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Halide perovskites are of recent interest for increasing the efficiency of photovoltaic energy conversion devices. The search space for halide perovskites is daunting considering there are over 1700 potential "simple" halide perovskites, not to mention their solid solutions and the additional enormous number of more complex halide perovskites and their solid solutions. Therefore, some questions become: which combination of atoms will form halide perovskites, which will not, and for those that do form halide perovskites, what will their properties be? Goldschmidt's tolerance factor formalism (GTFF), including the more recent Structure Prediction Diagnostic Software (SPuDS) algorithm based on GTFF, have been used over roughly the past century to guide discovery and development of perovskites. Here, four tractable methods: GTFF; SPuDS; coin-flip; and, "new simple" material model (NSMM) are used to investigated which of 864 potential simple halide perovskites should and which should not form. Output of GTFF, SPuDS, coin-flip and NSMM are compared to the literature, including the Joint Committee on Powder Diffraction Standards (JCPDS) files, and scored in a straightforward manner. From analysis of scoring, NSMM is shown to significantly outperform GTFF, including SPuDS, and the coin-flip methods for identifying which simple halide perovskites will and will not form. [ABSTRACT FROM AUTHOR]

BaTiO3 properties can be enhanced to improve capacitor energy storage density through electric-field (E) dipole engineering at the nanoscale (E-DENS). E-DENS allows engineers to modify the internal E through dipole interactions. E-DENS of Ba[(Y3+,Ta5+)xTi1-2x]O3 with 0.0000 ≤ x ≤ 0.0500 are investigated by substituting Y3+-Ta5+ dipole pairs for Ti4+-Ti4+ non-dipolar pairs within the BaTiO3 structure. The Y3+ and Ta5+ ions are more polarizable than Ti4+ and are expected to increase the temperature at which the material becomes cubic and paraelectric. Room temperature XRD, UV-Vis-NIR, LCR, and resistivity analysis have been used to characterize Ba[(Y3+,Ta5+)xTi1-2x]O3 with 0.0000 ≤ x ≤ 0.0500. [ABSTRACT FROM AUTHOR]

The Curie Law and Curie – Weiss Law, empirically determined relations, with experimentally determined Curie constant(s) and Curie temperature(s),Tc, are related, through correlation, to the permittivity. The Clausius – Mossotti relation, a fundamental equation that links: permittivity; index of refraction through the Lorentz – Lorenz equation; and, conductivity through Maxwell's formula; is here shown to incorporate both the ferroelectric Curie Law and Curie – Weiss Law. In light of recent developments with regard to coordination and temperature dependent ion properties, radii and polarizabilities, of Perovskites, it is now possible to model and design temperature dependent properties: lattice parameters and volumes; permittivity; as well as the temperature of polarization induced structural phase transitions; of at least Perovskites through the Clausius – Mossotti equation using fundamental ion properties which also form the foundational basis upon which the indices of refraction, through the Lorentz – Lorenz equation, and, conductivity, through Maxwell's formula, depend. [ABSTRACT FROM AUTHOR]

A comparison study of pure barium titanate BaTiO3, dipole-pair [Ga3+, Ta5+] substituted barium titanate Ba(Ga3+, Ta5+)0.005Ti0.99O3 ([Ga3+, Ta5+]: BaTiO3), single ion [Ga3+] substituted barium titanate Ba(Ga3+)0.01Ti0.99O3 ([Ga3+]: BaTiO3), and single ion [Ta5+] substituted barium titanate Ba(Ta5+)0.01Ti0.99O3 ([Ta5+]: BaTiO3) ferroelectric ceramics have been conducted in order to discern the unique electric and dielectric properties derived from dipole-pair substitution. The band gap, DC resistivity, relative permittivity, dissipation factor, and complex impedance have been measured and analyzed. The dipole-pair substituted material is demonstrated to be an excellent dielectric, which possesses high electrical resistivity, high activation energy, significant dielectric diffuseness, high relative permittivity and low dissipation factor, due to charge compensation and creation of dipole-pairs in barium titanate solid solution ceramic matrix. The single substituted (acceptor and donor, respectively) samples behave more like traditional semiconductors, which have lower electrical resistivity, lower activation energy, and exhibit strong dielectric anomaly and large dissipation factor due to charge imbalance (electrons and holes) in part compensated for through additional defect creation. The relaxor-like behavior of the dipole-pair substituted sample is distinguishable from the classic relaxor through electric properties and structural phase diagram and is anticipated to spark more attention and further exploration. The unique features of electric resistivity and dielectric diffuseness of the dipolar-pair engineered BaTiO3 affords opportunity for designing properties of novel relaxor-like ferroelectrics. [ABSTRACT FROM AUTHOR]

A new model describing physical structural constraints for the formation of “simple” “ideal” cubic perovskites is introduced and compared with Goldschmidt's tolerance formalism. Through a transformation or mapping into ionic radii space, the structural planar constraints of this new model are compared with the planar constraints of Goldschmidt's formalism, a semi-empirical relationship. The new model indicates: (1) a structural volume instability arises that has consistency with Goldschmidt's tolerance formalism, 0.77

A slab geometry, in which ferroelectric is inserted between two "cladding" layers with a microstrip electrode placed on top, is proposed as a way to integrate the properties of ferroelectric materials into microwave components. This structure distributes the propagating microwave fields between the ferroelectric and the cladding, so that the microwave dielectric constant is a weighted average of the dielectric constants of the two materials. It is shown that this geometry drastically reduces dissipation due to dielectric losses in the ferroelectric. In addition, by applying a dc bias to the microstrip line, the dielectric constant of the ferroelectric layer can be varied and with it the microwave properties of the structure. [ABSTRACT FROM AUTHOR]

Dopants play a significant role in electronic material design. In semiconductors, donor and acceptor doping enhance electron and hole conduction, respectively, while simultaneously donor and acceptor doping counteract one another. The role of dopants versus substitutions within dielectrics are not as well studied nor are the effects as well understood. From semi-conductor theory dopant is addition of a small fraction of atoms, roughly less than one part in ten-thousand (to parts per million), and it is not a charge neutral process. In this investigation, the effects of dipole substitution of In and Ta within BaTiO 3 are systematically investigated and frequency and temperature dependent dielectric properties are reported. Experimental data indicate that doping of In and Ta within BaTiO 3 follows semiconductor theory; yet, dipole substitution reduces conductivity and results in the evolution of BaTiO 3 from strict ferroelectric to diffuse phase transition to a relaxor-like ferroelectric within the formed solid solution Ba(In,Ta) y Ti 1-2y O 3 , 0 ≤ y ≤ 0.0375. This work of dipole dopant substitution within BaTiO 3 , provides generalized guidance for developing advanced (novel) materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Structural and electrical properties of Ba[(Ga0.05,Ta0.05)Ti0.9]O3 (BGT) and Ba0.8Sr0.2[(Ga0.05,Ta0.05)Ti0.9]O3 (BSGT) have been characterized to determine the effects of charge compensated dipole-like substitutions on temperature dependent material properties. BGT has a maxima in the relative permittivity curve that corresponds to a tetragonal (P4/mmm) to cubic ( Pm 3 ¯ m) phase transition which is consistent with the Rietveld refinement of XRD data. The ɛr value for BGT is 600 at 100 °C and varies by ∼25% over the temperature range [RT, 170 °C]. Sr addition in the B site of ABO3 is performed to increase the relative permittivity value while maintaining the same trend of temperature insensitivity of relative permittivity. [ABSTRACT FROM AUTHOR]

Physical Science Day at The University of Texas-Pan American (UTPA), in collaboration with the Edinburg Consolidated Independent School District, has been designed, developed and implemented to address an identified fundamental shortcoming in our educational process within this primarily (90+%) Hispanic serving border region. Physical Science Day overcomes the lack of knowledge about what physics is by raising youth awareness of physics as the foundation of science, engineering and technology disciplines, through activities including hands-on laboratory experiments, career orientation, and higher educational student and graduated student testimonials. Thus, Physical Science Day encourages, attracts, and enables more Hispanic youth towards science, technology and engineering disciplines in higher education. Pre- and post-survey results showed that Physical Science Day is effective at increasing student knowledge about physics, physical science, and chemistry programs, raising awareness of broad career opportunities, as well as for stimulating youth interest towards studying such disciplines at UTPA. [ABSTRACT FROM AUTHOR]

Ba{[Gax,Tax]Ti(1−2x)}O3 ceramics with x equal to 0, 0.0025, 0.005, 0.01, 0.025, and 0.05 have been prepared by conventional solid‐state reaction. Structural and dielectric characterization have been performed to investigate the effect of dipole‐pair substitution concentration on the macroscopic dielectric properties. Ba{[Gax,Tax]Ti(1−2x)}O3 evolves from a classic ferroelectric to a diffuse phase transition (DPT) as x increases. Ba{[Gax,Tax]Ti(1−2x)}O3 for x ≥ 0.01 possesses diffuseness parameters comparable to Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT) and recently reported (Ba0.97Pr0.03)(Ti0.9425Ce0.05)O3 (BPTC), yet it lacks the frequency and temperature dependence of Tm necessary to be a strictly defined relaxor ferroelectric. Additionally, Ba{[Ga0.05,Ta0.05]Ti0.9}O3 possesses a relative permittivity, ɛr, of 700 ± 16% and dissipation factor less than 0.05 at 10 kHz within the temperature range [−75°C, 120°C]. In comparison to BaTiO3, Ba{[Gax,Tax]Ti(1−2x)}O3 possesses enhanced electrical resistivity at and above room temperature. In situ XRD, including Rietveld refinement, have been performed to determine the lattice parameter, coefficient of thermal expansion, and phase transition temperature (Tc) of each composition within the temperature range [RT, 1000°C], thus linking the dielectric properties with the material's structure. These studies have been corroborated by temperature‐dependent Raman spectroscopy to compare the Tc determined by electrical and structural characterization. The properties of Ba{[Gax,Tax]Ti(1−2x)}O3 are discussed in context with available models that describe donor and acceptor dopants spatially separated in the parent matrix, inter‐relating lattice parameter, Curie temperature, and other material properties. [ABSTRACT FROM AUTHOR]

A grand challenge with regard to multilayer ceramic capacitor (MLCC) technology is to simultaneously increase permittivity, material break-down strength and resistivity, while reducing material dissipation loss, and temperature sensitivity of permittivity, using reasonably environmentally friendly constituents. Dipole-like substituted barium titanate (BaTiO3), Ba[(M1/20Ta1/20)Ti9/10]O3 where M is a trivalent ion, Sc3+, Cr3+, Mn3+, or Fe3+, and more complicated electric-field interaction materials, Ba[(M1/30Ta2/30)Ti9/10]O3 where M is a divalent ion, Mn2+, Ni2+, or Cu2+, are investigated as potential candidate materials for MLCC technology. Measured temperature dependent, 273 K to 1173 K, electrical conductivity of Ba[(M1/20Ta1/20) Ti9/10]O3 and Ba[(M1/30Ta2/30)Ti9/10]O3 are reported. The dipole-like substituted materials, Ba[(M1/20Ta1/20)Ti9/10]O3, possess activation energies ranging from 2.02 to 2.40 eV and are nearly independent of the M3+ ion utilized. More complicated electric-field interaction materials, Ba[(M1/30Ta2/30)Ti9/10]O3 possess activation energies ranging from 2.50 to 2.61 eV and are nearly independent of the M2+ ion utilized. The results suggest that the introduction of stronger dipole-like electric fields increase the activation energy of the matrix compared to BaTiO3. Hence, dipole-like substituted materials, Ba[(M1/20Ta1/20)Ti9/10] O3, and more complicated electric-field interaction materials, Ba[(M1/30Ta2/30) Ti9/10] O3, which can be used to significantly and controllable tailor the activation energy of BaTiO3 based materials, remain of interest for MLLC technology. [ABSTRACT FROM AUTHOR]

Spectroscopic, structural and electrical properties of Ba[(Ho,Sb)0.05Ti0.9]O3 have been characterized to determine the effects of charge compensated dipole-like (Ho3+, Sb5+) substitutions on temperature dependent material properties. XRD and Rietveld analysis have been used to determine lattice parameters and coefficients of thermal expansion from RT to 1373 K. Capacitance measurements have been conducted over the temperature range [198 K, 1073 K] and frequency range [10 Hz, 1 MHz] to investigate the dielectric properties, including Curie temperature. The microstructural features of the material, observed using a scanning electron microscope, show submicron grain size. The oxidation states of Ho3+ and Sb5+ substitutions within Ba[(Ho,Sb)0.05Ti0.9]O3 have also been indirectly investigated using X-ray photoelectron spectroscopy and are reported in relation to the observed Ti 2p spectrum. Ba[(Ho,Sb)0.05Ti0.9]O3 has a maximum relative permittivity of about 5000 at 267 K that corresponds to an orthorhombic () to tetragonal (P4/mmm) phase transition. Another structural phase transition of Ba(Ho0.05Sb0.05Ti0.9)O3, from tetragonal (P4/mmm) to cubic (), is observed between 623 K and 673 K through a peak in the dielectric constant as well as Rietveld refinement of XRD data. Thus, charge compensated dipole-like (Ho3+, Sb5+) substitutions within BaTiO3 result in the formation of a solid solution as observed through the material Ba[(Ho3+,Sb5+)0.05Ti0.9]O3. Compared with BaTiO3, the material possesses some similar properties, like the same structural sequence with increasing temperature, yet other properties, like diffuseness of the temperature dependent relative permittivity, are fundamentally different and consistent with a dipole-like glass state. Experimental results are compared with several currently utilized models in an effort to better understand the effect that dipole-like substitutions have on material properties. [ABSTRACT FROM AUTHOR]

Ba(Ga,Ta)0.05Ti0.90O3, a B-site dipole-like substituted material is investigated for structural phase transitions over the temperature range 30 to 900°C using x-ray diffraction. Rietveld refinement of the data suggests the material to be Pmm (cubic) from 200 to 900°C, P4/mmm (tetragonal) from 30 to 200°C with phases similar to those of BaTiO3[12]. Average grain size determined using scanning electron microscopy is 650 nm. Measurements of dielectric properties from −50 to 120°C and over a frequency range of 10 Hz to 2 MHz show a relatively flat dielectric constant that is electric-field tunable indicating that Ba(Ga,Ta)0.05Ti0.90O3is a reasonable candidate for frequency agile components. [ABSTRACT FROM AUTHOR]

The microwave ceramic Ba(Y,Sb)0.05Ti0.90O3,based upon random B-site dipole-like substitutions is structurally and electrically characterized over the temperature range −55°C to 120°C. X-ray diffraction information coupled together with scanning electron microscopy reveals that the material is single phase and has submicron grain sizes. Results show the tetragonal phase ranges from −30°C to 200°C, which is a broader temperature range than that of the parent material BaTiO3, 0°C to 120°C. The material Ba(Y,Sb)0.05Ti0.90O3also has a diffuse relative high dielectric constant of about 10,000 that peaks at the orthorhombic-tetragonal structural phase transition around −30°C. [ABSTRACT FROM AUTHOR]

Nanocomposites of single-walled carbon nanotubes dispersed within polyvinylchloride have been obtained by using the solution path. High-power sonication was utilized to achieve a good dispersion of carbon nanotubes. Thermogravimetric analysis revealed that during the synthesis, processing, or thermal analysis of these nanocomposites the released chlorine is functionalizing the single-walled carbon nanotubes. The loading of polyvinylchloride by single-walled carbon nanotubes increases the glass transition temperature of the polymeric matrix, demonstrating the interactions between macromolecular chains and filler. Wide Angle XRay Scattering data suggested a drop of the crystallite size and of the degree of crystallinity as the concentration of single-walled carbon nanotubes is increased. The in situ chlorination and amorphization of nanotube during the synthesis (sonication step) is confirmed by Raman spectroscopy. [ABSTRACT FROM AUTHOR]