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PostPosted: Jan 17, 2010 4:59 pm 
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Axil wrote:
The alkali metal borohydrides contain very high weight fractions of hydrogen..... Its beryllium content will multiply neutrons by a factor of 1.8.

As Cyril said -- what beryllium ??


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PostPosted: Jan 19, 2010 9:12 pm 
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Protactinium Flourides

By Lawrence Stein

Received January 16, 1964

Several protactinium fluorides have been prepeared with 5 to 200 mg. Amounts of Pa231. Tetraflouride, PaF4, is a dark brown compound, isomorphous with UF4 (monoclinic crystal structure), nonvolatile under vacuum up to 800C, and virtually insoluable in water and mineral acids. Protactinium pentaflouride, Pa F5, is a white compound, isomorphous with the B form of UF6 (tetragonal crystal structure), soluble in aqueous hydrofluoric acid. The pentaflouride is much less volatile than its homologs VF5, NbF5, and TaF5, but sublimes or distils under vacuum above 500C. A pentaflouride hydrate of approximate composition PaF5*2H2O is obtained as colorless, needle-like crystals on evaporation of solutions of protactinium in concentrated hydrofluoric acid. The hydrate decomposes at 160C, forming an oxyflouide, Pa2OF8, which is white, isomorphous with U2F8 (body-centered cubic structures), and slightly volatile under vacuum above 500C. The oxyflouride may also be prepared by several other methods.

http://pubs.acs.org/doi/abs/10.1021/ic50017a016


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PostPosted: Feb 19, 2010 4:31 pm 
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redbat wrote:
Protactinium Flourides

By Lawrence Stein

Received January 16, 1964

Several protactinium fluorides have been prepeared with 5 to 200 mg. Amounts of Pa231. Tetraflouride, PaF4, is a dark brown compound, isomorphous with UF4 (monoclinic crystal structure), nonvolatile under vacuum up to 800C, and virtually insoluable in water and mineral acids. Protactinium pentaflouride, Pa F5, is a white compound, isomorphous with the B form of UF6 (tetragonal crystal structure), soluble in aqueous hydrofluoric acid. The pentaflouride is much less volatile than its homologs VF5, NbF5, and TaF5, but sublimes or distils under vacuum above 500C. A pentaflouride hydrate of approximate composition PaF5*2H2O is obtained as colorless, needle-like crystals on evaporation of solutions of protactinium in concentrated hydrofluoric acid. The hydrate decomposes at 160C, forming an oxyflouide, Pa2OF8, which is white, isomorphous with U2F8 (body-centered cubic structures), and slightly volatile under vacuum above 500C. The oxyflouride may also be prepared by several other methods.

http://pubs.acs.org/doi/abs/10.1021/ic50017a016


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PostPosted: Feb 19, 2010 4:33 pm 
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So I wonder what happens when protactinium fluorides are exposed to temperatures over 800C?

Hmmmm........


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