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

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392 Part 3 Classes of Materials

140

120

100

200 800

Temperature (K)

120

100

–200 800

Temperature (°C)

400 600

0 200 400 600

a) Magnetization (emu g

–1

)

b) Magnetization (emu g

–1

)

FeRh Pd

0.0833

FeRh Ru

0.0833

FeRh Ir

0.0833

FeRh Pt

0.0833

FeRh Os

0.0833

Calculated for S = 1

Fig. 3.1-312a,b Metamagnetic behavior of (a) FeRh su-

perlattice alloy [1.218, p. 102].

(b) Variation by addition

of small amounts of Pd, Ru, Ir, Pt, Os [1.218, p. 102]

Thermal Properties.

Tables 3.1-212–3.1-214 show

the recrystalization temperature, thermal conductivity

and thermal expansion at different temperatures. Va-

por pressure at different temperatures is shown in

Fig. 3.1-273.

Optical Properties. Rhodium has the highest optical re-

ﬂectivity of all platinum-group metals (Fig. 3.1-274),

ranging about 20% below the reﬂectivity of Ag.

It is used as hard and corrosion-resistant coat-

ing on silver jewelry and for optical reﬂectors.

Data of the spectral emissivity are given in

Table 3.1-216.

Diffusion. Data for self-diffusion are given in

Table 3.1-217 (see [1.216] for further data).

Chemical Properties. Rhodium is not attacked by acids

or alkali even under oxidizing conditions (aqua regia)

(Fig. 3.1-313). Sodium hypochlorite attacks in the order

of increasing strength: Pt = Rh = Ir =Ru < Pd < Os.

Heating in air causes the formation of thin oxide lay-

ers above 600

◦

C which decompose above 1100

◦

(Fig. 3.1-314). Pt alloys with 5–40 wt% Rh are

corrosion-resistant against H

. A detailed survey

about these chemical properties is given in [1.216].

Rhodium is the effective component of the three-

way Pt/Pd/Rh alloy autocatalyst for the reduction of

2.0

1.6

1.2

0.8

0.4

–0.4

–0.8

–1.2

–1.6

–2 16

02468101214

Immune

Passive

Potential (V)

Fig. 3.1-313 Potential pH diagram for the system

−

O [1.217, p. 202]

+20

–20

–40

–60

020

Time (h)

4 8 12 16

1300°C

1200°C

1100°C

Weight change (10

–2

mg cm

–2

)

Fig. 3.1-314 Weight change of Rh in oxygen [1.217, p. 185]

Part 3 1.10

Metals 1.10 Noble Metals and Noble Metal Alloys 393

400

Temperature (K)

600

Temperature (K)

500 600

800 1000 1200

a) NH

formation rate (10

molecule cm

–2

–1

)

b) N

formation rate (10

molecule cm

–2

–1

)

Fig. 3.1-315a,b Product formation rates in N =−H

reactions on Pd- and Rh-catalyst foils. (a) NH

forma-

tion rates p(NO) = 9.4×10

−5

Pa, p(H

) = 4.9×10

−5

Pa.

(b) N

formation rates p(NO) = 1.1×10

−5

Pa, p(H

) =

1.9×10

−5

Pa [1.218, p. 287]

of exhaustion gases (Figs. 3.1-315a,b). Rhatalysts

surpass the group homolog, Co-based catalysts, with

lower reaction pressures and temperatures and higher

yields [1.216]. Complex organic rhodium compounds

on the basis of RhCl (PPH

) with different substi-

tute ligands are important homogeneous catalysts in

the technical production processes for hydrogenation

and hydroformulation (“oxo”-processes, e.g., synthesis

MeO

AcO

COOH

NHAc

MeO

AcO

COOH

NHAc

HO COOH

NHAc

[Rh ((R, R)-(DiPAMP) COD] BF

10 bar H

25 °C

ton 20 000, tof 1000 h

–1

100 % yield; 95% ee

L-DOPA

NEt

100 °C

[Rh-(–)-BINAP(COD)]CIO

ton 400 000

tof 440 h

–1

3 steps

94% ee

… allylamine

… enamine

L-menthol

Fig. 3.1-316a,b Examples of organic synthesis of chiral compounds catalysed by complex Rh compounds. (a) L-DOPA.

(b) L-menthol [1.291, p. 83]

of aldehydes and acetic acid). Replacement of PPH

by complex chiral phosphan ligands enables the syn-

thesis of asymmetric compounds, e.g., L-DOPA and

L-menthol (Fig. 3.1-316a,b) [1.291].

Iridium and Iridium Alloys

Applications. Iridium is used for crucibles to grow high-

purity crystals for lasers, medical scanners etc., anodes

to prevent corrosion of shipping vessels and under-water

structures, coatings of electrodes for the manufacturing

of chlorine and caustic soda, as an alloy component

of automotive exhaust catalysts, and as alloy compo-

nent and compounds of chemical process catalysts for

the production of acetic acid and complex organic com-

pounds. Iridium is an effective hardener for materials

used at high temperature, high wear, and high corrosion

conditions (e.g., spark plugs). It is also used as ﬁne-

grain forming addition in jewelry and dental gold alloys.

Commercial grades available are powder, shot, ingot,

and wire in a purity ranging from 98–99.9% (ASTM

671-81, reappraised 1987).

Production. Iridium is produced as powder and sponge

by chemical reduction or thermal decomposition of the

chloro–ammonia compound (NH

)

[IrCl

]. Bars, rods,

ingot, and wires are produced by compacting of powder

followed by extrusion. Coatings are produced galvani-

cally, by evaporation, or by sputtering.

Phases and Phase Equilibria. Figures 3.1-317–

3.1-319 [1.216] show the binary phase diagrams of

Ir alloys with Pt, Rh, and Ru. Miscibility gaps

exist in the solid state also in the alloy sys-

tems with Cu, Os, Re, and Ru. Iridium alloyed in

Fe lowers the α–λ transition temperature consider-

Part 3 1.10

394 Part 3 Classes of Materials

2600

2200

1800

1400

1000

600

100

Platinum (wt %) Pt

0 102030405060708090

10 20 30 40 50 60 70 80 90 100

Temperature (°C) Platinum (at. %)

(Ir) + (Pt)

(Ir, Pt)

1769 °C

2447 °C

2600

2000

1000

400

100

Rhodium (wt %) Rh

0102030405060708090

10 20 30 40 50 60 70 80 90 100

Temperature (°C) Rhodium (at. %)

1963 °C

2447 °C

(Ir) + (Rh)

(Ir, Rh)

~ 850 °C

Table 3.1-248 Thermodynamic data of Ir [1.217, p. 109]

T (K) c

(J/K mol) S (J/K mol) H (J/mol) G (J/mol) p (atm)

298.15 24.979 35.505 0 −10.586

400 25.695 42.946 2.581 −14.598 6.70× 10

−80

800 28.51 61.62 13.442 −35.875 2.81 × 10

−36

1400 32.733 78.647 31.795 −78.311 1.15 × 10

−17

T = Temperature, c

= speciﬁc heat capacity, S = Entropy, H = Enthalpy, G = free Enthalpy,

p = partial pressure of the pure elements

Table 3.1-249 Structure and lattice parameter of intermediate compounds [1.217, p. 117f f,]

Phase Pearson symbol a (nm) b (nm) c (nm) Concentration x A(1 −x)B(x)

−

Ir cF4 0.3629

−

Os hP2 0.27361 0.43417 0.65

−

Os cF4 0.38358 0.2

−

Rh cF4 0.3824 0.5

−

Ru hP2 0.2718 0.4331 0.56

−

Ru cF4 0.3818 0.47

HT = high temperature modiﬁcation, LT = low temperature modiﬁcation

Fig. 3.1-317 Phase diagram of Ir

−

Pt [1.217, p. 88]

2600

2000

1000

800

100

Ruthenium (wt %) Ru

0102030405060708090

10 20 30 40 50 60 70 80 90 100

Temperature (°C) Ruthenium (at. %)

2334 °C

(Ru)(Ir)

2447 °C

2395°C

35.4

36.3

Fig. 3.1-319 Phase diagram of Ir

−

Ru [1.217, p. 89]

ably (Fig. 3.1-343). Thermodynamic data are given in

Table 3.1-248 [1.216].

Structure and lattice parameters of selected in-

termediate compounds are given in Table 3.1-249

[1.216].

Fig. 3.1-318 Phase diagram of Ir

−

Rh [1.217, p. 89]

Part 3 1.10

Metals 1.10 Noble Metals and Noble Metal Alloys 395

Mechanical Properties. Iridium is extremely hard and

can only be deformed at temperatures above 600

◦

with repeated annealing steps at temperatures higher

than 1200

◦

C. The Young’s modulus is different for

different crystal directions (Table 3.1-250) [1.216], the

modulus of rigidity is 214 GPa, and the Poisson’s ratio

amounts to 0.26.

Characteristic data of mechanical properties of

Ir and Pt/Ir alloys are given in Tables 3.1-251–

3.1-253 [1.216] and Figs. 3.1-320–3.1-322 [1.289].

Two-phase Ir-based refractory superalloys with fcc and

structure of the components (Ir

−

12Zr and Ir

−

17Nb,

−

15Nb

−

5Ni) have resist temperatures up to 1200

◦

and exhibit marked creep resistance (Figs. 3.1-323–

3.1-325) [1.292, 293].

Table 3.1-250 Modulus of elasticity in crystal direc-

tion [1.217, p. 212]

E 110 E 111

47.4GPa 662 GPa

Table 3.1-251 Elastic constants of Ir [1.217, p. 212]

T = 300 K c

= 580 c

= 242 c

= 256

220

210

200

190

180

170

0.30

0.25

0.20

Temperature (°C)

520

500

480

460

440

420

400

380

0 200 400 600 800 1000 1200

a) Young’s modulus E (GPa)

b) Poisson’s ratio v

Modulus of rigidity G (GPa)

E Ir

G Ir

E/G

Fig. 3.1-320 (a) Young’s modulus of Ir at different tem-

peratures.

(b) Poisson’s ratio for as cast Ir at different

temperatures [1.289]

250

200

150

Temperature (°C)

100

Temperature (°C)

200 400 600 800 1000 1200

100 200 300 400 500 600 700 800 900 1000 1100

b) Modulus of rigidity G (GPa)

a) Young’s modulus E (GPa)

E 30% Ir

E 20% Ir

E 10% Ir

G 30% Ir

G 20% Ir

G 10% Ir

Fig. 3.1-321 (a) Young’s modulus of Pt

−

Ir alloys at differ-

ent temperatures.

(b) Modulus of rigidity of as cast Pt

−

alloys at different temperatures [1.289]

270

250

230

210

190

170

150

130

Iridium concentration (wt %)

10 20 30

25 °C

400 °C

800 °C

1200 °C

Young’s modulus E (GPa)

Fig. 3.1-322 Young’s modulus of as cast Pt

−

Ir alloys at

different temperatures [1.289]

Part 3 1.10

396 Part 3 Classes of Materials

Table 3.1-252 Mechanical properties of Ir at different temperatures [1.217, p. 213]

T (

◦

C) E (GPa) R

(MPa) A (%) R

p0.2

(MPa) HV

20 538 623 6.8 234 200

500 488 530 9 12.7 234 138

800 456 450 18 51 142 112

1000 434 331 − 80.6 43.4 97

A = elongation of rupture, E = modul of elasticity, R

= limit of proportionality, HV = Vickers hardness, R

= tensile strength

Table 3.1-253 Change of hardness of Ir by degree cold

forming V (%) [1.217, p. 312]

V (%) HV

0 240

10 425

20 485

30 475

59 590

2000

1500

1000

500

500 2000

Temperature (°C)

1000 1500

0.2% flow stress (MPa)

Ir-Zr

Ir-Nb

CMSX-10

Ir-Ta

Ir-Hf

Mar-M247

Ni-Al-Cr

Ir-Ti

Ir-V

W alloy

Fig. 3.1-323 High-temperature compression strength of se-

lected Ir-based alloys [1.292, p. 159]

140

120

100

500 2000

Temperature (°C)

1000 1500

Specific strength (MPa g

-1

)

(Ir

0.75

0.25

)

(Ir

0.5

)

(Ir

0.25

0.75

)

Fig. 3.1-324 Speciﬁc strength of Ir

−

Nb alloys [1.293,

p. 78]

2000

1500

1000

500

500 2000

Temperature (°C)

1000 1500

0.2% flow stress (MPa)

Ir-13.5Nb-8Ni-2Al

W alloy

Nb-Si-Mo-W

Ir-15Nb-5Ni

Ir-17Nb

Ir-12Zr

CMSX-10

Fig. 3.1-325 Comparison of compressive strength of Ir

alloys versus W and Nb/Mo alloys at various tempera-

tures [1.293, p. 77]

Part 3 1.10

Metals 1.10 Noble Metals and Noble Metal Alloys 397

Table 3.1-254 Speciﬁc electrical resisitivity [ρ

(T ) = ρ

+ρ

(T )] of Ir at temperatures T (ρ

= 0.10 µΩ cm) [1.217,

p. 157]

T (K) 15 40 140 273 700 1100 1500

(T ) 0.0013 0.10 1.96 4.65 13.90 23.20 34.02

Electrical Properties. The residual resistance ratio

(RRR) amounts to 85 (Table 3.1-203). The speciﬁc

electrical resistivity at different temperatures and the

dependence of the atomic resistivity are given in Tables

3.1-254, and 3.1-255 [1.216]. The RRR is listed in

Table 3.1-203.

Iridium becomes superconducting below 0.11 K.

Some ternary alloys show critical transition tem-

peratures between3 K andabove8 K (Table 3.1-256)[1.218].

Thermoelectrical Properties. Data for the absolute ther-

moelectric power and the thermoelectric voltage of

Ir, and the thermoelectric voltage of Ir/Rh alloys are

shown in Tables 3.1-206–3.1-208, 3.1-257 [1.216] and

Fig. 3.1-326 [1.217].

Magnetic Properties. Iridium is paramagnetic. Figures

3.1-271, 3.1-327, 3.1-328 [1.216] showthe mass suscep-

tibility of Ir and Pt/Ir alloys at different temperatures.

Iridium exhibits magnetostriction according the equa-

tion ∆l/l = S

, with S

=+3.8 (Table 3.1-211).

Table 3.1-255 Increase of atomic resistivity [1.217, p. 158]

Base element ρ/C (µ cm/at.%)

Ir Pt 1.33, Re 2.7, Cr 2, Mo 3.65, W 3, Fe 0.6

Table 3.1-256 Superconducting Ir alloys [1.218, p. 636]

Compound

(K)

IrTe3 1.18

Sc5Ir4Si10 8.46–8.38

Y5Ir4Si10 3.0–2.3

Lu5Ir4Si10 3.76–3.72

Table 3.1-257 Thermoelectric voltage of Ir at different temperatures [1.216, p. 95]

T (

◦

C) −200 −100 −50 +100 +200 +400 +800

Ir,Pt

(mV) −0.20 −0.35 −0.20 0.66 1.525 3.636 9.246

0 2500

Temperature (°C)

500 1000 1500 2000

Thermoelectric voltage (mV)

WRe(97/3)WRe(75/25)

MoRe(95/5)

MoRe(59/41)

Mo-MoRe(59/41)

IrRh(60/40)Ir

Fig. 3.1-326 Thermoelectric voltage of Ir

−

Rh alloys com-

paredtoMo

−

Re and W

−

Re alloys [1.217, p. 474]

2.5

1.5

0 1800

T (K)

300 600 900 1200 1500

(10

–9

/ kg)

Fig. 3.1-327 Mass susceptibility of Ir at different tempera-

tures [1.217, p. 164]

Part 3 1.10

398 Part 3 Classes of Materials

0 300

T (K)

50 100 150 200 250

x = 0.6870

x = 0.5002

x = 0.3008

x = 0.1987

x = 0.0512

1-x

(10

–9

/kg)

Fig. 3.1-328 Mass susceptibility of Pt

−

Ir alloysat different

temperatures [1.217, p. 68]

Thermal Properties.

Tables 3.1-212–3.1-214 give se-

lected data for the recrystallization temperature (varying

by purity, degree of cold forming, and annealing

time), thermal conductivity, and thermal expansion

coefﬁcient.

Optical Properties. The optical reﬂectivity of Ir is

markedly lower than that of Rh increasing in the wave-

length range from 0.4to0.8 µm (Figs. 3.1-191 and

3.1-274). Data of the spectral emissivity are given in

Table 3.1-216.

Diffusion. Table 3.1-217 gives only one value for self

diffusion of iridium but further information may be

obtained from Landolt–Börnstein [1.238].

Chemical Properties. Iridium is not attacked by acids

or alkali even under oxidizing conditions (aqua re-

–30

–80

–130

–180

10 50

Time (h)

20 30 400

Ir sheet

IrCr5

IrNb4Ce

IrTi20

IrAl9

IrAl12

RuAl21

Weight change (mg cm

–2

)

Fig. 3.1-330 Oxidation behavior of various Ir alloys at

1000

◦

C in air [1.294, p. 100]

120

030

Time (h)

040

Time (h)

6121824

10 20 30

a) Weight loss (10

–2

mg cm

–2

)

b) Weight loss (mg cm

–2

)

(wt% Ir)

40%

30%

20%

10%

1300°C

1200°C

1100°C

1000°C

Fig. 3.1-329a,b Evaporation losses. (a) Pt loss in oxygen.

(b) Pt

−

Ir clad loss in oxygen at 900

◦

C [1.217, p. 184]

gia). It forms volatile oxides in air above 1000

◦

but it can be heated up to 2300

◦

C without danger

of catastrophic oxidation. Pt alloys with 1–30 wt% Ir

are corrosion-resistant against H

. Figures 3.1-329

and 3.1-330 [1.216, 294] show data of the evapora-

tion and oxidation behavior of Ir alloys. A detailed

survey on the chemical properties is given in [1.216,

294].

Part 3 1.10

Metals 1.10 Noble Metals and Noble Metal Alloys 399

520

Water concentration (% w/w)

10 15

Ir/Ru

Rh only

Carbonylation rate (mol dm

–3

–1

)

Fig. 3.1-331 Carbonylation rates for Ir

−

Ru and Rh cata-

lysts in methylacetat reactions [1.295, p. 100]

Metal-organic Ir compounds are effective homoge-

neous catalysts for organo-chemical reactions such as

hydrogenation and carbonylation. The technical produc-

tion of acetic acid (“Cativa” process). Figure 3.1-331

shows an example for different carbonylation rates of

Rh- and Ir/Ru-based catalysts [1.295]. Complex or-

ganic Ir catalysts have high stereoselectivity in hydrating

cyclic alcohols [1.216].

Ruthenium and Ruthenium Alloys

Applications. Ruthenium is a component of alloys

and compounds of chemical process catalysts, and Pt-

based catalysts for proton-exchange fuel cells (PEFC).

Because of its corrosion resistance, it is used for

corrosion-preventing anodes in shipping vessels and

under-water structures, pipelines, in geothermal indus-

tries, and as coating of electrodes in chlorine and caustic

soda production. Ruthenium oxide (RuO

)andcom-

plexBi/Ba/Pt oxides are materials for electrical resistors.

Ruthenium layers on computer hard discs are used for

high density data storage improvement of data-storage

densities. Ruthenium is an effective hardener of Pd and

Pt. Commercial grades available are sponge, powder,

grains, and pellets in purity ranging from 99–99.95%

(ASTM B 717).

Production. Production of ruthenium starts with chem-

ical reduction of chloro compounds to powder, followed

by compacting to pellets. Coatings are produced by

galvanic processing, evaporation or sputtering.

Phases and Phase Equilibria. Selected phase diagrams

are shown in Figs. 3.1-332 – 3.1-334, thermodynamic

data are listed in Table 3.1-258, and molar heat capaci-

ties can be found in Table 3.1-190. Ruthenium alloyed

980

960

940

920

900

880

Ruthenium (wt %)

2600

2400

2200

2000

1800

1600

1400

1200

1000

Ru (at. %)

0.5 1 1.5 2 2.5 3 3.5 4 4.5

Ag 10 20 30 40 50 60 70 80 90

8070605040302010

4321

a) Temperature (°C)

Ruthenium (at. %)

b) T (K)

Ru (wt %)

(Ag) + ?

(Ag)

2.9

L + ?

+ L

920°C

962°C

Two liquids

Ag–Ru

1243 K

1193 K

(?)

1235 K

(2553 K)

Fig. 3.1-332a,b Phase diagram of Ag

−

Ru (a) and phase di-

agram of Ag

−

Ru in the high-temperature range

(b) [1.217,

245]

2400

2200

2000

1800

1600

1400

1200

1000

800

600

Ruthenium (wt %) Ru

100

10 20 30 40 50 60 70 80 90

100

10 20 30 40 50 60 70 80 90

Temperature (°C) Ruthenium (at. %)

2334°C

1583°C

(Pd)

~16.5

~82

(Ru)

1555°C

Fig. 3.1-333 Phase diagram of Pd/Ru [1.217]

Part 3 1.10

400 Part 3 Classes of Materials

Table 3.1-258 Thermodynamic data of Ru [1.217, p. 110]

T (K) c

(J/K mol) S (J/K mol) H (J/mol) G (J/mol) p (at)

298.15 23.705 28.535 0 −8.508

400 24.345 35.595 2.449 −11.79 1.50 × 10

−77

800 26.516 53.121 12.611 −29.885 4.83 × 10

−35

1400 30.97 69.01 29.77 −66.844 7.73 ×10

−17

T = Temperature, c

= speciﬁc heat capacity, S = Entropy, H = Enthalpy, G = free Enthalpy,

p = partial pressure of the pure elements

2800

2600

2400

2200

2000

1800

1600

1400

1200

Ru(at. %)

10 20 30 40 50 60 70 80 90

10 20 30 40 50 60 70 90

T(K) Ru(wt %)

2607 K

(Pt)

2042 K

Pt–Ru

(Ru)

Fig. 3.1-334 Phase diagram of Pt/Ru [1.245]

to Fe lowers the γ –α transition temperature consider-

ably (Fig. 3.1-343). Table 3.1-259 gives the structure

and lattice parameters of intermediate Co and Fe com-

Table 3.1-259 Structure and lattice parameter of intermediate compounds [1.217, p. 117ff.]

Phase Pearson symbol a (nm) b (nm) c (nm) Concentration x A(1 −x)B(x)

−

Ru hP2 0.261 0.4181 0.5

−

Ru cF4 0.3592 0.2

−

Ru cI2 0.2883 0.06

−

Ru hP2 0.258 0.414 0.2

−

Ru hP2 0.27193 0.4394 0.5

Table 3.1-260 Mechanical properties of Ru at different temperatures [1.217, p. 229], [1.216, p. 31]

◦

C) R

(MPa) A (%) R

p0.2

(MPa) HV

20 500 3 380 250–500

750 300 15 230 160–280

1000 220 (430) 14 190 100–200

at different crystal planes,

at 600

◦

A = Elongation of rupture, R

= Limit of proportionality,

HV = Vickers hardness, R

= Tensile strength

Table 3.1-261 Hardness (HV 5) of Pd/Ru and Pt/Ru alloys

at 300 K [1.217, p. 230]

Alloying HV 5

metal

alloy conc. (wt%)

0 20 40 60 80

Pd 350 412 425 284 243

Pt 350 330 446 293 253

pounds. The superlattice structures can be found in

Table 3.1-197.

Mechanical Properties. Ruthenium has a Young’s mod-

ulus of 485 GPa, the Poisson’s ratio amounts to 0.29,

and the modulus of rigidity is 172 GPa. Character-

isitic properties of Ru are given in Tables 3.1-260

and 3.1-261. The mechanical properties are marked

anisotropic. The hardness of different single crystal

faces varies between 100 HV and 250HV [1.216]. High

compression-strength alloys are formed by two-phase

−

Al intermetallic structures. Figure 3.1-335 gives

Part 3 1.10

Metals 1.10 Noble Metals and Noble Metal Alloys 401

1400

1200

1000

800

600

400

200

200 1400

Temperature (°C)

400 600 800 1000 1200

0.2% Proof stress (MPa)

RuAl

Ru–RuAl(RHIP)

Ru–RuAl (melt)

Fig. 3.1-335 High-temperature compression strength of

eutectic Ru-70/Al-30 in relation to its constituent

phases [1.288, p. 164]

an example of molten and hot isostatic-pressed eu-

tectic Ru (Ru-70/Al-30) in relation to the constituent

phases [1.296].

Electrical Properties. The residual resistance ratio

(RRR) amounts to 25 000 (Table 3.1-203). Character-

istic electrical properties of Ru are given in Tables

3.1-203, 3.1-262, and 3.1-263. The speciﬁc electri-

cal resistivity of RuO

is 3.5×10

−5

Ω cm (1 Ω cm for

PdO for comparison). Together with its low tempera-

ture dependence of the coefﬁcient of resistance, Ru

is suited for the production of resistors in sintered

form or as thick-ﬁlm layers covering resistors ranging

from ≈ 1.5to10 MΩ. Conductive components are either

RuO

,Pb

,orBi

together with additions

of doping oxides [1.218].

Ruthenium shows superconductivity below 0.47 K

[1.218]. Ternary alloys have critical transition tempera-

tures up to 12.7 K (Table 3.1-264).

Thermoelectric Properties. Data of thermoelectric

properties of Ru are given in Tables 3.1-206 and

3.1-265.

Table 3.1-262 Speciﬁc electrical resisti vity ρ

(T ) (µΩ cm) of Ru at different temperatures (ρ

= 0.016 µΩ cm) ρ(T ) =

+ρ

(T ) [1.217, p. 156]

T (K) 25 50 100 200 273 300 500

(T ) 0.005 0.105 1.25 4.38 6.69 7.43 13.2

Table 3.1-265 Thermal electromotive force of Ru at different temperatures [1.217, p. 159]

T (

◦

C) +100 +200 +300 +500 +800 +1000 +1200

Ru/Pt

0.684 1.600 2.673 5.119 9.519 13.003 16.864

Magnetic Properties. Figures 3.1-271, 3.1-337, and

3.1-336 present data of the magnetic mass susceptibility

of Ru and of Ru/Cr alloy at different temperatures.

Table 3.1-263 Increase of atomic resisitivity by alloying

(∆ρ/C (µΩ cm/at.%)) [1.217, p. 158]

Base element ρ/C (µ cm/at.%)

Ru Fe 0.21, Re 2, Y 1.5

Os Y10

Table 3.1-264 Critical transition temperature of supercon-

ducting Ru alloys [1.218, p. 636]

Composit T

(K)

TiRuP 1.33

ZrRuP 12.34–10.56

HrRuP 12.70–11.08

TiRuAs >0.35

ZrRuAs 11.90–1.03

HfRuAs 4.93–4.37

Y3Ru4Ge13 1.7–1.4

Lu3Ru4Ge13 2.3–2.2

0 100

Ru (at.%) Ru

20 40 60 80

(10

–9

–1

)

Ru–Cr

Fig. 3.1-336 Temperature dependence of the mass suscep-

tibility of Ru/Cr alloy [1.217, p. 166]

Part 3 1.10