Theoretical analysis of the thermal conductivity of diamond in a two-step model

Relative importance of grain boundaries and size effects in thermal conductivity of nanocrystalline materials

“…The calculated values of K 0 and R K are 1265 Wm −1 K −1 and 0.143 × 10 −9 m 2 KW −1 , respectively. Both calculated values of K 0 and R K are consistent with the previously reported results 9 20 25 26 , confirming that our computational method is reliable. The value of single crystal PMFP Λ 0 used in the calculation has been chosen as 180 nm , which is in the range of previously reported values (150 nm 20 and 400 nm 27 ).…”

Magnetic characterization of Ag-sheathed Bi(Pb)2223 tapes

“…The values of J c⊥ at 77 K are lower than the best values [6,7,8] obtained in the literature but they are reasonably high. On the other hand, on comparing our zero-field results with those reported by other authors [6][7][8], a relatively high critical current at T = 4.2 K can be noted; in fact, from extrapolating to 4.2 K the values of J c (77 K) reported in the literature [8,12], for our samples we expected a lower J c (4.2 K). This fact also may be ascribed to the small percentage of strong links in our samples.…”

“…A rapid decrease in J c⊥ with increasing magnetic field is clearly seen; it can be ascribed mainly to the weak connection between the grains which are easily decoupled by a magnetic field [1]. The values of J c⊥ at 77 K are lower than the best values [6,7,8] obtained in the literature but they are reasonably high. On the other hand, on comparing our zero-field results with those reported by other authors [6][7][8], a relatively high critical current at T = 4.2 K can be noted; in fact, from extrapolating to 4.2 K the values of J c (77 K) reported in the literature [8,12], for our samples we expected a lower J c (4.2 K).…”

“…The fact that quite a good fit to the experimental data on sample C (see figure 7) was obtained both by using the Kim-Anderson flux-creep equation ( 4) and by using equation ( 3) suggests that, at least for T near T c , insofar as our data are concerned, it is not possible to discriminate between the basic creep model [17] and a plausible superconducting glass model [7,21].…”

Influence of isotope scattering on the thermal conductivity of diamond

“…A two-step model for the normal processes was also proposed for diamond: 19 in the first step, the normal processes transfer low-frequency phonons into the high-frequency region, in the second step, phonons undergo the resistive processes.…”