Fuxiang Zhang

Green emission from B2N2CO thin films doped with Tb

Visible light emission has been obtained at room temperature by photoluminescence (PL) and cathodoluminescence (CL) from Tb-doped B2N2CO thin films prepared by radio-frequency magnetron sputtering. The films were deposited by sputtering TbBn (n=4, 6, 12, 25, and 50) targets in an atmosphere of Ar and N2 gas mixture. The films are uniformly composed of very small particles with particle size of about 20–40 nm, which consist of turbostratic BN phase and amorphous phase. The characteristic PL peaks are observed in the spectral range from 300 to 800 nm, and correspond to the two groups of transitions of Tb3+ ions: 5D3→7FJ (J=6, 5, 3) and 5D4→7FJ (J=6, 5, 4, 3). The strongest PL peak at ∼547.2 nm is about four times greater than the other signals in the investigated range, indicating that the films have strong green light emission. CL intensity is very weakly dependent on the temperature.

Incorporation of carbon atoms in rare earth boron-rich solids and formation of superstructures

Abstract The boron-rich solid of YB 25 can incorporate certain amounts of carbon atoms. With increase of carbon content, two kinds of superstructures of YB 25 , which modulate the basic structure in the (001) plane, appeared. The framework of boron icosahedra in the superstructures remains the same as that of YB 25 and the structural modulation is just caused by the variation of carbon distribution in the voids of the framework. In addition, one superstructure with a large unit cell is quenchable and transformed into another superstructure by thermal annealing at 1400°C for 80 h.

Low-temperature magnetism of the compound GdB18Si5

Low-temperature magnetic properties of single crystals of the B12 cluster compound GdB18Si5 (Rm) were investigated. A sharp drop in the a– b in-plane magnetic susceptibility is observed at TN = 3.2 K indicating an antiferromagnetic transition. Anisotropy between the in-plane and c-axis susceptibilities is observed, consistent with the spins ordering in the a– b plane. The logarithm of the resistivity follows the hopping T−0.25-behaviour which has been typically observed for B12 icosahedral boron-rich solids, and this indicates that the typical Ruderman–Kittel–Kasuya–Yosida interaction is not the mediating interaction. A λ-like peak is observed in the magnetic specific heat at 3.2 K and supports the notion of a long-range-order antiferromagnetic transition occurring in this system.

Crystal structure of new rare-earth boron-rich solids: REB28.5C4

Abstract New rare-earth boron-rich solids of the composition REB 28.5 C 4 (Re=Y, Ho, Er, Tm and Lu) were synthesized by solid state reaction and single crystals were grown using a high temperature metal solution method. The structure was solved by a direct method from single crystal X-ray diffraction data with Y–B–C as a representative. It shows a layered structure with trigonal symmetry (space group: R 3 m (No. 166)) and the unit cell parameters are: a = b =5.6457(9) A, c =56.8873(13) A.