Journal of Crystal Growth, Vol.412, 103-108, 2015
Synthesis and characterization of LiZnP and LiZnAs semiconductor material
Research for a reliable solid-state semiconductor neutron detector continues because such a device has not been developed, and would have greater efficiency, than present-clay gas-filled He-3 and (BF3)-B-10 neutron detectors. Further, a semiconductor neutron detector would be more compact and rugged than roost gas-filled or scintillator neutron detectors. The Li-6(n,t)He-4 reaction yields a total Q value of 4.78 MeV, a larger yield than the B-10(n,alpha)Li-7, and is easily identified above background radiation interactions. Hence, devices composed of either natural Li (naturally 7.5% Li-6) or enriched Li-6 (approximately 95% Li-6) may provide a semiconductor material for compact high-efficiency neutron detectors. A sub-branch of the III-V semiconductors, the filled tetrahedral compounds, known as Nowotny-Juza compounds (A(I)B(II)C(V)), are desirable for their cubic crystal structure and semiconducting electrical properties. These compounds were originally studied for photonic applications. In the present work, Equimolar portions of Li. Zn, and P or As were sealed under vacuum (10(-6) Torr) in quartz ampoules with a boron nitride lining, and loaded into a compounding furnace. The ampoule was heated to 200 degrees C to form the Li-Zn alloy, subsequently heated to 560 degrees C to form the ternary compound, LiZriP or LiZnAs, and finally annealed to promote crystallization. The chemical composition of the synthesized starting material was confirmed at Galbraith Laboratories, Inc. by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), which showed the compounds can be reacted in equal ratios, 1-1-1, to form ternacy compounds. Recent additions to the procedure have produced higher yields, and greater synthesis reliability. Synthesized powders were also characterized by x-ray diffraction, where lattice constants of 5.751 +/- .001 angstrom and 5.939 +/- .002 angstrom for LiZnP and LiZnAs, respectively, were determined. (C) 2014 Elsevier B.V. All rights reserved.
Keywords:Crystal structure;Radiation;X-ray diffraction;Lithium compounds;Semiconducting ternary compounds