CBN crystals show a one- and a two-dimensionally modulated modification. The former is isotypic with orthorhombic Ba4Na2Nb10O30 and the latter with the tetragonal tungsten bronze type of crystal structure. The orthorhombic form irreversibly transforms to the tetragonal polymorph at the ferroelectric phase transition near 603 K. Orthorhombic and tetragonal CBN24 slightly differ in the distribution of the Ba and Ca atoms over the incompletely filled Me1 and Me2 sites. The tetragonal symmetry is further broken in orthorhombic CBN24 by different amplitudes of the positional modulations of O atoms which are symmetrically equivalent in the TTB structure. A similar orthorhombic phase of CBN31 could be obtained by quenching from 1473 K.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1107/S2052520614011676 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Polar Vortices in Relaxor Ferroelectric Ceramics for High-Efficiency Capacitive Energy Storage.
ACS Nano
January 2025
Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai 201804, P. R. China.
Polar vortices are predominantly observed within the confined ferroelectric films and the ferroelectric/paraelectric superlattices. This raises the intriguing question of whether polar vortices can form within relaxor ferroelectric ceramics and subsequently contribute to their energy storage performances. Here, we incorporate 10 mol % CaSnO into the 0.
View Article and Find Full Text PDFCrystal Structure, Cation Occupation, and Phase Transitions in Ba(LiNa)NbO Tetragonal Tungsten Bronzes.
Inorg Chem
January 2025
Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim 7491, Norway.
The chemical flexibility of the tetragonal tungsten bronze (TTB) structure offers a large potential for compositional engineering. Cation size and vacancy concentration are known to affect its structure, cation disorder, and functional properties. However, the compositional complexity also makes the TTB structure challenging to understand.
View Article and Find Full Text PDFAtomic-scale structure of ZrO: Formation of metastable polymorphs.
Sci Adv
January 2025
Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996, USA.
Metastable phases can exist within local minima in the potential energy landscape when they are kinetically "trapped" by various processing routes, such as thermal treatment, grain size reduction, chemical doping, interfacial stress, or irradiation. Despite the importance of metastable materials for many technological applications, little is known about the underlying structural mechanisms of the stabilization process and atomic-scale nature of the resulting defective metastable phase. Investigating ion-irradiated and nanocrystalline zirconia with neutron total scattering experiments, we show that metastable tetragonal ZrO consists of an underlying structure of ferroelastic, orthorhombic nanoscale domains stabilized by a network of domain walls.
View Article and Find Full Text PDFDual Ferroelectric Polarization and Dielectric Response Improvement in Epitaxial HfZrO/HfO Nanolaminates.
ACS Appl Mater Interfaces
January 2025
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193, Spain.
Nanolaminates based on ferroelectric polycrystalline doped HfO have gained interest because those compounds show enhanced functional properties. Here, we achieve coexisting improvement of remanent polarization and dielectric permittivity in wake-up-free epitaxial HfZrO/HfO nanolaminates with different numbers of HfO nanolayers if compared with HfZrO single films of equivalent thickness or other reported polycrystalline nanolaminates. Comprehensive structural characterization reveals that the origin of the enhancement must be the larger amount of the orthorhombic phase in the nanolaminates.
View Article and Find Full Text PDFBirch-Bark-Inspired Synergistic Fabrication of High-Performance Cellulosic Materials.
ACS Sustain Resour Manag
December 2024
FSCN Research Center, Organic Chemistry, Mid Sweden University, Holmgatan 10, 851 70 Sundsvall, Sweden.
There is a growing demand for the utilization of sustainable materials, such as cellulose-based alternatives, over fossil-based materials. However, the inherent drawbacks of cellulosic materials, such as extremely low wet strength and resistance to moisture, need significant improvements. Moreover, several of the commercially available wet-strength chemicals and hydrophobic agents for cellulosic material treatment are toxic or fossil-based (e.
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!