# Presentation: 344285

## INTERACTIONS IN THIN FILM 

**MULTILAYERS OF POLYMER**
** ****FERROELECTRICS**

- 	University of Nebraska, Lincoln
**JIHEE KIM, STEVE DUCHARME, SHIREEN  ADENWALLA**
- Argonne National Lab-**HOYDOO YOU**

- DOE LAB PARTNERSHIP

- DOE/NSF EPSCOR CONFERENCE 15th June 2004

## Polyvinylidene fluoride  [C2H2F2]n 

**FERROELECTRIC MATERIALS**
- •**Possess a spontaneous**
** ****net polarization below a Curie temperature T****c**
- •**First order transition**
- •**Polarization is reversible on application of an electric field**
**(hysteresis loops)**
**PEROVSKITE** **eg.  PbZrTiO****3****, BaTiO****3**
**POLYMERS** : **narrow rod-like polymers with an electric dipole **
**moment****.  ****Like Polymers**
**Polyvinylidene fluoride  [****C****2****H****2****F****2****]****n**** **
**od-Like Polymers**
**Electric**

## PVDF Poly(vinylidene fluoride)[C2H2F2]n

**PVDF Poly(vinylidene fluoride)[****C****2****H****2****F****2****]****n**

**Net polarization-reversible**

## (TrFE)-[C2HF3 ] decreases Tc

**Koga et al. *****J. Appl. Phys*****, 1986**

- Addition of Trifluoroethylene
- (TrFE)-[**C****2****H****F****3** ] decreases Tc

## LANGMUIR BLODGETT DEPOSITION

- (pioneered at Institute of Crystallography-Moscow)

## Crystallinity

## X-ray diffraction as a measure of TC

- X-ray diffraction as a measure of TC

## Phase Coexistence:X-ray Diffraction Studies

******    ****HEATING**
-   **COOLING**

- X-rays allow us to quantify
- amount of material in each phase

## Ferroelectric Polymer

- No Suppression of Tc
**Constant Transition Temperature**

- Other Ferroelectrics
- Supression of Ferroelectricity
**Finite-size effect**

- PbTiO3 particles
- Ishikawa 1988

## Multilayer Samples

- <date/time>

**Multilayer Samples**

**(50/50)****10**

**(80/20)****10**

**Multilayer (****10****:****10****)**

**Multilayer (****5****:****5****)**

**Multilayer (****1****:****1****)**

**Films used in this study**
**   ****- Pure copolymer films**
**        **** ****50/50 ****- P(VDF-TrFE 50:50) **
**         ****80/20 ****- P(VDF-TrFE 80:20) **
**  ****- Mixture of 50/50 and 80/20**
**         ****(50/50)**** + ****(80/20)**** = ****?**
**  ****- Multilayer films of 50/50 and 80/20**
**        ****(50/50)****10**** ****(80/20)****10  **** -  ****(10:10)**
**         ****(50/50)****5**** ****(80/20)****5****     -  ****(5:5)**
**         ****(50/50)****1****(80/20)****1**** ****     -  ****(1:1)**

## Interaction effects may manifest themselves as 

- -However, strong size effect and strain make it difficult to
- analyze results.
- -Ferroelectric polymers are soft materials-strain negligible
- -
- Almost no variation in Tc with thickness (earlier slide)
**Interaction effects may manifest themselves as **
**changes in T****c**

## Low Z films -

- weak scatterers
- Synchrotron needed
- See Jihee Kim’s poster
- #13 this afternoon

## Post doc at Argonne 1993-1996

- Building 223 2nd floor

- Hoydoo You’s office

- My office

- Hoydoo’s lab(4 circle rotating anode
-  temperature dependent x-ray )

- INITIATION OF DOE LAB INVOLVEMENT

## Initial informal involvement

- Temperature dependence of x-ray diffraction
- ( A Lattice Stiffening Phase Transition in Copolymer Films of
- Vinylidene Fluoride (70%) with Trifluroethylene (30%), C.N. Borca,
- S. Adenwalla, Jaewu Choi, P.T. Sprunger, Stephen Ducharme,
- Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin,
-  H. You and P.A. Dowben, Phys. Rev. Lett. **83**. 4562 (1999).
- Led to DOE EPSCOR proposal
- STUDENTS INVOLVED
- Matt Poulsen
- Jihee Kim
- Approximately 1-2 times a year(~$1200 per person per trip)
- Sometimes to APS
- Sometimes to use the 4 circle diffractometer

## LESSONS LEARNT

- •Lab scientists are busy-they appreciate results(i.e. papers)*fast*
- • Travel with the student the first time, especially if it is a new
-  technique or a very green student-makes it more efficient
- • Find a lab scientists that shares your interest
- • Take along 2X the number of samples you think you’ll need
- • Keep communicating-if you can’t be ready on time,
- tell her/him why and keep informed of progress

## University of Nebraska-LincolnM. Bai, C. Borca, A. V. Bune, J. Choi, P. A. Dowben, Y. Dzenis, N. Ianno, J. Li, B. Petersen, M. Poulsen, T. Reece, A. V. Sorokin, J. M. Takacs, C. ZhuInstitute of Crystallography-MoscowL. M. Blinov, V. M. Fridkin, S. P. Palto, N. N. Petukhova, K. Verkhovskaya, G. Vizdrik, S. G. Yudin, A. Zlatkin