In the review, peculiarities of spectra of one-dimensional photonic crystals made of anisotropic and/or magnetooptic materials are considered. The attention is focused on band gaps of a special type-the so called degenerate band gaps which are degenerate with respect to polarization. Mechanisms of formation and properties of these band gaps are analyzed. Peculiarities of spectra of photonic crystals that arise due to the linkage between band gaps are discussed. Particularly, it is shown that formation of a frozen mode is caused by linkage between Brillouin and degenerate band gaps. Also, existence of the optical Borrmann effect at the boundaries of degenerate band gaps and optical Tamm states at the frequencies of degenerate band gaps are analyzed.
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http://dx.doi.org/10.3390/ma5061055 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Department of Mechanical Engineering, National University of Singapore, Singapore 117575, Singapore.
The development of efficient sliding ferroelectric (FE) materials is crucial for advancing next-generation low-power nanodevices. Currently, most efforts focus on homobilayer two-dimensional materials, except for the experimentally reported heterobilayer sliding FE, MoS/WS. Here, we first screened 870 transition metal dichalcogenide (TMD) bilayer heterostructures derived from experimentally characterized monolayer TMDs and systematically investigated their sliding ferroelectric behavior across various stacking configurations using high-throughput calculations.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Physics, Florida State University, 612 Keen Building, Florida State University, Tallahassee, Florida, 32306, UNITED STATES.
We argue that alternating-layer structures of lattice mismatched or misaligned (twisted) atomically-thin layers should be expected to be more efficient absorbers of the broad-spectrum of solar radiation than the bulk material of each individual layer. In such mismatched layer-structures the conduction and valence bands of the bulk material, split into multiple minibands separated by minigaps confined to a small-size emerging Brillouin zone due to band-folding. We extended the Shockley-Queisser approach to calculate the photovoltaic efficiency for a band split into minibands of bandwidth $\Delta E$ and mini-gaps $\delta G$ to model the case when such structures are used as solar cells.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, Henan, People's Republic of China.
Silicon germanium alloy materials have promising potential applications in the optoelectronic and photovoltaic industries due to their good electronic properties. However, due to the inherent brittleness of semiconductor materials, they are prone to rupturing under harsh working environments, such as high stress or high temperature. Here, we conducted a systematic search for silicon germanium alloy structures using a random sampling strategy, in combination with group theory and graph theory (RG), and 12 stable SiGe structures in 2-8 stacking orders were predicted.
View Article and Find Full Text PDFCommun Chem
January 2025
National Institute of Chemistry, Hajdrihova 19, SI-1001, Ljubljana, Slovenia.
Iminophosphoranes with the general formula (RP═NR') have great potential in synthetic chemistry as valuable precursors/intermediates in organic synthesis or as building blocks for various organic compounds. However, the synthetic approaches and conditions to prepare iminophosphoranes are still poorly understood, limiting the utility of this chemistry for organic materials. In this article, a simple and efficient synthesis of previously unattainable poly(arylene iminophosphoranes) is reported.
View Article and Find Full Text PDFOMICS
January 2025
OMICS: A Journal of Integrative Biology, New Rochelle, New York, USA.
UN Women is the United Nations "entity dedicated to gender equality and the empowerment of women". UN Women is an example of the institutions of global governance that followed the gender turn in women's rights over the past 2 decades. This opinion commentary unpacks a brief history of UN Women, and the ongoing disparities in gender diversity, equity, and inclusion (DEI) in science, engineering, and medicine, not to mention in science communication, with the aim to shed light on the adverse impacts of gender essentialism and gender binary.
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