Synthesis and Magnetic Characterization of Siderite Particles with Varying

Morphologies: Implication for Rock Magnetic Properties Lindsay A. Hegner1, Jennifer H. Strehlau1, Becky E. Strauss2, Joshua M. Feinberg2, and R. Lee Penn1

1Department of Chemistry, University of Minnesota, Minneapolis, MN 2Institute for Rock Magnetism, Department of Earth Sciences, University of Minnesota, Minneapolis, MN

Results

Discussion

At different initial Fe(II) concentrations, there was a difference in particle

morphology, particle size, and magnetic data obtained.

SEM confirms radial growth texture consistent with naturally occurring siderite.

XRD confirms pure siderite samples when the suspension was aged at 130 °C in

the autoclave.

MPMS data is inconsistent between various concentration trials and current

literature. There is a shift in Néel temperature (from <40 K to >50 K) from

previous literature.2,3

Higher Fe(II) concentrations result in increased initial growth of particle seeds.

This contributed to a greater variety in morphologies, but particles are smaller and

have less growth due to resources being used more quickly.

Lower Fe(II) concentrations result in fewer particle seeds. This contributed to less

variety of morphologies but larger particles, due to more growth since resources

are used slowly.

Future Work

Perform characterization on a siderite standard for comparison

Determine if drying effects are present

Conduct a time series to determine size dependency of the Néel temperature

Determine single domain size

Apply Mössbauer spectroscopy to determine any presence of Fe(III)

Perform synthesis with different reducing agents

Acknowledgements This work was supported by:

1) Frederichs, T., Von Dobeneck, T., Bleil, U., & Dekkers, M. J. (2003). Towards the identification of siderite, rhodochrosite, and vivianite in sediments by their low-temperature magnetic properties. Physics and Chemistry of the Earth, Parts A/B/C, 28(16), 669-679.

2) Pan, Y., Zhu, R., Liu, Q., Jackson, M. (2002). Low-temperature magnetic behavior related to thermal alteration of siderite. Geophys. Res. Lett, 29(23), 2087-2090.

3) Roh, Y., Zhang, C. L., Vali, H., Lauf, R. J., Zhou, J., & Phelps, T. J. (2003). Biogeochemical and environmental factors in Fe biomineralization: magnetite and siderite formation. Clays and Clay Minerals, 51(1), 83-95.

4) Qu, X. F., Yao, Q. Z., & Zhou, G. T. (2011). Synthesis of siderite microspheres and their transformation to magnetite microspheres. European Journal of Mineralogy, 23(5),759-770.

5) Romanek, C. S., Jiménez-López, C., Navarro, A. R., Sánchez-Román, M., Sahai, N., & Coleman, M. (2009). Inorganic synthesis of Fe–Ca–Mg carbonates at low temperature. Geochimica et Cosmochimica Acta, 73(18), 5361-5376.

6) Mozley, P. S., & Burns, S. J. (1993). Oxygen and carbon isotopic composition of marine carbonate concretions; an overview. Journal of Sedimentary Research, 63(1), 73-83.

Introduction

Siderite is an iron(II) carbonate (FeCO3) mineral commonly found in a range of

natural environments, including anaerobic aqueous ecosystems, systems containing

biomineralization and extraterrestrial formations.1-5

Siderite can be identified by a characteristic magnetic transition at low

temperatures below 40 K.1,2 It is important to be able to detect siderite through low

temperature rock magnetic analysis due to its ability to undergo phase transformation

to magnetite under certain conditions.2 It can also complicate carbon and oxygen

isotopic analyses in natural rock samples.6 Additionally, it may greatly assist in the

identification of biomineralization processes and paleoclimates.4

The goal of this project was to synthesize and characterize siderite particles of

varying morphologies and grain sizes. Using X-ray diffraction (XRD), scanning

electron microscopy (SEM), and Magnetic Properties Measurement System (MPMS)

analyses, we aim to determine trends between particle morphology, grain size, and

rock magnetic properties.

Experimental

The following synthetic procedure4 was completed at varying initial Fe(II)

concentrations: 0.033 M, 0.067 M, and 0.10 M.

One solution of 0.2 M sodium carbonate (Na2CO3) was combined with a solution

containing 0.2 M ascorbic acid and varying concentrations of ferrous sulfate

(FeSO4) in an autoclave with a total volume of 60 mL.

Particle suspension was aged for 4 hours at 130 °C. Once removed from oven,

suspension was cooled overnight to room temperature.

The suspension was then purified using dialysis until particles settled from

solution.

20 30 40 50 60 70 80

Inte

nsi

ty

2 Theta

Siderite

Siderite PDF

Ferrihydrite PDF

20 30 40 50 60 70 80

Inte

nsi

ty

2 Theta

Siderite

Siderite PDF

20 30 40 50 60 70 80

Inte

nsi

ty

2 Theta

Siderite

Siderite PDF

20 30 40 50 60 70 80

Inte

nsi

ty

2 Theta

Siderite

Siderite PDF

0

2

4

6

8

10

12

14

0 50 100 150 200 250 300

M (

10

-3A

m2/k

g)

Temperature (K)

FC

ZFC

0

5

10

15

20

0 50 100 150 200 250 300

M (

10

-6A

m2/k

g)

Temperature (K)

Cooling

Warming

0.15

0.25

0.35

0.45

0.55

0.65

0 50 100 150 200 250 300

M (

Am

2/k

g)

Temperature (K)

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250 300

M (

Am

2/k

g)

Temperature (K)

0

1

2

3

4

5

6

0 50 100 150 200 250 300

M (

10

-3A

m2/k

g)

Temperature (K)

FC

ZFC

0

5

10

15

20

25

30

35

40

45

0 50 100 150 200 250 300

M (

10

-6A

m2/k

g)

Temperature (K)

Cooling

Warming

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 50 100 150 200 250 300

M (

Am

2/k

g)

Temperature (K)

0

1

2

3

4

5

6

7

8

9

10

0 50 100 150 200 250 300

M (

10

-3A

m2/k

g)

Temperature (K)

FC

ZFC

0

5

10

15

20

25

30

35

0 50 100 150 200 250 300

M (

10

-6A

m2/k

g)

Temperature (K)

Cooling

Warming

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250 300

M (

Am

2/k

g)

Temperature (K)

~59 K

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 50 100 150 200 250 300

M (

10

-3A

m2/k

g)

Temperature (K)

FC

ZFC

0

2

4

6

8

10

12

14

16

18

0 50 100 150 200 250 300

M (

10

-6A

m2/k

g)

Temperature (K)

Cooling

Warming

0.0

67 M

at

90 °

C

0.0

33 M

at

130 °

C

0.0

67 M

at

130 °

C

0.1

0 M

at

130 °

C

Parts of this work were carried out in the Characterization

Facility, University of Minnesota, which receives partial

support from NSF through the MRSEC program.

Undergraduate Research Opportunity Program

Institute for Rock Magnetism

National Science Foundation

References

SEM XRD Saturation Magnetization Field Cooled – Zero Field Cooled

Remanence Room Temperature Remanence

Figure 1: Analysis of siderite particles at various temperatures and initial Fe(II) concentrations. (left to right) Results of SEM, XRD, saturation magnetization, field cooled and zero-field cooled remanence and room temperature remanence. (top to

bottom) Concentration and temperature series including 0.067 M Fe(II) at 90 °C, 0.033 M Fe(II) at 130 °C, 0.067 M Fe(II) at 130 °C and 0.10 M Fe(II) at 130 °C.

~54 K

~57 K

~54 K

~60 K

~59 K

~60 K

~62 K