The absence of ferroelectric polarization in layered and rock-salt ordered NaLnMnWO6 (Ln = La, Nd, Tb) perovskites

2014 ◽  
Vol 16 (11) ◽  
pp. 5407-5411 ◽  
Author(s):  
Chandan De ◽  
Tai Hoon Kim ◽  
Kee Hoon Kim ◽  
A. Sundaresan
Keyword(s):  
Electric Field ◽  
Time Dependence ◽  
Rock Salt ◽  
Ferroelectric Polarization ◽  
Negative Electric Field

Time dependence of current in response to the first and second negative electric field pulses indicating the absence of ferroelectricity in NaNdMnWO6.

The Lobe Structure in Ice Accreted on an Aluminium Conductor in The Presence of a Dc Electric Field

1983 ◽  
Vol 4 ◽  
pp. 228-235 ◽  
Author(s):  
Luan C. Phan ◽  
Jean-Louis Laforte ◽  
Du D. Nguyen
Keyword(s):  
Electric Field ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Air Bubbles ◽  
Experimental Conditions ◽  
Charged Droplets ◽  
Water Drops ◽  
The Difference ◽  
Negative Electric Field ◽  
Corona Wind

Supercooled droplets of 38 μm mean volume diameter are accreted on a smooth aluni mum cylinder of 3.15 cm in diameter in order to study the effect of an electrostatic field upon ice formation on a power-line conductor. The results obtained show that ice grown in the presence of an applied negative field of 15 kV cm−1 exhibits a cusped-lobe structure characterized by surfacial outward knobs, convex rings of fine air bubbles and radial lines of large air bubbles; in the same conditions, a positive electric field of 15 kV cm−1 does not produce such lobe features. On the other hand, accretion tests performed in the absence of an electric field with a 33 μm droplet spectrum show that the well-developed cusped-lobe structure appears in ice at low ambient temperature and air velocity. In the present experimental conditions, the formation of cusped lobes observed in the presence of a negative electric field could be explained by a decrease in the temperature of the deposit due to a reduction of impact velocity of the charged droplets and/or an increase in the local heat-transfer coefficient at the surface of the ice accretion. Corona wind from ice points, always in the opposite direction to the impinging droplets, may also reduce their impact velocities. In addition, corona wind and roughness of the surface may contribute to a better evacuation of the latent heat and thus decrease the deposit temperature. The difference between the effects of a negative DC field and those of a DC positive field of the same strength comes from a stronger ionization intensity and/or a stronger deformation of water drops in the negative electric field.

Self-consistent Calculation of the Photocurrent in Polycrystalline Polarized Pb(ZrTi)O3 Films

2007 ◽  
Vol 1034 ◽  
Author(s):  
Lyuba A. Delimova ◽  
V. S. Yuferev ◽  
A. A. Petrov ◽  
V. P. Afanasjev ◽  
I. V. Grekhov
Keyword(s):  
Electric Field ◽  
Grain Boundaries ◽  
Electrostatic Potential ◽  
Carrier Transport ◽  
Ferroelectric Polarization ◽  
Reciprocal Effect ◽  
Consistent Calculation ◽  
Pzt Film ◽  
Pzt Films ◽  
Self Consistent

AbstractA polycrystalline Pb(ZrTi)O3 (PZT) film with Pb excess is considered as a heterophase medium that consists of PZT grains and semiconductor PbO phase. The latter is segregated on PZT grain boundaries during the PZT formation and forms conducting channels between the electrodes. In such medium, uncompensated polarization charge of PZT grains generates an electric field both inside PZT grains and PbO phase. This electric field affects on ferroelectric polarization itself and stimulates carrier transport through the PbO channels. A theory is developed, where the reciprocal effect of the electric field on the polarization is taken into account. The polarization is found due to this effect to be increased up to ∼30% near the interfaces, which differs from reduction of the polarization near the interfaces in homogeneous PZT films. Using the theory, the electric field, electrostatic potential and carriers transport in PbO channels are calculated. A comparison is made with the results calculated for the approach of the polarization constancy.

REMARKS ON THE GENERALIZED SOLUTION OF ELECTRON DIFFUSION

2003 ◽  
Vol 17 (07) ◽  
pp. 1043-1069
Author(s):  
ANDREI DOLOCAN
Keyword(s):  
Diffusion Equation ◽  
Electric Field ◽  
Time Dependence ◽  
Electromagnetic Fields ◽  
Electron Distribution ◽  
Constant Electric Field ◽  
Generalized Solution ◽  
Short Discussion ◽  
Surface Distribution ◽  
Boundary Functions

A generalized solution of the diffusion equation for a beam of electrons, accelerated in a constant electric field, hitting a solid parallelepiped probe is presented. The solution is taken for the n-dimensional case. We propose a few formula for the boundary functions which can provide useful information about the electron distribution on the hit surface of the probe. Furthermore a time dependence for the surface distribution, as well as for the inner one, is achieved by integration over the correspondent spaces. A short discussion about the case of the accelerated electrons in the presence of electromagnetic fields, constant and variable, is done in the end.

Ferroelectric polarization in multiferroics

2019 ◽  
Vol 4 (9) ◽  
Author(s):  
Stephan Krohns ◽  
Peter Lunkenheimer
Keyword(s):  
Electric Field ◽  
Strong Coupling ◽  
Degrees Of Freedom ◽  
Ferroelectric Properties ◽  
Charge Order ◽  
Electric Polarization ◽  
Ferroelectric Polarization ◽  
Past Century ◽  
Type I ◽  
Solid State Physics

Abstract Multiferroic materials, showing ordering of both electrical and magnetic degrees of freedom, are promising candidates enabling the design of novel electronic devices. Various mechanisms ranging from geometrically or spin-driven improper ferroelectricity via lone-pairs, charge-order or -transfer support multiferroicity in single-phase or composite compounds. The search for materials showing these effects constitutes one of the most important research fields in solid-state physics during the last years, but scientific interest even traces back to the middle of the past century. Especially, a potentially strong coupling between spin and electric dipoles captured the interest to control via an electric field the magnetization or via a magnetic field the electric polarization. This would imply a promising route for novel electronics. Here, we provide a review about the dielectric and ferroelectric properties of various multiferroic systems ranging from type I multiferroics, in which magnetic and ferroelectric order develop almost independently of each other, to type II multiferroics, which exhibit strong coupling of magnetic and ferroelectric ordering. We thoroughly discuss the dielectric signatures of the ferroelectric polarization for BiFeO3, Fe3O4, DyMnO3 and an organic charge-transfer salt as well as show electric-field poling studies for the hexagonal manganites and a spin-spiral system LiCuVO4.

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