Effect of pressure on the Néel and the ferrimagnetic Curie temperatures of FeS1+δ

Anzai, S.; Ozawa, K.

doi:10.1002/pssa.2210240144

Cited by 9 publications

(2 citation statements)

References 11 publications

(4 reference statements)

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“…It can be shown ) that a large, negative d2T/dP 2 is a direct consequence of the compression behavior measured for these two phases in the present study; further, taking this derivative into account, qualitative agreement is obtained between the observed and calculated phase boundaries. The pressure dependencies of the secondorder spin-flip and MnP-to-NiAs transitions are unknown, but Anzai & Ozawa (1974) have obtained a slope of +32(1) K GPa -~ for T N in measurements taken up to 0.85 GPa. Through determinations of the eutectic melting temperature for Fe + FeS (Brett & Bell, 1969;Usselman, 1975), the incongruent melting point of FeS has been found to be nearly pressure independent up to 5.2 GPa, acquiring a linear pressure dependence of approximately 30 K GPa -~ above this pressure.…”

Section: Phase Relationsmentioning

confidence: 98%

High-pressure and high-temperature polymorphism of iron sulfide (FeS)

King¹,

Prewitt²

1982

Acta Crystallogr Sect B

154

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The pressure-and temperature-induced phase transitions in FeS have been explored by X-ray diffraction measurements made on single-crystal samples. It is found that the room temperature and pressure structure, troilite (a close relative of the NiAs-type structure), with space group P(~2c and a unit cell of a = v/3A and c ---2C (where A and C refer to an NiAs-type structure and are approximately 3.4 and 5.9A, respectively), transforms at 420 K and ambient pressure, and at 298 K and 3.4 GPa to an MnP-type structure. This structure has space group Pnma and the orthohexagonal unit-cell dimensions a = C, b = ,4 and c -v/3A. For FeS, the deviation of its unit cell from these ideal dimensions is small, and although the transformation results in a triply twinned crystal, the profiles of reflections containing contributions from multiple-twin domains are broadened but not split. A comparison of data from structure refinements adjacent to these transitions shows that, in both cases, the MnP-type phase has an increased distortion of the S atoms from planarity, a less distorted FeS 6 polyhedron, and longer Fe-Fe bonds. The differences in distortion between the structures suggests that their stabilities may depend upon the relative energy contributions from the distorted polyhedron and the Fe-Fe bond. Further increases in temperature produce a second-order transition to an NiAs-type structure, space group P63/mmc, whereas higher pressures cause an increasing sinusoidal distortion of the essentially h.c.p. S atoms. At 298 K and 6.7 GPa another transition takes place to an unknown structure. This transition is accompanied by a 9% volume change and a large decrease in C/A.

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Section: Phase Relationsmentioning

confidence: 98%

High-pressure and high-temperature polymorphism of iron sulfide (FeS)

King¹,

Prewitt²

1982

Acta Crystallogr Sect B

154

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“…Unfortunately, the volumetric data for hightemperature hexagonal pyrrhotite are sparse, although numerous measurements of volumes for low-temperature (<3208C) polymorphs have been reported. In this study we adopt the equation of state for stoichiometric FeS derived by Balabin and Urusov (1995) from the experimental data of Taylor (1969), King and Prewitt (1982), Novikov et al (1982), Anzai and Ozawa (1974). For nonstoichiometric pyrrhotite, Fe 1 d S , the following linear equation for the molar volume at room temperature V Fe 1 d S cm 3 = 18.366 6.231d, may be obtained from least-squares tting of the data from Fleet (1968), Novikov et al (1982) and Kruse (1990), utilizing only points with 0.012584d40.05 as representative of the NiAs structure with disordered, 'free' vacancies (Novikov et al, 1988;Kruse, 1990).…”

Section: N Sphmentioning

confidence: 99%

Thermodynamics of (Zn,Fe)S sphalerite. A CVM approach with large basis clusters

Balabin

Sack

2000

Mineral. mag.

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We have developed a cluster variation method (CVM) model based on cuboctahedral and octahedral basis clusters containing 13 and 6 atoms, respectively, and applied it to the analysis of the thermodynamic mixing properties of (Zn,Fe)S solid solutions. The model, in which the internal energy of the lattice is approximated by next to nearest neighbour (nnn) pair interactions and many-body interactions associated with nearest neighbour (nn) equilateral triangles, describes the FeS contents of sphalerites equilibrated with pyrrhotite and pyrite, and with pyrrhotite and iron metal within experimental uncertainties. The model predicts moderate deviations from ideality; the mean values of the Lewis and Randall activity coefficient of FeS and ZnS are, 1.48 and 1.03, respectively. Predictions of the model are in qualitative agreement with cell-edge data. The model also predicts that sphalerites undergo long-range ordering to lower-symmetry structures at temperatures only slightly below those investigated experimentally, a result in agreement with inferences from an existing Mössbauer investigation of synthetic sphalerites.More realistic models in which interactions are ascribed to larger species (nn triangular and centred square species) predict that such long-range ordering occurs at even higher temperatures and underscore the need for better characterization of the structures of (Zn,Fe)S minerals.

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Fe(1-x)S: crystal structure, physical properties

Landolt-Börnstein - Group III Condensed Matter

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Effect of pressure on the Néel and the ferrimagnetic Curie temperatures of FeS1+δ

Cited by 9 publications

References 11 publications

High-pressure and high-temperature polymorphism of iron sulfide (FeS)

High-pressure and high-temperature polymorphism of iron sulfide (FeS)

Thermodynamics of (Zn,Fe)S sphalerite. A CVM approach with large basis clusters

Fe(1-x)S: crystal structure, physical properties

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