characterisation of texture of strontium hexaferrite with ebsd and …rahi/mtexworkshop16/... ·...

Timmy Reimann

Characterisation of texture of

strontium hexaferrite with EBSD

and XRD

Timmy Reimann, Arne Bochmann, Jörg Töpfer

MTEX Workshop 26.02.2016

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0. Outline

1. Introduction

2. EBSD results

3. XRD results

4. Evaluation with MTEX

5. Summary

6. Outlook

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1. Introduction – field of interest

Functional ceramics

Soft ferrites

o Mn-Zn ferrites for multilayer inductors

o M-, Y-, Z-type hexaferrites

Hard ferrites

o Sr hexaferrites for permanent magnets

Dia- and Piezoelectrics

o CaCu3Ti4O12

o PZT (PbZrO3)

o Pb free BNBT (Bi0.5Na0.5)TiO3 – BaTiO3

and KNN (K0.5Na0.5NbO3)

Thermoelectrics

o CCO (Ca3Co4O9); CaMnO3

Low temperature ceramic cofiring (LTCC)

devices sintered at 900°C

multi layer round coil

multi layer capacitor

H. Bartsch

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1. Introduction - Hexaferrite

R-Block

S-Block

𝑆𝑟2+𝐹𝑒123+𝑂192−

M-Type hexagonal ferrites (Ba/Sr)Fe12O19:

most important material group for permant

magnets

Sinter Ferrite (47%)

Compound-Ferrite (21%)

Sinter-NdFeB (19%)

Compound-NdFeB (6%)

Sinter-SECo (6%)

Compound-SECo (1%)

market share:

SG: 6/mmm

a = b = 5.8836 Å

c = 23.0376 Å

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1. Introduction - Tridelta Maniperm® 882

Data sheet

Maniperm 882 :

flux density B

remanence:

BR = 405-415 mT

magnetic field H

coercivity:

HCB = 270-240 kA/m

energy product:

(BH)max = 32 kJ/m2

-600 -400 -200 0 200 400 600

-1,0

-0,5

0,0

0,5

1,0

B (

T)

H (kA/m)

Tridelta Maniperm 882

EAH Jena Permagraph

sample 70A

𝐵 = 𝐽 + 𝜇0𝐻𝐽 …𝑚𝑎𝑔𝑛𝑒𝑡𝑐 𝑝𝑜𝑙𝑎𝑟𝑖𝑠𝑎𝑡𝑖𝑜𝑛

𝜇0 …𝑚𝑎𝑔𝑛𝑒𝑡𝑖𝑐 𝑓𝑖𝑒𝑙𝑑 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡

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uniaxial pressing with

applied magnetic field

sample

𝐻 = 𝐼𝑁

𝑙2 + 𝐷2

𝑁 …𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑤𝑖𝑛𝑑𝑖𝑛𝑔𝑠

𝑙 … 𝑙𝑒𝑛𝑔𝑡ℎ

𝐷 …𝑐𝑜𝑖𝑙 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟

𝐼 … 𝑐𝑢𝑟𝑟𝑒𝑛𝑡

current variation:

0 A; 20 A; 40 A; 60 A; 70 A

1. Introduction – sample preparation

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H field in z direction

orientation of c axis in powder

particles of slurry in z direction

due to uniaxial magneto-

crystalline anistropy of

SrFe12O19

goal:

increase of remanence in z

direction

1. Introduction - sample preparation

uniaxial pressing with

applied magnetic field

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-350 -300 -250 -200 -150 -100 -50 00,00

0,08

0,16

0,24

0,32

0,40

J (

T)

H (kA/m)

70 A

20 A

0 A

1. Introduction – magnetic properties

increase of remanence

with increasing H field in

pressing process

observed

task:

characterisation of

texture

2. quadrant of H – J plot

𝐵 = 𝐽 + 𝜇0𝐻

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1. Introduction – goals

Characterisation of texture

measurement of texture with EBSD and XRD and evaluation of both data sets

with same procedure

computing ODF

tetermine vector of main orientation

calculating amount of fibre texture

derivation around main orientation and calculating Br according to the ODF

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2. EBSD results – 0 A sample

IPFX Map

112 x 84 µm

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IPFX Map

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IPFX Map

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2. EBSD results – ODF (MTEX)

To calculate the ODFs given in the pole figures below a kernel function with a

halfwidth of 5 ° was used.

0 A 20 A

70 A

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3. XRD results

15,0 17,5 20,0 22,5 25,0 27,5 30,0 32,5 35,0 37,5

(0004)

(10-1

0)

(10-1

1)

(10-1

2)

(10-1

3)

(0006)

(10-1

5)

(10-1

6)

(11-2

0)

(0008)

(11-2

2)

(10-1

7)

(11-2

4)

(20-2

0)

(20-2

1)

(10-1

8)

(20-2

2)

(20-2

3)

(11-2

6)

inte

nsity (

a. u.)

2 (°)

Hexaferrit 60 A pellet

c-axis in x directionSrFe

12O

19

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(1010) (1017) (1124)

Calculated polfigure for fibre texture

Polfigures

3. XRD results – Bruker Multex

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phases

rotation axis

halfwidth: 30°

f.polar = 82,32°

f.azimuth = 177,49°

rotation axis f

3. XRD results – Bruker Multex

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Polfigures plotted with MTEX (halfwidth = 5°)

Calculation of ODF

Plot of polfigures

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polefigure of ODF

Multex Fit

fibre: 72 % , halfwidth: 30 %

MTEX Fit

ODF_mea = x*ODF_Fibe + (1-x)*ODF_Uni*

fibre:69 %, halfwidth: 17 %

uniform: 31%


*matlab script at the end

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0 20 40 60 800

20

40

60

80

100

cu

mula

tive s

um

fib

re a

mo

un

t (v

ol.%

)

halfwidth (°)

20 40 60 800

2

4

6

8

10

12

14

16

vo

lum

e f

ractio

n (

%)

halfwidth (°)

60 A

Anteilfibre = [];

i = 1;

for theta = 5 : 5 : 90

theta_array(i) = theta;

Anteilfibre(i) = fibreVolume(odf_measured, Miller(0,0,1,cs), o_min_vector,…

theta*degree) * 100;

i = i+1;

end


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Br (theo.) = 0.437 T

in c direction

𝐵𝑅𝑖 = 𝐵𝑅𝑡ℎ𝑒𝑜 cos𝜑𝑖

𝜑

𝐵𝑅𝑔𝑒𝑠 =

𝑖

𝑁90°

𝐵𝑅𝑡ℎ𝑒𝑜 cos(Δ𝜑 ∗ 𝑖)

𝐵𝑅𝑔𝑒𝑠 = 0.413 𝑇;𝐵𝑅𝑔𝑒𝑠𝐵𝑅𝑡ℎ𝑒𝑜

100 = 95 %

0 20 40 60 800,00

0,01

0,02

0,03

0,04

0,05

0,06

0,07

60 A

Ante

il an

Br g

es -

Br i (

T)

halfwidth (°)

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

cm

ula

tive s

um

Br g

es (

T)


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MTEX Fit

fibre: 75 %, halfwidth = 20,5°

uniform: 25 %

EBSD polefigure of ODF

5. Summary – 60 A sample

fibre:69 %, halfwidth: 17°

uniform: 31%

XRD polefigure of ODF

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0 10 20 30 40 50 60 70 80 900

20

40

60

80

100

cu

mula

tive s

um

fib

re (

vol.%

)

halfwidth (°)

Hexaferrit 60 A

XRD

EBSD

0 20 40 60 800,0

2,5

5,0

7,5

10,0

12,5

15,0

17,5

vo

lum

e f

ractio

n (

%)

halfwidth (°)

Hexaferrit 60 A

XRD

EBSD

Br (XRD) = 0.413 T

Br (EBSD) = 0.416 T

Measured Br:

Br (Robograph) = 0.405 T

0 10 20 30 40 50 60 70 80 900,0

0,1

0,2

0,3

0,4

Hexaferrit 60 A

XRD

EBSD

cu

mula

tive s

um

Br

(T)

halfwidth (°)

5. Summary – 60 A sample

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6. outlook

measuring of a sample with c in z direction with XRD and EBSD

use of Co-radiation instead of Cu-radiation

preparation of an isotrop SrFe12O19 sample for calibration of XRD polefigures

XRD Pole figures of 70 A sample

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6. outlook

15 mm

Characterisation of screen printed thick

film hexaferrites for circulators

Characterisation of KNN piezoelectics

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Thanks!

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Script for MTEX Fit

%% Fitten Fibre

Miller_c_Achse = Miller (0 ,0 , 1 ,cs);

fibrevector = odf_max_orientation*Miller_c_Achse;

odf_fibre = fibreODF(Miller(0,0,1,cs),fibrevector,'halfwidth',20*degree);

% definition Anfangsvektor, x(1): Amplituden; x(2), x(3), x(4): Eulerwinkel (°), x(5): Halfwidth unimodale ODF

[h1, h2, h3] = Euler(odf_max_orientation,'Bunge');

x0 = [0 h1/degree h2/degree h3/degree 10];

% Definition Nebenbedingungen: 0<= x(1) <= 1; 0<= x(5) <= 45;

A = [-1 0 0 0 0; ...

1 0 0 0 0; ...

0 0 0 0 -1; ...

0 0 0 0 1];

b = [0;1;0;45];

min_func = @(x)calc_ODF_Error(x,odf_measured, ss,cs);

[x,fval,exitflag,output] = fmincon(min_func,x0,A,b,[],[],[],[],[],optimset('Algorithm','interior-point','Display','iter-

detailed'));

o_min = orientation('Euler',x(2)*degree,x(3)*degree,x(4)*degree,cs,ss);

o_min_vector = o_min*Miller_c_Achse;

ampl_min = x(1);

halfwidth_min = x(5);

odf_min = ampl_min*fibreODF(Miller(0,0,1,cs), o_min_vector,'halfwidth',halfwidth_min*degree) + (1-

ampl_min)*uniformODF(cs,ss);

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characterisation of texture of strontium hexaferrite with ebsd and …rahi/mtexworkshop16/... ·...

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