Search results for "Solid"
showing 10 items of 3575 documents
Sb Effect on Structural, Dielectric, and Ferroelectric Properties of Na0.5K0.5NbO3Ceramics
2015
Lead-free Na0.5K0.5(Nb1-xSbx)O3 (0<x<0.05) ceramics were fabricated by the solid-state reaction method and materials with more than 95% densification were obtained. A microstructure study confirms that the ceramics are well sintered. All compositions show complete perovskite solid solutions. Structural, dielectric and ferroelectric investigations for these specimens were performed. X-ray measurements showed that all compositions have a single perovskite structure with orthorhombic symmetry. Dielectric study revealed that the ceramics obtained are normal ferroelectrics. However some signs of diffuse phase transition were observed. The transition temperatures and the maximum electric permitti…
Synthesis, microstructure and dielectric properties of (1−x)PSN−xPLuN
2008
Ceramic lead niobates and their solid solutions PSN–PLuN (pure lutecium niobate) were synthesized by solid state reactions. The sequence of phases formed at PSN–PLuN synthesis has been studied by X-ray analysis. Their symmetry changed from rhombohedral for PSN to pseudo-monoclinic for the 0.75PSN–0.25PLuN compositions. The performed EDS investigations revealed that the samples PSN–PLuN are perfectly sintered. They contain a little glassy phase and their grains are well shaped. The increase of lutecium content in the examined solid solution caused downward shift of the temperature of the phase transition. The decrease of the achieved permittivity values ϵ was observed as well.
Reorientations and phase transitions in (Kr)1-x(CH4-nDn)x
1990
The condensed isotopic modifications of methane, CH4, CH2D2, and CD4 and their solutions with Kr were investigated using dielectric techniques. The polarizabilities were computed from the permittivities of the pure liquids. Phase diagrams of methane-krypton alloys were deduced in the liquid-solid coexistence region and for the low temperature phases (T<30 K). From the Curielaws, which described the permittivities of the (Kr)1-x(CH2D2)x mixed crystals, the permanent dioole moment of CH2D2 is calculated to be 4 mD. In the octopolar ordered phases of the solid solutions the effective dipole moments are enhanced significantly.
Dielectric properties of BaTiO3 based materials with addition of transition metal ions with variable valence
2013
Dielectric properties of BaTiO3(BT), BaTiO3+0.1wt.%MnO2(BTMn) and BaTiO3+0.1 wt.%Fe2O3 (BTFe) solid solution was investigated. The effects of substitution on the microstructure and on the electric properties of BaTiO3 samples were studied by performing X-ray diffraction and electric measurements. X-ray diffraction analysis of the samples shows the formation of single-phase compound with a tetragonal structure at room temperature. SEM microphotographs exhibit the uniform distribution of grains. The electric properties (a real part of electrical permittivity(e') and an imaginary part of electric modulus (M")) were investigated in the temperature range from 150K to 600K and in the frequency ra…
Structure and dielectric properties of Na<inf>1/2</inf>Bi<inf>1/2</inf>TiO<inf>3</inf>-BaTiO<inf>3</inf&…
2012
Dielectric properties, polarization and x-ray diffraction are studied for (1−x)Na 1/2 Bi 1/2 TiO 3 -xBaTiO 3 solid solutions in a concentration range above the morphotropic phase boundary. It is showed that all the studied compositions have tetragonal structure with maximal tetragonality slightly above the morphotropic phase boundary. Ferroelectric relaxor behavior is observed in a wide concentration range of BaTiO 3 . Stability of the relaxor state decreases with increasing BaTiO 3 concentration, but only for compositions with low Na 1/2 Bi 1/2 TiO 3 content the normal ferroelectric-paraelectric phase transition, which is characteristic to pure BaTiO 3 , occurs. Mechanisms, which influence…
INFLUENCE OF ZIRCONIUM ON STRUCTURAL, MICROSTRUCTURAL AND FERROELECTRIC PROPERTIES OF BaZr0.20Ti0.80O3 CERAMIC
2009
ABSTRACT Barium zirconium titanate BaZrxTi1-xO3 ceramics have been obtained by conventional method. The X-ray diffraction analysis showed that the BaZr0.20Ti0.80O3 crystallizes in the cubic structure. The lattice parameter a increases with temperature, at temperature ∼308 K a small deviation is observed. The performed EDS study revealed that the samples were perfectly sintered and that the material was chemically homogeneous. It contains a little glassy phase and the grains are well shaped. The zirconium content (20 mol%) in the examined solid solution caused downward shift of the temperature T m . The increase of the achieved permittivity values ϵm was observed as well.
Proton glass behavior and hopping conductivity in solid solutions of antiferroelectric betaine phosphate and ferroelectric betaine phosphite.
1991
Measurements of the dielectric permittivity are reported for solid solutions of antiferroelectric betaine phosphate and ferroelectric betaine phosphite at frequencies 10 −2 Hz T c the dielectric response is dominated by ac and dc conduction. The 40% sample exhibits pure relational behavior indicative of a transition into an orientational glass state
Solids and Hydraulic Retention Time Effect on N2O Emission from Moving-Bed Membrane Bioreactors
2018
Biological nutrient removal was operated at different solids (SRT) and hydraulic retention times (HRT) in order to assess their influence on nitrous oxide (N2O) emission from a hybrid moving-bed membrane bioreactor. The observed results show that the N2O production decreased when the SRT/HRT was decreased. The maximum N2O gaseous concentration was measured in the aerobic reactor at the end of phase I, and it decreased through phases II and III. From mass balances over the reactors of the system, the aerated (aerobic and membrane) reactors were the largest producers of N2O, showing that the greater part of N2O was produced during the nitrification process.
Mycotoxin Incidence in Some Fish Products: QuEChERS Methodology and Liquid Chromatography Linear Ion Trap Tandem Mass Spectrometry Approach
2019
The inclusion of vegetal raw materials in feed for fish farming has increased the risk of mycotoxin occurrence in feed, as well as in edible tissues from fish fed with contaminated feed, due to the carry-over to muscle portions. Therefore, the objective of this study was to evaluate the occurrence of 15 mycotoxins in processed fish products, which are commonly consumed, such as smoked salmon and trout, different types of sushi, and gula substitutes. A QuEChERS method was employed to perform the mycotoxin extraction from fish samples. For mycotoxin identification and quantitation, the selected technique was the liquid chromatography-tandem mass spectrometry linear ion trap (LC-MS/MS-LIT). Sm…
Sensitive screening of synthetic cannabinoids using liquid chromatography quadrupole time-of-flight mass spectrometry after solid phase extraction.
2021
Analysis of synthetic cannabinoids still poses a challenge for many institutions due to the number of available substances and the constantly changing drug market. Both new and well-known substances keep appearing and disappearing on the market, making it hard to adapt analytical methods in a timely manner. In this study, we developed a qualitative screening approach for synthetic cannabinoids and their metabolites by means of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Samples were measured in data-dependent auto-MS/MS mode and identified by fragment spectra, retention time and accurate mass. Two established solid phase extractions were compared using fo…