Chikara Hirayama

Vapor pressures and thermodynamic properties of lanthanide triiodides

The vapor pressures of the stable lanthanide triiodides from C e l ~ to Tml3 are measured in the Knudsen cell range. The vapor pressures of these compounds are all similar, with a variation of a factor of three between Cel3 and Tml3, the lowest and highest vapor pressures, respectively. The standard enthalpies of sublimation of these iodides do not decrease monotonically with the atomic number of the lanthanides. Thermodynamic properties of the lanthanide triiodides are derived from the vapor-pressure data.

Nd3+ in germanate glasses: spectral and laser properties

The absorption and fluorescent properties of Nd3+ in potassium-barium germanate glasses have been determined. The quantum efficiency of the 1.06 μ emission in the germanates is higher than that in silicates at low Nd3+ concentration; however, concentration quenching sets in at lower activator concentrations in the germanates. 3 × 14inch laser rods had slope efficiencies approaching one percent, and a threshold of 12.4 joules. The gain in a germanate rod, as determined by measurements of threshold vs. resonator reflectivity, was higher than that in barium crown silicate.

Dielectric properties of glasses

It is known that the electrical conductivity of most inorganic glasses is electrolytic in nature and generally determined by its alkali metal content. It has been shown1 from simple assumptions of elasticity and of ionic crystal theory that the Na+ ion has the highest conductivity in glasses, and all observations indicate this. The high mobility of the alkali metal ion is also shown in the high dielectric losses of glasses which contain such ions. Stevels2 and Sutton3 have excellent reviews of the electrical properties of glasses.

Dielectric properties of glasses in the system TiO 2 -Na 2 O-SiO 2

The incorporation of titanium oxide in glasses is widely practiced. From the more fundamental aspect the contribution of the titanium ion to the dielectric properties, particularly the dielectric constant, is of special interest. The dielectric constant of glasses in the TiO<inf>2</inf>-Na<inf>2</inf>O-SiO<inf>2</inf> system has been measured up to 10¹⁰ cycles per second. These glasses have dielectric constants as high as 13 even at this high frequency. The polarisability of Ti⁺⁴ is small as may be seen by comparison of the molar refraction of Ti⁺⁴ (0.47 cm³) with that of Pb⁺⁴ (1.56 cm³) and Ba⁺² (3.9 cm³). Hence, the high dielectric constant of the TiO<inf>2</inf> containing glasses cannot be attributed to the electronic polarization but must be attributed to ionic orientation of the Ti⁺⁴ ion.