Two static high‐pressure X‐ray diffraction (XRD) studies of potassium chlorate have been performed at pressures of up to ∼14.3 GPa in a diamond anvil cell at ambient temperature using the 16 ID‐B undulator beamline at the Advanced Photon Source for the X‐ray source. The first experiment was conducted to ascertain decomposition rates of potassium chlorate as a function of pressure. Below 2 GPa, the sample was observed to decompose rapidly in the presence of the X‐ray beam and release oxygen. Above 2 GPa (near the phase I → phase II transition), the decomposition rate dramatically slowed so that good quality XRD patterns could be acquired. This suggests a phase‐dependent decomposition rate. In the second study, X‐ray diffraction spectra were collected at pressures from 2 to 14.3 GPa by aligning virgin portions of the sample into the focused X‐ray beam at each pressure. The results suggest the co‐existence of mixed monoclinic (I) and rhombohedral (II) phases of potassium chlorate near 2 GPa. At pressures beyond 4 GPa, the XRD patterns show a very good fit to KClO3 in the rhombohedral phase with space group R3m, in agreement with earlier studies. No further phase transitions were observed with pressure. Decompression of the sample to ambient pressure indicated mixed phases I and II coupled with a small amount of synchrotron X‐ray‐induced decomposition product. The equation of state within this pressure regime has been determined.

We have developed and demonstrated a novel method to load oxygen in a sealed diamond anvil cell via the x-ray induced decomposition of potassium chlorate. By irradiating a pressurized sample of an oxidizer (KClO(3)) with either monochromatic or white beam x-rays from the Advanced Photon Source at ambient temperature and variable pressure, we succeeded in creating a localized region of molecular oxygen surrounded by unreacted sample which was confirmed via Raman spectroscopy. We anticipate that this technique will be useful in loading even more challenging, difficult-to-load gases such as hydrogen and also to load multiple gases.

We performed the first reported static high pressure studies of the wide bandgap material aluminum nitride (AlN) using mid‐infrared (IR) and X‐ray Raman spectroscopy (XRS) up to 35 and 33 GPa, respectively, in a diamond anvil cell (DAC) at ambient temperature. For the first (IR) experiment, we employed a synchrotron IR source. Below the wurtzite (WZ) → rock salt (RS) phase transition, the IR spectra shift monotonically toward higher energy with pressure. Above this phase transition, the spectral multiplet stabilizes and then shifts toward lower energies suggesting a weakening of the bonding with pressure. To better examine the bonding changes we utilized the 16 ID‐D undulator beamline at the Advanced Photon Source (APS) for the second experiment. The spectrometer collected photons with ∼410 eV energy loss (nitrogen edge) with respect to incident beam energy near 10 keV. The sample commenced in the WZ phase and upon pressurization above ∼15 GPa, the sample converted into the high pressure RS form as evidenced by visual darkening of the sample and a marked change in the XRS pattern suggesting fundamental changes in intramolecular bonding. Upon pressure release, the sample remained in the high pressure RS phase and partially reverted to the low pressure WZ phase [confirmed with X‐ray diffraction (XRD)]. Theoretical calculations qualitatively agree with experimental observations.

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This paper discusses the formation of porous silicon through porous alumina using pulsed anodization for various parameters of anodization, type of acid for the formation of porous alumina, and their characterization using photoluminescence. The porous alumina has been synthesized using sulfuric, oxalic and phosphoric acids and luminescent porous silicon through the porous alumina has been obtained in each case. The porous silicon through porous alumina formation has also been investigated using pulsed anodization. The duty cycle and frequency of the square wave pulse have been varied and the optical properties of the porous silicon, so formed, through the porous alumina, have been investigated.