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post #3 of (permalink) Old 11-07-2010, 12:24 AM Thread Starter
Algae Grower
Join Date: Jan 2007
Location: Florida, USA
Posts: 33
well it is pyroelectric and is used in industry, just not sure what that has to do with my fish tank. even the jewelry channel talks about it pyroelectric value

INTRODUCTION Tourmalines are naturally occurring minerals with the general formulaXY3Z6 (B03)3Si6018 (O,OH,F)4'where usuallyX= Na, Ca, ora vacancy, Y=AI, Li, Fe2+, FeH, and many other cations, and Z= AI, Mg, and FeH. It has been known for centuries (Dietrich, 1985) that tourmaline crystals are pyroelectric materials that develop an electrostatic charge when heated or cooled. Careful mea- surementsofthe combined primary and secondary pyroelectric effects in these minerals were first reported by Ackermann (1915). The results of that work showed that tourmaline exhibits pyroelectricity over awidetemper- aturerange. Tourmaline is stable to high temperatures and may find application as an infrared detector where ferroelectric materials such as LaTi03 fail (Hamid, 1980). Importantly, Ackermann's (1915) measurements show that differently colored tourmalines exhibit different degrees of pyroelectricity. For example, black varieties are the weakest whereas rose colored tourmalines are the most strongly pyroelectric. Subsequent investigations support these observations and show that tourmaline pyroelectric coefficients (P'3) range between-1.8 and 5.4~C/(m2. K) at 296K (Hayashi, 1912; Rontgen, 1914; Ackermann, 1915; Gladkiiand Zheludev, 1965; Gavrilova, 1965; Fa- bel and Henish, 1971; DrozhdinetaI., 1975; Gavrilova et al. 1989; the present work). Related studies have shown that piezoelectricity, the inducement of an electric charge by an applied stress, is also stronger in translucent col- oredtourmalines than in certain opaque black varieties (Cady, 1946). None of these previous studies has addressed the vari- ationinthe pyroelectric coefficients with either the pre- cisechemical composition or crystal chemistry of differ- entlycolored tourmalines. Tourmaline crystal chemistry is complex because the size and anion coordination of theX, Y, and Zcationsitesare different. As a result many different cations can be accommodated in tour~ maline by coupled isomorphous substitution (e.g., Henry andGuidotti, 1985; FoitetaI., 1989; Burt, 1989). An indication of this complexity is given by the summary of natural and synthetic tourmaline end-members as well as by the references to their structural descriptions in Table 1" (Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Queensland 4072, Australia)
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