NATO COLLABORATIVE   LINKAGE  GRANT  PST.CLG.980055    NEW FERROELECTRIC - RELAXOR OXIDES FOR MICROELECTRONIC APPLICATION

web-coordination: I. Luk'yanchuk

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Objectives:

Fundamental importance:  Ferroelectric transition involves a large variety of internal degrees of freedom (elasticity, nano-clustering, ion tunnelling) that leads to various intermediate incommensurate and relaxor phases of yet unknown structure.

Importance for applications:  Several electro-mechanical characteristics are better then that for traditionally used perovskite materials that make them attractive for  technology application in  RAM, sensors, detectors, transducers, nonlinear electro-optic switches.  Environment-friendly lead-free composition.

We suppose: understand the mechanisms of ferroelectric transitions, the structural organization of the involved intermediate phases and evaluate the eligibility of these compounds for microelectronics.

Long-term objective:  Install the NATO - Mediterranean well-structured research network able to solve the complex problems of material science of ferroelectrics and related materials.  This distributed network is integrated in the research structures of the NATO and Mediterranean countries, takes an advantage of the experimental setup and experience of each laboratory. It includes the complete material research cycle: elaboration – characterization – modelling – evaluation for application and will give the  impact on the joint formation of the PhD students “by research”.
 

 
  Participants:

History:

 Application    March 2003       Project: (pdf)
 Acceptance :  August 2003      Letter and general conditions, (pdf)
 Credit:            December 2003

Visits:

 

Progress and results

PKLN single crystal (PbK2LiNb5O15)

motivation:  Unconventional splitting of ferroelectric transition. (on ferroelectric and ferroelastic?) To be clarrified
synthesis: single crystals were already elaborated in Marrakech and in Toulon-Amiens by Gagou
characterization:   almost done. To complete in 2004: Raman  and T-dependendent X-rays in Amiens.
publications:  [1,2]  + in progress

PKRN ceramics Pb2(1-x)K1+xRxNb5O15 (R = La, Nd, Sm, Eu and Gd)

motivation:  Clarify phase diagram when x changes from x=0 (P parallel to c) to x=1 (P perpendicular to c)
synthesis:  A wealth of ceramics elaborated in Marrakech. Necessity of elaboration of single crystals will be discussed in sept. 2004 and proposed to Madrid.
characterization: Preliminary  dielectric and X-ray  mesurements  were already done  in Marrakech.  Precise impedance, T-dependendent X-ray and Raman mesurements are in progress in Amiens in 2004.
publications:  [3]  + in progress

 BNN ceramics with Pb  Ba2-xPbxNayNb5O15

motivation:  Incommensurate phase is known to exists at x=0. What happens with
substitution of Pb with reorientation of P from c to a direction?
synthesis:  ceramics xith x=0, 0.2, 0.4, 0.6, 0.8, 1 were elaborated in Marrakech in spring 2004.  Single crystal will be discussed.
characterization:  to be done in 2004-2005, Amiens-Marrakech.

Modeling

Amiens-Marrakech  Effective field approach for statistical models of ferroelectric transitions, application to nano-scale superlattices, To develop: application  to TTB compounds. 2 joint publications.

Joint Publications*

*Please note in acknolegement: "This work was supported by NATO collaborative linkage grant PST.CLG.980055"

1. Y. Gagou, Ch. Muller, M.-A. Fremy, D. Mezzane, E. Elkaïm and P. Saint-Grégoire; Structural study of ferroelectric and paraelectric phase in PbK2LiNb5O15; Physica Status Solidi, B241, 2629 (2004)
2. M. Oualla, M. Elaatmani, M. Daoud 1, D. Mezzane, I. Luk’yanchuk  and A. Zegzouti Study of New Rare Earth Family Pb1.6K1.2R0.2Nb5O15 (R = La, Nd, Sm, Eu and Gd)  of Tetragonal Tungsten Bronze - Type Ferroelectrics, Solid State Communication, 130, 777 (2004) 
3. A. Tabyaoui, A. Ainane, M. Saber and I. Lukyanchuk, Phase transition property of ferroelectric superlattice with three alternative layers from Ising model in a transverse field, Physica Scripta. 72, 265  (2005),
   
4. Yaovi Gagou , Mimoun Elmarssi, Marie Angèle Frémy, Nadir Aliouane, Daoud Mezzane, Pierre Saint-Grégoire,  Mechanism of the Phase Change in PbK2LiNb5O15: Dielectric, structural, and Raman scattering studies, http://xxx.lanl.gov/abs/cond-mat/0601516, submitted to Europ. Phys. J. (2005)
5. M. Saber, I. Lukyanchuk, M. Madani , A. Tabyaoui  and A. Ainane, The transverse spin-1/2 Ising order-disorder superlattice, submitted to Chin. J. Phys. (2005)