Search results for "Lithium iodate"
showing 5 items of 5 documents
Very narrow-bandwidth tunable infrared difference frequency generation with injection-locked dye lasers
1989
Two flashlamp pumped dye lasers of very high spectral quality are mixed in a LiIO3 crystal to generate a tunable infrared beam through the difference frequency mixing. Thanks to the injection-locking process of the pulsed dye lasers leading to a linewidth of 6 MHz with peak powers of about 10 kW, we obtain an IR beam tunable from 3.5 to 5.9 μm with a peak power of 40 W and a linewidth of 9 MHz. As an application we present a spectrum of N2O obtained by differential absorption near 1880 cm−1. The lines of thisQ-branch are Doppler limited at the working pressure (102 Pa).
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 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.
Raman study of crystals
1997
In this work we present a polarized Raman study of single crystals for several values of the concentration made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range . In each of the spectra we found two bands at about 590 and , probably associated with the existence of structures in the solid solutions.
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…