In reply to Michel Jullian's message of Wed, 31 Jan 2007 00:43:54 +0100: Hi, [snip] >34 kV/cm ~ 3E6 V/m would be no better than air indeed, maybe the breakdown >field is that of the gas in the pores? > You may be correct.
A couple of other references: --------------------------------------------------------------------------------------- http://semiconductorglossary.com/default.asp?searchterm=silicon+dioxide%2C+SiO2 which yields values in the MV/cm range for some ceramics. --------------------------------------------------------------------------------------- http://en.wikipedia.org/wiki/Dielectric_strength which has 8 MV/m (not cm) for Strontium Titanate. (and 60 for Teflon). --------------------------------------------------------------------------------------- http://72.14.253.104/search?q=cache:1wQMcK_VQaAJ:www.advceramics.com/geac/products/pyrolytic_bn/+%22dielectric+strength%22+ceramics&hl=en&gl=au&ct=clnk&cd=1&client=firefox-a This site claims that Pyrolitic Boron Nitride has the highest dielectric strength known, which is 200 kV/mm which equates to 2 MV/cm (200 MV/m). Yet this is lower than EEStor are claiming for Barium Titanate. Nevertheless, it is in the same ballpark, and slightly better than the Wiki claim for Teflon . --------------------------------------------------------------------------------------- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TX0-49N98HJ-V&_user=10&_coverDate=12%2F31%2F2004&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e20c7d9777c4a9257ddf5733c5ee4900 This one claims a "good" dielectric strength for sintered Barium Titanate with deliberate impurities of 65 kV/cm (6.5 MV/m). --------------------------------------------------------------------------------------- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TW0-44JDBYS-3N&_user=10&_coverDate=11%2F30%2F2001&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6ca5ce5ed69bd6a08b50436cb92ee598 While not directly related to Barium Titanate, this one claims strengths up to 16.7 MV/m (not cm) for some thin coatings specifically made to be non-porous. --------------------------------------------------------------------------------------- http://news.thomasnet.com/news/1305 This appears to be from the Thomas registry, and has a mixture of products/manufacturers with dielectric strengths maxing out at about 400 V/mil = 15.7 MV/m (not cm). --------------------------------------------------------------------------------------- http://www.aist.go.jp/aist_e/latest_research/2004/20041019_3/20041019_3.html This once claims 150-300 kV/mm of greater (300 MV/m) for Alumina films. BTW the cold AD process may be of use to EEStor. --------------------------------------------------------------------------------------- I'm rapidly coming to the conclusion that there is a whole range of figures available and none of them appear to be reliable. (To be fair some people mention the difficulty of measuring this quantity). Perhaps reliable measurements can only be done in high vacuum? Regards, Robin van Spaandonk http://users.bigpond.net.au/rvanspaa/ Competition provides the motivation, Cooperation provides the means.
