> > >Ceramics in Asia

98 Vol. 56 (2007) [2]

Synthesis, Properties and Applications of Cordierite Ceramics, Part 2A. Chowdhury, S. Maitra, H.S. Das, A. Sen, G.K. Samanta, P. Datta

5 Applications of cordierite ceramics

Cordierite is widely used in various fields of ce-

ramics. Its traditional applications are as fol-

lows:

• Refractory products ➝ saggars, kiln furniture

(widely popular in whiteware industries), gas

burners, etc.

• Electro-ceramics ➝ resistors, fusibles, flame

guards, etc.

• Tablewares ➝ Flameproof application devel-

opments in fast-firing techniques which allow

wide temperature variations during the cool-

ing cycle have renewed interest in this type of

body.

• Cordierite is common as a refractory filler. Re-

fractory fillers are frequently blended with

powdered solder glass to increase the strength

Anirban Chowdhury is apost-graduate research stu-dent working in the area ofsol gel ferroelectrics for hisPhD at the Institute for Ma-terials Research, University

of Leeds, UK. He earned his BTech in Ceramicsfrom the College of Ceramic Technology, Uni-versity of Calcutta and MTech in Materials Sci-ence from IIT Kanpur. He received the presti-gious ORS award and a Tetley & Lupton Schol-arship for 2005–2008.

AbstractAs an engineering material, cordierite has manyapplications in different fields exploiting itsunique electrical, mechanical and thermal prop-erties. The synthetic aspect of cordierite is ofconstant interest to researchers. Elucidation ofits structure and establishing the properties ofits structure has always been considered a fas-cinating subject by researchers. In the presentpaper these different aspects of cordierite arebriefly reviewed.

Keywords:

Cordierite, processing, properties, applications

Interceram 56 (2007) [2]

of the finished seal and/or to lower the ther-

mal contraction coefficient of the composite.

• The MgO–Al2O3–SiO2 system is a very popu-

lar one for glass-ceramics where cordierite is

the dominant phase along with clinoenstatite

(MgO-SiO2). These materials are character-

ized by higher temperature stability under load

than lithium aluminosilicates together with

good thermal and mechanical shock resist-

ance. Their low permittivity and high resistiv-

ity lead to a broad range of applications, e.g.

microwave component materials, radomes, etc.

• A very recent application for cordierite is in

making thick films.

5.1 Applications in kilns and furnaces Cordierite is extensively used as a material for

kiln furniture in whiteware industries due to its

excellent thermal shock resistance. Mohr [44]

worked on the development of cordierite kiln

furniture, focusing on parameters such as the

effect of grog addition (low expansion grog, like

fused silica, can be used in special cases; gener-

ally, grogs with thermal expansion larger than

cordierite are preferred), the effects of time and

temperature, and the development of slag re-

sistance (good grades of kyanite and kaolin, cal-

cined to 1580–1600 °C provide excellent grogs

for commercial cordierites).

5.2 Cordierite-mullite composites A major field of application for cordierite lies in

the production of composites and fibre strength-

ening. Different attempts have been made to de-

velop cordierite-mullite composites with good

thermal shock resistance as well as high me-

chanical strength.Camerucci et al. [45] prepared

cordierite and cordierite-mullite ceramics by

the slip casting method. The rheological behav-

iour of the slip became Newtonian when the sol-

id content was reduced to 60 mass-% and a plas-

ticizer was added. This led to higher green den-

sities (~63 %) of the body. Different firing cy-

cles were tested to improve the sintered density,

which ultimately reached values between 96.5

and 97.5 % of the theoretical density. In all cas-

es,both the green and the sintered densities were

significantly higher than those obtained by ax-

ial pressing.Yu et al. [46] studied the influence

of different silica fume contents on the struc-

ture and properties of mullite-cordierite com-

posites. The cordierite content increases while

mullite decreases with increasing silica fume

contents. The optimum formulation is as fol-

lows: cordierite - 66.3 %, mullite - 33.7 % and

bulk density - 2.69 g/cm3. Hipedinger et al. [47]

developed a cold-setting refractory material us-

ing the magnesia-phosphate reaction.A cement

paste based on alumina, silica fume, magnesia

and orthophosphoric acid was designed to form

cordierite-mullite during heating. This cement

paste set at room temperature and

MgHPO4·3H2O (newberyite) phase was ob-

served.

5.3 Other composites of cordierite Taruta et al. [48] fabricated a machinable

cordierite-mica composite by low temperature

sintering. 40 mass-% mica-composition glass

powder was mixed with conventional magne-

sia, alumina and silica powders (raw materials

of cordierite) and then compacted and fired in

a sealed Pt container. Mica crystallized at about

730 °C, cordierite was suddenly formed at

1050–1100 °C, and densification was achieved

at 1000–1100 °C. The formation and sintering

of cordierite were promoted by a small amount

of fluorine gas or fluorides (AlF3) which evap-

orated from the glass at >800 °C, and HF gas

was formed by reaction of the fluorine with the

water evaporated from the glass. Machinability

was achieved by the interlocking microstruc-

ture of mica developed in the composite. Shi et

al. [49] prepared cordierite-ceria composite ce-

ramics with oxygen storage capacity. Oxygen

storage capacity (OSC) is an important param-

eter in three-way catalysts (TWC) for the pu-

rification of exhausts from automotive gasoline

engines. The authors prepared the composite

using the sol-gel method so as to append the

OSC to the support to which the catalyst is ap-

plied. CeO2 particles are uniformly and sepa-

rately distributed in the cordierite matrix, their

number and granularity being dependent on

the amount of Ce4+ addition. The cordierite and

10 mass-% CeO2 possess an apparent OSC, ap-

Ceramics in Asia

100 Vol. 56 (2007) [2]

propriate porosity, flexural strength and ther-

mal expansion coefficient. It will be helpful to

enhance the OSC of the catalytic converters and

so improve the purification effects for the ex-

hausts. Ma et al. [50] fabricated AlN-cordierite

composites using different AlN contents and in-

vestigated the effect of AlN content on the me-

chanical, thermal and dielectric properties of

these materials. It was observed that there ex-

ists an optimum AlN content for the mechani-

cal and thermal properties while the dielectric

property decreases with an increase in AlN con-

tent. Kaya et al. [51] fabricated stainless steel

(316L) fibre-reinforced cordierite-matrix com-

posites of tubular shape using electrophoretic

deposition and pressureless sintering. The sin-

tered composites, which had an internal and ex-

ternal deposit thickness of ~1 mm, were free of

surface cracks when a deposition time of 2.5 min

was used.Metal-fibre-reinforced cordierite com-

posites such as those developed here may con-

stitute a promising alternative for manufactur-

ing damage-tolerant tubular components for

applications at temperatures up to ~900 °C.Shyu

and Wang [52] studied the relationship of the

amount and viscosity of glass with the sintered

densities of cordierite-borosilicate glass com-

posites. The dielectric constant of these com-

posites was in the range of 4.9–5.7 at 1 MHz.

Sonje et al. [53] incorporated cordierite as a low

coefficient of thermal expansion (CTE) ceram-

ic particulate filler into different epoxy resins to

produce an isotropic low CTE polymeric com-

posite material for electronic circuit board ap-

plications. The dependence of the CTE values

on the properties of the epoxy resins, the nature

of interfacial bonding and the dispersion of the

fillers in the resin matrix were also studied.

5.4 Cordierite coatings Weaver et al. [54] studied the role of bulk nu-

cleation in the formation of crystalline cordierite

coatings produced by air plasma spraying.

Cordierite glasses doped with 6.3, 8.3 and 10.1

mass-% TiO2 were plasma sprayed onto SiO2-

based refractory concrete substrates. Only the

cordierite powders containing 8.3 and 10.1

mass-% TiO2 produced crystalline coatings. For

compositions with less than 8 mass-% TiO2 the

crystallization is believed to be controlled by

surface nucleation at imperfections. Bulk nu-

cleation-controlled crystallization was observed

at compositions above 8 mass-% TiO2 and the

presence of Al2TiO5 was detected in these com-

positions. Ferraris et al. [55] synthesized

cordierite-mullite coating to be applied on

SiCf/SiC composites. The composites were coat-

ed by a simple and low cost slurry technique and

heat treated at 1180 °C for 1 h in order to obtain

a uniform, pore-free and crystalline coating

through the glass-ceramic method. The melt-

ing point of the crystalline phases formed in the

coating during the coating process (cordierite,

2MgO-2Al2O3-5SiO2 and mullite, 3Al2O3-2SiO2

rate of 3 : 1 mass-%) was measured at about

1430 °C. Perham et al. [56] also worked in a

somewhat similar direction as they developed

a method for the joining of SiC substrates us-

ing a cordierite glass-ceramic which, being

amorphous, melts the SiC substrates to form a

strong bond when rapidly fired. Doping with a

fluoride ion flux can lower the peak processing

temperature without significantly altering the

crystallizing path.High strength can be achieved

through this process (σF >500 MPa).

5.5 Cordierite thick films A more recent but highly promising application

of cordierite is the synthesis of cordierite thick

films. Mei et al. [57] prepared thick films of

cordierite-based glass ceramics by aqueous tape

casting from suspensions containing

cordierite/glass mass-% of 70/30 to 30/70. The

suspensions with 50–60 mass-% glass showed

the lowest viscosity values, while the green tape

containing 30 mass-% glass showed a homoge-

neous microstructure at both the top and bot-

tom surfaces. The green densities increased with

the glass content. The sintered tapes (1150 °C,

2 h) containing 50–60 mass-% glass showed the

lowest values for the dielectric constant (simi-

lar to 5.2) and dielectric loss (similar to 0.002)

at 1 MHz. Cho et al. [58] developed a cordierite

based thick film on an oxidized copper layer

where the authors found evidence of copper dif-

fusion as it was incorporated into the cordierite

and the remaining Cu was precipitated, which

ultimately lowered the densification and crys-

tallization temperature. The authors also stud-

ied the microstructure, crystallization kinetics

and properties of nonstoichiometric cordierite

(2.4 MgO, 2Al2O3, 5SiO2, containing 3 mass-%

P2O5 and 3 mass-% PbO) based thick film di-

electrics. A stable glass ceramic thick film mi-

crostructure that was formed in a 96 % alumi-

na substrate was observed after firing at a tem-

perature of 915 °C for 30 min in nitrogen at-

mosphere. The activation energy for

crystallization of the thick film was determined

to be ~83 kcal/mol (~350 kJ/mol). In the case

of the 3 mass-% PbO sample fired in a nitrogen

atmosphere at 950 °C for 30 min, the remaining

glass was estimated using the parallel mixing

rule, to have a dielectric constant of 15.3 at

1 MHz. The estimated coefficient of thermal ex-

pansion of the remaining glass for the 3 mass-%

PbO sample was 19 � 10–6 / K.

5.6 Cordierite filters Cordierite has been successfully tried in a num-

ber of industrial day-to-day applica-tions. Ne-

gro et al. [59] studied the mechanical behaviour

of cordierite ceramic filters for automotive emis-

sion control in a fired condition after thermal

shock and thermal ageing. Park et al. [60] inves-

tigated the feasibility of porous cordierite in

foam type structures such as filters for dust col-

lection.Various shaped porous cordierites with

different pore sizes and with constant porosity

of 80 % were prepared by the conventional me-

chanical foaming method combined with gel

casting using water-soluble polymers. Gas per-

meability of the membrane layers of 150 µm was

above 200 � 10–13 m2. In the dust collection

test, the removal efficiency for particulates fin-

er than 10 µm was above 99.99 %. Montanaro

[61] studied the interactions of sodium sulphite,

iron oxide and cerium oxide from fuel additives

with a cordierite monolith filter in the operat-

ing temperature range of a diesel soot filter. He

concluded that the said oxides do not react sig-

nificantly with the filter, but sodium sulphite

leads to a diffuse etching starting from low op-

erating temperatures. However, the total poros-

ity and pore size distribution were not affected

by these interactions. Park et al. [62] developed

a new trap to reduce the particulate matter emis-

sion from diesel engines and to control the com-

bustion rate of the particulate matter filtered in

the trap. Cordierite is a major component of the

trap as it is susceptible to thermal shock.

5.7 Cordierite substratesReznik et al. [63] utilized cordierite as substrate

material and produced pyrolytic carbon de-

posits by the CVD technique on a planar

cordierite substrate using methane as a source

gas. The surface morphology was characterized

by a cell structure induced by grains elongated

perpendicular to the substrate surface. The ma-

terial located at the interface was more amor-

phous compared to the graphite-like materials

101Vol. 56 (2007) [2]

> > >

located within the cells. Chen et al. [64] studied

the potential of burying inductors in multilay-

er ceramic substrates by inserting a ferrite lay-

er into a low-temperature cofired cordierite sub-

strate. Bi2O3 was doped to lower the sintering

temperature and increase the permeability of

Ni-Zn-Cu ferrite. Sohn et al. [65] investigated

the suitability of glass-ceramics containing

cordierite as a crystal phase for application to

magnetic disk substrates to achieve higher stor-

age capacity. Parent glasses were prepared with

a CeO2 addition as flux, and α-cordierite was

precipitated after heat treatment. The optimum

properties for the magnetic memory disk sub-

strates are as follows: Bending strength - 192 MPa,

Vickers hardness - 642.1 kg/mm., CTE -

39 � 10–7 / K, and surface roughness - 2.7 nm.

5.8 Cordierite supports Recent advances have been made in research on

cordierite monolithic catalyst supports, partic-

ularly on honeycombs and ceramic foams. Car-

ty and Lednor [66] reported that honeycombs

are used as catalyst supports for the removal of

gaseous or particulate emissions from combus-

tion engines and for reducing nitrogen oxide

emissions from power plants. They also noted

that ceramic foams are attracting attention as

catalyst supports due to their high thermal sta-

bility, high porosity and increased tortuosity

with respect to honeycombs.Yamuna et al. [67]

prepared honeycomb and pellet type carriers

from kaolin-based cordierite composition, and

their efficiency in pollution monitoring was

studied in two-stroke vehicles. The convention-

ally prepared kaolin based cordierite system re-

moved 78 % of the CO and 82 % of the hydro-

carbons from the exhaust gases under idling

conditions. Cordierite honeycombs are used as

catalyst supports and must be coated with

porous alumina to increase their specific sur-

face area. Hua et al. [68] tried to prepare porous

alumina with a large surface area on the inter-

nal surface of cordierite honeycombs through

in-situ and dip-coating methods of loading

γ-Al2O3 prior to its hydrolysis during the prepa-

ration of alumina sol. Seijger et al. [69] studied

the in situ synthesis of binderless ferrierite coat-

ings on 300 si cordierite honeycomb supports.

The silica-to-alumina ratio of the synthesis mix-

ture and the development of the ferrierite coat-

ing as a function of time were also investigated.

Schneider et al. [70] studied the catalytic behav-

iour of perovskite (LaMnO3, LaCoO3, etc.)

supported on cordierite monoliths in the total

oxidation of chlorinated hydrocarbons. In the

case of monolith supported LaCoO3 perovskite,

an irreversible catalyst deactivation was ob-

served. Orlandi et al. [71] investigated the bio-

compatibility of two cordierite ceramics (DF

and Cord 1014) with similar chemical compo-

sition and different porosity, as a potential sup-

port for cell growth in a continuous-flow, sol-

id-bed reactor. They concluded that Cord 1014

could be a promising support for growing CHO

(Chinese hamster ovary) cells in great numbers

and producing recombinant hepatitis B surface

antigens.

5.9 Optical applications Park and Shin [72] prepared glass-ceramics con-

taining cordierite and a small amount of rutile

as the major crystalline phases for application

as IR reflectors. Nucleation occurred at 750 °C

for 3 h and crystal growth at 1100 °C for 5 h.

This material showed over 90 % reflectance in

the spectral range of 570 to 2500 nm.

5.10 Electrical and electronic applications Cordierite electric ceramics have an important

role in modern technology.They have been used

in electrothermics for the production of elec-

tric heater supports. Nowadays, due to its elec-

trical, electromechanical and thermal proper-

ties, this ceramic finds its applications in elec-

tronics for the production of microelectronic

components and in the machine-building in-

dustry for the manufacture of internal combus-

tion components.Acimovic et al. [73] prepared

cordierite ceramics based on sepiolite and ex-

amined their applications in foundries, defin-

ing the technological parameters for the pro-

duction of refractory coatings for sand moulds

and cores, and of refractory linings for use in

the lost loam process. Ting et al. [74] studied the

interactions between ruthenia-based resistors

and cordierite-glass substrates in low-temper-

ature co-fired ceramics which are composed of

a RuO2-based resistor and a cordierite-glass

substrate that are sintered at temperatures of

850 °C and 900 °C. X-ray diffractometry re-

vealed that the lead ruthenate pyrochlore

(Pb2Ru2O6.5) in peak-fired thick-film resistors

(TFR) disappears and the co-fired samples con-

tain only RuO2 in the resistor film when sintered

at 900 °C. The overall resistance of the LTCC re-

sistors is increased by a factor of ~3 when the

temperature is raised from 850 to 900 °C. The

increase in the resistance of the LTCC resistors

is attributed to the interruption of the conduc-

tion path by platelike anorthite crystals that are

produced in the resistor-substrate interface dur-

ing co-firing.

5.11 Electrochemical applications Domenech-Carbo et al. [75] studied the elec-

trochemistry of α-, β-, and µ-cobalt containing

cordierites (Co2Al4Si5O18) attached to paraffin-

impregnated graphite electrodes by linear scan

and cyclic voltametries in HCl + NaCl and

NaOH electrolytes. Cordierite-modified elec-

trodes display a significant site-dependent cat-

alytic effect on the electrochemical oxidation of

mannitol in 0.1 (M) NaOH.

5.12 Electromagnetic applications Wang et al. [76] synthesized cordierite by sol-

gel processing with the aim of using it as MLCI

material. It has a low dielectric coefficient (3.5)

at high frequency (1.8 GHz). The sintering tem-

perature decreased with increasing Bi2O3 and

B2O3 additions. Luo et al. [77] also synthesized

a sol-gel derived cordierite ceramic that had a

low dielectric constant and a low dissipation fac-

tor and could be co-fired with highly conduc-

tive metals such as Au,Ag, Pd, and Cu paste be-

low 1000 °C, suggesting that it would be a prom-

ising material for high frequency MLCIs.Wang

et al. [78] developed cordierite-based ceramics

by sintering at 950 °C a glass selected from the

MgO–Al2O3–SiO2 system with a small amount

of B2O3 and P2O5 with the aim of using the ma-

terial in high frequency chip inductors. Crys-

talline phases in this sintered sample are most-

ly α-cordierite (hexagonal high cordierite) with

trace amounts of µ-cordierite. It achieved 99 %

of theoretical density, a dielectric constant of

5.5, a dielectric loss of 0.001 and a thermal ex-

pansion coefficient of 26.7 � 10–7/K. It has a

uniformly dense microstructure with granular

crystals.Yue et al. [79] prepared a series of nov-

el composites of NiCuZn ferrite and cordierite

crystallites by sintering the mixtures of nano-

sized NiCuZn ferrite particles and MgO-Al2O3-

SiO2 glass powder to be used for MLCIs. These

composite materials have tuneable electromag-

netic properties with high resonance frequen-

cies. In another work, Yue et al. [80] fabricated

ferrite-glass-cordierite nanocomposites by mix-

ing and sintering NiCuZn ferrite nanopowder

and MgO-Al2O3-SiO2 gel powder prepared by

Ceramics in Asia

102 Vol. 56 (2007) [2]

��the sol-gel process. The composites have tune-

able electric and magnetic properties with res-

onant frequencies higher than 2 GHz.

In addition to the traditional application of

cordierite in kiln furniture, its use as compos-

ite material has been discussed. Among these,

ceria-cordierite composites show an oxygen

storage capacity (OSC), which is helpful for en-

hancing the efficiency of catalytic converters in

automobile engines. The application of crys-

talline cordierite as a coating and joining mate-

rial between two SiC substrates has a promis-

ing future. Cordierite material proved effective

in the filtration of the automotive emissions, es-

pecially in a foam structure. The potential use

of ceramic substrates in capacitor and magnet-

ic disks for higher memory storage capacity has

been discussed.Honeycomb and pellet type car-

riers from kaolin-based cordierite composition

and their efficiency in pollution monitoring have

been described for two-stroke vehicles.The con-

ventionally prepared kaolin based cordierite

system removes 78 % of CO and 82 % of hydro-

carbons under idling conditions. The catalytic

behaviour of perovskite (LaMnO3,LaCoO3,etc.)

supported on cordierite monoliths in the total

oxidation of chlorinated hydrocarbons has al-

so been discussed in this paper. It was shown

that the biocompatibility of two cordierite ce-

ramics could be a promising support for grow-

ing CHO (Chinese hamster ovary) cells in great

numbers and producing recombinant hepatitis

B surface antigens. Cordierite ceramics can al-

so be used in optical applications such as IR re-

flectors with glass-ceramics containing

cordierite and a small amount of rutile as the

main crystalline phases. Nowadays, this ceram-

ic finds its applications in electronics for the pro-

duction of microelectronic components and in

the machine-building industry for the manu-

facture of internal combustion components.The

use of cordierite materials in electrochemical

applications and in electromagnetic applica-

tions in MLCIs and high frequency chip induc-

tors has gained increased importance in recent

years.

6 Summary and conclusion

Cordierite can be synthesized both by conven-

tional techniques using solid state reaction, em-

ploying relatively cheap raw materials, and by

using solution techniques using synthetic ma-

terials such as different organic and inorganic

salts. Some novel synthesis techniques have al-

so been reported in this field. Different addi-

tives were observed to exert profound influences

on the synthesis techniques and the property

(particularly, mechanical and electrical) devel-

opment of cordierite ceramics.Apart from var-

ious traditional applications, several new appli-

cations of cordierite either in the single state or

in the form of composites, exploiting its differ-

ent advantageous properties, have been report-

ed. More research is required to improve upon

its properties and to explore its newer applica-

tions.

References[43] Wu, J.-M., Hwang, S.-P.: J.Amer. Ceram. Soc. 83

(2000) [5] 1259–1265

[44] Mohr,W.C.: Ceramic Bulletin 56 (1976) 428–430

[45] Camerucci, M.A., Cavalieri,A.L., Moreno, R.: J.

Europ. Ceram. Soc. 18 (1998) [14] 2149–2157

[46] Yu, Y., Ruan, Y.Z., Zhou, Q.Q., Du, Y.H., Wu,

W.G., Lin, C.-Y.: Chinese J. of Structural Chem-

istry 22 (2003) [2] 215–220

[47] Hipedinger, N.E., Scian,A.N.,Aglietti, E.F.: Ce-

ment and Concrete Research 32 (2002) [5]

675–682

[48] Taruta, S., Hayashi, T., Kitajima, K.: J. Europ. Ce-

ram. Soc. 24 (2004) [10–11] 3149–3154

[49] Shi, Z.M., Liu, Y., Yang, W.Y., Liang, K.M., Pan,

F., Gu, S.R.: J. Europ. Ceram. Soc. 22 (2002) [8]

1251–1256

[50] Ma, J., Liao, K., Hing, P.: J. Mater. Sci. 35 (2000)

[16] 4137–4141

[51] Kaya, C., Kaya, F., Boccaccini,A.R.: J.Amer. Ce-

ram. Soc. 85 (2002) [10] 2575–2577

[52] Shyu, J.J.,Wang, J.K.: J. Mater. Res. 15 (2000) [8]

1759–1765

[53] Sonje, P.U., Subramanian, K.N., Lee,A.: J. of Ad-

vanced Materials 36 (2004) [1] 22–29

[54] Weaver, D.T., Van Aken, D.C., Smith, J.D.: J.

Mater. Sci. 39 (2004) [1] 51-59

[55] Ferraris, M., Salvo, M., Smeacetto, F.: J. Europ.

Ceram. Soc. 22 [13] 2343–2347

[56] Perham, T.J., De Jonghe, L.C., MoberlyChan,

W.J.: J.Amer. Ceram. Soc. 82 (1999) [2] 297–305

[57] Mei, S., Yang, J., Ferreira, J.M.F., Martins, R.:

Aqueous Tape Casting of low-k Cordierite Sub-

strate: The influence of Glass Gontent.Advanced

Materials Forum II Materials Science Forum

455-456 (2004) 168–171

[58] Cho, Y.S., Schulze, W.A., Amarakoon, V.R.W.,

Hoelzer, T.: J.Amer. Ceram. Soc. 82 (1999) [11]

3186–3192

[59] Negro, A., Montanaro, L., Demaestri, P.P., Gi-

achello,A., Bachiorrini,A.: J. Europ. Ceram. Soc.

12 (1993) [6] 493–498

[60] Park, J.K., Lee. J.S., Lee, S.I.: Journal of Porous

Materials 9 (2002) [3] 203–210

[61] Montanaro,L.: Ceramics International 25 (1999)

[5] 437–445

[62] Park, D.S., Kim, J.U., Kim, E.S.: Combustion and

Flame 114 (1998) [3–4] 585–590

[63] Reznik, B., Fotouhi, M., Gerthsen, D.: Carbon

42 (2004) [7] 1311–1313

[64] Chen, L.S., His, C.S., Fu, S.L., Lin, J.Y.: Japanese

J. of Applied Physics Part I – Regular Papers

Short Notes and Review Papers 39 (2000) [1]

150–154

[65] Sohn, S.B., Choi, S.Y., Lee,Y.K.: J. Mater. Sci. 35

(2000) [19] 4815–4821

[66] Carty,W.M., Lednor, P.W.: Current Opinion in

Solid State and Materials Science 1 (1996) [1]

88–95

[67] Yamuna, A., Johnson, R., Mahajan, Y.R.,

Lalithambika, M.: J. Europ. Ceram. Soc. 24

(2004) [1] 65–73

[68] Hua, J.M., Cai, Y.L., Lin, X.Y., Zheng, Q., Wei,

K.M.: Chinese J. of Catalysis 24 (2003) [7]

513–519

[69] Seijger, G.B.F., van den Berg, A., Riva, R., Kr-

ishna, K., Calis, H.P.A., van Bekkum, H., van

den Bleek, C.M.: Applied Catalysis A – Gener-

al 236 (2002) [1–2] 187–203

[70] Schneider, R., Kiessling, D.,Wendt, G.: Applied

Catalysis B – Environmental 28 (2000) [3–4]

187–195

[71] Orlandi, L., Solmi, R., Krajewski,A., Bearzatto,

A., Biagini, G., Ciccopiedi, E., Ravaglioli,A.: Bio-

materials 18 (1997) [14] 955–961

[72] Park, K.H., Shin, D.W.: J. of Ceramic Process-

ing Research 3 (2002) [3] 153–158, Part 2

[73] Acimovic, Z., Pavlovic, L., Trumbulovic, L.,An-

dric, L., Stamatovic, M.: Materials Letters 57

(2003) [18] 2651–2656

[74] Ting, C.-J., His, C.-S., Lu, H.-Y.: J.Amer. Ceram.

Soc.Vol. 83 (2000) [12] 2945–2953

[75] Domenech-Carbo,A., Torres, F.J.,Alarcon, J.: J.

of Solid State Electrochemistry 8 (2004) [2]

127–137

[76] Wang, H.F., Zhou, H.P.,Wang, S.H., Ning, X.S.,

Chen, K.X.: Rare Metal Materials and Engineer-

ing 31 (2002) 376–379, Suppl. 1

[77] Luo, L.H., Zhou, H.P., Xu, C.: J. Mater. Sci. Ma-

terials in Electronics 13 (2002) [7] 381–386

[78] Wang, S.H., Zhou, H.P., Luo, L.H.: Mater. Res.

Bull. 38 (2003) [8] 1367–1374

[79] Yue, Z.X., Li, L.T., Zhou, J., Zhang, H.G., Ma,

Z.W., Gui, Z.L.: Materials Letters 44 (2000) [5]

279–283

[80] Yue, Z.X., Zhou, J., Zhang, H.G., Li, L.T., Gui,

Z.L.: J. of Inorganic Materials 14 (1999) [3]

375–379

Received: 16.03.2005