Pressure-induced phase transition study of magnesiochromite (MgCr2O4) by Raman spectroscopy and X-ray diffraction

Yong, Wenjun; Botis, Sanda M.; Shieh, Sean R.; Shi, Weiguang; Withers, A. C.

doi:10.1016/j.pepi.2012.02.011

Cited by 53 publications

(31 citation statements)

References 78 publications

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“…4(b)]. This volume drop was not detected in the previous investigation 29 , but is consistent with the high-pressure behavior of several other Cr-based spinels which undergo similar transitions 19,20,22,23 . The first-order character of the cubictetragonal transition is unexpected from group symmetry considerations 69 , since the SG I4 1 /amd is a direct subgroup of SG Fd3 m. Actually, the tetragonal unit cell can be easily derived from the cubic one, since the tetragonal c-axis equals the cubic lattice parameter a cub , whereas the tetragonal axis a tetr = a cub /√2 (we note that we employ the normalized a* = a tetr √2 tetragonal lattice parameter in our discussion and graphs from now on, for direct comparison with the a cub ).…”

Section: Fd⎯3msupporting

confidence: 88%

“…The straightforward effect of compression is the reduction of the Cr-Cr distances, which in turn causes the enhancement of the AFM J 1 interactions over the FM J 2 ones. Besides from tuning the magnetic interactions, pressure can also lead to structural [18][19][20][21][22][23] , electronic 21,24,25 , and even magnetic 21 27 . A red-shift of E g was detected below T C 27 , but without any apparent complementary structural effect 5,28 .…”

Section: Introductionmentioning

confidence: 99%

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Pressure-induced phase transitions in the CdCr2Se4 spinel

et al. 2016

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We have conducted high-pressure x-ray diffraction and Raman spectroscopic studies on the CdCr 2 Se 4 spinel at room temperature up to 42 GPa. We have resolved three structural transitions up to 42 GPa, i.e. the starting Fd3 m phase transforms at ~11 GPa into a tetragonal I4 1 /amd structure, an orthorhombic distortion was observed at ~15 GPa, whereas structural disorder initiates beyond 25 GPa. Our ab initio DFT studies successfully reproduced the observed crystalline-to-crystalline structural transitions. In addition, our calculations propose an anti-ferromagnetic ordering as a potential magnetic ground state for the high-pressure tetragonal and orthorhombic modifications, as compared to the starting ferromagnetic phase. Furthermore, the computational results indicate that all phases remain insulating in their stability pressure range, with a direct-to-indirect band gap transition for the Fd3 m phase taking place at 5 GPa.We attempted also to offer an explanation behind the peculiar first-order character of the Fd3 m (cubic)→I4 1 /amd (tetragonal) transition observed for several relevant Cr-spinels, i.e. the sizeable volume change at the transition point, which is not expected from space group symmetry considerations. We detected a clear correlation between the cubic-tetragonal transition pressures and the next-nearest-neighbor magnetic exchange interactions for the Crbearing sulphide and selenide members, a strong indication that the cubic-tetragonal transitions in these systems are principally governed by magnetic effects.

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Section: Fd⎯3msupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Pressure-induced phase transitions in the CdCr2Se4 spinel

et al. 2016

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“…Even though similar first-order Fd3 m -I4 1 /amd transitions have been observed for other spinels under pressure 60,61 , the volume change at the transition point cannot be rationalized by SG symmetry considerations alone 46 . We discuss this point in more detail below.…”

Section: Structural Properties Under Pressurementioning

confidence: 74%

“…Another common feature of these systems is the noticeable volume change at the Fd3 m→I4 1 /amd transition point 28,29,60,61 , which is unexpected from group symmetry considerations. Following our previous discussion on CdCr 2 Se 4 27 , we focus on the magnetic exchange interactions of ZnCr 2 S 4 .…”

Section: Comparison With Relevant Cr-spinelsmentioning

confidence: 97%

Structural Behavior of ZnCr₂S₄ Spinel under Pressure

et al. 2016

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The series of Cr-chalcogenide spinels ACr 2 X 4 (A = Zn, Cd, Hg; X = S, Se) exhibits a rich phase diagram upon compression, as revealed by our recent investigations. There exist, however, some open questions regarding the role of cations in the observed structural transitions. In order to address these queries, we have performed X-ray diffraction and Raman spectroscopic studies on the ZnCr 2 S 4 spinel up to 42 GPa, chosen mainly due to the similarity of the Zn 2+ and Cr

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“…Upon comression and/or heating, the oxide spinels tend to adopt a denser orthorhombic CaTi 2 O 4 -, CaMn 2 O 4 -, or CaFe 2 O 4 -type phase [7][8][9][10][11] , occasionally through an intermediate tetragonal structure (SG I4 1 /amd, Z = 4) [12][13][14] . A transformation from the cubic phase towards the Cr 3 S 4 -type structure has not been reported for any oxide Cr-spinel.…”

Section: Introductionmentioning

confidence: 99%

Structural transition in the magnetoelectricZnCr2Se4spinel under pressure

et al. 2016

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Τhe magnetoelectric ZnCr 2 Se 4 spinel, with space group Fd3 m, undergoes a reversible first-order structural transition initiating at 17 GPa, as revealed by our highpressure X-ray diffraction studies at room temperature. We tentatively assign the high-pressure modification to a AMo 2 S 4 -type phase, a distorted variant of the monoclinic Cr 3 S 4 structure. Furthermore, our Raman investigation provides evidence for a pressure-induced insulator-metal transition. Our density functional theory calculations successfully reproduce the structural transition. They indicate significant band gap and magnetic moment reduction accompanying the pressure-induced structural modification. We discuss our findings in conjunction with the available high-pressure results on other Cr-based chalcogenide spinels.

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Pressure-induced phase transition study of magnesiochromite (MgCr2O4) by Raman spectroscopy and X-ray diffraction

Cited by 53 publications

References 78 publications

Pressure-induced phase transitions in the CdCr2Se4 spinel

Pressure-induced phase transitions in the CdCr2Se4 spinel

Structural Behavior of ZnCr₂S₄ Spinel under Pressure

Structural transition in the magnetoelectricZnCr2Se4spinel under pressure

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Pressure-induced phase transition study of magnesiochromite (MgCr2O4) by Raman spectroscopy and X-ray diffraction

Cited by 53 publications

References 78 publications

Pressure-induced phase transitions in the CdCr2Se4 spinel

Pressure-induced phase transitions in the CdCr2Se4 spinel

Structural Behavior of ZnCr2S4 Spinel under Pressure

Structural transition in the magnetoelectricZnCr2Se4spinel under pressure

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Product

Resources

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Structural Behavior of ZnCr₂S₄ Spinel under Pressure