Ternary heterostructured phosphide nanoparticles: MnP@InP

Magnetic MnP nanoparticles have been overcoated with the III–V semiconductor InP (MnP@InP nanoparticles) to create all-phosphide heterostructured nanoparticles. MnP nanoparticles are prepared by reaction of Mn₂(CO)₁₀ with P(SiMe₃)₃ in trioctylphosphine oxide–myristic acid at 220–250 °C for 36–48 h, and successful overcoating was achieved by injection of InCl₃ and P(SiMe₃)₃ followed by heating at 260 °C for 30 min to 4 h. The resultant nanoparticles are spherical, with sizes on the order of 5 to 5.5 nm in diameter and narrow polydispersities (ca. 10%). InP shell thicknesses are estimated to be 0.35–0.55 nm based on the size increase upon addition of the InP precursor mixture relative to primary MnP particles. X-Ray powder diffraction patterns indicate the presence of both MnP and InP crystalline phases. Magnetic susceptibility measurements are consistent with previous data acquired on MnP nanoparticles, indicating that the overlayer does not impact the intrinsic magnetic properties; however, diffuse reflectance UV-visible spectroscopy shows that the optical band gap of InP is completely suppressed. These data are consistent with the formulation of MnP nanoparticles with a distinct InP overlayer in which the semiconducting properties are compromised by the proximity of the metallic core.