Article pubs.acs.org/JPCC
Spectroscopic Characterization of Rocksalt-Type Aluminum Nitride Kevin Keller,*,† Erica Brendler,‡ Steve Schmerler,⊥ Christian Röder,⊥ Gerhard Heide,† Jens Kortus,⊥ and Edwin Kroke§ †
Institute of Mineralogy, ‡Institute of Analytical Chemistry, ⊥Institute of Theoretical Physics, and §Institute of Inorganic Chemistry, TU Bergakademie Freiberg, Freiberg, Germany S Supporting Information *
ABSTRACT: Starting from nanocrystalline and submicron wurtzite-aluminum nitride (w-AlN) powder rocksalt structure (rs-AlN) samples were synthesized by two different methods of shock wave recovery experiments. The resulting samples contained up to 86% rs-AlN, stable at room temperature, giving for the first time the possibility to comprehensively characterize the material by powder X-ray diffraction, Fourier transform infrared (IR), Raman, and 27Al NMR spectroscopy. Raman and IR modes were calculated by density functional theory, allowing for the interpretation of the respective experimental spectra. By 27Al NMR the chemical shift of rsAlN was determined, and the quadrupolar coupling constant was estimated.
1. INTRODUCTION
2. EXPERIMENTAL SECTION 2.1. Sample Preparation. The investigated AlN powders were synthesized by shock wave recovery experiments using the flyer plate method. The sample is housed in a special steel container and precompacted to a desired porosity. A metal plate is accelerated by the detonation of a high explosive (plasticized PETN, vD = 7500 m/s) and striking the sample container. Details of the setup are described elsewhere.14,15 Two different sample geometries where applied, namely, the reflection and impedance method. In the first case the sample thickness has to be
