Alkali borohydrides MBH 4 and their deuterides have been investigated by X-ray and neutron powder diffraction (M = K, Rb, Cs) and by infrared and Raman spectroscopy (M = Na, K, Rb, Cs). At room temperature the compounds crystallize with a cubic high temperature (HT) structure having Fm3m symmetry in which the [BH 4 ] − complexes are disordered. At low temperature (LT) the potassium compound transforms into a tetragonal low temperature structure having P4 2 /n mc symmetry in which the [BH 4 ] − complexes are ordered such as in the isotypic sodium congener. The B-H distances within the complex as measured on the deuteride at 1.5 K are 1.205(3) Å. Indications for a partial ordering in the rubidium and cesium compounds exist but are not sufficient for a full structural characterization. Infrared and Raman spectra at room temperature are fully assigned for both hydrides and deuterides, including the overtones and combination bands, the Fermi resonance type interactions and the 10 B to 11 B splitting due to the presence of natural boron in the samples.

Polycrystalline LiBH has been studied by Raman spectroscopy in the temperature interval 295-412 K and the frequency range 4 21 2 2700-130 cm. The Raman active modes are consistent with the presence of a (BH) ion having a distorted tetrahedral configuration. 4 As the temperature is increased the sudden disappearance of mode splitting points to the onset of a structural phase transition that leads to 2 a higher local symmetry of the (BH) tetrahedron. The transition occurs at |384 K, is of first-order and has a hysteresis of about 8 K. A 4 strong and discontinuous broadening of bands remaining after the transition suggests the onset of large vibrational amplitudes of the 2 (BH) tetrahedra about their trigonal axis. 4

Raman spectra of the alkali borohydride series MBH 4 (M = Li, Na, K, Rb, Cs) have been measured as a function of temperature in the range 300-540 K. For the cubic modification of M = Na, K, Rb and Cs, the analysis of the Raman line widths suggests that the energy barrier of reorientation of the [BH 4 ] − anions decreases as a function of cation size in the sequence Na: 12.1(5), K: 9.2(4), Rb: 8.8(3) and Cs: 8.2(4) kJ/mol. For the hexagonal high temperature modification of LiBH 4 , the data suggest two energy barriers of reorientation at ∼5 and ∼60 kJ/mol, respectively.

Biphasic Calcium Phosphates (BCP) are bioceramics composed of hydroxyapatite (HAp, Ca(PO)(OH)) and beta-Tricalium Phosphate (β-TCP, Ca(PO)). Because their chemical and mineral composition closely resembles that of the mineral component of bone, they are potentially interesting candidates for bone repair surgery. Doping can advantageously be used to improve their biological behaviors; however, it is important to describe the doping mechanism of BCP thoroughly in order to fully appraise the benefit of the doping process. The present paper scrutinizes in detail the incorporation of copper cation in order to correctly interpret the behavior of the Cu-doped bioceramic in biological fluid. The understanding of the copper doping mechanism, related to doping mechanism of others 3d-metal cations, makes it possible to explain the rates and kinetic of release of the dopant in biological medium. Finally, the knowledge of the behavior of the copper doped ceramic in biological environment allowed the tuning of its cytotoxicity properties. The present study resulted on pre-treated ceramic disks which have been evaluated as promising biocompatible ceramic for bone substitute and/or prosthesis coating: good adherence of bone marrow cells with good cell viability.