Real-time Crystal Growth Visualization and Quantification by Energy-Resolved Neutron Imaging

Abstract

Energy-resolved neutron imaging is investigated as a real-time diagnostic tool for visualization and in-situ measurements of “blind” processes. This technique is demonstrated for the Bridgman-type crystal growth enabling remote and direct measurements of growth parameters crucial for process optimization. The location and shape of the interface between liquid and solid phases are monitored in real-time, concurrently with the measurement of elemental distribution within the growth volume and with the identification of structural features with a ~100 μm spatial resolution. Such diagnostics can substantially reduce the development time between exploratory small scale growth of new materials and their subsequent commercial production. This technique is widely applicable and is not limited to crystal growth processes.

Crystal structure evolution of BaBrCl and BaBrCl:5%Eu up to 1073 K by neutron diffraction

“…Neutron diffraction data were analyzed for all five rings simultaneously using the Rietveld method (Rietveld, 1969) via the General Structure Analysis System (GSAS) (Larson & Von Dreele, 2004), automated by scripts through gsaslanguage (Vogel, 2011). The script ensures not only application of identical analysis to each data set, but also documentation of the refinement steps.…”

“…Yan et al (2016) acknowledged the issue of cracking during post-growth cooling in Czochralski growth of 5% Eu-doped BaBrCl, noting the need for additional insulation and reflectors to make a more isothermal zone for crack-free cooling. Tremsin et al (2016Tremsin et al ( , 2017 used cold, thermal and epi-thermal neutron radiography to image Eu concentration variations and crystal cracking in situ during growth in a Bridgman furnace, discovering that cracks propagated from clusters of low Eu concentration. In particular, through real-time visual inspection of Eu-doped BaBrCl in transparent Bridgman and Czochralski furnaces, our group has observed cracking during cooling around 673 K (well below the melting temperature of 1159 K).…”

Energy-Resolved Neutron Imaging for Reconstruction of Strain Introduced by Cold Working

“…Energy-resolved neutron imaging and its related applications have seen quite substantial progress over recent years due to the development of bright pulsed neutron beamline facilities [1][2][3][4] at neutron spallation sources, as well as recent development in fast neutron counting detectors operating in a time-of-flight mode at high counting rates [5,6]. This imaging mode provides unique opportunities to non-destructively study various crystallographic properties for both polycrystalline and single crystal materials [7][8][9][10][11][12][13], to study the elemental and isotopic composition of samples [14][15][16], to remotely map temperature [17,18], in some cases, to measure pressure within sealed samples [19], to image magnetic fields [20], to optimize the processes of crystal growth [21], and many others. The present short article demonstrates the possibility of reconstructing macroscopic residual strain maps with sub-mm spatial resolution across an entire field of view, all from one measurement, without the need to scan across the sample.…”

Neutron Imaging at LANSCE—From Cold to Ultrafast

“…The results of these efforts are reported in several publications [55][56][57]. Furthermore, the unique capabilities of energy-resolved neutron imaging for single crystal characterization were applied to characterize natural gold single crystals [58].…”