spark-plasma-sintering-apparatus-used-for-formation-strontium

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...

University of California, Davis

Although increasing diversity at the national scale is a well-documented trend, substantial variation in patterns of ethnoracial change occurs across American communities. Our research considers one theoretically implied path: that some communities are 'bucking the trend', becoming more homogeneous over time. Using 1980 through 2010 decennial census data, we calculate panethnic (five-group) entropy index scores to measure the magnitude of diversity for nearly 11,000 census-defined places. Our results indicate that while certain places reach their diversity peak in 1980 or 1990, they are few in number. Moreover, they experience a variety of post-peak trajectories other than monotonic diversity decline. Decreasing diversity is concentrated in the South and West, among places with higher levels of diversity and larger proportions of Hispanic or black residents at the beginning of the study period. These places exhibit complex shifts in racial-ethnic structure, but Hispanic succession predominates.

Bucking the Trend: Is Ethnoracial Diversity Declining in American Communities?

The scanning electron microscope provides a platform for subnanometer resolution characterization of material morphology with excellent topographic and chemical contrast dependent on the used detectors. For imaging applications, the predominantly utilized signals are secondary electrons (SEs) and backscattered electrons (BSEs) that are emitted from the sample surface. Recent advances in detector technology beyond the traditional Everhart-Thornley geometry have enabled the simultaneous acquisition and discrimination of SE and BSE signals. This study demonstrates the imaging capabilities of a recently introduced new detector system that consists of the combination of two in-lens (I-L) detectors and one in-column (I-C) detector. Coupled with biasing the sample stage to reduce electron-specimen interaction volumes, this trinity of detector geometry allows simultaneous acquisition of signals to distinguish chemical contrast from topographical changes of the sample, including the identification of surface contamination. The I-C detector provides 4× improved topography, whereas the I-L detector closest to the sample offers excellent simultaneous chemical contrast imaging while not limiting the minimization of working distance to obtain optimal lateral resolution. Imaging capabilities and contrast mechanisms for all three detectors are discussed quantitatively in direct comparison to each other and the conventional Everhart-Thornley detector.

Simultaneous Scanning Electron Microscope Imaging of Topographical and Chemical Contrast Using In-Lens, In-Column, and Everhart-Thornley Detector Systems.

Article	Year
Bucking the Trend: Is Ethnoracial Diversity Declining in American Communities? Population research and policy review\| PubMed ID: 26023247	2015
Simultaneous Scanning Electron Microscope Imaging of Topographical and Chemical Contrast Using In-Lens, In-Column, and Everhart-Thornley Detector Systems. Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada\| PubMed ID: 27142307	2016

Lauren A. Hughes

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