0000000000591398
AUTHOR
Christine Galez
showing 4 related works from this author
Comparative study of electrical behavior and phase transitions in pure and chromium doped α-LiIO3single crystals
1999
Abstract The polymorphic phase transitions of undoped and chromium doped α-LiIO3 crystals have been investigated by means of DTA experiments at slow heating rates and electrical measurements vs temperature and frequency. Upon heating the well known α ⇔ γ ⇒ β sequence appears to be influenced by the sample's morphology, acidity of the growing solution and doping. Dielectric response at room temperature is close to the type “superposition of d.c. ionic conductivity and dipolar response”. We describe the thermal behavior of conductivity along the c polar axis at three frequencies. Electrical measurements also highlight a higher value of ionic conductivity and a less destructive transition for …
Dielectric response of α-LiIO3 acid type crystals
1998
Abstract α-LiIO 3 is often used as non-linear optical material. In view of its preparation, low pH aqueous solutions are used as mother solutions, which give crystals with some hydrogen incorporated to the lattice. Thus, dielectric characterization appears as a very important tool. In this work, the dielectric properties of acid type α-LiIO 3 crystals (conductivity, permittivity, loss-angle tangent) are investigated as functions of temperature and frequency, through an original method allowing seemingly continuous measurements and avoiding space charge contributions to the measurements. The results show the dipolar and low frequency conductivity contributions to the dielectric response. The…
Low-Frequency Relaxation Phenomena in α-LiIO3: The Nature and Role of Defects
2002
The lithium iodate ionic conduction in the polar c-axis direction is studied between 35 and 470 K for crystals grown in various conditions. So far, to separate processes induced by the nature of electrodes, the impedance spectroscopy technique had been used at room temperature with both metallic and ideally polarizable insulating electrodes, so that a relaxation of space charges was clearly identified. Here, the temperature dependence of the hopping ionic conductivity exhibits quite different activation energies well related to the growth conditions. Following low-temperature Raman and thermodynamic experiments, a new approach based on a vacancy diffusion mechanism is proposed. Experimental…
Dielectric characterization and ionic conductivity of α-LiIO3 crystals related to the growth conditions
2000
Abstract The dielectric response of α-LiIO3 has been studied at room temperature between 20 Hz and 1 MHz with various types of electrodes and compared to the results in the literature. By changing the sample thickness, a relaxation of space charges is clearly identified and the bulk ionic conductivity is deduced from the admittance diagram. Finally a comparison is carried out between chromium doped and undoped crystals obtained from acid and neutral growth solutions.