The software program SPuDS has been developed to predict the crystal structures of perovskites, including those distorted by tilting of the octahedra. The user inputs the composition and SPuDS calculates the optimal structure in ten different Glazer tilt systems. This is performed by distorting the structure to minimize the global instability index, while maintaining rigid octahedra. The location of the A-site cation is chosen so as to maximize the symmetry of its coordination environment. In its current form SPuDS can handle up to four different A-site cations in the same structure, but only one octahedral ion. Structures predicted by SPuDS are compared with a number of previously determined structures to illustrate the accuracy of this approach. SPuDS is also used to examine the prospects for synthesizing new compounds in tilt systems with multiple A-site coordination geometries (a(+)a(+)a(+), a(0)b(+)b(+), a(0)b(-)c(+)).

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Prediction of the crystal structures of perovskites using the software program SPuDS.

Luminescence and scintillation characteristics of four selected material systems, namely CsI:Tl(Na), CeF 3 , PbWO 4 and Ce-doped aluminium perovskites XAIO 3 :Ce (X=Y, Lu, Y-Lu) are reviewed. The progress in their physical understanding and related optimisation of their characteristics and technology are demonstrated. The important role of various defect states in the scintillator performance of these materials is stressed, which has led to the need for a deeper study of the processes of energy transfer and storage to achieve their intrinsic limits and full exploitation in scintillation detectors.

Wide Band Gap Scintillation Materials: Progress in the Technology and Material Understanding

The phosphorescence mechanisms of various phosphors were explored by taking into consideration the presence of interactions between dopant cations and vacancies as well as the effect of co-dopant cations on these interactions. Our study indicates that the distribution of dopant and co-dopant cations around vacancies is not random, and luminescent properties are strongly influenced by this nonrandom distribution. To a first approximation, the ionization potentials of dopants, co-dopants, and host cations can be used to rationalize their tendencies for this nonrandom distribution. On the basis of our analysis, we explained the properties of known phosphorescent materials, examined several factors important for designing new improved phosphors, and discussed how point defects might affect phosphorescence as well as fluorescence.

Formulation of phosphorescence mechanisms in inorganic solids based on a new model of defect conglomeration

Revised versions of our published pob-TZVP [Peintinger, M. F.; Oliveira, D. V. and Bredow, T., J. Comput. Chem., 2013, 34 (6), 451-459.] and unpublished pob-DZVP basis sets, denoted as pob-TZVP-rev2 and pob-DZVP-rev2, have been derived for the elements HBr. It was observed that the pob basis sets suffer from the basis set superposition error (BSSE). In order to reduce this effect, we took into account the counterpoise energy of hydride dimers as an additional parameter in the basis set optimization. The overall performance, portability, and SCF stability of the resulting rev2 basis sets are significantly improved compared to the original pob basis sets. © 2019 Wiley Periodicals, Inc.

BSSE-correction scheme for consistent gaussian basis sets of double- and triple-zeta valence with polarization quality for solid-state calculations.

Recent progress in developing new rare earth materials for hole burning and coherent transient applications

Growth and physical properties of fresnoite Ba2TiSi2O8

Crystal structure of GdFeO3-type rare earth gallates and aluminates

Second harmonic generation in fresnoite, Ba2TiSi2O8

Color centers created during growth processes as well as formed under various external influences (UV and γ-irradiation, thermal treatments) are studied in YAP–Nd crystals obtained under different technological conditions. The role of impurity ions (including Fe and Cr) in growth and induced crystal coloration as well as models of color centers are discussed.

F. Wallrafen

Papers

Growth and physical properties of fresnoite Ba2TiSi2O8

Crystal structure of GdFeO3-type rare earth gallates and aluminates

Second harmonic generation in fresnoite, Ba2TiSi2O8

Growth and Induced Color Centers in YAlO3–Nd Single Crystals

Photo and gamma induced color centers in the YAlO3 and YAlO3 : Nd single crystals