High‐Pressure Behavior of Mullite: An X‐Ray Diffraction Investigation

Kalita, Patricia; Schneider, Hartmut; Lipinska, Kristina; Sinogeikin, Stanislav V.; Hemmers, Oliver; Cornelius, Andrew

doi:10.1111/jace.12191

Cited by 9 publications

(15 citation statements)

References 37 publications

(70 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further out to the undeformed parts of the crystal areas of high plastic deformation with dislocation networks, radial microcracks and bend contours occur . Degradation of the mullite crystal structure versus a complete loss of the long‐range order by microindentation may be compared with similar effects produced by static and dynamic pressure loading and by intense ball milling …”

Section: Properties Of Mullitementioning

confidence: 99%

Mullite: Crystal Structure and Related Properties

2015

Self Cite

View full text Add to dashboard Cite

Mullite is certainly one of the most important oxide materials for both conventional and advanced ceramics. Mullite belongs to the compositional series of orthorhombic aluminosilicates with the general composition Al 2 (Al 2+2x Si 2-2x )O 10-x . Main members are sillimanite (x = 0), stoichiometric 3/2-mullite (x = 0.25), 2/1-mullite (x = 0.40), and the SiO 2 -free phase ι-alumina (x = 1, crystal structure not known). This study gives an overview on the present state of research regarding single crystal mullite. Following a short introduction, the second part of the review focuses on the crystal structure of mullite. In particular, the characteristic mullite-type structural backbone of parallel chains consisting of edge-sharing MO 6 octahedra and their specific cross-linkage by TO 4 tetrahedra is explained in detail, the role of cation disorder and structural oxygen vacancies is addressed, and the possibility of cation substitution on different sites is discussed. The third part of the study deals with physical properties being relevant for technical applications of mullite and includes mechanical properties (e.g., elasticity, compressibility, strength, toughness, creep), thermal properties (e.g., thermal expansion, heat capacity, atomic diffusion, thermal conductivity), electrical conductivity, and optical properties. Special emphasis is put on structure-property relationships which allow for interpretation of corresponding experimental data and offer in turn the possibility to tailor new mullite materials with improved properties. Finally, the reported anomalies and discontinuities in the evolution of certain physical properties with temperature are summarized and critically discussed.

show abstract

Section: Properties Of Mullitementioning

confidence: 99%

Mullite: Crystal Structure and Related Properties

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…on the elastic behavior and pressure‐induced structural evolution of 2:1 and 3:2 mullite in comparison to sillimanite. The response of materials to high‐pressure offers a sensitive probe of their structural integrity, structural instabilities, and possible phase transitions . Moreover, investigations of pressure‐induced structural changes in mullites will also contribute to the in‐depth fundamental understanding of their crystal chemistry.…”

Section: Introductionmentioning

confidence: 99%

High Pressure Behavior of 7:4 Mullite and Boron‐Substituted Mullite: Compressibility and Mechanisms of Amorphization

et al. 2014

Self Cite

View full text Add to dashboard Cite

The high-pressure elastic properties behavior, phase stability, and mechanisms of amorphization of the alumino-silicate 7:4 mullite and a corresponding mullite doped with boron were investigated in situ by powder synchrotron X-ray diffraction with a diamond anvil cell in quasi-hydrostatic conditions. The samples of 7Al 2 O 3 :4SiO 2 (Al 4.66 Si 1.33 O 9.67 ), referred to as 7:4 mullite and an alumino-silicate mullite with 3.5(4) mol% B 2 O 3 , referred to as B-mullite, were compressed, in small pressure steps, up to 27.8 and 28.9 GPa, respectively, and then decompressed back to ambient pressure. All along the compression path both samples' patterns are indexable with a mullite structure. Compression data are smooth up to a threshold pressure, from which point the diffraction peaks appeared to broaden, and the refined unit cell parameters deviate significantly down from the compressional trend. Above~23 GPa the diffraction patterns are not indexable anymore, suggesting amorphization. Rietveld structural refinements allow for a description of the pressure-induced main deformation mechanisms and structural trends. Pressure-induced mechanisms of amorphization are also discussed. A third-order Birch Murnaghan equation of state is fitted to the pressure-volume data to obtain experimental bulk moduli, as well as axial compressibilities for 7:4 mullite and B-mullite. Finally the volume compression in response to the applied pressure, combined with thermal expansion coefficients, allows a P-T-V equation-of-state for B-mullite to be proposed.

show abstract

“…For different mullite types, Al 4+2x Si 2−2x O 10−x , the composition of the mullite significantly changed the required pressure for amorphisation (20 GPa or more than 22 GPa, whereas for one kind of mullite only partial amorphisation was observed even above 30 GPa [10]). CePO 4 monazite can be amorphised via Kr 2+ irradiation as confirmed by selective area electron diffraction.…”

Section: Introductionmentioning

confidence: 99%