Co-doping of Lead-free Bi1/2Na1/2TiO3 (BNT) - Bi1/2K1/2TiO3 (BKT) · 2020-06-19 · Co-doping of Lead-free Bi 1/2 Na 1/2 TiO 3 (BNT) - Bi 1/2 K 1/2 TiO 3 (BKT) -based Piezoceramics

Co-doping of Lead-free

Bi1/2Na1/2TiO3 (BNT) - Bi1/2K1/2TiO3 (BKT)

-based Piezoceramics

16/10/2014 | TU Darmstadt / Materials Science / Ceramics Group | Martin Blömker | 1

M. Blömker1, E. Erdem2, S. Wollstadt1, J. Rödel1

1: Institute of Materials Science,

Technische Universität Darmstadt, Germany

2: Institut für Physikalische Chemie I

Universität Freiburg, Germany

Why Doping / Co-doping?


Erdem, E. et al., IEEE Trans. Ultras. Ferroel. Freq. Control

55, 1061-1068 (2008)

Cao, W., Disorder and Strain-Induced Complexity in Funct.

Mater. Vol. 148, Ch. 7, 113-134 (Springer Berlin, 2012)

Acceptor doping, e.g.: 𝑀𝑛2𝑂3 → 2𝑀𝑛𝑇𝑖,𝑍𝑟′ + 𝑉𝑂

.. + 3𝑂𝑂𝑋

Donor doping, e.g.: 𝑁𝑏2𝑂5 + 𝑃𝑏𝑂 → 2𝑁𝑏𝑇𝑖,𝑍𝑟. + 𝑉𝑃𝑏

′′

In-

fluen-

ces

Defect dipoles Schottky barriers Domain walls

What are Possible Applications?


Piezoelectric flow meters

Nano-positioning

Energy harvesting

High power applications

Compositions / Synthesis /

XRD Characterization


20 40 60 80

undoped BNKT10

Rietveld refinement

doped BNKT10

222310220

200 211

210111

110

100

rel.

in

ten

sit

y /

a.u

.

degree / 2

56 58 60

undoped BNKT10

Rietveld refinement

doped BNKT10

211

degree / 2

Bi0.5(Na(1-x)Kx)0.5Ti0.995CuyV(0.005-y)O3 , BNKT20 + excess V2O5

Bi0.5(Na(1-x)Kx)0.5Ti1-y(Mn,V,Cu,Mo,Al)y O3

mixing + milling 12h in

ethanol

calcining

800 - 900 °C

milling 12h in

ethanol

uniaxial+

isostatic

at 350 MPa

sintering

1080 - 1150 °C

Solid state sythesis

Less rhombohedral

character upon

(co-)doping

SEM Investigation / Density


BNKT10 undoped More homogeneous size

distribution of doped BNKT10

%TD increases with Cu-content

0 20 40 60 80 100

94

96

98

100

the

ore

tic

al

de

ns

ity

(T

D)

/ %

Cu to V co-dopant ratio

BNKT10:0.3Cu,0.2V

Bi0.5Na0.45K0.05Ti0.995CuyV(0.005-y)O3

5 µm

5 µm

Excess Doping of BNKT20 and

BNKT25 with V2O5


-6 -3 0 3 6

-30

-20

-10

0

10

20

30

po

lari

zati

on

/ µ

C/c

m2

electric field / kV/mm

0.1 wt% V2O5

0.2 wt% V2O5

0.3 wt% V2O5

0.4 wt% V2O5

BNKT25

-6 -3 0 3 6

0.0

0.5

1.0

1.5

2.0

no

rmalized

str

ain

/ ‰


0.1 wt% V2O5

0.2 wt% V2O5

0.3 wt% V2O5

0.4 wt% V2O5

BNKT25

0 50 100 150 200 250 300 350 400 4500

1000

2000

3000

tan

pe

rmit

tivit

y /

r

T / °C

100 Hz

1 kHz

10 kHz

100 kHz

1 MHz

0

50

100

BNKT25 + 0.2% V2O5

f

f

Pinching of

P-E loop

Strain

increase for

BNKT25

Tf-r lowered

and

broadened

Frequency

dispersion

0.0 0.1 0.2 0.3 0.4

150

200

250

300

BNKT25+xV2O

5

BNKT20+xV2O

5d* 3

3 /

pm

/V

excess V2O

5 / wt.%


-6 -4 -2 0 2 4 6-1.0

-0.5

0.0

0.5

1.0

str

ain

/ ‰


BNKT10

: 0.5 Cu

: undoped

-6 -4 -2 0 2 4 6

0.0

0.5

1.0

1.5

str

ain

/ ‰


BNKT20

: 0.5Cu

: undoped

(Co)-doping V + Cu Overview

High strain at MPB + some

tetragonal compositions

(Co)-doping V + Cu Overview


0.4Cu,0.1V fixed,

BKT varied

BKT fixed to 20 %,

Cu to V ratio varied

Tf-r lowered with BKT

content; d*33 rises

d*33 generally higher

due to co-doping

10 20 3040

60

80

100

120

140

160

d*

33

Tf-r

BKT / %

Tf-

r /

°C

0

50

100

150

200

250

300

d* 3

3 /

pm

/V

0 20 40 60 80 10040

60

80

100

120

140

160

pure

BNKT20

Cu to V co-dopant ratio / %

Tf-

r /

°C0

50

100

150

200

250

300

d*

33

Tf-r d

* 33 /

pm

/V

(Co)-doping BNKT10


0 20 40 60 80 1000

10

20

30

Pmax

(6 kV/mm) Pr (6 kV/mm) E

c

V to Cu ratio / %

po

lari

za

tio

n /

µC

/cm

²

4.5

4.8

5.1

5.4

pure

BNKT10

pure

BNKT10

Ec /

kV

/mm

0 50 100 150 200 250 300 350 400 4500

1000

2000

3000

4000

pe

rmit

tiv

ity

( r)

T / °C

100 Hz

1 kHz

10 kHz

100 kHz

1 MHz

0

20

40

60

80

100

BNKT20:0.1V0.4Cu

Ta

n /

%

f

f

BNKT10 based samples →

no bias field

PZT or BT →

bias field upon doping

Hall, D. A. et

al., Journal of

Physics:

Condensed

Matter 10,

9129 (1998).

2000 4000 6000 8000 100000

5000

10000

15000

20000

25000

imp

ed

an

ce (

Z)

/

frequency / kHz

Resonance Measurements

(Co-)doped BNKT10


400 410 420 430 440 4500

2000

4000

6000

imp

ed

an

ce (

Z)

/

frequency / kHz

BNKT10:0.5Cu

2.0 2.5 3.0 3.5

200

400

600

800

1000

1200

imp

ed

an

ce (

Z)

/

frequency / MHz

20 40 60 80 1000.0

0.2

0.4

0.6

0.8

1.0

pure

BNKT10

pure

BNKT10 K

P

QM (P)

co

up

lin

g f

ac

tor

0

20

40

60

80

100

120

QM

20 40 60 80 1000.0

0.2

0.4

0.6

0.8

1.0

Cu to V co-dopant ratio / %

co

up

lin

g f

ac

tor

(th

ick

ne

ss

)0

20

40

60

80

100

120

pure

BNKT10

pure

BNKT10

KT

QM (T)

QM

QM (planar) decreased by Cu

High (up to 0.58) thickness

mode coupling (QM around 5)

b1g


Electron Paramagnetic Resonance

(Co-)doped BNKT10

eg*

t2g

b1g

a1g

b2g

eg

EPR

Oh

octahedral

splitting D4h

Jahn-Teller

splitting

magnetic field

splitting

Elongation X-band EPR

of Cu-doped

BNKT10

Peak

broadening

Cu2+ at

grain

boundaries

/ above

solubility

limit

Electron Paramagnetic Resonance

(Co-)doped BNKT10


𝑉2𝑂5 → 2𝑉𝑇𝑖𝑋

𝐶𝑢𝑂 → 𝐶𝑢′𝑇𝑖′ + 𝑉𝑂

..

𝑉2𝑂5 → 2𝑉𝑇𝑖. + 𝑉𝐵𝑖

′′′ / 𝑉𝑁𝑎,𝐾′

!

V incorporated

as V4+

Cu-V-ratio

influences V-

oxidation state

X-band EPR of sintered samples TiO2

TiO2

TiO2

Summary / Conclusions


Co-doping at rhombohedral site of MPB (BNKT10)

Butterfly-type strain curve, high KT, Pr, Pmax, Ec and Tf-r

Transducers, high power applications

Co-doping at MPB (BNKT20) / excess doping

Polarization loop pinching, high Smax, low Ec, relatively low Tf-r

Actuator applications

Vanadium state V5+? / V4+; Cu2+ at grain boundaries

Thank you

for your attention!


Documents

Co-doping of Lead-free Bi1/2Na1/2TiO3 (BNT) - Bi1/2K1/2TiO3 (BKT) · 2020-06-19 · Co-doping of Lead-free Bi 1/2 Na 1/2 TiO 3 (BNT) - Bi 1/2 K 1/2 TiO 3 (BKT) -based Piezoceramics