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Electrical conductivity and conduction mechanisms in (Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> ) <sub/>1?x</sub> (BiScO <sub/>3</sub> ) <sub/>x</sub> (0.00 ≤ <i>x</i> ≤ 0.25) solid solutions
摘要： The electrical properties of (Na0.5Bi0.5TiO3)1-x(BiScO3)x (NBT-BS, 0.00 ≤ x ≤ 0.25) solid solutions are established by ac impedance spectroscopy and electromotive force transport number measurements. The bulk conductivity decreases with increasing BS incorporation but the oxide-ion transport number remains high (≥0.85) over a wide compositional range 0.00 ≤ x ≤ 0.15 and drops to ≈0.7 for x ≥ 0.20. NBT-BS solid solutions can only present either predominant oxide-ion conduction or mixed ionic-electronic conduction behaviour, indicating that oxide-ion conduction cannot be fully eliminated by incorporation of BS. This is in contrast from our previous study where incorporation of ≈7% BiAlO3 (BA) can fully suppress the oxide-ion conduction in NBT. The conductivity–composition relationships of NBT-BS solid solutions are attributed to a competing effect from lattice expansion, which enlarges the channel for oxygen ion migration, with trapping between B-site acceptor ions, Sc'Ti, and oxygen vacancies, V??O, which decreases oxygen ion migration. Comparisons between NBT-BS, NBT-BA and NBT-BiGaO3 (BG) solid solutions suggest that small acceptor ions on the B-site are more effective in trapping oxygen vacancies and consequently more effective to suppress the oxide-ion conduction and thus reduce dielectric loss at elevated temperatures.
关键词： transport number,electrical conductivity,solid solutions,sodium bismuth titanate,oxide-ion conduction,conduction mechanisms,impedance spectroscopy,BiScO3
更新于2025-11-14 17:28:48
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Polarization and acoustic properties of barium-modified lead-free potassium–sodium niobate ceramics
摘要： Results of polarization and polarization switching in samples prepared by solid phase synthesis of the (1-х)(K0.5Na0.5)(Nb0.93Sb0.07)O3–xBaTiO3 + 0.5mol%MnO2 system at x = 0.01, 0.02, and 0.04 (KNNS7–xBT) studied over a wide range of temperatures are reported. The observed features of the dielectric nonlinearity at the ferroelectric and structural phase transitions in the materials are described. The dielectric response data of the samples of different contents of the admixture in the KNNS7–xВT ceramics are compared with the behaviour of their elastic properties.
关键词： dielectric permittivity,polarization,solid solutions,elastic properties,relaxors,ferroelectrics,ceramics
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Iasi, Romania (2018.10.18-2018.10.19)] 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Limits and Particularities of the Synthesis of Ba<inf>1-x</inf>Ca<inf>x</inf>TiO<inf>3</inf> for Piezoelectric Applications, by Topochemical Conversion from Molten Salt Solutions
摘要： Because of the unique properties of the ferroelectric perovskite particles with a well-defined anisotropic form like shape- and size dependent at low dimensions they have all the attention of the scientific world. Extensive morpho-structural techniques will be used to characterize the piezoelectric material.
关键词： synthesis,solid solutions,morpho-structural characteristics
更新于2025-09-23 15:22:29
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Mixing Thermodynamics and Photocatalytic Properties of GaP-ZnS solid solutions
摘要： Preparation of solid solutions represents an effective means to improve the photocatalytic properties of semiconductor-based materials. Nevertheless, the effects of site-occupancy disorder on the functional properties of materials are difficult to predict and consequently many experimental trials may be required before achieving enhanced photocatalytic activity. Here, first-principles methods are employed to estimate the mixing free energy and the structural and electronic properties of (GaP)x(ZnS)1?x solid solutions. The method relies on a multi-configurational supercell approach that takes into account the configurational and vibrational contributions to the free energy. Phase competition among the zinc-blende and wurtzite polymorphs is also considered. Overall excellent agreement with the available experimental data is demonstrated, namely: 1) zinc-blende is energetically most favorable, 2) the solid solution energy band gap lies within the 2–3 eV range, and 3) the energy band gap of the solid solution is direct for compositions x ≤ 75%. It is found that at ambient conditions, (GaP)x(ZnS)1?x solid solutions with x ≈ 25%, 50% and 75% render promising hydrogen evolution photocatalysts for water splitting under visible light, owing to their favorable energy band gaps and band levels relative to vacuum.
关键词： multiconfigurational supercell approach,semiconductor solid solutions,density functional theory calculations,photocatalytic materials
更新于2025-09-23 15:22:29
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A thermodynamic potential for barium zirconate titanate solid solutions
摘要： Barium zirconate titanate [Ba(ZrxTi1?x)O3] solid solutions are promising lead-free ferroelectric materials that have received substantial interest. Thermodynamic analysis based on phenomenological Landau–Devonshire theory is a powerful method for theoretical investigation of ferroelectric materials, but cannot be applied to Ba(ZrxTi1?x)O3 because there is no thermodynamic potential. In this paper, a thermodynamic potential for Ba(ZrxTi1?x)O3 (0 ≤ x ≤ 0.3) solid solutions is constructed, and then a thermodynamic analysis carried out. The results accurately reproduce known phase structures and their transition temperatures, with good agreement with experimentally measured polarization, dielectric, and piezoelectric constants. It is found that Ba(ZrxTi1?x)O3 solid solutions at room temperature have three phase boundaries, including a tetragonal–orthorhombic phase boundary at x = 0.013, an orthorhombic–rhombohedral phase boundary at x = 0.0798, and a rhombohedral–paraelectric phase boundary at x = 0.2135. The results also indicate that the chemical composition-induced ferroelectric–paraelectric phase boundary has superior electromechanical properties, suggesting a new way to enhance electromechanical coupling in Ba(ZrxTi1?x)O3 solid solutions.
关键词： Landau–Devonshire theory,electromechanical properties,solid solutions,lead-free ferroelectric materials,Barium zirconate titanate,phase boundaries,thermodynamic potential
更新于2025-09-23 15:21:21
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Soluble and insoluble polymer-inorganic systems based on poly(methyl methacrylate), modified with ZrO2-LnO1.5 (Ln = Eu, Tb) nanoparticles: Comparison of their photoluminescence
摘要： The study of the lanthanide ion luminescence as a function of their environment in polymer-inorganic composites is necessary for better understanding of the electron energy transfer processes in a condensed state. From a practical point of view, these materials are promising for optics and medicine. The nanoparticles of ZrO2-LnO1.5 (Ln = Eu, Tb) solid solutions were synthesized by hydrothermal method. The surface functionalization of the obtained nanoparticles by vinyl groups was carried out using 3-(trimethoxysilyl)propyl methacrylate. Soluble and cross-linked composites based on poly(methyl methacrylate) with ZrO2-LnO1.5 nanoparticles were synthesized using radical polymerization in solution and bulk. Molecular weight, thermal stability, and microhardness of the obtained composite materials were determined. The influence of both the polymerization conditions and the forming composite structure on the lanthanide ion photoluminescence in ZrO2 nanoparticles covalently bonded to the polymer matrix was studied. The combination of ZrO2-EuO1.5 and ZrO2-TbO1.5 nanoparticles in the poly(methyl methacrylate) resulted in the production of composites with photoluminescence spectra overlapping the red and green regions of the visible range. It was shown that the structure of the composite affects the absorbing capacity of luminescent centers and allows shifting the excitation spectrum in the longer wavelength region.
关键词： hydrothermal synthesis,poly(methyl methacrylate),rare-earth ions,solid solutions,zirconia,hybrid nanomaterials
更新于2025-09-23 15:21:21
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Electrophysical and Physical-Chemical Properties of Ohmic Contacts to III-N Compounds
摘要： Experimental data on studying ohmic contacts based on single-layer and multilayer metallizations on GaN and (In, Al, Ga)N solid solutions are analyzed. The contact resistance of the Ti/Al/Mo/Au and Ti/Al/Mo/W/Au metallizations on undoped GaN is studied. The dependences of the contact resistance on the GaN surface treatment before the metallization and on the metallization annealing regimes are investigated.
关键词： gallium nitride,surface treatment,(AlInGa)N solid solutions,ohmic contacts,metallization,charge neutrality level
更新于2025-09-19 17:15:36
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Ruddlesden–Popper 2D Component to Stabilize γ‐CsPbI <sub/>3</sub> Perovskite Phase for Stable and Efficient Photovoltaics
摘要： In this work, a predictive nonrandom two-liquid (NRTL) equation analyzed from binary experimental data is proposed to model the solid?liquid equilibrium in the n-alkanes mixture. The predictive NRTL describes the nonideality of the ordered solid phase, whose binary interaction parameters are obtained from a correlation formula. The mathematical form of the correlation formula is summarized from the relationship between the excess Gibbs free energy and the carbon number mismatch parameter in binary mixtures. The coe?cients of the correlation formula are regressed from binary experimental data. With this model, it is possible to provide ordered-rotator solid transition phase diagrams with complete or partial miscibility. The crystallization behaviors of nine mixtures are also used to test the model, indicating adequate accuracy. Furthermore, the predictive NRTL can predict potential multiple solid solutions, whose number is changeable with the n-alkanes range of the feed, and the concentration of each solid solution is a normal distribution.
关键词： binary interaction parameters,predictive NRTL,multiple solid solutions,n-alkanes,solid?liquid equilibrium
更新于2025-09-19 17:13:59
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Computer simulation for formation of critical spaces in II–VI solid solutions
摘要： Predicting of optimal properties of II–VI materials is an important task in solving the problems of micro- and nanoelectronics. Multicomponent solid solutions based on such semiconductors are promising for modern optoelectronics, for they allow creating devices that operate in a wide spectral range. However, under certain conditions multicomponent solid solutions lose their thermodynamic stability, and thus the properties of the devices based on such materials degrade. Modern methods of computer simulation are used to analyze processes of formation of self-organizing ordered structures. The authors use di?erential topological approach to obtaining multicomponent phase diagrams taking into account the possibility of existence of bifurcation spaces, critical spaces, and spaces of phase coexistence of di?erent orders.
关键词： Solid solutions,Computer simulation,Semiconducting II–VI materials,Phase diagrams,Alloys
更新于2025-09-11 14:15:04
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Parallels and Interrelated Regularities in the Change of the Bulk and Surface Properties of CdBVI–CdTe Systems
摘要： Comprehensive studies of the volume (structural, optical, electrophysical) and surface (acid-base, adsorption) properties of solid solutions and binary components of the CdS–CdTe and CdSe–CdTe systems are carried out. The regularities in the changes of these properties with a variation in the composition and the parallels between the patterns within each system and under their comparison are established. The leading influence of the common binary component, cadmium telluride, on the properties of solid solutions of both systems is revealed. The possibility of predicting the surface activity of these new materials with respect to gases of different electronic natures is shown on the basis of the results of less labor-intensive studies of the bulk physical and chemical properties (in comparison with direct studies of the surface characteristics, i.e., acid-base and adsorption characteristics). Practical recommendations on using the obtained materials in corresponding sensors are made.
关键词： acid-base,adsorption properties,sensors,solid solutions,chalcogenides,new materials,electrophysical,structural,optical
更新于2025-09-11 14:15:04