Effectively control negative thermal expansion of single-phase ferroelectrics of PbTiO3-(Bi,La)FeO3 over a giant range

Control of negative thermal expansion is a fundamentally interesting topic in the negative thermal expansion materials in order for the future applications. However, it is a challenge to control the negative thermal expansion in individual pure materials over a large scale. Here, we report an effective way to control the coefficient of thermal expansion from a giant negative to a near zero thermal expansion by means of adjusting the spontaneous volume ferroelectrostriction (SVFS) in the system of PbTiO3-(Bi,La) FeO3 ferroelectrics. The adjustable range of thermal expansion contains most negative thermal expansion materials. The abnormal property of negative or zero thermal expansion previously observed in ferroelectrics is well understood according to the present new concept of spontaneous volume ferroelectrostriction. The present studies could be useful to control of thermal expansion of ferroelectrics, and could be extended to multiferroic materials whose properties of both ferroelectricity and magnetism are coupled with thermal expansion

Giant polarization in super-tetragonal ferroelectric thin films through interphase strain

Strain engineering has emerged as a powerful tool to enhance the performance of known functional materials. Here we demonstrate a general and practical method to obtain super-tetragonality and giant polarization using interphase strain. We use this method to create an out-of-plane–to–in-plane lattice parameter ratio of 1.238 in epitaxial composite thin films of tetragonal lead titanate (PbTiO3), compared to 1.065 in bulk. These thin films with super-tetragonal structure possess a giant remanent polarization, 236.3 microcoulombs per square centimeter, which is almost twice the value of known ferroelectrics. The super-tetragonal phase is stable up to 725°C, compared to the bulk transition temperature of 490°C. The interphase-strain approach could enhance the physical properties of other functional materials.PostprintPeer reviewe

Ferroelectricity in layered bismuth oxide down to 1 nanometer

Atomic-scale ferroelectrics are of great interest for high-density electronics, particularly field-effect transistors, low-power logic, and nonvolatile memories. We devised a film with a layered structure of bismuth oxide that can stabilize the ferroelectric state down to 1 nanometer through samarium bondage. This film can be grown on a variety of substrates with a cost-effective chemical solution deposition. We observed a standard ferroelectric hysteresis loop down to a thickness of ~1 nanometer. The thin films with thicknesses that range from 1 to 4.56 nanometers possess a relatively large remanent polarization from 17 to 50 microcoulombs per square centimeter. We verified the structure with first-principles calculations, which also pointed to the material being a lone pair-driven ferroelectric material. The structure design of the ultrathin ferroelectric films has great potential for the manufacturing of atomic-scale electronic devices.This work was supported by the National Key Research and Development Program of China (2018YFA0703700, 2017YFE0119700, and 2020YFA0406202), the National Natural Science Foundation of China (21801013, 51774034, 51961135107, 62104140, 12175235, 22090042, 12074016, 11704041, and 12274009), the Fundamental Research Funds for the Central Universities (FRF-IDRY-19-007 and FRF-TP-19-055A2Z), the National Program for Support of Top-notch Young Professionals, the Young Elite Scientists Sponsorship Program by CAST (2019-2021QNRC), and Lingang Laboratory Open Research Fund (grant LG-QS-202202-11). Use of the Beijing Synchrotron Radiation Facility (1W1A beamlines, China) of the Chinese Academy of Sciences is acknowledged. Y.-W.F. acknowledges the support of Masaki Azuma’s group during his stay at the Tokyo Institute of Technology. Y.L. acknowledges the support of the Beijing Innovation Team Building Program (grant no. IDHT20190503), the Beijing Natural Science Foundation (Z210016), the Research and Development Project from the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering (2022SX-TD001), and the General Program of Science and Technology Development Project of Beijing Municipal Education Commission (KM202110005003).Peer reviewe

The Genomes of Oryza sativa: A History of Duplications

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000–40,000. Only 2%–3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family

Single-nucleotide polymorphism discovery by high-throughput sequencing in sorghum

<p>Abstract</p> <p>Background</p> <p>Eight diverse sorghum (<it>Sorghum bicolor </it>L. Moench) accessions were subjected to short-read genome sequencing to characterize the distribution of single-nucleotide polymorphisms (SNPs). Two strategies were used for DNA library preparation. Missing SNP genotype data were imputed by local haplotype comparison. The effect of library type and genomic diversity on SNP discovery and imputation are evaluated.</p> <p>Results</p> <p>Alignment of eight genome equivalents (6 Gb) to the public reference genome revealed 283,000 SNPs at ≥82% confirmation probability. Sequencing from libraries constructed to limit sequencing to start at defined restriction sites led to genotyping 10-fold more SNPs in all 8 accessions, and correctly imputing 11% more missing data, than from semirandom libraries. The SNP yield advantage of the reduced-representation method was less than expected, since up to one fifth of reads started at noncanonical restriction sites and up to one third of restriction sites predicted <it>in silico </it>to yield unique alignments were not sampled at near-saturation. For imputation accuracy, the availability of a genomically similar accession in the germplasm panel was more important than panel size or sequencing coverage.</p> <p>Conclusions</p> <p>A sequence quantity of 3 million 50-base reads per accession using a <it>Bsr</it>FI library would conservatively provide satisfactory genotyping of 96,000 sorghum SNPs. For most reliable SNP-genotype imputation in shallowly sequenced genomes, germplasm panels should consist of pairs or groups of genomically similar entries. These results may help in designing strategies for economical genotyping-by-sequencing of large numbers of plant accessions.</p

Microporous Mesoporous Mat.

Three novel organically templated layered cerium materials, [enH(2)](0.5)[(CeF3)-F-IV(HPO4)] (CeFPO), (enH(2)](0.5)[Ce-III (PO4)(HSO4)(H2O)] (CePSO), and [enH(2)](0.5)[Ce-III (SO4)(2)] (CeSO), have been synthesized by hydrothermal synthesis techniques and characterized by single-crystal and powder XRD, TG-DTA, IR, ICP, CHN, and magnetic susceptibility measurement. These compounds possess unique cerium-centered polyhedra CeO3F5, CeO8(H2O), and CeO9, and their layers are separated by the ethylenediaminium cations. (c) 2006 Elsevier Inc. All rights reserved.Three novel organically templated layered cerium materials, [enH(2)](0.5)[(CeF3)-F-IV(HPO4)] (CeFPO), (enH(2)](0.5)[Ce-III (PO4)(HSO4)(H2O)] (CePSO), and [enH(2)](0.5)[Ce-III (SO4)(2)] (CeSO), have been synthesized by hydrothermal synthesis techniques and characterized by single-crystal and powder XRD, TG-DTA, IR, ICP, CHN, and magnetic susceptibility measurement. These compounds possess unique cerium-centered polyhedra CeO3F5, CeO8(H2O), and CeO9, and their layers are separated by the ethylenediaminium cations. (c) 2006 Elsevier Inc. All rights reserved

Coprecipitation synthesis and negative thermal expansion of NbVO5

We develop a coprecipitation synthesis route to prepare NbVO 5 with simple oxide Nb2O5 and NH4VO3 as starting materials. No metal alkoxide or organometallic substance was used in the process. Nano-crystal NbVO5 was obtained by calcination of the coprecipitates at 550°C for 2 h. DSC/TG and XRD investigations indicate that the target compound NbVO5 is completely formed up to 504.5°C and is thermally stable below 658°C. Rietveld XRD refinements give an orthorhombic structure with space group Pnma and lattice parameters, a = 11.8453(2), b = 5.5126(3) and c = 6.9212(2) Å, respectively. In particular, HTXRD determinations show a negative thermal expansion in NbVO 5 with a TEC of -6.63 × 10 -6 °C -1 in the temperature range of RT-600 °C. This fact is ascribed to the tilting of NbO6 octahedra and VO4 tetrahedra in the flexible framework structure. The present synthesis route is facile and easy to be extended to prepare analogues such as TaVO 5, etc

Nd1-xCaxFeO3 (x = 0, 0.3) hollow core-shell microspheres for ethanol gas sensing

The use of mesoporous and hollow structures is a promising strategy to enhance gas-sensing properties. The framework of perovskite oxides has the ability to accommodate different cations, which endows it with rich oxygen deficiencies for preferable gas adsorption. Herein, we outline the fabrication of perovskite Nd1-xCaxFeO3 (x = 0, 0.3) hollow core-shell microspheres by using carbonaceous microspheres as templates. The gas-sensing properties of Nd0.7Ca0.3FeO3 core-shell microspheres were systematically investigated. The response to 500 ppm ethanol was 17 at 140 °C, which is much higher than the response of Nd0.7Ca0.3FeO3 nanoparticles. Also, rapid response and recovery characteristics were achieved. Furthermore, after 50 cyclic tests and 10 testing days, the gas response of the Nd0.7Ca0.3FeO3 hollow core-shell microspheres to 500 ppm ethanol at 140 °C was nearly constant. The long-term stability, good sensitivity, and rapid response and recovery times demonstrate the potential application of these hollow core-shell microspheres as a sensing material. Nd1-xCaxFeO3 (x = 0, 0.3) hollow core-shell microspheres are prepared by a template method, and the sensing properties of Nd0.7Ca0.3FeO3 for ethanol gas detection are studied. The long-term stability, good sensitivity, and rapid response and recovery times demonstrate the potential application of these core-shell microspheres as a sensing material