Hence, while the macroscopic observations in figures 4, 5 show differences
between quartz and sapphire as supports, they do
not provide any definitive evidence for the sintering mechanism. The slower rate of sintering of Pd on quartz
compared to sapphire is surprising, since Pd would be
expected to bond more strongly to the sapphire. This is borne out in the contact angle measurements [14], but
since support mobility also contributes to sintering at
these temperatures, the stronger metal support adhesion
may actually lead to enhanced rate of sintering.