c The fits are only sensitive to the b angle because h is nearly zero. depending on the preparation conditions, with NbCx (0.7 ≤ x < 1) yielding quadrupolar 93 Nb signals. Overlapping lines preclude an accurate fitting of the quadrupolar parameters of the NbCx impurity in Nb4AlC3 here but a small CQ (~2 MHz) improved the fit. For Nb2SnC (Figure ), a sharp 93 Nb signal was observed with an isotropic shift of -189(3) ppm; this is 300 ppm higher frequency than the isostructural Nb2AlC. In the wideline static VOCS measurement, Nb metal was also observed as a secondary phase at ~7200 ppm.