The p-type InMnP:Be epilayers, which were prepared by thermal diffusion of Mn through in-situ deposition of Mn layer using molecular beam epitaxy (MBE) onto MBE-grown InP:Be epilayers and subsequent in-situ annealing at 300–350 °C, were investigated. InMnP:Be epilayers prepared by the above sequence clearly showed the Mn-related emission band at 1.1–1.2 eV, which indicates the effective incorporation of Mn2+ ions into the host layer InP:Be. The samples demonstrated very large ferromagnetic hysteresis loops with enhanced coercivity, and the ferromagnetic-to-paramagnetic transition of the samples was observed to occur at ∼85 K. These results suggest that InP-based ferromagnetic semiconductor layers having enhanced ferromagnetism can be effectively formed by the above-mentioned sequential in-situ processes. 相似文献
The low solubility of Er in GaAs results in the formation of ErAs nanostructures when GaAs is grown with 5–6 at% Er/Ga ratio by molecular beam epitaxy on GaAs surfaces. For growth on the (4 1 1)A GaAs surface, cross-sectional scanning transmission electron microscopy images show the presence of ErAs nanorods embedded in a GaAs matrix extending along the [2 1 1] direction with a spacing of roughly 7 nm and a diameter of roughly 2 nm. Growth on the GaAs (4 1 1)B surface resulted in only nanoparticle formation. Variation of the polarized optical absorption with in-plane polarization angle is consistent with coupling to surface plasmon resonances of the semimetallic nanostructures. 相似文献
For application in positron emission tomography (PET), PrP9 , a N,N′,N′′‐trisubstituted triazacyclononane with methyl(2‐carboxyethyl)phosphinic acid pendant arms, was developed as 68Ga3+ complexing agent. The synthesis is short and inexpensive. GaIII and FeIII complexes of PrP9 were characterized by single‐crystal X‐ray diffraction. Stepwise protonation constants and thermodynamic stabilities of metal complexes were determined by potentiometry. The GaIII complex possesses a high thermodynamic stability (log K[GaL]=26.24) and a high degree of kinetic inertness. 68Ga labeling of PrP9 is possible at ambient temperature and in a wide pH range, also at pH values as low as 1. This means that for the first time, the neat eluate of a TiO2‐based 68Ge/68Ga generator (typically consisting of 0.1 M HCl) can be directly used for labeling purposes. The rate of 68Ga activity incorporation at pH 3.3 and 20 °C is higher than for the established chelators DOTA and NOTA. Tris‐amides of PrP9 with amino acid esters were synthesized to act as models for multimeric peptide conjugates. These conjugates exhibit radiolabeling properties similar to those of unsubstituted PrP9 . 相似文献
Potential host systems based on a rigid 1,8‐diethynylanthracendiyl backbone were synthesised by treatment of 1,8‐diethynylanthracene with the Group 13 trialkyls AlMe3, GaMe3, InMe3, AlEt3 and GaEt3. The resulting products were characterised by IR and multinuclear NMR spectroscopy, elemental analyses and determination of their crystal structures by X‐ray diffraction. The compounds are dimeric in the solid state and comprise two M2C2 heterocycles. Depending on the steric demand of the alkyl substituents at the metal atom, different types of binding modes were observed, which can be classified to lie between the ideals of side‐on coordination with almost linear primary M? C?C units and the 3c–2e coordination with symmetrically bridging alkynyl units in M‐C‐M bonds. As a solution in THF the dimers are broken into monomers and some are found to undergo ligand scrambling reactions. 相似文献
The existence of preferential crystallographic alignment in hot pressed and die upset manganese phosphide (MnP) was investigated using magnetic measurements and electron backscatter diffraction (EBSD). Pole figures calculated from the EBSD data show that die upsetting causes the 〈1 1 0〉 directions to align preferentially along the die upset (DU) direction with the 〈0 0 1〉 direction preferentially perpendicular to the DU direction. Magnetic measurements show that the die upsetting can reduce the saturation field relative to that of a similar sample with randomly oriented grains. Since the low-field magnetocaloric effect in single crystals of MnP has been shown to be greatest along the 〈0 1 0〉 direction and smallest along the 〈1 0 0〉 direction, this technique offers a means to achieve the advantages of single crystal alignment with the economy of using bulk processing techniques on polycrystalline material. The peak magnetic entropy change measured with the field applied along the DU direction in the DU sample was 3%, 5%, and 8% greater than the peak entropy change of a randomly oriented powder at fields of 2.0, 1.0, and 0.5 T, respectively. 相似文献
Inner virtue : The reaction of [Mo0(GaCp*)6] with ZnMe2 yields the novel multinuclear zinc system [MoZn12Me9Cp*3] which geometrically resembles a classical Wade–Mingos cluster (with an interstitial molybdenum atom, see picture). In reality, its electronic structure features little direct Zn? Zn bonding, relying instead on Mo? Zn three‐center, two‐electron bonds spanning the body diagonals of the approximately icosahedral framework.