<div dir="ltr">Marc Papakyriakou,<div><br></div><div>Coincidentally regarding your query, a few days ago the topic of Sr deposition, an alkali metal, came up in the Marvell NanoLab. I'll share a few thoughts but first an anecdote.</div><div><br></div><div>Many of the alkali metals are pyrophoric and strongly react with air and water. With water they liberate H2. I began my career as a research glassblower in a tube lab. Several decades ago, in a clean up of a microwave tube laboratory, we ran across a Copal jar containing metalic sodium (Na) covered in kerosene. My senior colleague asked if I had ever seen what happened when sodium came in contact with water. He filled a large stainless lab sink with water and the lump tossed in the sodium - about the size of an walnut.. It immediately floated (sp. gr. 0.968) and began melting into smaller and smaller droplets, hissing as they spread out over the surface of the water. Each droplet glowed and was surrounded by a the aura of a white cloud. Given the generation of H2 an unanticipated explosion resulted blowing the water in the sink, as well as Na droplets, up onto the ceiling. This came down as a shower of water and some reaming droplets of Na. Fortunately, no one was hurt; everyone was surprised. </div><div><br></div><div>Thus, a graphic demonstration of a alkali metal reacting with water. An artifact of the event was all of the small holes burned into the fabric of our clothes from the hot Na droplets. I lost a good shirt that day.</div><div><br></div><div>Na, along with Ba, Ca, Sr and other alkali metals are routinely used as cathodes and photo-cathodes. The technical issue is how to deposit them in such a way the films not react destroying their properties. Air, Oxygen and water vapor will react upon contact. In the case of creating triple-oxide electron tube cathodes we wanted the oxide; however, the oxides quickly and irreversibly hydrate in the presence of the moisture of air destroying low electron work functions.</div><div><br></div><div>When having to do repair work on cathode assemblies that had been formed we tried a method of using a battery pack to keep the cathodes above 250 C thus preventing oxidation and hydration with some success. In creating photocathodes for photomultipliers we resorted to "dispensers", i.e. an evaporation source that is stable in air and evaporable in situ, under vacuum. </div><div><br></div><div>SAES Getters Inc. offers dispenser-sources such as cessium (I note Sr is not listed. SAES may do custom work or have experience with Sr .</div><div><br></div><div>The big question is how do our labs safely handle more and more of the periodic table and how do researches use classic deposition tools to produce reactive films that are retrievable and workable. </div><div><br></div><div>The safety end of this equation is likely the easiest to solve. </div><div><br></div><div>Regards,</div><div>Bob Hamilton </div><div><br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div><div><div><div><div><br>Robert Hamilton<br></div>University of CA, Berkeley<br>Marvell NanoLab Equipment Manager<br></div>Rm 520 Sutardja Dai Hall, MC 1754<br></div>Berkeley, CA 94720<br></div>Phone 510-809-8618 (desk - preferred)<br></div>Mobile 510-325-7557 (my personal mobile)<br></div>E-mail preferred: <a href="mailto:bob@eecs.berkeley.edu" target="_blank">bob@eecs.berkeley.edu</a><br><a href="http://nanolab.berkeley.edu/" target="_blank">http://nanolab.berkeley.edu/</a><br><br><div><div><div><div><div><div></div></div></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Fri, Feb 27, 2015 at 6:27 AM, Papakyriakou, Marc R <span dir="ltr"><<a href="mailto:mpapakyriakou@gatech.edu" target="_blank">mpapakyriakou@gatech.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear MTL lab network,<br>
<br>
I am a graduate student at Georgia tech and I have a question about possible use of strontium in a cleanroom environment. I am working to get strontium qualified as a material for use in Georgia Tech's cleanroom, but they want to know what handling procedures other cleanrooms use for dealing for strontium before they agree to let it be used. I am specifically trying to sputter pure strontium. Does anyone in this network have experience with using it in this way? And if not specifically strontium, is there a general handling procedure for use of highly reactive and/or pyrophoric materials?<br>
<br>
Thank you,<br>
<br>
Marc Papakyriakou<br>
Graduate Research Assistant<br>
Woodruff School of Mechanical Engineering<br>
Georgia Institute of Technology<br>
<a href="http://www.yeelab.gatech.edu" target="_blank">http://www.yeelab.gatech.edu</a><br>
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