Qinghui Li

Room temperature ferromagnetism of Fe-implanted ZnO film

The ZnO-based diluted magnetic semiconductors (DMSs) with room temperature ferromagnetism were achieved by ion implantation. Fe+ ions at 80keV with doses ranging from 1×1016to8×1016cm−2 were implanted into n-type ZnO films at room temperature. Subsequently, the samples were annealed at 700°C for 1h in air ambient. The Fe-implanted content was determined by proton induced x-ray emission. The magnetic property was measured by the Quantum Design MPMS superconducting quantum interference device magnetometer. No trace of secondary phases or clusters was observed within the sensitivity of x-ray diffraction. Raman spectrum showed that the Fe ions replaced Zn atoms and incorporated into the crystal lattice positions of ZnO. Apparent ferromagnetic hysteresis loops measured at 300K were observed, and the temperature-dependent magnetization showed that their Curie temperature exceeded room temperature.

Nondestructive identification of ancient Chinese glasses by Raman and proton-induced X-ray emission spectroscopy

Nondestructive Raman spectroscopy and external-beam proton-induced X-ray emission (PIXE) technique to analyze eight ancient glasses unearthed from the provinces of Henan, Hubei, and Jiangsu, which allowes for a good characterization of the glass matrix and chemical compositions, is carried out. The results indicate that all the eight glass samples could be typically divided into three systems: faience (sample No. SZWG-4), PbO-BaO-SiO2 (sample Nos. NYWKI-5-1, HNWKII-88, and HNWKII-84), and Na2OCaO-SiO2 (sample Nos. HBWKI-16, HBWKI-17, HBWKI-18, and SZWG-1). Additional relationships between the Raman spectra and parameters, such as residues of raw materials and opacifying agent, are also discussed by respectively comparing them with similar glass samples excavated from other historical sites.

Spectral Analysis of Nanomaterials using a Transition-Edge Sensor Microcalorimeter Mounted on a Field-Emission Scanning Electron Microscope

A prototype transition-edge sensor (TES) microcalorimeter is successfully integrated into a commercial field-emission scanning electron microscope (FE-SEM). The microcalorimeter is composed of a gold (Au) absorber, a Au/Ti bilayer thermometer and a thermal isolation structure with a SiNx membrane. Operating temperatures of 100–150 mK are obtained with a dilution refrigerator. The measured energy resolution was between 19–22 eV for Al Kα at an acceleration voltage of 5 keV. The newly developed system was applied to the analysis of nanosheets for the first time at a low acceleration voltage (≤ 5 kV). The energy dispersive spectrometer (EDS) spectra of Nb3O8 nanosheets of different thicknesses (less than 20 nm) were successfully detected. Moreover, Au particles on carbon nanotubes with a thickness less than 1 nm are detected clearly. With further improvement of both energy resolution and count rate, this system holds the promise for practical X-ray compositional characterization of nanomaterials with high image spatial resolution in the low-acceleration-voltage regime.

Chemical Analyses of Potash–Lime Silicate Glass Artifacts from the Warring States Period in China

Potash–lime silicate (K2O–CaO–SiO2) glass dated to the Warring States Periods is one of the earliest glass types that have been found in China, but scientific research about this type of glass is scarce at home and abroad. In the present study, a total of 23 potash–lime silicate glass samples of the Warring States Period, excavated from different areas of China, were analyzed noninvasively using a portable X-ray fluorescence spectrometer (pXRF). The chemical composition of these K2O–CaO–SiO2 glasses was analyzed and compared with that of the potash silicate (K2O-SiO2) glasses of the Han Dynasties. The possible raw materials used to make the ancient K2O–CaO–SiO2 glasses were discussed. It appears that the ancient K2O–CaO–SiO2 glasses were produced in China and the potash glasses were of versatile origins. This research provides useful clues to trace the technical development of ancient Chinese glass.

Characterization of some tin-contained ancient glass beads found in China by means of SEM-EDS and raman spectroscopy.

A total of nine tin‐contained ancient glass beads were characterized by a combination of scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry and Raman spectroscopy. These glass beads dated from 1st century BC to 10th century AD were excavated from the Xinjiang and Guangxi provinces of China. Two kinds of tin‐based opacifiers/colorants included crystalline cassiterite (SnO2) and lead‐tin yellow types II were first found in these soda lime glass beads. The tentative chronology of the tin‐based opacifiers/colorants used in ancient glasses from China and the West was compared. In addition, several transition metal ions colorants were also found in these beads. The detailed study of the glassy matrices, crystalline inclusions, and the microstructural heterogeneities for these glass beads has revealed some valuable information to trace the possible making technology and provenances. Microsc. Res. Tech., 2013.

Atomic force microscopy study of the growth mechanism of ultrathin YBa2Cu3O7 (YBCO) films

An atomic force microscope (AFM) was used to study the growth mechanism of ultrathin YBa2Cu3O7 (YBCO) films with thicknesses of 2.5 nm, 7.5 nm, 12.5 nm and 25 nm. The YBCO films were grown on SrTiO3 (100) crystal substrates with and without a 40 nm thick buffer layer of PrBa2Cu3O7 (PBCO) respectively. The AFM data indicated that the films grew with spiral and layer by layer growth modes, with screw dislocations being the typical spiral growth modes. Three kinds of screw dislocation were found on the 7.5 nm thick films with buffer layer. Two of them showed constant terrace heights, which were 0.6 nm and 1.1 nm respectively, and the third kind of screw dislocation showed a combination of three different terrace heights of 1.6 nm, 1.0 nm and 0.6 nm. All of the screw dislocations had a common feature: the top of the screw dislocation had a columnar core and the height was four times greater than the length of the unit cell along the c-axis. Moreover, the heights of the terraces in all three kinds of screw dislocation were 0.6 nm or multiples of this value. This is approximately half the c-axis lattice parameter of YBCO, suggesting a two-dimensional growth mode along the film plane.

Identification of the man-made barium copper silicate pigments among some ancient Chinese artifacts through spectroscopic analysis

This article describes the complementary application of non-invasive micro-Raman spectroscopy and energy dispersive X-ray fluorescence spectrometry to the characterization of some ancient Chinese silicate artifacts. A total of 28 samples dated from fourth century BC to third century AD were analyzed. The results of chemical analysis showed that the vitreous PbO-BaO-SiO2 material was used to sinter these silicate artifacts. The barium copper silicate pigments including BaCuSi4O10, BaCuSi2O6 and BaCu2Si2O7 were widely identified from colorful areas of the samples by Raman spectroscopy. In addition, other crystalline phases such as Fe2O3, BaSi2O5, BaSO4, PbCO3 and quartz were also identified. The present study provides very valuable information to trace the technical evolution of man-made barium copper silicate pigments and their close relationship with the making of ancient PbO-BaO-SiO2 glaze and glass.

Investigation of Ancient Chinese Potash Glass by Laser Ablation Inductively Coupled Plasma Atomic Emission Spectroscopy

ABSTRACT In the present study, laser ablation inductively coupled plasma atomic emission spectroscopy (LA-ICP-AES) was successfully used to classify 26 ancient potash glass beads. These samples, mainly dated from the Han Dynasty to the Jin Dynasty, were from several provinces of both China and Vietnam. Quantitative analyses were done with both weathered and polished samples in order to consider the effects of surface weathering. Based on the characteristics of major, minor, and trace elements, we divided the samples into three subgroups (the percentage for each subgroup was 50%, 42%, and 8%, respectively) and also determined their main colorants. The results obtained provide new clues to trace the possible producing centers of ancient potash glasses in Asia. This study also reveals a complex network related to the trade of ancient potash glasses.

Morphology and chemical composition analysis of inorganic nanosheets by the field-emission scanning electron microscope system

Nanosheets can be used as building blocks to fabricate versatile nanostructured materials. In this paper, morphology of the Cs(4)W(11)O(36) and Nb(3)O(8) and TaO(3) sheets with different layers are analyzed by different field-emission scanning electron microscopes (FE-SEMs). Chemical composition of the single-layered Cs(4)W(11)O(36) with thickness of about 2 nm, and multilayered Nb(3)O(8) nanosheets with thickness of less than 14 nm are analyzed by both the Si(Li) solid-state detector and transition edge sensor (TES) microcalorimeter, successfully. The effects of energy resolution, accelerating voltage and substrate on the quantitative analysis are discussed briefly.

Apparatus for statically testing the properties of magnetic coupling and hybrid recording thin films

We designed and built up an apparatus for measuring the properties of magnetic coupling thin films and hybrid recording media. The temperature of the tested points of the thin film samples change as irradiated by focused laser beam through adjusting laser power. By calculation, we also simulated the distribution of temperature in TbFeCo magneto-optical films irradiated by laser, in order to get the relationship between the film coercive force and the irradiating laser power. Using this apparatus, we can determine the Curie temperature and compensation temperature of the films. The apparatus might present an effective approach for studying the variation of magneto-optical characteristics of films at different temperatures and the properties of magnetic coupling multilayer films, and it could be useful for studying hybrid recording.