Surfaces, Interfaces and Crystal Growth of Marcasite FeS<sub>2</sub>

Arrouvel, Corinne

doi:10.1590/1980-5373-MR-2020-0383

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Articles • Mat. Res. 24 (1) • 2021 • https://doi.org/10.1590/1980-5373-MR-2020-0383 copy

Surfaces, Interfaces and Crystal Growth of Marcasite FeS₂

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Marcasite mineral is a metastable iron sulphide, α-FeS₂, less known and less abundant than pyrite β-FeS₂. Their chemical compositions are similar, formed by S₂^2- dimers and Fe²⁺ species, but the marcasite crystal structure is orthorhombic while pyrite is cubic. The thermodynamic stability of a range of selected surfaces and their kinetic growth are analysed with molecular mechanics simulations implemented in METADISE code. The most stable surface of marcasite corresponds to the (101) surface having the lowest surface energy (marcasite $γ_{101}^{}$ = 1.06 Jm^-2) and the most favoured kinetic growth rate is expected for the [010] direction (the attachment energy of (010) surface is 0.20 |eV|/at). Mirror twinning is another characteristic of the mineral contributing to a distinctive crystal growth forming different shapes such as striated needles or pseudo-pentagonal flowers. Similarities, differences and overgrowth between the two dimorphs are highlighted.

Keywords:
FeS₂; force field; morphology; grain boundary; striations

q (\|e\|)	Fe +2.0 S -1.0
Buckingham potentials	A (eV)	ρ (Å)	C (eVÅ^-6)
Fe-S	94813.90	0.18125	0.0000
S-S	1777.08	0.33080	97.4915
Constant Force	k (eV)	r₀ (Å)
S-S	8.44	2.23
3-body potential	k (eVrad^-2 )	θ₀
S-S-Fe	12.5	109.503º

	Marcasite	Marcasite	Pyrite	Pyrite
	Experimental data	This study	Experimental data	This study
Lattice Parameters (Å)	a=4.44^a a Buerger29; b=5.41 c=3.38	a=4.47 b=5.55 c=3.43	a=5.42^c	a=5.48
V (Å³)	81.2^a	85.23	159.0^c c Benbattouche et al.31;	164.56
S1-S2 bond length	2.21^a	2.3	2.18^c	2.18
Elastic constants ('10¹¹ dyn/cm²)
C₁₁	-	28.95	38.2^d d Simmons and Birch32;	31.99
C₂₂	-	34.24
C₃₃	-	26.42
C₁₂	-	4.78	3.1^d	5.54
C₁₃	-	9.85
C₂₃	-	6.65
C₄₄	-	8	10.9^d	10.8
C₅₅	-	13.47
C₆₆	-	15.14
Voigt modulus B (GPa)	146.5^b b Chattopadhyay and Von Schnering30;	147	146.9^d	144
Shear modulus G (GPa)	-	119		75
Young modulus E (GPa)	-	281		192
Poisson’s ratio n	-	0.18		0.28
Dielectric constants
ε₁₁	-	2.04	10.9^e e Husk and Seehra33.	2.31
ε₂₂	-	2
ε₃₃	-	2.27

Indices	d spacing (Å)	Attachment energy (\|eV\|/at)	Surface energy unrelaxed ( $γ_{h k l}$ ) (Jm^-2)	Surface energy relaxed ( $γ_{h k l}$ ) (Jm^-2)	Unrelaxed Termination
(010)	5.55	0.20	1.30	1.13 (1.54^a a Kitchaev and Ceder35, , 1.53^b b Dzade and Leeuw15 )	S1
(100)	4.47	0.58	3.02	2.77 (2.12^a)	S2
(110)	3.48	1.20	5.70	4.12 (1.68^a, 1.86S^b, 2.67Fe^b)	S1 (att.)/ Fe
(001)	3.43	0.45	1.84	1.58 (1.70^a)	Fe S1 S2
(011)	2.92	1.13	3.86	2.98 (1.75^a)	S2 S2
(101)	2.72	0.35	1.16	1.06 (1.07^a, 1.16^b)	S1 S2
(111)	2.44	0.77	1.98	1.73 (1.67^a)	S2
(120)	2.36	2.31	5.52	3.44	S2
(021)*	2.16	1.62	3.86	3.48	S2
(210)	2.07	2.57	5.29	4.11	S1 Fe
(121)	1.94	1.21	2.39	2.08	S1
(201)^* * Extinguished XRD peaks	1.87	1.69	3.52	3.15	S2
(211)	1.78	1.65	3.28	2.93	S1
(130)	1.71	2.76	4.76	2.89 (1.74^b)	S2
(031)	1.63	1.87	3.68	2.30	Fe
(102)	1.60	0.68	1.52	1.34	S2
(103)	1.11	1.02	1.64	1.43	S1 S2
(305)	0.62	3.59	3.24	2.54	(S1 S2 att.) Fe

ABM, ABC, ABPol UFSCar - Dep. de Engenharia de Materiais, Rod. Washington Luiz, km 235, 13565-905 - São Carlos - SP- Brasil. Tel (55 16) 3351-9487 - São Carlos - SP - Brazil
E-mail: pessan@ufscar.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *e-mail: corinne@ufscar.br

Brasil

Brasil

Surfaces, Interfaces and Crystal Growth of Marcasite FeS2

Abstract

Surfaces, Interfaces and Crystal Growth of Marcasite FeS₂