A mullite single crystal with composition AlSiO exhibiting sharp satellite reflections was investigated by means of X-ray diffraction. For the refinement of a superspace model in the superspace group Pbam(α0½)0ss different scale factors for main and satellite reflections were used in order to describe an ordered mullite structure embedded in a disordered polymorph. The ordered fraction of the mullite sample exhibits a completely ordered vacancy distribution and can be described as a block structure of vacancy blocks (VBs) that alternate with vacancy-free blocks (VFBs) along a and c. The incommensurate nature of mullite originates from a modulation of the block size, which depends on the composition. The displacive modulation is analyzed with respect to the vacancy distribution and a possible Al/Si ordering scheme is derived, although the measurement itself is not sensitive to the Al/Si distribution. An idealized, commensurate approximation for 2/1 mullite is also presented. Comparison of the ordered superspace model with different preceding models reconciles many key investigations of the last decades with partly contradicting conclusions, where mullite was usually treated as either ordered or disordered instead of considering simultaneously different states of order.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1107/S2052520617001652 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Rotational Locking of Charged Microparticles in Quadrupole Ion Traps.
Phys Rev Lett
December 2024
Laboratoire De Physique de l'École Normale Supérieure, ENS, PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, 75005 Paris, France.
Article Synopsis
- Electric quadrupole traps effectively levitate charged objects, from protons to small particles, influencing their rotational behavior when charge distribution varies.
- Experiments reveal a shift in motion for microparticles, transitioning from librational to synchronized rotation with the trap drive due to torque effects from the electric quadrupole.
- This technique showcases versatility by spinning various particles like silicon microrods and microdiamonds, with the latter enabling detailed motion analysis through embedded nitrogen vacancy centers, promising advances in levitated quantum nanomechanics.
Interplay between A-site and oxygen-vacancy ordering, and mixed electron/oxide-ion conductivity in = 1 Ruddlesden-Popper perovskite SrNdZnO.
Chem Sci
December 2024
College of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 China
Oxygen vacancies in Ruddlesden-Popper (RP) perovskites (PV) [AO][ABO] play a pivotal role in engineering functional properties and thus understanding the relationship between oxygen-vacancy distribution and physical properties can open up new strategies for fine manipulation of structure-driven functionalities. However, the structural origin of preferential distribution for oxygen vacancies in RP structures is not well understood, notably in the single-layer ( = 1) RP-structure. Herein, the = 1 RP phase SrNdZnO was rationally designed and structurally characterized by combining three-dimensional (3D) electron diffraction and neutron powder diffraction.
View Article and Find Full Text PDFYttrium-doped LiTiO nanoparticles as anode for high-rate and high-energy lithium-ion batteries.
Discov Nano
December 2024
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu, 611731, Sichuan, People's Republic of China.
LiTiO (LTO) batteries are known for safety and long lifespan due to zero-strain and stable lattice. However, their low specific capacity and lithium-ion diffusion limit practical use. This study explored modifying LTO through yttrium doping by hydrothermal method to form LiYTiO nanoparticles.
View Article and Find Full Text PDFIn Situ MXene-Controlled Synthesis of Polycrystalline TiO for Highly Efficient Enrichment of Phosphopeptides.
ACS Appl Mater Interfaces
December 2024
Key Laboratory of Phytochemistry and Natural Medicines, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R. China.
Phosphopeptide enrichment methods based on commercial TiO suffer from difficulties in regulating intermolecular interactions, resulting in low coverage rate and the loss of information on multiphosphorylation sites, thereby limiting comprehensive phosphoproteomic analysis. In this work, MXene TiCT was incorporated into the design of enrichment materials, with its surface structure functionalized and regulated to address the low elution efficiency of TiO for multiphosphorylated peptides. Upon oxidation treatment, the TiCT material formed numerous uniformly distributed TiO nanoparticles on the surface of TiCT-O, providing abundant affinity sites (Ti-O) for selective phosphopeptide enrichment.
View Article and Find Full Text PDFWhy do similar 1D-polyhedron-chain copper chloride semiconductors have 2-order-distinct luminescence quantum efficiencies?
J Chem Phys
December 2024
Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People's Republic of China.
The "green" copper halides with one-dimensional polyhedron chains are very interesting novel semiconductors. These weakly interacting parallel quantum wires (1D polyhedron chains) play key roles in their photophysical properties. Unlike Cs3Cu2I5, which has been much investigated, its homologous compounds Cs3Cu2Cl5 and CsCu2Cl3 remain less studied and their properties are controversial.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!