Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure

Tschauner, Oliver; Errandonea, Daniel; Serghiou, George

doi:10.1016/j.physb.2005.09.042

Cited by 10 publications

(10 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While the actual frequencies remain near constant, for lower symmetry the Raman and IR active peaks are significantly different. The use of superstructure modes to address the vibrational properties of MgB 2 is discussed by Tschauner et al 52 For example, a doubling of the c axis parameter for MgB 2 and in space group P6 3 mc allows for two Raman active modes, while space group P% 3c1 allows for three modes, P% 6c2 allows for six and P6 3 cm allows for eight Raman active modes. Note that in some cases, the mutual exclusion rule for IR and Raman active modes in centrosymmetric groups is not upheld.…”

Section: Modelling Resultsmentioning

confidence: 99%

“…For example, the 413.3 to 416.9 mode is Raman active for P6 and P6mm symmetries but not for all other symmetries listed in Table 5. 52 In space group P3c1, nine modes are both Raman and IR active. [49][50][51] Fig.…”

Section: Modelling Resultsmentioning

confidence: 99%

“…Note that in some cases, the mutual exclusion rule for IR and Raman active modes in centrosymmetric groups is not upheld. 52 In this work, examples of lower symmetry which cannot be represented in a single unit cell have also been explored. 6 IR spectra collected from freshly exposed (a) Sample A and (b) Sample B.…”

Section: Modelling Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Phonon modes of MgB₂: super-lattice structures and spectral response

Alarco

Chou

Talbot

et al. 2014

Phys. Chem. Chem. Phys.

105

View full text Add to dashboard Cite

Micrometre-sized MgB2 crystals of varying quality, synthesized at low temperature and autogenous pressure, are compared using a combination of Raman and infra-red (IR) spectroscopy. These data, which include new peak positions in both spectroscopies for high quality MgB2, are interpreted using DFT calculations on phonon behaviour for symmetry-related structures. Raman and IR activity additional to that predicted by point group analyses of the P6/mmm symmetry are detected. These additional peaks, as well as the overall shapes of calculated phonon dispersion (PD) models are explained by assuming a double super-lattice, consistent with a lower symmetry structure for MgB2. A 2× super-lattice in the c-direction allows a simple correlation of the pair breaking energy and the superconducting gap by activation of corresponding acoustic frequencies. A consistent physical interpretation of these spectra is obtained when the position of a phonon anomaly defines a super-lattice modulation in the a-b plane.

show abstract

Section: Modelling Resultsmentioning

confidence: 99%

Section: Modelling Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Phonon modes of MgB₂: super-lattice structures and spectral response

Alarco

Chou

Talbot

et al. 2014

Phys. Chem. Chem. Phys.

105

View full text Add to dashboard Cite

show abstract

“…The combination of the experimental studies with ab initio calculations was crucial for the assignment of the structure of the post-fergusonite phase. Here it is important to mention that peak intensities can be slightly distorted in x-ray powder diffraction x-ray DAC experiments [109,110] and thus an analysis based on residuals alone is in some cases not enough to discriminate between competing crystal structures. In such a case, the help of ab initio calculations is more than recommendable.…”

Section: Ii-type Phases Inmentioning

confidence: 99%

Pressure effects on the structural and electronic properties of ABX4 scintillating crystals

Errandonea

Manjón

2008

Progress in Materials Science

Self Cite

335

328

View full text Add to dashboard Cite

Studies at high pressures and temperatures are helpful for understanding the physical properties of the solid state, including such classes of materials as, metals, semiconductors, superconductors, or minerals. In particular, the phase behaviour of ABX 4 scintillating materials is a challenging problem with many implications for other fields including technological applications and Earth and planetary sciences. A great progress has been done in the last years in the study of the pressure-effects on the structural and electronic properties of these compounds. In particular, the highpressure structural sequence followed by these compounds seems now to be better 2 understood thanks to recent experimental and theoretical studies. Here, we will review studies on the phase behaviour of different ABX 4 scintillating materials. In particular, we will focus on discussing the results obtained by different groups for the scheelitestructured orthotungstates, which have been extensively studied up to 50 GPa. We will also describe different experimental techniques for obtaining reliable data at simultaneously high pressure and high temperature. Drawbacks and advantages of the different techniques are discussed along with recent developments involving synchrotron x-ray diffraction, Raman scattering, and ab initio calculations.Differences and similarities of the phase behaviour of these materials will be discussed, on the light of the Fukunaga and Yamaoka´s and Bastide´s diagrams, aiming to improve the actual understanding of their high-pressure behaviour. Possible technological and geophysical implications of the reviewed results will be also commented.

show abstract

“…On top of that, indications of a phase transition in MgB 2 above 9 GPa at RT after stress relaxation by laser heating [179] have been observed. The transition was detected using Raman spectroscopy and X-ray diffraction [180]. The structure of MgB 2 (P6/mmm) is composed of planar hexagonal arrays of B atoms intercalated by Mg atoms such that each Mg atom has 12 B atoms in equal distance as nearest neighbors, while each B is surrounded by six equidistant Mg atoms.…”

Section: Ax 2 Compoundsmentioning

confidence: 99%

Pressure‐induced structural phase transitions in materials and earth sciences

Manjón

Errandonea

2008

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

Pressure is an important thermodynamic parameter since it allows an increase of matter density by reducing volume. The reduction of volume by applying high pressures leads to an overall decrease of interatomic and intermolecular distances that allows exploring in detail atomic and molecular interactions. Therefore, high‐pressure research has improved our fundamental understanding of these interactions in solids, liquids and gasses. The study of the structure of matter under compression is a rapid developing field that is receiving increasing attention especially due to continuous experimental and theoretical developments. In this article, we give a brief description of the experimental and theoretical methods employed in the study of solid matter at high pressures and summarize the high‐pressure phases of the most relevant elements and inorganic compounds of the AX, A2X, AX2, ABX2, A2X3, ABX3, ABX4 and AB2X4 families giving an overview of the state of the art in high‐pressure research by highlighting recent discoveries, hot spots, controversial questions, and future directions of research. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure

Cited by 10 publications

References 36 publications

Phonon modes of MgB₂: super-lattice structures and spectral response

Phonon modes of MgB₂: super-lattice structures and spectral response

Pressure effects on the structural and electronic properties of ABX4 scintillating crystals

Pressure‐induced structural phase transitions in materials and earth sciences

Contact Info

Product

Resources

About

Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure

Cited by 10 publications

References 36 publications

Phonon modes of MgB2: super-lattice structures and spectral response

Phonon modes of MgB2: super-lattice structures and spectral response

Pressure effects on the structural and electronic properties of ABX4 scintillating crystals

Pressure‐induced structural phase transitions in materials and earth sciences

Contact Info

Product

Resources

About

Phonon modes of MgB₂: super-lattice structures and spectral response

Phonon modes of MgB₂: super-lattice structures and spectral response