Han Shi-Ying

EPR studies of Fe3+ in Mg-doped LiNbO3 crystals

Abstract The X-band electron paramagnetic resonance of eight LiNbO 3 : Fe crystals with different Mg doping levels and Li Nb ratios was studied at room temperature. The EPR spectra obtained fall into two classes with quite different spin-Hamiltonian parameters. The critical Mg content which distinguishes the two classes decreases (increases) with increasing (decreasing) Li Nb ratio. The sites occupied by the Fe ions in the two classes of crystals are postulated to be different. The spin-Hamiltonian parameters of Fe 3+ in Li-rich LiNbO 3 : Mg(5 mol%): Fe(0.05 wt%) crystals were found to be: g | = 2.025, g ⊥ = 1.910, B 0 2 = 0.266 × 10 −1 cm −1 , B 0 4 = 0.551 × 10 −5 cm −1 , B 3 4 = 0.326 × 10 −3 cm −1 , and those in LiNbO 3 : g | = 1.971, g ⊥ = 1.940, B 0 2 = 0.546 × 10 −1 cm −1 , B 0 4 = 0.290 × 10 −4 cm −1 , B 3 4 = 0.1

Investigation of Nanocrystalline SnO2 by Electron Spin Resonance

Electron spin resonance studies of nanocrystalline SnO2 indicated that the experimental spectrum can be decomposed into two spectra attributed to crystalline and interfacial components respectively. The results confirmed the proposed two components model of nanocrystalline materials.

The XRD study of the effect of slight change in structure on the superconductivity of Y-Ba-Cu-O system material

In this paper the differences in diffraction intensities from some crystal planes in the X-ray diffraction patterns of high Tc Y-Ba-Cu-O system superconductors prepared by different processing conditions and the difference among various structure cells in references are interpreted using computer fitting. The results suggest that there exists two structure cells in the single phase YBa2Cu3O7−x samples. Both structure cells have the same crystal symmetry and almost the same lattice parameters, a=3.821A, b=3.892A and c=11.676A, but the different distortion degree of Cu2-O plane. According to EPR spectra measured on the same samples, it is considered that the improvement of superconductivity for the samples prepared by two-step annealing in flowing oxygen may be related to concentration of the structure cell with more serious distortion on the Cu2-O plane.

Microwave magnetostatic delay line

Abstract A magnetostatic delay line (MSDL) composed of a longitudinally magnetized YIG single crystal rod is constructed. The multiple round trip echoes observed, especially at short delay times, are sucessfully suppressed by changing the sample shape. At S-band the useful delay time controlled magnetically ranges from 0 to 0.5 μs. The untuned insertion losses at 2 and 4 GHz are ⩽26 dB.