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2015
Solid State Synthesis of Mixed Metal Oxides
Ramón B. Colón Rivera1 and Ann M. González Piñeiro2
1 University of Puerto Rico, Cayey, Department of Natural Sciences
2 University of Puerto Rico, Cayey, Department of Chemistry
ABSTRACT
New compound synthesis is a very important application in the chemistry material field.
In this investigation metals from groups 13-15 in the periodic table were used to accomplish the
major purpose of the research. Ternary and quaternary reactions were selected as part of our
experimentation and eco-friendly protocols were included in the experimentation. We expect to
see crystal formation and eventually characterize it. Our hypothesis was partially proved.
Although we had negative outcomes it is incorrect to say that the hypothesis was not proved
because powder is a miniature particle with crystal structure.
INTRODUCTION
Dr. Lucasz Koscielski was an inorganic chemistry professor who was committed to the
solid state synthesis of new compounds in order to find novel ways of conducting energy without
increasing our planet’s pollution. Solid state synthesis is a branch of material chemistry which
consists of mixing and matching solids in order to obtain new compounds with useful properties.
In his laboratory, metals from groups 13-15 in the periodic table were used.
Our research work consisted in trying new combinations of metal oxides in order to
synthesize new compounds. It seemed really easy, but it was not. Solid state synthesize is a try
and error methodology in which metals combination are endless. Ternary and quaternary
reactions were selected as part of our experimentation. Eco-friendly protocols were included in
the experimentation to minimize radiation or contamination. That is why a maximum of 30mg of
the heaviest element was permitted. A high temperature furnace was used to complete the
reactions having in mind the melting points of the elements.
Our hypothesis established that a successful synthesis could be achieved. To evidence a
success it was necessary to observe a crystal production. If positive outcomes were observed,
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characterization and new mixed metals combinations can be done as future work. Hopefully the
results will help to develop new technologies.
MATERIALS AND METHODS
Reactant Selection:
Ternary and quaternary compounds from groups 13-15 of the periodic table were chosen
to react. An extensive study of the elements properties such as oxidation states and melting
points was done. The ternary and quaternary combinations selected are showed in Table 1.
Stoichiometric calculations were completed in order to determine the minimum of milligrams
that could be added by element. Intrinsic oxygen unable us to determine with certainty the
possible synthesized compound.
Table 1: Elements Combinations for Reactions
Ternary Quaternary
5 In : 3 Sb 1 Co : 2 In : 1 S
5 Sn : 3 Pb 1 Co : 1 Bi : 1 S
5 Bi : 3 Pb 1 In : 2 Co : 2 S
1 Bi : 2 Pb 1 In : 1 Bi : 1 S
Silica tube preparation:
Before the experimentation was started the silica tubes passed through two different
protocols: heat alignment and carbon coating. The initial silica tube was four feet long. It was
split with a crystal cutter into four halves of twelve inches each one in order to fit in the fume
hood. Then, each twelve inches piece was divided in two halves using an oxygen acetylene torch
which is really powerful and commonly used in welding. Carbon coating was the next step; it is a
process which help to inhibit light from reacting with the compound in study and the compound
from reacting with the tube. Acetone was heated inside each tube in three occasions until the
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walls turned black. Once the tubes were ready each mixture of elements were inserted in
different silica tubes.
Conversion using Stoichiometric Relations:
Working with toxic compounds is a possibility that we can encounter in the
experimentation. In order have an eco-friendly response towards this situation we established
that we will be using a maximum of 30mg per element. Depending in the molar mass and the
ratio selected for each reaction, the quantities of each element will vary. That is why a
stoichiometric conversion is necessary before loading the reactions. The final quantities of each
element are showed in Table 2.
Table 2: Final Quantities for each Reaction
Ternary Quantity (mg) Quaternary Quantity (mg)
5 In : 3 Sb 30mg In + 19mg Sb 1 Co : 2 In : 1 S 8mg Co + 30mg In + 4mg S
5 Sn : 3 Pb 29mg Sn + 30mg Sn 1 Co : 1 Bi : 1 S 8mg Co + 30mg Bi + 5mg S
5 Bi : 3 Pb 30mg Bi + 18mg Pb 1 In : 2 Co : 2 S 29mg In + 30mg Co + 16mg S
1 Bi : 2 Pb 15mg Bi + 30mg Pb 1 In : 1 Bi : 1 S 16mg In + 30mg Bi + 2mg S
GSL-1100x Furnace:
A special GSL-1100x high temperature furnace is used to heat the reactions. This
powerful furnace is needed because the melting points of metals usually stands between 200ºC
and 1000 ºC. Depending on the melting points of the elements present in the reaction a heating
curve is prepared. An example of a heating curve is showed in Figure 1. This curve can vary
since the melting points of all the elements aren’t the same. The reactions are under heat until the
temperature of the highest melting points is accomplished. Then a constant temperature period
will let the reactants to mix and react. At the end a slow process of cooling will provide crystal
formation.
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RESULTS AND DISCUSSION
After one week in the furnace the reactions were completed. We proceeded to break the
silica tubes in order to spread the product in different petri dishes and analyze the results using a
dissecting microscope. We were looking for crystals, but we found powder. The results of the
ternary compounds can be found in Figures 2-5. In Figure 4 and 5 powder attached to the tube
wall was observed. First we thought we have found crystals, but after consulting with our mentor
we concluded that crystal formation was not seen. Compacted powder in the wall of the silica
tube may be a result of a poor carbon coating procedure. Oxidation reactions were distinguished
by the change in color of some of the elements. That could be explained because of the intrinsic
oxygen present during the reaction. Oxygen cannot be quantified and as a consequence it reacts
freely with the metals producing a change in color.
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Figure 1: Example of a Heating Curve
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We confronted some limitations that included time and lack of appropriate equipment.
Because of the limited time we were not able
to run the quaternary reactions. Also, we supposed that negative results were observed as a
consequence of the inappropriate conditions in which the reactions were run. In order to avoid
limitations and achieve positive results we proposed for future work to repeat the experiment
increasing the quality of the carbon coating and using the appropriate equipment. We also want
to try new ternary and quaternary combinations until a new compound is synthesized and
characterized.
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Figure 3: 5 Sn : 3 PbFigure 2: 5 In : 3 Sb
Figure 5: 1 Bi : 2 PbFigure 4: 5 Bi : 3 Pb
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Our hypothesis was partially proved. Although we had negative outcomes it is incorrect
to say that the hypothesis was not proved because powder is a miniature particle with crystal
structure. We found crystals, but not the ones that we were looking for.
REFERENCES
1. Avtar R, Samui P, Gupta N.K., Parida S.C.2014. Synthesis, characterization and heat capacities of ternary oxides in the Ti–Nb–O system.Thermochimica Acta[Internet];[revised 2014 July 31; cited 2015 May 15].592:31-36.URL: http://www.sciencedirect.com.ezproxy.cayey.upr.edu:2048/science/article/pii/S0040603114003608
2. Bang S, Pan Z, Hun Y, Woo D, Min K.2013. Y2MoSe3O12 and Y2MoTe3O12: Solid-state synthesis, structure determination, and characterization of two new quaternary mixed metal oxides containing asymmetric coordination environment.J. of Solid State Chemistry[Internet];[revised 2013 Sept. 24; cited 2015 May 16].208:65-70.URL: http://www.sciencedirect.com.ezproxy.cayey.upr.edu:2048/science/article/pii/S0022459613004593?np=y
3. Burnett D, Harunsani M, Kashtiban R, Playford H, Sloan J, Hannon A, Walton R.2014.Investigation of some new hydro(solvo)thermal synthesis routes to nanostructured mixed-metal oxides.J. Solid State Chemistry[Internet];[cited 2015 May 16].214:30-37.URL: http://www.sciencedirect.com.ezproxy.cayey.upr.edu:2048/science/article/pii/S0022459613005288
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5. Tanaka M, Zhang S, Tanaka Y, Inumaru K, Yamanaka S.2013.High pressure synthesis and crystal structure of a ternary superconductor Ca2Al3Si4 containing layer structured calcium sub-network isomorphous with black phosphorus.J. of Solid State Chemistry[Internet];[revised 2012 Nov 9; cited 2015 May 16].198:445-451.URL: http://www.sciencedirect.com.ezproxy.cayey.upr.edu:2048/science/article/pii/S0022459612006950
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