Structure of KTiOPO<Subscript>4</Subscript> single crystals grown by the top-seeded solution and spontaneous flux crystallization methods

This paper reports on the results of precision X-ray structural investigations of KTiOPO₄ single crystals grown by one method (crystallization from a solution in the melt) in two variants (the spontaneous formation of crystallization centers or top-seeded solution growth during slow cooling of saturated solution melts). It is shown that spontaneous flux crystallization leads to the formation of a larger number of defects. Potassium atoms are found to be disordered. The splitting of the K1 and K2 potassium positions is equal to 0.347(4) and 0.279(3) Å, respectively, for the crystals grown by the top-seeded solution method and 0.308(5) and 0.321(4) Å, respectively, for the crystals grown through the spontaneous flux crystallization.     

Reaction of Graphite with Sulfuric Acid in the Presence of KMnO<Subscript>4</Subscript>

The reaction of graphite with sulfuric acid in the presence of KMnO₄ (oxidant : graphite ratio 0.027–0.55) involves consecutive and concurrent reactions: graphite intercalation and direct oxidation of the carbon matrix. The properties of graphite bisulfate and its reaction products are determined by the stage number of the intercalation compound; the decomposition enthalpies of the stage I–IV graphite bisulfate correlate with the enthalpies of graphite intercalation with sulfuric acid.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 184–191.Original Russian Text Copyright © 2005 by Sorokina, Khaskov, Avdeev, Nikol’skaya.     

Analysis of the ferromagnetic resonance spectra of aggregates of magnetite nanoparticles formed by a magnetic field

The ferromagnetic resonance (FMR) spectra of magnetite nanoparticles in aqueous solutions and solid polymer films were analyzed at different particle concentrations, matrix rigidities, temperatures, external magnetic effects, and positions of flat samples in the field of the spectrometer. The formation of linear aggregates of nanoparticles under the influence of magnetic fields is the major factor that changes the FMR spectrum shape and position. The results were analyzed in terms of phenomenological theory of FMR. The applicability of the equations of phenomenological theory was verified, and the fraction of nanoparticles in linear aggregates was evaluated.     

Time-resolved Fourier transform intracavity spectroscopy with a Cr2+:ZnSe laser

Intracavity laser absorption spectroscopy (ICLAS) with an evacuated Cr2+:ZnSe laser is performed with a high-resolution time-resolved Fourier transform interferometer with a minimum detectable absorption coefficient equal to 4 x 10(-9) cm(-1) Hz(-1/2) in the 2.5 microm region. This represents the extreme limit currently reached in the infrared by ICLAS with Doppler-limited resolution. The broad gain band of the crystal allows a spectral coverage at most equal to 125 nm, wide enough to see entire vibration bands. Weak CO2 bands observed up to now only in the Venusian atmosphere are recorded for the first time, to our knowledge, in a laboratory. An H2O detection limit down to 0.9 parts per billion by volume is also demonstrated.     

New methods of synthesis of boron,germanium, and tin derivatives of pentavalent phosphorus thioacids

The reactions of S‐trimethylsilyl esters of S‐propyl‐4‐methoxyphenyltrithiophosphonic, bis(dialkylamido)dithiophosphoric, and S‐ethyl‐diethylamidotrithiophosphoric acids with trialkyl borates, triorganylbromogermanes, trimethyl(isobutylthio)germane, and trialkylchlorostannanes were studied. On the basis of these studies, new methods of synthesizing S‐boron, S‐germyl, and S‐stannyl derivatives of pentavalent phosphorus thioacids were developed. S‐Diethylaminomethyl O‐isopropyl‐4‐ethoxyphenyldithiophosphonate was obtained by the reaction of the diisopropylboron derivative of the corresponding dithiophosphonic acid with the aminal 6 . © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:27–35, 2002; DOI 10.1002/hc.1103