Spitzer mid-IR spectrum of the PN Tc 1 (black line) compared with the best photoionization model spectrum including α-SiC dust grains only (green line ) are shown (top panel). The C₆₀ (blue line) and C₇₀ (red line) emission bands and UIR plateau emission features are indicated. We note that the narrow emission features seen in the best model spectrum (green line) are just atomic nebular emission lines, whose detailed modeling is out of the scope of the present work. The best photoionization model including α-SiC grains in conjunction with graphite dust grains (green line) is also shown for comparison (bottom panel).