Martienssen W., Warlimont H. (Eds.). Handbook of Condensed Matter and Materials Data

Подождите немного. Документ загружается.

932 Part 4

TGS ((NH

COOH)

· H

) Family

(NH

COOH)

· H

(TGS) (LB Number 60A-1). This

crystal is ferroelectric below 49.4

◦

C (Figs. 4.5-83 and

4.5-84). Critical slowing-down takes place (Fig. 4.5-9).

(CH

NHCH

COOH)

· CaCl

Family

(CH

NHCH

COOH)

· CaCl

(LB Number 64A-1). This crys-

tal is ferroelectric below 127 K (Figs. 4.5-85 and 4.5-86).

The Curie–Weiss constant is small (40 K). As discussed

in Sect. 4.5.3, two components are expected in the di-

electric constants of displacive-type ferroelectrics: one

contribution from the soft optical phonon and one con-

tribution from cluster boundary motion. This crystal

provides a good example of this situation. Softening

of the optical phonon mode B

occurs (Fig. 4.5-11),

indicating that the transition is of the displacive type,

100 150 200 250

T (K)

Fig. 4.5-85 (CH

NHCH

COOH)

· CaCl

. κ

versus T .

f = 10 kHz

0.3

0.2

0.1

100 125

(10

–2

C m

–2

)

T (K)

Fig. 4.5-86 (CH

NHCH

COOH)

· CaCl

. P

versus T

while critical slowing-down takes place in the GHz

region (Fig. 4.5-10); this seems to take place in the

contribution from cluster boundary motion. The value

of the dielectric constant at the Curie point at 1.0 GHz

seems to contain a contribution from the optical phonon

mode.

(CH

)

NCH

COO · CaCl

· 2H

O Family

(CH

)

NCH

COO · CaCl

· 2H

O (LB Number 66A-1). This

crystal is ferroelectric below 46 K. It exhibits at least

ten phase transitions (eight can be recognized in

Fig. 4.5-87), and the crystal structure is commensurately

or incommensurately modulated between 46 and 164 K,

with a feature known as a devil’s staircase. Multiple hys-

teresis loops are observed in the modulated phases, as

shown in Fig. 4.5-88.

Rochelle Salt (NaKC

· 4H

O) Family

NaKC

· 4H

O (Rochelle Salt, RS) (LB Number

67A-1).

Rochelle salt was the ﬁrst ferroelectric crys-

tal to be discovered. It is ferroelectric between −18 and

◦

C (Figs. 4.5-89 and 4.5-90). It is rare that an or-

dered ferroelectric phase of lower symmetry (P2

this case) appears in an intermediate temperature range

between disordered phases of the same higher symmetry

(P2

2). Figure 4.5-91 shows X-ray evidence for such

space group changes. For theoretical studies, readers

should refer to [5.7].

LAT (LiNH

· H

O) Family

LiNH

· H

O (LAT) (LB Number 68A-1). Ferro-

electric activity appears along the b axis below 106 K

(Fig. 4.5-92). The dielectric constant of the clamped

50 100 150 200 250 300

f = 10 kHz

T (K)

E = 1.2 kV/m

Fig. 4.5-87 (CH

)

NCH

COO · CaCl

· 2H

O. κ

ver-

sus T

Part 4 5.4

Ferroelectrics and Antiferroelectrics 5.4 Physical Properties of 43 Representative Ferroelectrics 933

30 40 50 60 70 80 90 100 110 120 130

E (10

V/m)

P (10

–2

C/m

)

T (K)

Fig. 4.5-88 (CH

)

NCH

COO · CaCl

· 2H

O. P

, E

, P

,andE

versus T . Deﬁnitions of P

(i = 1, 2, 3) and E

are

shown in the top ﬁgure

crystal





shows no anomaly at the transition tem-

perature (Fig. 4.5-7), while the elastic compliances

–180 –160 –140 –120 –100–120 –80 –40 –20 0 20 40 60

T (°C)

f = 1 kHz

900 Hz

RS Deuterated RS

Fig. 4.5-89 NaKC

·4H

O (RS)and NaKC

· 4D

O (deuterated RS). κ

versus T

exhibit a pronounced anomaly (Fig. 4.5-93). These data

indicate that the ferroelectric phase transition is of the

indirect type III

triggered by an elastic anomaly (see

Sect. 4.5.3). The crystal is piezoelectric in the paraelec-

–30 40–20 –10 0 10 20 30

T (°C)

(10

–3

–2

)

Deuterated RS

Fig. 4.5-90 NaKC

·4H

O (RS)and NaKC

· 4D

O (deuterated RS). P

versus T

Part 4 5.4

934 Part 4

0.07

0.06

0.05

0.04

0.03

0.02

0.01

–20 –10 0 10 20 30

T (°C)

(10

–4

)

I(050) (arb. units)

I(050)

Fig. 4.5-91 NaKC

· 4H

O. I

(050)

versus T . I

(050)

the integrated intensity of the X-ray (050) reﬂection, which

should disappear in the space group P2

2below−18

◦

and above 23

◦

C. The solid line is P

normalized to ﬁt to

(050)

tric phase and the elastic anomaly causes a dielectric

anomaly in the free crystal (κ

in Fig. 4.5-92 and κ

in Fig. 4.5-7), but no dielectric anomaly in the clamped

crystal (κ

in Fig. 4.5-7).

160

120

280120 160 200 240

T (K)

Fig. 4.5-92 LiNH

· H

O. κ

versus T

320

180

140

200

160

120

75 100 125 150 175 200 225 250

T (K)

(10

–11

–1

)

(10

–11

–1

)

(10

–11

–1

)

– s

(0)

)

–1

(10

N m

–2

)

II–I

– s

(0)

)

–1

– s

(0)

)

–1

Fig. 4.5-93 LiNH

· H

O. s

, s

,ands

ver-

sus T . s

, s

,ands

are the shear components of the

elastic compliance tensor at constant electric ﬁeld. The two

straight lines show



−s

(0)



−1

and



−s

(0)



−1

where s

is s

at constant electric displacement,

(0) = 18.0m

−1

,ands

(0) = 17.0m

−1

Liquid Crystal Family

DOBAMBC, p-decyloxybenzylidene p



-amino 2-me-

thylbutyl cinnamate (LB Number 71A-1 (A)) (Liquid

Crystal).

This liquid crystal is ferroelectric in the smec-

tic C

∗

phase between about 76 and 92

◦

C on heating. On

cooling, the C

∗

phase is transformed into a smectic H

∗

Part 4 5.4

Ferroelectrics and Antiferroelectrics 5.4 Physical Properties of 43 Representative Ferroelectrics 935

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

50 60

70 80 90 100

T (°C)

f = 30 Hz

f =110 Hz

f =330 Hz

f = 1 Hz

f = 3 kHz

f = 10 kHz

Fig. 4.5-94 DOBAMBC. κ versus T . Parameter: f . Sam-

ple cell thickness = 2.3 µm

–35 –30 –25 –20 –15 –10 –5 0

(10

–5

–2

)

(deg)

(°C)

II–I

T–

Fig. 4.5-95 DOBAMBC. P

and θ versus T −Θ

II−I

. θ is

the apparent tilt angle, and Θ

II−I

is the ferroelectric transi-

tion temperature

Fig. 4.5-96a,b MHPOBC. D − E hysteresis loops ob-

tained from switching-current measurements. D is the

electric displacement. Sample cell thickness = 3 µm.

(a) Double hysteresis loop at 2 Hz. (b) Single hysteresis

loop at 100 Hz

θ(°)

+20

+10

–10

–20

–10 –5

+5 +10

Fig. 4.5-97 MHPOBC. θ versus E. θ is the apparent tilt

angle. Sample cell thickness = 3 µm

phase at about 63

◦

C, retaining the ferroelectric activity

(Figs. 4.5-94 and 4.5-95).

MHPOBC, 4-(1-methylheptyl oxycarbonyl)phenyl 4



octyloxybiphenyl-4-carboxylate (LB Number 71B-

1 (A)) (Liquid Crystal).

Seven phases are known for this

liquid crystal. It exhibits an antiferroelectric hysteresis

loop at low frequency, as shown in Fig. 4.5-96a, between

f = 2 Hz

f = 100 Hz

Part 4 5.4

936 Part 4

100

40 60 80 100 120 140

T (°C)

x = 0.59

(10

–3

–2

)

x = 0.65

x = 0.75

Fig. 4.5-98 ((CH

)

(CF

CHF)

1−x

)

. P

versus T.Pa-

rameter: x. Thickness of specimen ﬁlm = 50 µm

65 and 119.7

◦

C. The antiferroelectric behavior can be

best demonstrated by measuring the apparent tilt an-

gle, as shown in Fig. 4.5-97. The hysteresis loop turns

into a triple one between 119.7 and 120.6

◦

C, and into

a normal ferroelectric hysteresis loop between 120.6and

122.1

◦

C. The phase exhibiting the triple hysteresis loop

is called “ferrielectric” by several authors.

Polymer Family

((CH

)

(CF

CHF)

1−x

)

,Vinylidene ﬂuoride–triﬂuoro-

ethylene Copolymer, ((VDF)

(TrFE)

1−x

)

(LB Num-

ber 72-2) (Polymer).

Random polymers (CH

)

(CF

CHF)

1−x

exhibit a ferroelectric hysteresis loop for

–50 0 50 100

T (°C)

0.59

0.65

0.69

0.73

x = 1

x = 0

0.13

0.37

0.47

Fig. 4.5-99 ((CH

)

(CF

CHF)

1−x

)

. κ



versus T .

Parameter: x. f = 1 kHz. Thickness of specimen ﬁlm

= 50 µm

x > 0.5 (Figs. 4.5-98 and 4.5-99). Ferroelectric activity

is preserved up to the melting point for x > 0.8.

References

5.1 Y. Shiozaki, E. Nakamura, T. Mitsui (Eds.): Ferro-

electrics and Related Substances: Oxides: Perovskite-

Type Oxides and LiNbO

Family, Landolt–Börnstein,

New Series III/36 (Springer, Berlin, Heidelberg

2001)

5.2 Y. Shiozaki, E. Nakamura, T. Mitsui (Eds.): Fer-

roelectrics and Related Substances: Oxides: Oxides

Other Than Perovskite-Type Oxides and LiNbO

Fam-

ily, Landolt–Börnstein, New Series III/36 (Springer,

Berlin, Heidelberg 2002)

5.3 Y. Shiozaki, E. Nakamura, T. Mitsui (Eds.): Ferro-

electrics and Related Substances: Inorganic Crystals

Other Than Oxides, Landolt–Börnstein, New Series

III/36 (Springer, Berlin, Heidelberg 2004)

5.4 Y. Shiozaki, E. Nakamura, T. Mitsui (Eds.): Ferro-

electrics and Related Substances: Organic Crystals,

Liquid Crystals and Polymers, Landolt–Börnstein,

New Series III/36 (Springer, Berlin, Heidelberg 2005)

in preparation

5.5 J. Valasek: Piezoelectric and Allied Phenomena in

Rochelle Salt, Phys. Rev. 15, 537 (1920)

5.6 J. Valasek: Piezo-Electric and Allied Phenomena in

Rochelle Salt, Phys. Rev. 17, 475 (1921)

5.7 T. Mitsui, E. Nakamura, I. Tatsuzaki: An Introduction

to the Physics of Ferroelectrics (Gordon and Breach,

New York 1976)

5.8 F. Jona, G. Shirane: Ferroelectric Crystals (Dover Pub-

lications, New York 1993)

5.9 B. A. Strukov, A. P. Levanyuk: Ferroelectric Phenom-

ena in Crystals: Physical Foundations (Springer,

Berlin, Heidelberg 1998)

5.10 M. E. Lines, A. M. Glass: Principles and Applications

of Ferroelectrics and Related Materials (Clarendon,

Oxford 1979)

Part 4 5

Ferroelectrics and Antiferroelectrics References 937

5.11 Y. Xu: Ferroelectric Materials and Their Applications

(North-Holland, Amsterdam 1991)

5.12 B. Jaffe, W. R. Cook Jr., H. Jaffe: Piezoelectric Ceram-

ics (Academic Press, London 1971)

5.13 J. Zelenka: Piezoelectric Resonators and Their Appli-

cations (Elsevier, Amsterdam 1986)

5.14 T. Ikeda: Fundamentals of Piezoelectricity (Oxford

Univ. Press, Oxford 1990)

5.15 R. A. Cowley: Structural Phase Transitions (Consul-

tant Bureau, New York 1980)

5.16 K. A. Miller, H. Thomas (Eds.): Structural Phase Tran-

sitions I, Topics in Current Physics, Vol. 23 (Springer,

Berlin, Heidelberg 1981)

5.17 M. Fujimoto: The Physics of Structural Phase Transi-

tions (Springer, Berlin, Heidelberg 1997)

5.18 R. Blinc, A. P. Levanyuk (Eds.): Incommensurate

Phases in Dielectrics, Modern Problems in Con-

densed Matter Science 14 (Elsevier, Amsterdam

1986)

5.19 F. J. Scott: Soft-mode spectroscopy: Experimental

studies of structural phase transitions, Rev. Mod.

Phys. 46, 83 (1974)

5.20 G. Shirane: Neutron scattering studies of struc-

tural phase transitions, Rev. Mod. Phys. 46, 437

(1974)

5.21 C. H. Wang: Raman and Brillouin scattering spec-

troscopy of phase transitions in solids. In: Vibra-

tional Spectroscopy of Phase Transitions,ed.by

Z. Iqbal, F. J. Owens (Academic Press, Orlando 1984)

pp. 153–207

5.22 J. M. Herbert: Ceramic Dielectrics and Capacitors,

Electrocomp. Sci. Mon., Vol. 6 (Gordon and Breach,

New York 1985)

5.23 B. E. Vugmeister, M. D. Glinchuk: Dipole glass and

ferroelectricity in random-site electric dipole sys-

tems, Mod. Phys. 62, 993 (1990)

5.24 L. E. Cross: Relaxor ferroelectrics, Ferroelectrics 76,

241 (1987)

5.25 S. Singh: Nonlinear optical materials. In: Handbook

of Lasers with Selected Data on Optical Technol-

ogy, ed. by R. J. Pressley (The Chemical Rubber Co.,

Cleveland 1971) pp. 489–525

5.26 V. G. Dmitriev, G. G. Gurzadyan, D. N. Nikogosyan:

Handbook of Nonlinear Optical Crystals, Springer Se-

ries in Optical Science, Vol. 64, ed. by A. E. Siegman

(Springer, Berlin, Heidelberg 1991)

5.27 P. Yeh: Introduction to Photorefractive Nonlinear

Optics (Wiley, New York 1993)

5.28 G. Rosenman, A. Skliar, A. Arie: Ferroelectric do-

main engineering for quasi-phase-matched non-

linear optical devices, Ferroelectr. Rev. 1,263

(1999)

5.29 N. Setter, E. L. Colla: Ferroelectric Ceramics (Birk-

häuser, Basel 1993)

5.30 B. A. Tuttle, S. B. Desu, R. Ramesh, T. Shiosaki: Fer-

roelectric Thin Films IV (Materials Research Society,

Pittsburgh 1995)

5.31 C. P. Araujo, J. F. Scott, G. W. Taylor (Eds.): Ferro-

electric Thin Films: Synthesis and Basic Properties

(Gordon and Breach, New York 1996)

5.32 R. Ramesh (Ed.): Thin Film Ferroelectric Materials

and Devices, Electronic Materials Science and Tech-

nology, Vol. 3 (Kluwer, Dordrecht 1997)

5.33 J. F. Scott: The physics of ferroelectric ceramic thin

ﬁlms for memory applications, Ferroelectr. Rev. 1,1

(1998)

5.34 D. Damjanovic: Ferroelectric, dielectric and piezo-

electric properties of ferroelectric thin ﬁlms and

ceramics, Rep. Prog. Phys. 62, 1267 (1998)

5.35 J. F. Scott: Ferroelectric Memories, Springer Series in

Advanced Microelectronics, Vol. 3 (Springer, Berlin,

Heidelberg 2000)

5.36 R. M. White: Surface elastic waves, Proc. IEEE 58, 1238

(1970)

5.37 G. W. Farnell, E. L. Adler: Acoustic Wave Propagation

in Thin Layers. In: Physical Acoustics,Vol.9,ed.by

W. P. Mason, R. N. Thurston (Academic Press, New

York 1972) pp. 35–127

5.38 A. A. Oliner (Ed.): Acoustic Surface Waves (Springer,

Berlin, Heidelberg 1978)

5.39 K.-Y. Hashimoto: Surface Acoustic Wave Devices

in Telecommunications, Modeling and Simulation

(Springer, Berlin, Heidelberg 2000)

5.40 J. M. Herbert: Ferroelectric Transducers and Sensors,

Electrocomp. Sci. Mon., Vol. 3 (Gordon and Breach,

New York 1982)

5.41 W. H. de Jeu: Physical Properties of Liquid Crystalline

Materials (Gordon and Breach, New York 1980)

5.42 J. W. Goodby, R. Blinc, N. A. Clark, S. T. Lagerwall,

M. A. Osipov, S. A. Pikin, T. Sakurai, K. Yoshino,

B. Zeks: Ferroelectric Liquid Crystals: Principles,

Properties and Applications, Ferroelectrics and Re-

lated Phenomena, Vol. 7 (Gordon and Breach, New

York 1991)

5.43 G. W. Taylor (Ed.): Ferroelectric Liquid Crystals: Prin-

ciples, Preparations and Applications (Gordon and

Breach, New York 1991)

5.44 L. M. Blinov, V. G. Chigrinov: Electric Effects in Li-

quid Crystal Materials (Springer, Berlin, Heidelberg

1994)

5.45 A. Fukada, Y. Takanishi, T. Isozaki, K. Ishikawa,

H. Takezoe: Antiferroelectric Chiral Smectic

Liquid Crystals, J. Mater. Chem. 4, 997 (1994)

5.46 P. J. Collings, J. S. Patel (Eds.): Handbook of Li-

quid Crystal Research (Oxford Univ. Press, Oxford

1997)

5.47 S. T. Lagerwall: Ferroelectric and Antiferroelectric Li-

quid Crystals (Wiley VCH, Weinheim 1999)

5.48 T. Furukawa: Ferroelectric Properties of Vinyli-

dene Fluoride Copolymers, Phase Transitions 18, 143

(1989)

5.49 D. K. Das-Gupta (Ed.): Ferroelectric Polymer and

Ceramic-Polymer Composites (Trans Tech Publica-

tions, Aedermannsdorf 1994)

Part 4 5

938 Part 4

5.50 H. S. Nalva (Ed.): Ferroelectric Polymers: Chemistry,

Physics and Applications (Marcel Dekker, New York

1995)

5.51 H. Kodama, Y. Takahashi, T. Furukawa: Effects of

Annealing on the Structure and Switching Charac-

teristics of VDF/TrFE Copolymers, Ferroelectrics 205,

433 (1997)

5.52 N. A. Clark, S. T. Lagerwall: Submicrosecond Bistable

Electro-Optic Switching in Liquid Crystals, Appl.

Phys. Lett. 36, 899 (1980)

5.53 A. D. L. Chandani, E. Gorecka, Y. Ouchi, H. Takezoe,

A. Fukuda: Antiferroelectric Chiral Smectic Phases

Responsible for the Tristable Switching in MHPOBC,

Jpn. J. Appl. Phys. 28, L1265 (1989)

Part 4 5

939

Special Stru

Part 5

Part 5 Special Structures

1 Liquid Crystals

Sergei Pestov, Moscow, Russia

Volkmar Vill, Hamburg, Germany

2 The Physics of Solid Surfaces

Gianfranco Chiarotti, Roma, Italy

3 Mesoscopic and Nanostructured Materials

Fabrice Charra, Gif-sur-Yvette, France

Susana Gota-Goldmann, Fontenay aux Roses,

France

940

This page intentionally left blank

941

Liquid Crystal

5.1. Liquid Crystals

Liquid crystals (LCs) are widely used in information-

processing devices, for optical visualization of

physical inﬂuences (heat, IR, high-frequency

radiation, pressure, etc.), for nondestructive

testing, and for thermography.

5.1.1 Liquid Crystalline State ....................... 941

5.1.1.1 Chemical Requirements ........... 943

5.1.1.2 Physical Properties

of Liquid Crystals..................... 943

5.1.1.3 Applications of Liquid Crystals... 944

5.1.1.4 List of Abbreviations ................ 944

5.1.1.5 Conversion Factors .................. 945

5.1.2 Physical Properties of the Most Common

Liquid Crystalline Substances ............... 946

5.1-2 Acids ..................................... 946

5.1-3 Two-ring Systems without

Bridges .................................. 947

5.1-4 Two-ring Systems with Bridges . 955

5.1-5 Three and Four-ring Systems .... 964

5.1-6 Ferroelectric Liquid Crystals ...... 967

5.1-7 Cholesteryl (cholest-5-ene)

Substituted Mesogens .............. 968

5.1-8 Discotic Liquid Crystals ............. 972

5.1-9 Liquid Crystal Salts .................. 973

5.1.3 Physical Properties

of Some Liquid Crystalline Mixtures ...... 975

5.1-10 Nematic Mixtures .................... 975

5.1-11 Ferroelectric Mixtures .............. 975

References .................................................. 977

5.1.1 Liquid Crystalline State

Liquid crystals represent an intermediate state of or-

der (mesophase) between crystals and liquids. Crystals

have a three-dimensional long-range order of both pos-

ition and orientation (Fig. 5.1-1a). Liquids, in contrast,

do not show any long-range order (Fig. 5.1-1b). In plas-

tic crystals (disordered crystals, Fig. 5.1-1c), positional

order is maintained, but orientational order is lost. In

mesophases, imperfect long-rangeorder is observed, and

thus they are situated between crystals and liquids. The

reasons for the formation of a mesophase can be the mo-

lecular shape or a microphase separation of amphiphilic

compounds.

More than 100 000 individual liquid crystals have

been prepared until now [1.1–4]. About 2000 of them

have been tested for physical properties and technical

applications [1.5–14]. These materials can be classiﬁed

by chemical structures and physical characteristics (see

Table 5.1-1).

Generally, molecules of liquid crystalline substances

have the following shapes:

•

rod-like molecules, which form calamitic liquid

crystals (nematicand smectic phases);

•

disk-like molecules, which form discotic liquid crys-

tals (discoid nematic and discotic phases);

•

amphiphilic compounds, which form layered colum-

nar or cubic phases in the pure state and in solution.

The simplest and most widespread liquid crystalline

phase is the nematic phase. The molecules are statis-

tically distributed within the medium, but the long axes

are orientated in one direction, the director (Fig. 5.1-2a).

A special class of nematic phases is the cholesteric phase

Part 5 1