Barium halides

Image plates use stimulated luminescence from storage phosphor materials. The commercially available plates are composed of extremely fine crystals of BaFBrEu2+. X-rays excite an electron of Eu2+ into the conduction band, where it is trapped in an F-center of the barium halide with a subsequent oxidation of Eu2+ to Eu3+. By exposing the BaFBrEu" complex to light from a HeNe laser the electrons are liberated with the emission of a photon at 390 nm [38]. 

Barium reacts violently with dilute acids, evolving hydrogen. Reactions with halogens give barium halides ... 

The following ammino-barium halides have been described ... 

Ammino-derivatives of Salts oe Subgroup A—Derivatives of Calcium Halides, Strontium Halides, and Barium Halides. 

In the case of some salts, the volume changes on fusion are smaller than are indicated in Table 5.10. Thus, calcium, strontium, and barium halides have volume changes that are about a fifth of the changes for the corresponding alkali halides. This is because such salts crystallize in a form that already contains plenty of open space in the solid lattice. When these open-lattice salts are melted, a smaller volume increase is needed than is the case for the space-filled lattices of the solid alkali halides. 

A salt contains only barium and one of the halide ions. A 0.158-g sample of the salt was dissolved in water, and an excess of sulfuric acid was added to form barium sulfate (BaS04), which was filtered, dried, and weighed. Its mass was found to be 0.124 g. What is the formula of the barium halide ... 

Most of the alkali metal and barium halides dissolve in water without changing the pH, although there is undoubtedly some hydration of the ions. The alkali metal fluorides give slightly alkaline reactions, however, because of the comparatively low ionisation of HF ... 

The reactions of rubidium and caesium sulphates with barium halides in the solid state and under anhydrous conditions have been studied. With BaCl2, BaBr2, or Bal2, reaction proceeds in two stages in the absence of air to produce BaS04 and the alkali-metal halide at 828—963 K. Conductivity and thermal measurements showed that the exothermic first stage involved formation of a ternary eutectic, whereas the second stage was endothermic. A combination of... 

Barium halides are characterized by high boiling temperatmes, but thermal plasma temperatures are obviously sufiicient to vaporize and dissociate them. Their thermal decomposition can be represented by the dissociation of BaCl2 (Tbou = 1830 K) ... 

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