The results of a round robin series of measurements of the thermal conducti
vity and thermal diffusivity of chemical-vapor-deposited (CVD) diamond are
reported. The present round robin (RR2) is an outgrowth of an earlier serie
s (RR1) aimed at understanding which measurement techniques are best suited
to measuring the high conductivity of CVD diamond. RR2 includes diamond sp
ecimens of higher homogeneity, non-diamond specimens of lower conductivity
as controls, and measurements by 14 laboratories using five techniques, wit
h all techniques but one used by more than one laboratory. The data are con
verted to thermal conductivity at 25 degrees C to facilitate comparisons am
ong specimens and laboratories. The statistical analysis excludes outliers
using Chauvenet's criterion, resulting in data from typically two or three
laboratories being excluded for each specimen. The analysis arrives at mean
values in the range 1300-2000 W m(-1) K-1 for the diamond samples, as expe
cted because of the conditions of preparation, with uncertainties in the ra
nge 1.5-4%. For the non-diamond materials, SIC and AIN, the results are 268
W m(-1) K-1 +/- 2.2% and 178 W m(-1) K-1 +/- 2.5%, respectively. Comparing
techniques, the d.c.-heated bar is found to be the most accurate, typicall
y +/-5% or better. Under favorable conditions, Angstrom's thermal wave meth
od can apparently yield relative uncertainties of +/-5-10%, and the mirage
effect +/-5-15%. Too few laboratories used the transient thermal grating an
d laser flash methods to make general comments on their accuracy, but one e
xpects a comparable accuracy if used on specimens that are fine-grained and
thermally isotropic. Deviations, sometimes large, from these optimal accur
acies are examined, and it is suggested that certain experimental details a
re important for achieving accuracy. It is also found that the estimates of
experimental uncertainty provided by most laboratories seriously underesti
mate the actual deviations of their data from the mean conductivity. (C) 19
98 Elsevier Science S.A. All rights reserved.