Solid solution

About: Solid solution is a research topic. Over the lifetime, 27867 publications have been published within this topic receiving 469519 citations.

Synthesis and thermal stability of rare-earths molybdates and tungstates with fluorite- and scheelite-type structure

Abstract: Polycrystalline samples of rare-earths molybdates and tungstates, i.e., CdRE4Mo3O16 (RE = Eu, Gd, Y, Ho) and Pb1–3x□xEu2xWO4 (0 < x ≤ 0.1296 and □ denotes cationic vacancies) have been successfully prepared by high-temperature annealing of adequate CdMoO4/RE2MoO6 and PbWO4/Eu2(WO4)3 mixtures, respectively. According to the X-ray diffraction analysis, the CdRE4Mo3O16 compounds crystallize in a cubic, fluorite-related-type structure with space group $$Pn\bar{3}n$$ . In turn, new Pb1–3x□xEu2xWO4 phases crystallize in the scheelite-type, tetragonal symmetry, space group I41/a. Cadmium and rare-earth molybdates decompose in the solid state and the solid products of their decomposition are two RE molybdates, i.e., RE2MoO6 and RE2(MoO4)3. Thermal stability of CdRE4Mo3O16 decreases with decreasing of RE3+ radius. The melting point of each sample of Pb1–3x□xEu2xWO4 solid solution is lower than melting point of pure matrix, i.e., PbWO4 (1116 °C), and it decreases with increasing in Eu content. Both CdRE4Mo3O16 as well as Pb1–3x□xEu2xWO4 samples are insulators, and their optical band gap (E g) is bigger than 3 eV.

Synthesis and Physicochemical Properties of Crystalline and Glassy La14 – x – yGd x Eu y (BO3 )6(GeO4)2O8 Solid Solutions

Abstract: Using solid-state reactions, La14 – x – yGd x Eu y (BO3)6(GeO4)2O8 solid solutions isostructural with Ln14(BO3)6(GeO4)2O8 (Ln = Pr, Nd, Sm, Eu, Gd) were prepared for the first time, and their melting points and melting behavior were established. Liquid quenching of the solid solutions was found to yield thermally stable glasses containing as much as ≃60 mol % rare-earth oxides. The composition limits of the glass-forming region were determined, and the luminescence spectra of both crystalline and glassy solid solutions were studied.

Investigation on the Decomposition Enthalpy of Novel Mixed Mg(1–x)Znx(BH4)2Borohydrides by Means of Periodic DFT Calculations

Abstract: The combination of Mg(BH4)2 and Zn(BH4)2 compounds has been theoretically investigated as a possible mixed borohydride prone to give an enthalpy of decomposition around 30 kJ/molH2, that is, suitable for a dehydrogenation process close to room temperature and pressure The total energy of pure compounds and solid solutions has been computed by means of periodic DFT calculations To generate the Mg(1–x)Znx(BH4)2 solid solutions, the α-phase of Mg(BH4)2 (space group P6122) has been considered in which Mg2+ ions have been progressively replaced with Zn2+, without lowering the symmetry of the crystalline structure A charge density topological analysis is reported to better understand the chemical bonding in the pure and mixed metal borohydrides The decomposition enthalpy of the mixed borohydrides according to two different reaction paths that lead to MgH2, Zn, H2, and α-B or B2H6, respectively, as products has been estimated As regards the former, a value of about 30 kJ/molH2 has been predicted for a Mg(1–

Phase Diagram of Ternary Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 Ferroelectric Ceramics Prepared Via a B-site Oxide Mixing Route

Abstract: xPb(Mg1/3Nb2/3)O3-yPbZrO3-(1-x-y)PbTiO3 (PMN-PZ-PT) ferroelectric ceramics were prepared by the conventional ceramic processing via a B-site oxide mixing route. Complete solid solutions can be formed for PMN-PZ-PT in the whole composition range studied, which exhibits pure tetragonal, morphotropic phase boundary (MPB) or rhombohedral perovskite structure depending on compositions. Enhanced structure and electrical performance detected by XRD measurement, and dielectric, ferroelectric and piezoelectric properties characterization confirm the MPB effect. Such phenomena correspond well with the composition-induced successively structural change from rhombohedral, across MPB, and to tetragonal perovskite structure with the increase of the PbTiO3 content. The preliminary composition phase diagram of the PMN-PZ-PT system is determined by XRD measurement combining with electrical properties characterization. The mechanisms of the structure and electrical properties enhancement are related to easy paths with flat...

Probing local lattice distortion in medium- and high-entropy alloys

Abstract: The atomic-level tunability that results from alloying multiple transition metals with d electrons in concentrated solid solution alloys (CSAs), including high-entropy alloys (HEAs), has produced remarkable properties for advanced energy applications, in particular, damage resistance in high-radiation environments. The key to understanding CSAs radiation performance is quantitatively characterizing their complex local physical and chemical environments. In this study, the local structure of a FeCoNiCrPd HEA is quantitatively analyzed with X-ray total scattering and extended X-ray absorption fine structure methods. Compared to FeCoNiCr and FeCoNiCrMn, FeCoNiCrPd with a quasi-random alloy structure has a strong local lattice distortion, which effectively pins radiation-induced defects. Distinct from a relaxation behavior in FeCoNiCr and FeCoNiCrMn, ion irradiation further enhanced the local lattice distortion in FeCoNiCrPd due to a preference for forming Pd-Pd atomic pairs.