We report accurate photoionization calculations of resonance energies and widths of the 2pns 1P° and 2pnd 1P° Rydberg series (n = 4–25) of the Be-like ions (Z = 8–18). Calculations are performed using the screening constant by unit nuclear charge (SCUNC) method. The results are analyzed in the framework of the standard quantum defect theory, as well as of the SCUNC-procedure, by evaluating the effective nuclear charge. The results for Na7+ to Ar14+ ions are believed to be the first theoretical data. Those for O4+, F5+ and Ne6+ ions compare well with the available theoretical results. The new data obtained may provide useful guidelines for future photoionization studies on Be-like ions with Z = 11–18.

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Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN–PT) are promising full materials for nonresonant or large bandwidth transducers due to the large values of their piezoelectric properties (dij, kij) and their mechanical quality factor (Qij). However the properties of these materials depend greatly on the content of titanium which influences very significantly the symmetry of the crystal. In this paper we try to understand the influence of the percentage of Titanium in these crystals by studying the two compositions that are in very different phases at room temperature (rhombohedral and tetragonal symmetries). Crystals of pure PZN–4.5PT and PZN-12PT were grown by a Flux technique. The typical single crystals obtained are brown yellow. The room temperature dielectric permittivity along the <001> direction is about 900 for the PZN-12PT, which is smaller than that of the PZN–4.5PT (5840). The Curie point Tc of the tetragonal crystal is about 220 °C (which is higher than that of the rhombohedral one (166 °C)), while the ferroelectric phase transition temperature is 130 °C for the PZN-4.5PT single crystal. The remnant polarization and coercive field of <001> oriented crystals measured at 1 kHz are around 40 μC/cm2 and 3.30 kV/cm, respectively for the PZN-4.5PT, 27μC/cm2 and 11.1 kV/cm for the PZN-12PT single crystal. The d33 versus uniaxial stress shows that this coefficient is more stable for the single crystal with low Ti than for that with high rate of Ti. The study of temperature stability on these crystals shows a possible presence of an unidentified phase in the low and negative range temperature for the PZN-4.5PT.

The title polymeric coordination compound, {[Co2(C10H2O8)(H2O)8]·8H2O}n, was obtained by slow diffusion of a dilute aqueous solution of CoCl2and the sodium salt of benzene-1,2,4,5-tetracarboxylic acid (H4btec) through an agar–agar gel bridge in a U-shaped tube. The two independent Co2+ions are each situated on an inversion centre and are coordinated in a slightly distorted octahedral geometry by four water O atoms and two carboxylate O atoms from two btec4−ligands (-1> symmetry), forming a layer parallel to (11-1). This layer can be described as a molecular two-dimensional square grid with the benzene rings at the nodes and the CoIIatoms connecting the nodes. O—H...O hydrogen-bonding interactions involving the coordinating water molecules, the carboxylate O atoms and lattice water molecules lead to the formation of a three-dimensional network.

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