Spectroscopic Properties of TmF-Doped CaF Crystals.

In this study, we report the growth and comprehensive spectroscopic analysis of TmF-doped CaF crystals, grown using the vertical Bridgman method. The optical absorption and photoluminescence properties of both trivalent (Tm) and divalent (Tm) thulium ions were investigated. Optical absorption spectra in the UV-VIS-NIR range reveal characteristic transitions of Tm ions, as well as weaker absorption bands corresponding to Tm ions.

Phase Transitions and Physical Properties of the Mixed Valence Iron Phosphate Fe(POOH)(HO).

Iron phosphate materials have attracted a lot of attention due to their potential as cathode materials for lithium-ion rechargeable batteries. It has been shown that lithium insertion or extraction depends on the Fe mixed valence and reduction or oxidation of the Fe ions' valences. In this paper, we report a new synthesis method for the Fe(POOH)(HO) mixed valence iron phosphate.

Oxygen storage capacity and structural flexibility of LuFe2O4+x (0≤x≤0.5).

Combining functionalities in devices with high performances is a great challenge that rests on the discovery and optimization of materials. In this framework, layered oxides are attractive for numerous purposes, from energy conversion and storage to magnetic and electric properties. We demonstrate here the oxygen storage ability of ferroelectric LuFe2O4+x within a large x range (from 0 to 0.

Effect of coupled ferroelectric and antiferromagnetic fluctuations on dielectric anomalies in spin induced multiferroics.

Dielectric and magnetodielectric peaks have been evidenced by ε(T, H) measurements in spin induced ferroelectrics: CuCrO(2) and AgCrO(2) delafossites. Such behaviour, also found in several other improper ferroelectrics, can be explained in the frame of Landau analysis of phase transitions with two coupled order parameters: antiferromagnetic ordered moment, L, and polarization, P. The existence of such anomalies in the dielectric constant observed at T(N) is very general.