各向异性双3次Hermite元的超收敛性与点态超收敛性

本文研究了双三次Hermite 矩形元的超收敛问题. 利用双线性引理和Bramble-Hilbert引理, 在无正则性条件的假设下, 得到了双三次Hermite 矩形元的自然超收敛性及点态超收敛性结果.该结论与传统的有限元正则条件下的结论一致; 与传统的超收敛分析方法-积分恒等式法相比, 本文的方法既简单又便于推广.     

Defect characterization and magnetic properties in un-doped ZnO thin film annealed in a strong magnetic field

Highly c-axis oriented un-doped zinc oxide（Zn O） thin films, each with a thickness of ～ 100 nm, are deposited on Si（001） substrates by pulsed electron beam deposition at a temperature of ～ 320℃, followed by annealing at 650℃ in argon in a strong magnetic field. X-ray photoelectron spectroscopy（XPS）, positron annihilation analysis（PAS）, and electron paramagnetic resonance（EPR） characterizations suggest that the major defects generated in these Zn O films are oxygen vacancies. Photoluminescence（PL） and magnetic property measurements indicate that the room-temperature ferromagnetism in the un-doped Zn O film originates from the singly ionized oxygen vacancies whose number depends on the strength of the magnetic field applied in the thermal annealing process. The effects of the magnetic field on the defect generation in the Zn O films are also discussed.