K. ZUPAN et al.: PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM PEROVSKITE MATERIALS ...
743–748
PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM
PEROVSKITE MATERIALS FOR SOFC ANODES PREPARED BY
THE CARBONATE-COPRECIPITATION METHOD
RAZVOJ KRISTALNIH FAZ IN MIKROSTRUKTURE LSCM
PEROVSKITNIH MATERIALOV ZA SOFC ANODE,
PRIPRAVLJENIH S KARBONATNO METODO KOPRECIPITACIJE
Klementina Zupan, Marjan Marin{ek, Tina Skalar
University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ve~na pot 113, 1000 Ljubljana, Slovenia
klementina.zupan@fkkt.uni-lj.si
Prejem rokopisa – received: 2015-07-21; sprejem za objavo – accepted for publication: 2015-10-09
doi:10.17222/mit.2015.232
Most SOFC development has been based on nickel yttria-stabilized zirconia anodes. Such materials have excellent catalytic
properties for fuel oxidation, high electrical conductivity, good mechanical strength and an appropriate thermal expansion coef-
ficient compatible with other cell components. Unfortunately, cermet anodes based on doped zirconia exhibit some disadvan-
tages, e.g., the catalysing side reaction of carbon deposition during hydro-carbon fuel oxidation and a susceptibility to sulphur
poisoning. Perovskite-type compounds based on lanthanum-strontium-manganese-chromium oxide (LSCM) can serve as an al-
ternative material. Since the optimal perovskite composition is still not known, La1–xSrxMnyCr1.yO3± (x from 0 to 0.3 and y from
0.4 to 0.6) ceramics were prepared with the co-precipitation method. Crystalline phase formation was followed by X-ray powder
diffraction and Rietveld refinement. Quantitative microstructure analysis of the samples sintered at various temperatures was
performed on SEM micrographs using Axiovision 4.8 software.
Keywords: co-precipitation, oxide LSCM anode, phase development, microstructure
Ve~ina razvoja visokotemperaturnih gorivnih celic je temeljila na anodnih materialih na osnovi niklja in cirkonijevega dioksida,
stabiliziranega z itrijem. Ta ima odli~ne katalitske lastnosti pri reakciji oksidacije goriva, visoko elektri~no prevodnost, dobro
mehansko trdnost in temperaturni razteznostni koeficient, skladen z ostalimi komponentami celice. @al so ti materiali med
delovanjem podvr`eni ne`elenim reakcijam izlo~anja ogljika in zastrupljanja z `veplom, zato jih posku{amo nadomestiti z
oksidnimi spojinami perovskitnega tipa, z lantan-stroncij-mangan-krom oksidom (LSCM). Optimalna sestava teh materialov {e
ni znana, zato smo z metodo soobarjanja pripravili keramiko La1–xSrxMnyCr1.yO3±  (x od 0 do 0,3 in y od 0,4 do 0,6). Z
rentgensko pra{kovno analizo in Rietveldovim prilagajanjem smo spremljali razvoj kristalnih faz. Z analizo SEM posnetkov
vzorcev po sintranju pri razli~nih temperaturah smo mikrostrukture pripravljenih materialov kvantitativno ovrednotili z uporabo
programa Axiovision 4.8.
Klju~ne besede: kopercipitacija, oksidna LSCM anoda, razvoj faz, mikrostruktura
1 INTRODUCTION
Fuel cells can be considered as devices that electro-
chemically convert fuels into electricity or, more pre-
cisely, batteries with permanent fuel supplies. Solid-ox-
ide fuel cells (SOFCs), based on an ion-conducting
electrolyte, have several advantages over other types of
fuel cells, including their potential fuel flexibility and
very high chemical-to-electrical conversion efficiency
due to the absence of Carnot limitations. Further energy
gains can be achieved in SOFC systems when cogene-
rated heat is used for the internal reforming of methane
or other hydrocarbon fuels directly on the anode.1
Porous Ni/YSZ-based materials are conventionally
used as SOFC anodes due to their high electrical conduc-
tivity, activity for electrode electro-chemical oxidation,
stability under reduced environmental conditions, appro-
priate thermal expansion and a chemical compatibility
with other cell components.2 Despite the many advan-
tages they possess, there are some drawbacks, such as a
low tolerance to sulphur impurities3 and a tendency to
coke when hydrocarbons are used as fuels4.
Alternative cermet anode materials have been
extensively studied, such as Cu-CeO2-YSZ. Researchers
have demonstrated their operation using various fuels.5,6
Recently, another alternative approach aiming to prepare
all-oxide anode materials has been proposed in order to
develop electrodes that exhibit catalytic, electron- and
ion-conducting properties. Many problems with all-oxide
anodes have been overcome with the introduction of
novel perovskite-structure materials with the general
formula ABO3–. The A element is typically lanthanide,
while the B element is the transition metal. In principle,
catalytic activity toward fuel oxidation, electron- and
ion-conductivity can be tailored by a wide range of
doping elements. The oxidation states of the A-site and
B-site cations determine the oxygen vacancy
concentration .2 Among various perovskites, a
particularly complex metal oxide with the composition
La0,75Sr0,25Mn0,5Cr0,5O3– has attracted much attention as a
Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748 743
UDK 67.017:661.8’02:621.3.032.22:537.533 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 50(5)743(2016)
promising anode material, due to its good catalytic activ-
ity, excellent redox stability, reduced carbon deposition
susceptibility and improved sulphur-poisoning stability.7
An introduction of alkaline earth ions, i.e., Mg2+, Ca2+,
and Sr2+, into the A site of lanthanum chromite can en-
hance the electrical conductivity by two orders of magni-
tude.7 L. Deleebeck et al.9 first demonstrated that the
removal of Sr from La1–xSrxMn1–yCryO3± improves the
thermo-chemical stability and the electronic conductivity
in a humidified H2 atmosphere. In their second study,
they reported that the catalytic activity toward H2 oxida-
tion decreases with increasing Cr content (y = 0.4–0.6),
while the relatively high Sr content (x = 0.2) shows a
lower catalytic activity.10 The optimal LSCM material
composition is not yet known.
Various chemical routes to prepare LSCM powders
have been reported, including the solid-state reaction,7
the chelating method,11 gel casting,12 and combustion
synthesis.13–16 However, the synthesis of single-phase
LSCM composed of fine powders requires a further im-
provement. Co-precipitation is a promising and simple
chemical method to prepare well-defined and less-ag-
glomerated perovskite powders. It was reported that the
most significant synthesis parameter for LSCM prepara-
tion via co-precipitation is the pH value of the reaction
mixture, which should be maintained slightly below 8 in
order to ensure that all the cations precipitate.17 In addi-
tion to an appropriate chemical composition of the
LSCM material, the electrode performance in an operat-
ing SOFC is also essentially dependent on the electrode
microstructure, final porosity and potential presence of
secondary phases.
In this work, we applied the "reverse strike" carbon-
ate co-precipitation method for batch
La1–xSrxMn1–yCryO3± perovskite preparation in which the
Sr content and the Cr-to-Mn molar ratio were varied. The
aim of this work is to describe the relationship between
the microstructure parameters and the LSCM composi-
tion using various analytical techniques.
2 EXPERIMENTAL PROCEDURE
La1–xSrxMn1–yCryO3± (x = 0, 0.1, 0.2 or 0.3 and y =
0.4, 0.5 or 0.6) oxides were prepared using co-precipita-
tion synthesis (Table 1). La(NO3)3⋅6H2O (99 %),
Sr(NO3)2 (98 %), Cr(NO3)3⋅9H2O (98.5 %) and
Mn(NO3)2⋅4H2O (98 %), all from Alfa Aesar, were used
as the source of metal ions. The carbonate precursors
were prepared using the "reverse strike" method in which
a mixed metal nitrate solution is added to a precipitant
carbonate solution to achieve a more uniform cation dis-
tribution by instantaneous precipitation. A total of
600 mL of 0.125-M aqueous solution of (NH4)2CO3 was
poured into a jacket glass reactor (1.25 L); 0.5-M metal
nitrates solutions were prepared, as were adequate vol-
umes of each LSCM component regarding the desired fi-
nal LSCM composition. The solutions were mixed to-
gether and dripped into a stirring precipitant solution.
The precipitating solution was kept at 60 °C under a CO2
protective atmosphere to prevent manganese oxidation
during synthesis. The pH inside the jacket glass reactor
was kept at 7.8±0.1 by the periodic addition of ammonia
(25 %, aq.). Afterwards, the precipitate was filtered off
under a CO2 environment and washed three times
(50 mL) with a 0.125-M solution of (NH4)2CO3, dried for
6 h at 110 °C and finally calcined at 1000 °C in an air at-
mosphere.
Table 1: Compositions and sample notations
Tabela 1: Sestave in poimenovanje vzorcev
Sample composition Sample name
La0,7Sr0,3Cr0,5Mn0,5O3–d La7Cr5
La0,8Sr0,2Cr0,5Mn0,5O3–d La8Cr5
La0,9Sr0,1Cr0,5Mn0,5O3–d La9Cr5
La1Cr0,5Mn0,5O3–d La10Cr5
LaCr0,6Mn0,4O3 La10Cr6
La0,9Sr0,1Cr0,6Mn0,4O3 La9Cr6
La0,9Sr0,1Cr0,4Mn0,6O3 La9Cr4
LaCr0,4Mn0,6O3 La10Cr4
The synthesized powders were milled in an agate
mortar and un-axially pressed into pellets (100 MPa) and
sintered at various temperatures (1250 °C, 1300 °C, 1400 °C
and 1500 °C) for 1 h. The calcined and sintered samples
were analysed with a PANalytical X’Pert PRO MPD
apparatus. For the determination of the microstructure,
the sintered tablets were polished (diamond pastes of 3
μm and 0.25 μm), thermally etched, and subsequently
analysed with a FE-Zeiss ULTRA Plus SEM. The
quantitative analyses of the microstructures were per-
formed on digital images (images were digitized into
pixels with 255 different grey values) using Axiovision
4.8 image-analysis software.
3 RESULTS AND DISCUSSION
The carbonate co-precipitation route is an appropriate
method for the preparation of complex metal oxides,
such as La1–xSrxMn1–yCryO3± (LSCM). When the "re-
versed strike" co-precipitation method is used and the
mixed solution of metal ions drips into the concentrated
precipitant solution, the various cations within each
droplet precipitate almost instaneously.18 Lanthanum car-
bonate precipitated at pH > 4.2, manganese carbonate at
pH > 5 and strontium carbonate at pH > 7.3. Chromium
precipitates as a hydroxide in a very narrow pH range
from 6.6 to 7.3; however, Cr(OH)3 starts to dissolve at a
pH value of 7.9.17 Therefore, the precipitation of mixed
metal oxide should be carried out carefully in the tiny pH
range from 7.3 and 7.9. If we take into account only sim-
ple carbonate and hydroxide species (Equations (1) to
(4)) for the calculation for the stoichiometric amount of
ammonium carbonate as a precipitant agent, we can con-
clude that an excess of 50 % is used during the precipita-
K. ZUPAN et al.: PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM PEROVSKITE MATERIALS ...
744 Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748
tion process. Thus, the super-saturation ratio in the case
of the LSCM synthesis calculated from the molar ratio of
ammonium carbonate and total metal ions is 1.5.
3(NH4)2CO3 + 2La
3+ 	 La2(CO3)3 + 6NH4
+ (1)
(NH4)2CO3 + Sr
2+ 	 SrCO3 + 2NH4
+ (2)
3(NH4)2CO3 + Cr
3+ + H2O 	 Cr(OH)3 + 6NH4
+ +
+ 3HCO3
– (3)
(NH4)2CO3 + Mn
2+ 	 MnCO3 + 2NH4
+ (4)
According to Figure 1, the perovskite LSCM phase
formation for all the samples is practically complete after
calcination at 1000 °C for 1 h (the perovskite peaks are
denoted with a letter "P"). The main perovskite phase is
quite well crystallised. In the sample La7Cr5, with the
highest Sr content and equal amounts of chromium and
manganese, the XRD analysis revealed a small amount
of strontium secondary phase SrCrO4 (denoted with the
letter "S"). It is described in the literature that in the hu-
midified hydrogen atmosphere SrCrO4 further transforms
into the Ruddlesden-Popper phase Sr2CrO4.9 Addi-
tionally, the X-ray powder diffraction indicates that in
samples with the lowest Cr content (0.4), a lanthanum-
rich secondary phase La2CrO6 is formed (denoted with
the letter "L"). Varying the Sr content in this Cr-poor
sample reveals that in the Sr-free and Sr = 0.1 samples
the La2CrO6 content determined according to the Riet-
veld refinement is 3.1 % and 7.6 %, respectively. Multi-
ple RTG peaks observed in some patterns are a conse-
quence of a perovskite lattice superstructure. This lattice
superstructure is formed due to the octahedron tilting,
which has its origin in the random Sr-incorporation into
the perovskite structure.19,20 By doping lanthanum-man-
ganite with Sr and Cr, the symmetry of the structure is
lowered due to the different sizes of the introduced cat-
ions compared to the original ions. Consequently, octa-
hedrons defined by a central cation (B-site cation) and
the surrounding oxygen ions are slightly tilted and the
repeating structure pattern is defined by eight original
unit cells.
The secondary phases are highly undesired in the fi-
nal LSCM since they result in the so-called layered
perovskite structure with additional layers of Sr-oxide,
La-oxide, or a mixture of both separating the LSCM at
temperatures around 1100 °C and in a H2 atmosphere.
Furthermore, the secondary phases decrease the thermo-
chemical stability, catalytic activity and electrical con-
ductivity of the LSCM.9,12
K. ZUPAN et al.: PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM PEROVSKITE MATERIALS ...
Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748 745
Figure 2: X-ray diffraction patterns of all samples after calcination at
1250 °C
Slika 2: Rentgenogram vseh vzorcev po kalcinaciji pri 1250 °C
Figure 1: X-ray diffraction patterns of prepared samples after calcina-
tion at 1000 °C
Slika 1: Rentgenogram pripravljenih vzorcev po kalcinaciji pri
1000 °C
Figure 3: SEM micrographs of all samples sintered at 1250 °C and
sample La9Cr6 sintered at 1250 °C, 1300 °C, 1400 °C and 1500 °C
Slika 3: SEM-posnetki vseh vzorcev po sintranju pri 1250 °C in vzor-
ca La9Cr6, sintranega pri 1250 °C, 1300 °C, 1400 °C in 1500 °C
After the sintering at 1250 °C, the only phase present
in all the samples is the LSCM perovskite, as shown in
Figure 2. The absence of secondary phases indicates that
they re-dissolve in the main LSCM phase when the
sintering temperature is increased. This discovery also
gives a very effective tool for controlling the amount of
secondary phases in LSCM or even eliminates them
completely. Due to the possibility of eliminating the sec-
ondary phases from the LSCM, it is reasonable to con-
clude that the co-precipitation method offers an essential
advantage over the synthesis processes that are based on
the solid-state reactions in which local inhomogeneity in
chemical composition are quite common.
One of the major challenges in applying LSCM mate-
rial as an anode in ceramic fuel cells is achieving the
continuity of the electrode material as well as the conti-
nuity of the pores. Good contact between the particles is
critical for forming continuous paths throughout the
formed anode, reaching a high conductivity. The sinter-
ing behaviour of all the samples after sintering at 1250 °C
is demonstrated in Figure 3. Since all the microstructure
parameters that are important for an exact anode analysis
are sometimes difficult to deduce simply from the SEM
micrographs, a detailed quantitative microstructure
analysis of sintered samples is performed. For statisti-
cally reliable data in each case, 5 to 10 different regions
were analyzed. The results of the quantitative micro-
structure analysis are summarized in Table 2. The
parameters d , dx, dy and 
 are represented as the diameter
of the area-analogue circle – Dcircle, the intercept lengths
in the x and y directions – FERETX, FERETY and the
Shape factor fcircle. Spore and FERETMAX are determined as
the pore areas and maximum intercept lengths of the
pore while rel and  are determined from the geometric
densities of the tablets and the theoretical densities that
were calculated using the Rietveld refinement.
SEM micrographs sintered at 1250 °C reveal that the
microstructure parameters greatly depend on the sample
composition. When comparing samples with equal
amounts of Cr and Mn with various Sr contents we can
observe that the presence of strontium promotes sinter-
ing. It is also evident that the grains are larger in samples
K. ZUPAN et al.: PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM PEROVSKITE MATERIALS ...
746 Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748
Table 2: Results of quantitative microstructure analysis of the sintered samples
Tabela 2: Rezultati kvantitativne analize mikrostrukture sintranih vzorcev
T/°C /% dy/μm dx/μm d/μm 
 Spore/μm2 FERETMAX/μm
teor /
g cm–3 rel /%
La10Cr5
1250 51.9 0.30 0.31 0.28 0.67 0.44 1.02
6.71
48.1
1300 50.9 0.43 0.44 0.41 0.74 0.86 1.66 49.1
1400 40.1 1.00 1.01 0.92 0.73 1.31 2.03 59.9
1500 27.4 1.85 1.91 1.70 0.70 1.27 1.82 72.6
La9Cr5
1250 44.6 0.52 0.53 0.48 0.70 0.77 1.69
6.60
55.4
1300 41.5 0.60 0.61 0.55 0.71 0.72 1.60 58.5
1400 25.4 1.10 1.11 1.02 0.74 0.58 1.26 74.6
1500 9.9 2.89 2.92 2.67 0.69 0.39 0.65 90.1
La8Cr5
1250 43.7 0.50 0.49 0.45 0.70 0.36 1.05
6.56
56.3
1300 40.3 0.62 0.60 0.55 0.67 0.20 0.76 59.7
1400 27.0 1.22 1.25 1.14 0.74 0.77 1.46 73.0
1500 16.0 2.54 2.65 2.35 0.72 0.65 1.12 84.3
La7Cr5
1250 45.9 0.56 0.58 0.53 0.72 0.37 0.80
6.45
54.1
1300 42.1 0.86 0.86 0.79 0.76 0.74 1.04 57.9
1400 31.2 1.23 0.86 1.14 0.75 0.66 1.47 68.8
1500 21.8 1.94 2.00 1.79 0.73 0.39 0.87 78.2
La10Cr6
1250 54.2 0.44 0.45 0.42 0.72 1.12 1.42
6.72
45.8
1300 48.1 0.76 0.77 0.72 0.75 1.33 1.92 51.9
1400 37.9 1.20 1.21 1.13 0.77 1.33 2.06 62.1
1500 23.4 1.97 1.96 1.84 0.76 1.94 2.31 76.6
La9Cr6
1250 54.0 0.24 0.23 0.22 0.79 0.37 1.07
6.57
46.0
1300 50.5 0.39 0.39 0.36 0.79 3.10 2.73 49.5
1400 40.7 0.67 0.69 0.63 0.76 2.54 2.94 59.3
1500 38.6 1.70 1.73 1.60 0.78 1.35 2.02 61.4
La10Cr4
1250 44.5 0.40 0.41 0.38 0.78 0.59 1.11
6.73
55.5
1300 39.2 0.77 0.78 0.72 0.71 0.36 1.01 60.8
1400 31.6 1.21 1.19 1.11 0.72 0.83 1.42 68.4
1500 24.0 2.15 2.09 1.94 0.70 1.11 1.47 76.0
La9Cr4
1250 54.1 0.43 0.43 0.40 0.72 2.63 2.76
6.59
45.9
1300 50.7 0.69 0.67 0.64 0.73 1.65 2.43 49.3
1400 34.1 1.43 1.44 1.33 0.76 2.30 2.65 65.9
1500 22.5 2.68 2.60 2.44 0.75 1.13 1.18 77.5
that contain Sr than in the Sr-free sample. Although no
secondary phases are detected in the Sr-free sample
(La10Cr5), the microstructure is composed of regions
with larger and smaller grains. All Sr-free samples with a
lower Cr-content behave similarly. The presence of a
secondary phase SrCrO4 in the sample with the highest
Sr content (La7Cr5) evidently does not have a significant
effect on the LSCM grain size distribution. In contrast,
the presence of a lanthanum-rich secondary phase
La2CrO6 in samples with a lower Cr content (La10Cr4
and La9Cr4) causes non-homogenous microstructures
with the denser regions containing larger grains and the
less dense regions containing smaller grains. In the
phase-pure LSCM sample with a Cr content y = 0.6
(La9Cr6), a very interesting microstructure is formed af-
ter sintering at 1250 °C. In this sample, the formation of
well-connected fine grains is observed.
The results of a quantitative microstructural analysis
are in good agreement with optical observations. The rel-
ative sintered density increases and the porosity de-
creases with the increasing sintering temperature. Sam-
ples with a Sr content x = 0.1, 0.2 or 0.3 and equal
contents of Cr and Mn sinter at the lowest sintering tem-
perature of 1250 °C to somewhat higher densities than
the Sr-free sample (La10Cr5). At the same sintering tem-
perature, rel reaches 48.1 %, 55.4 %, 56.3 % and 54.1 %
for the samples La10Cr5, La9Cr5 La8Cr5 and La7Cr5,
respectively. The addition of strontium to the perovskite
also results in grain growth, during which grains reach
an average size of 0.28 μm at 1250 °C in a Sr-free sam-
ple, while for the highest Sr content in sample x = 0.3 the
average grain size grew to 0.53 μm. At the highest sinter-
ing temperature (1500 °C), rel. reaches 90.1 %, 72.6 %,
84.3 % and 78.2 % for the samples La9Cr5, La10Cr5,
La8Cr5 and La7Cr5, respectively. From this fact, it can
be deduced that the addition of Sr to some amount x =
0.1 accelerates sintering, while adding Sr to perovskite
above a certain concentration x = 0.2 and 0.3 supresses
the densifying process. At a lower Sr concentration,
SrCrO4 (according to phase diagram SrO–Cr2O3) forms a
liquid phase due to eutectic and peritectic reactions21 that
promote sintering.22 In principle, a higher Sr-content in-
creases the amount of SrCrO4 phase which reacts to the
liquid phase and secondary solid phase through a peri-
tectic transformation. This secondary solid phase hinders
sintering. A higher sintering temperature also results in
pronounced grain growth in which originally sub-micro-
metre grains grow to almost ~2.7 μm in size at 1500 °C.
With this pronounced growth the grains become less
similar to an ideal sphere, which is manifested as a slight
decrease in the shape factor. Similar behaviour was ob-
served for the sintering of a combustion-derived LSCM
ceramic.23
In the LSCM phase, with a pure sample (La9Cr6)
with Cr content y = 0.6 and a low Sr-addition, the forma-
tion of well-connected grains is observed after sintering
at 1250 °C. With increasing sintering temperature, the
densification process normally advances and the grains
grow; however, the grain growth is somehow less pro-
nounced than that in other samples. The average grain
size for sample La9Cr6 sintered at various temperatures
1250 °C, 1300 °C, 1400 °C and 1500 °C is 0.22 μm, 0.36
μm, 0.63 μm and 1.6 μm, respectively. Furthermore, for
the sample La9Cr6, a calculation of the average
FERETMAX of pores versus the grain diameter gives the
highest value among all the samples. Since the average
pore diameter is comparable at sintering temperature
1250 °C in all samples, this value somehow indicates a
low average LSCM grain size and pore appearance in the
sample, which contribute mainly to the open porosity.
This fact together with the absolute value of porosity is
very important from the practical point of view if such
material is to be used as an anode layer in the operating
SOFC. In order to form a continuous phase of pores in
sintered samples, the porosity should be at least 30
vol.%, while the pore appearance should contribute to
open porosity to keep the LSCM anode layer permeable
for gases.
Several very important findings arise from the quanti-
tative microstructure analysis of LSCM samples. Re-
garding sintering optimisation, a lower Sr content (x =
0.1) with a somewhat higher chromium content (y = 0.6)
(sample La9Cr6) leads to proper microstructure forma-
tion at 1250 °C, where the grain-to-grain contact area is
enlarged, making it progressively easier to find a solid
continuous path of LSCM throughout the sample. At the
same time, the appropriate porosity is preserved and the
average grain size is the smallest, thus enlarging the in-
terface area where gaseous reactants meet the electro-
catalytic solid surface in a potential fuel cell. With addi-
tional information from the literature10 regarding LSCM
catalytic activity toward H2 oxidation, it can be con-
cluded that La0,9Sr0,1Cr0,6Mn0,4O3 is the most appropriate
LSCM chemical composition, which will also ensure the
desired microstructure characteristics at the relatively
low sintering temperature of 1250 °C.
4 CONCLUSIONS
La1–xSrxMn1–yCryO3± perovskite materials (x from 0
to 0.3 and y from 0.4 to 0.6) were prepared using the "re-
verse strike" carbonate co-precipitation method, which
has been shown to be an appropriate method since it al-
lows good control over the reaction system and the prep-
aration of LSCM materials with various compositions.
After calcination of the precipitated mixed carbon-
ate-hydroxide precursors at 1000 °C, the main crystalline
phase in all the samples is LSCM perovskite. In the sam-
ple with the highest Sr content (x = 0.3) and equal
amounts of chromium and manganese (y = 0.5), a stron-
tium secondary phase SrCrO4 was detected, while in
samples with a lower Cr content (y = 0.4) a lanthanum-
rich secondary phase La2CrO6 is formed. After sintering
at 1250 °C, the secondary phase re-dissolved into the
perovskite.
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Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748 747
Microstructure parameters for the LSCM ceramics
greatly depend on the sample composition. In samples
with equal contents of Cr and Mn, a slight addition of Sr
(x = 0.1) accelerates the sintering, while adding Sr to the
perovskite above a concentration of x = 0.2 supresses the
densifying process. In samples with a lower Cr content
(x = 0.4), the presence of a lanthanum-rich secondary
phase La2CrO6 causes non-homogenous microstructures
to form.
Samples with a lower Sr content (x = 0.1) and a
somewhat higher chromium content (y = 0.6) (La9Cr6)
lead to appropriate microstructure formation at sintering
temperatures as low as 1250 °C. Such a composition and
sintering temperature are also recognized as the most ap-
propriate parameters for suitable LSCM material.
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K. ZUPAN et al.: PHASE AND MICROSTRUCTURE DEVELOPMENT OF LSCM PEROVSKITE MATERIALS ...
748 Materiali in tehnologije / Materials and technology 50 (2016) 5, 743–748