Creator:F.P. Bundy
Date Created:
Place Created:
Keywords:ultrahigh pressure apparatus calibration
Context:report by F.P. Bundy
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Discussion of ASME Paper Mo. 60-WA-178 "Calibration Techniques in Ultrahigh Pressure Apparatus" (Discussion by the author, F.P. Bundy)
Since the manuscript of this paper was sent in some important experimental results have been reported. These arex
I. 6.C. Kennedy and P.N. LaMori report the following values for the volume transitions listed below, using their improved apparatus:
Bi(l-2)	25.4	tO.lkb
Bi(2-3)	27.9	to.2kb
Tl( 2-3)	36.7	tO.lkb
Cs(1-2)	22.6	to.6kb
Cs(2-3)	41.8	tl.Okb
Ba(2-3)	60	t ? kb
II. H.G. Drickamer	reports	\R tests
his "optical" apparatus1, using optical absorption band edge
1 Fitch, Slykhouse & Drickamer, J.Opt.Soc.Am. 1015(1957)
calibration above 25kb;
low Bi 25 kb Ba 58-60kb high Bi S9-92kb Note that these values for 4R transitions agree quite well with AV transitions reported by Bridgman. This agreement strengthens the belief that the AV and AR transitions originally reported by Bridgman to occur at different pressure are in reality the same phenomena (for a given metal) and that Bridgman's AV values have the best absolute accuracy.
III. Balchan and Drickamer2 have modified their "optical"
o	r''	'	......
A.S, Balchan and H.6. Drickamer, MS submitted to Rev.Sci.
Instr. for publication.
ultra-high pressure apparatus to attain considerably higher pressures and have obtained AR measurements at pressures as high as 500kb. Their calibration for this high pressure range was based on R/Rq as a function of V/Vo of metals like Pt and Pb which exhibit smooth normal behavior in the 0 to 30kb region according to Bridgman's measurements in apparatus with liquid pressure medium. They then extrapolated to pressure higher than 30kb by using PV data for these metals obtained by shock wave methods. Such a large extrapolation (30 to 300kb) would be considered very precarious except that a strong AR transition in Fe was found at 133kb on this scale, which checks very well with a pronounced AV transition already known in Fe at 131kb from shock pressure experiments. Pressures in shock wave experiments are known with an absolute accuracy closer than one percent so that AR transition in Fe found by Balch&n and Drickamer may be considered as a fairly accurate pressure calibration point.
In addition to the Fe transition, Balchan and Drickautei found one in Ba at I44kb, one in Pb at 16lkb, and one in Kb at 193xb. Tbey found a rather broad maximum in tne resistance of Ca at about 375kb.
On the basis of these very recent results it may now be concluded that a fairly reliable absolute pressure calibration scale up to 200kb at room temperature is available, based on the following nine abrupt electrical resistance transitions: low Bi, 25.4kb	Fe, 133kb
Tl# 37 kb	high Ba, 144kb
Cs, 42 kb	Pb, l6lkb
low Ba, 59 kb	Rb, 193kb
high Bi, 89 kb
The B/Ro's vs pressure for these metals are shown graphically in Fig. 1.
Ba
Bi
ca.
Rb
— - » • Fe

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cs,