A clear pattern of systematic error is found in thermal expansion values for Al, Ag, and Au commonly recommended and used as internal references for temperature determination in x‐ray diffraction. Evidence comes from a critical analysis of the literature, including several studies of temperature measurement errors in powder cameras, and from new calibration of a thermometer used previously in precise lattice and length expansion studies. Necessary changes in the commonly accepted values for expansion of Pt and MgO are implied.

1.
W.
Hume‐Rothery
and
P. W.
Reynolds
,
Proc. Roy. Soc. (London)
A167
,
25
(
1938
).
2.
J. D.
Wilkinson
and
L. D.
Calvert
,
J. Sci. Instrum.
34
,
545
(
1963
).
3.
T. W.
Baker
,
P. J.
Baldock
, and
W. E.
Spindler
,
J. Sci. Instrum.
43
,
803
(
1966
).
4.
J. A.
Brand
and
H. J.
Goldschmidt
,
J. Sci. Instrum.
33
,
41
(
1956
).
5.
J. L. White, in Physicochemical Measurements at High Temperatures, J. Bockris, J. L. White, and J. D. Mackenzie, Eds. (Butterworths Scientific Publications, London, 1959), p. 344.
6.
W. J. Campbell, in Handbook of X‐rays, E. Kaelble, Ed. (McGraw‐Hill Book Co., New York, 1967), Chap. 13, p. 12.
7.
F. V. Schossberger, Ref. 6, Chap. 14, p. 30.
8.
H.
Esser
and
H.
Eusterbrock
,
Arch. Eisenhuttenw.
14
,
341
(
1941
).
9.
For example see the articles in Advances in X‐ray Analysis, W. M. Mueller, Ed. (Plenum Press, Inc., New York, 1962), Vol. 5,
by W. J. Campbell, S. Stecura, and C. Grain, p. 169;
by F. A. Mauer and L. H. Bolz, p. 229;
by D. A. Vaughan and C. M. Schwartz, p. 238.
10.
S. M.
Lang
,
Acta Cryst.
19
,
210
(
1965
).
11.
R. S.
Pease
,
J. Sci. Instrum.
32
,
476
(
1955
).
12.
R. G.
Merryman
and
C. P.
Kempter
,
J. Amer. Ceram. Soc.
48
,
202
(
1965
).
See also R. G. Merryman, Report LA‐2687, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, 1964.
13.
The most comprehensive summary of published lattice thermal expansion data is W. B. Pearson, Handbook of the Lattice Spacing and Structures of Metals and Alloys (Pergamon Press, Inc., New York, 1967), Vol. II;
see also Vol. I.
14.
R. O.
Simmons
and
R. W.
Balluffi
,
Phys. Rev.
117
,
52
(
1960
).
15.
R. O. Simmons, in Proceedings of the Symposium on Thermal Expansion, R. K. Kirby, Ed. (National Bureau of Standards Miscellaneous Publication, Washington, D.C., 1970).
16.
G.
Bianchi
,
D.
Mallejac
,
C.
Janot
, and
G.
Champier
,
Compt. Rend.
263
,
1404
(
1966
).
17.
A. J.
Cornish
and
J.
Burke
,
J. Sci. Instrum.
42
,
212
(
1965
).
18.
Direct comparison is given in Table I of Ref. 14; subsequent direct comparisons for other metals are given similarly.
19.
R. O.
Simmons
and
R. W.
Balluffi
,
Phys. Rev.
119
,
600
(
1960
).
20.
R. O.
Simmons
and
R. W.
Balluffi
,
Phys. Rev.
125
,
862
(
1962
).
21.
W. J. Campbell, U.S. Bur. Mines Rep. Investig. No. 6115 (1962).
22.
J. B.
Austin
,
Physics
3
,
240
(
1932
).
23.
S. Cohn and Company, Mt. Vernon, New York, reference‐grade material with stated accuracy −0.0,+1 deg near 1000°C.
24.
American Smelting and Refining Company, South Plainfield, New Jersey, Grade A‐58.
25.
R. O.
Simmons
and
R. W.
Balluffi
,
Phys. Rev.
129
,
1533
(
1963
).
26.
Three different Cu specimens melted at indicated thermocouple emfs in the range 10.542 to 10.547 mV. The subsequent N.B.S. calibration table for the thermocouple gave 1083.0°C = 10.546 mV.
27.
N.B.S. Test No. 196319, comparison calibration as described in Sec. 4.1 of N.B.S. Circular 590. Uncertainties were established by N.B.S. not to exceed 5 μV in the range 0° to 1100°C. Near 1100°C one degree is about 12 μV for Pt/Pt‐10% Rh.
28.
Distinction between (Int. 1948) and the 1968 International Practical Scale is almost significant. The Au melting point is 1063.0°C (Int. 1948) or 1064.43±0.2°C (Int. 1968),
C. R.
Barber
,
Metrologia
5
,
35
(
1969
). All the tables in the present paper refer to the former scale.
29.
P. J. Baldock, W. E. Spindler, and T. W. Baker, Report AERE‐R5674 (Her Majesty’s Stationery Office, London, 1968).
30.
D. M.
Shakhtin
,
E. V.
Levintovich
,
T. I.
Pivovar
, and
G. G.
Eliseeva
,
Ogneupory
33
(
8
),
51
(
1968
)
[English transl.: Refractories (Plenum Publ. Corp., New York, 1968)].
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