magnetic Phase Transitions in Multiferroic PbFe0.5 B 0.5O3âPbTiO3 (BÂ =Â Nb, Ta) Solid Solution Ceramics
Electronic structure of PbSc1/2Nb1/2O3 single-crystal ferroelectric-relaxor in the paraelectric and ferroelectric state
The Effect of Mechanical Activation on the Synthesis and Properties of Multiferroic Lead Iron Niobate
Misfit strain-induced changes in the Fe-sublattice of multiferroic Pb(Fe1/2Nb1/2)O3 epitaxial nanofilm seen via Raman spectroscopy
Effect of a bias field on the dielectric properties of NaNbO3 solid solutions in the range of the giant temperature hysteresis of a phase transition
Effect of a bias electric field on the dielectric properties of lead-free (Na,Sr,Li)NbO3 ceramics with diffuse phase transition
Quasivertical line in the phase diagram of single crystals of Pb Mg1 3 Nb2 3 O3 -x PbTiO3 (x=0.00, 0.06, 0.13, and 0.24) with a giant piezoelectric effect
We show that the phase diagram of the (001) Pb Mg1 3 Nb2 3 O3 -x PbTiO3 (PMN- x PT) (x=0.00, 0.06, 0.13, and 0.24) and (111) PMN-0.24PT lead-magnesium niobate mixed with lead titanate possesses a quasivertical line in the E electric field - T temperature plot, which hardly depends on the field. The existence of this line has been confirmed by independent studies of single crystals grown in different laboratories, by measuring the dielectric permittivity, compliances, and optical transmission, also in different laboratories. A thermal hysteresis inherent to first order phase transitions complicates the phase diagram. The piezoelectric coefficients of the (001) PMN- x PT (x = 0.06 and 0.13) have two peaks versus temperature, at finite fields. The first peak is due to the quasivertical phase boundary. The second is in the vicinity of a turning point of the Tm (E) temperature of the dielectric permittivity diffuse maximum. We show that the second peak prevails at reasonable fields, and the piezoelectric coefficients have comparatively large values at this peak, even at small x. © 2007 The American Physical Society