Emergent low-symmetry phases and large property enhancements in Ferroelectric KNbO3 bulk crystals

The design of new or enhanced functionality in materials is traditionally viewed as requiring the discovery of new chemical compositions through synthesis. Large property enhancements may however also be hidden within already well-known materials, when their structural symmetry is lowered from equilibrium through a small local strain or field. This work reports on the discovery of enhanced material properties associated with a new metastable phase of monoclinic symmetry within bulk KNbO3. This phase is found to co-exist with the nominal orthorhombic phase at room temperature, and is both induced by and stabilized with local strains generated by a network of ferroelectric domain walls. While the local microstructural shear strain involved is only ~0.017%, the concurrent symmetry reduction results in an optical second harmonic generation response that is over 550% higher at room temperature.Moreover, the meandering walls of the low symmetry domains also exhibit enhanced electrical conductivity on the order of 1 S m-1. This discovery reveals a potential new route to local engineering of significant property enhancements and conductivity through symmetry lowering in bulk ferroelectric crystals

Crystallographic data of double antisymmetry space groups

This paper presents crystallographic data of double antisymmetry space groups, including symmetry-element diagrams, general-position diagrams and positions, with multiplicities, site symmetries, coordinates, spin vectors, roto vectors and displacement vectors.</jats:p

Thermodynamic Stabilization of Grain Size in Nanocrystalline Metals

This paper describes the stabilization of nanocrystalline grain sizes in Pd and Fe by the addition of Zr solute atoms. The grain size as a function of annealing temperature was measured by both x-ray diffraction (XRD) line broadening analysis and microscopy methods. The latter methods showed that the XRD grain size measurements for the samples annealed at the higher temperatures were not valid. It appears that thermodynamic stabilization may still be operative in the Fe-4at.% Zr alloy but not in the Pd-19at.% Zr alloy from the experimental results and calculations of the enthalpy of segregation.</jats:p

Growth, Evapotranspiration, and Ion Uptake Characteristics of Alfalfa and Triticale Irrigated with Brackish Groundwater and Desalination Concentrate

Persistent drought, low snowfall, and low rainfall have reduced availability of fresh water for irrigating agricultural crops in many arid and semi-arid regions of the world. Brackish groundwater (electrical conductivity; EC &gt; 3 dSm&minus;1) is increasingly used for irrigation in New Mexico. This study investigates the effect of ion uptake from brackish groundwater and concentrate irrigation on the performance of two forage species, alfalfa (Medicago sativa) and triticale (&times;Triticosecale), in sand soils in greenhouse conditions. Two simultaneous experiments were run for 90 days using tap water (control; 0.7 dSm&minus;1), brackish groundwater (BGW; 4 dSm&minus;1), reverse osmosis concentrate (RO; 8 dSm&minus;1, Ca2+ dominant), and BGW plus sodium chloride (BGW + NaCl; 8 dSm&minus;1, Na+ dominant). BGW + NaCl irrigation significantly reduced the evapotranspiration (ET) of both the species. Deep percolation (DP) increased significantly with RO and BGW + NaCl irrigation in alfalfa but only with BGW + NaCl irrigation in triticale. Alfalfa plant growth decreased with increasing salinity, while triticale plants followed an opposite trend. ET continued to decrease with increasing salinity for both species. Na+ dominant (BGW + NaCl) irrigation produced robust growth and early flowering and ear head formation in triticale. Na+ ion concentration in shoots was above 0.66%, which led to reduced alfalfa growth, while more than 1.22% did not decrease triticale growth or biomass. Increased Ca2+ sequestration in alfalfa played a crucial role in reducing Na+ ion toxicity. Species performance primarily confirmed that alfalfa is moderately salt-tolerant while triticale is confirmed to be a halophyte producing abundant growth and biomass with higher Na+ uptake. Triticale proved to be a promising species for reuse of RO concentrate for agriculture in marginal lands

Germination and Emergence Responses of Alfalfa, Triticale and Quinoa Irrigated with Brackish Groundwater and Desalination Concentrate

Increasing human population has raised the demand for food and forage production for a secure future. Current agriculture is challenged by increasing salinity and decreasing vegetation, especially in the arid and semi-arid regions of the world. Western United States, especially, New Mexico is confronting continued drought, sodic soils, and degrading rangelands. Groundwater is increasingly used to supplement surface water for irrigation, despite being brackish, with an EC greater than 3 dSm−1. One way to supplement irrigation water supply is to desalinize brackish groundwater using a reverse osmosis (RO) process and utilize the RO concentrate to irrigate food and forage crops. The objective of this study were to determine the germination and emergence of three species, alfalfa (Medicago sativa-VNS (variety not stated)), triticale (×Triticosecale (VNS)), and quinoa (Chenopodium californicum-hand selected from native stand in S. California), when irrigated with brackish and RO concentrate waters. A germination experiment was conducted with alfalfa, triticale, and quinoa for 20 days in growth chambers set at their optimum germination temperatures of 29/18 °C, 17/7 °C, and 17/7.2 °C day/night, respectively, with a 12-hour photoperiod. An emergence experiment was conducted with the same species under controlled conditions in a greenhouse. In both the experiments, seeds were irrigated with four irrigation water salinity treatments (EC 0.7 dSm−1 (tap water as control)), 4.0 dSm−1 brackish groundwater (BGW), 8.0 dSm−1 reverse osmosis concentrate (RO), and 10.0 dSm−1 (BGW + NaCl) irrigation. Germination %, and emergence %, mean germination and emergence time, germination and emergence index, Timson’s index and Timson’s modified index were calculated. Results showed triticale had the highest germination % (80.5% as soils main effect and 87.84 % as species main effect irrespective of salinity) and emergence % (91.25% with control and BGW, 87.19% with RO) while quinoa was the most sensitive to salinity. Sand soil was favorable promoting higher germination up to 8 dSm−1 and clay soil promoted good emergence in alfalfa and triticale. The mean germination and emergence time was the shortest for triticale followed by alfalfa and longest for quinoa. This clearly demonstrates triticale as a promising salt tolerant forage species that can be cultivated in dry and degraded rangelands.</jats:p