1. References
Conclusion
Reevesite and similar compounds are
minerals belonging to the group of anionic
clays. Anionic clays are commonly referred
to as layered double hydroxides,
hydrotalcite like compounds (HTlc), and
mixed metal hydroxides. These minerals
follow the general formula:
[M(II)1-xM(III)x(OH)2]An-
x/n•mH2O
Where M(II) represents a divalent cation,
M(III) represents a trivalent cation, and A
represents an anion.1,2
There is a large variety of trivalent
cations, divalent cations, and anions that
can be accommodated in the structure
(Table 1). Some uncommon complex
anions include polyoxometalates, halides,
and even some pharmaceutical drugs1.
Anionic clays are stacked structures of
cation hydroxyl sheets held together by
hydrogen bonding.1 Figure 1 shows the
structure of the hydroxyl sheets in the
anionic clay hydrotalcite.
Figure 1: Cation hydroxyl sheet in hydrotalcite.2
When a trivalent cation replaces a
divalent cation an anion is placed in the
interlayer to charge balance. These anions
are either loosely connected directly to the
hydroxyl layers or held on with water.
The diversity of these minerals allows
there to be numerous applications (see
Figure 2) in everything from antipeptins to
flame retardants.
Background Experimental Results
3:1 and 2:1 cation ratios of Ni(II)Fe(III) and Co(II)Fe(III)
synthesized materials show anionic clay arrangement.
Hydrothermal treatment had adverse affects depending on
the sample, but in the Ni(II) samples it did increase the
crystalline structure. Magnetic moment data shows that the
curie temperature will like below 50K and more data needs
to be collected.
Synthesis is conducted via the wet
chemical route of coprecipitation in a
supersaturated environment. Solution A
contains 200 ml of H2O and varying rations
of cation nitrate salts. Solution B contains
200 ml of H2O and .2M of Na2CO3. Solution
A was added dropwise into solution B
while vigorously stirred (Figure 3).
Meanwhile a 2M solution of sodium
hydroxide, NaOH, is added to maintain a
constant pH. Samples are filtered via
vacuum filtering and dried at
90 oC for 20 h. and the powder was
subsequently split into Group A, B, or C.
Samples undergoing hydrothermal
treatment (B), are mixed into a solution of
H2O at 10 wt%. Then sealed in a Teflon bag
and placed inside a Parr digestion vessel
(Figure 4). The vessel is heated to 150-180
oC for 24 h.
Samples being calcined (C) are
pressed into pellets and heated in a tube
furnace to either 400 or 750 oC for 4h.
At this point samples are characterized
by X-ray Diffraction (XRD), Scanning
Electron Microscopy (SEM), and Vibrating
Sample Magnetometer (VSM) for
characterization.
Synthesis and Characterization of Reevesite and Analogous Minerals
John Salasin1 and Claudia Rawn2
1Shippensburg University
2Department of Material Science and Engineering, University of Tennessee
1: F. Cavani, F. Trifiro, A. Vaccari. Catalysis
Today. 11 (1991) 171
2: W. T. Reichle. Solid States Ionics 22
(1986) 135
Ni(II)Fe(III) and Co(II)Fe(III) anionic clays were successfully
synthesized. After the synthesis the calcination or hydrothermal
treatment had differing results. Depending on the Ni/Fe ratio the
hydrothermal treatment produced different results. In general,
post synthesis hydrothermal treatment resulted in a more
crystalline sample (the background was less noisy and Bragg
peaks became narrower and often had increased intensity).
However, the X-ray diffraction data are hard to interpret due to the
fact that these clays also show a large amount of preferred
orientation that can skew the intensities. The calcination
procedures produced multiple phases featuring NiO and Fe2O3.
Hydrothermal treatment of the Co(II)Fe(III) samples were not
successful and multiple phases were observed.
Applications
Medicine
Antiacid
Antipeptin
Stabilizer
Catalyst
Hydrogenation
Polymerization
Steam
reforming
Adsorbent
Halogen Scav.
PVC stabilizer
wastewater
Industry
Flame
retardant
Molecular
Sieve
Ion exchanger
Catalyst
Support
Ziegler-Natta
CeO2
Table 1: Anionic Clay Building Blocks
Divalent Cations Trivalent Cations Anions
Mg Al CO3
Mn Cr SO4
Fe Mn Cl
Co Fe
Ni Co
Cu La
Zn Y
Ca
Introduction
The goal of this research is to
synthesize anionic clay compounds with
various trivalent and divalent magnetic
cations. Then through studying these
cations that are located on a
triangularlattice we can see any magnetic
properties.
Iron [Fe(III)], Nickel [Ni(II)], and cobalt
[Co(II),Co(III)] were chosen as the cations.
Carbonate, CO3, was chosen as the anion.
Table 2 indicates the cation ratios and
minerals to be synthesized.
After synthesis samples will be split
into three separate groups: Group A is as
synthesized, Group B will be subjected to
hydrothermal treatment, and Group C will
undergo a calcination procedure.
Hydrothermal treatment is necessary
to increase the crystalline structure of the
sample and is important due to the
disordered and often amorphous nature of
as synthesized anionic clays.
Samples are characterized with
X-ray powder diffraction (XRD) and
Vibrating Sample Magnetometer (VSM)
measurements.
Figure 2: Anionic clay applications.1
Table 2: Hypothesized synthesized minerals
Divalent
Cation
Ratio Trivalent
Cation
Anion pH
Nickel 2 1 Iron Carbonate 8-9
Nickel 3 1 Iron Carbonate 8-9
Nickel 3 1 Cobalt Carbonate 8-9
Cobalt 2 1 Iron Carbonate 8-10
Cobalt 3 1 Iron Carbonate 8-10
Figure 3: Coprecipitation synthesis Figure 4: Parr digestion vessel
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
0
100
200
300
400
500
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
800
1000
1200
1400
1600
1800
2000
Calcination (750C)
As Synthesized
Hydrothermal Treatment
Co(II).67Fe(III).33(OH)2(CO3)n-x/n•mH2O
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
0
200
400
600
800
As Synthesized
Hydrothermal Treatment
Co(II).75Fe(III).25(OH)2(CO3)n-x/n•mH2O
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
1400
1600
1800
2000
2200
2400
2600
2800
3000
Calcination (750C)
3:1 Ni(II)/Fe(III) Magnetic Moment
Temperature (K)
0 50 100 150 200 250 300 350 400
MagneticMoment(emu)
0.002
0.003
0.004
0.005
0.006
0.007
0.008
1k Oe magnetic field
Vibrating Sample Magnetometer (VSM) characterization (Figure 7)
indicate that changes are occurring as a function of temperature and warrant
further data collection at temperatures below 50 K.
Figure 7: VSM data on 3:1 Ni(II)Fe(III)
sample
Figure 6: XRD on Ni(II)Fe(III) samplesFigure 5: XRD on Ni(II)Fe(III) samples
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
0
100
200
300
400
500
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
800
1000
1200
1400
1600
1800
2000
Calcination (750C)
As Synthesized
Hydrothermal Treatment
Co(II).67Fe(III).33(OH)2(CO3)n-x/n•mH2O
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
0
200
400
600
800
As Synthesized
Hydrothermal Treatment
Co(II).75Fe(III).25(OH)2(CO3)n-x/n•mH2O
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
1400
1600
1800
2000
2200
2400
2600
2800
3000
Calcination (750C)
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
0
1000
2000
3000
4000
5000
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
600
800
1000
1200
1400
1600
1800
2000
2200
2400
Calcination (400C)
Calcination (750C)
As Synthesized
Hydrothermal Treatment
Ni(II).75Fe(III).25(OH)2(CO3)n-x/n•mH2O
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
-200
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2-Theta(Deg)
0 10 20 30 40 50 60 70 80
Intensity(Counts)
800
1000
1200
1400
1600
1800
2000
2200
2400
Calcination (400C)
Calcination (750C)
As Synthesized
Hydrothermal Treatment
Ni(II).67Fe(III).33(OH)2(CO3)n-x/n•mH2O