Unknown Crystalline Research Articles

Preparation and Electrochemical Characterization of LiCoO2 Single Crystal Particles prepared by Super Critical Water Synthesis (SCWS)

ABSTRACTLiCoO2 single crystal particles were obtained by super critical water synthesis (SCWS) under optimized preparation conditions. The particle size of the LiCoO2 was less than 1 μm, which was much smaller than that of LiCoO2 prepared by a standard method. However, some unknown crystalline and amorphous phases coexisted with the well defined LiCoO2 single crystal particles. The discharge and charge characteristics of the LiCoO2 prepared by the SCWS were examined by some electrochemical methods. In the first cycle, an irreversible behavior was observed, and then the gradual decrease of the discharge capacity with discharge and charge cycle was also detected. The stable discharge capacity was estimated to be 80 mA h g−1 after the 100th cycle. This result may be due to the existence of amorphous phases and some structural defects.

Dynamic mechanical properties of strontium stearate

The dynamic modulus ( G′) and the loss ( G″) were measured as a function of temperature for strontium stearate which undergoes successive phase transitions from crystal (Cr)–unknown liquid crystalline (lc) (X), rhombohedral lc (R), body-centered cubic (Q) and hexagonal lc (H) phases. This Letter shows that in the Q phase only, G′ and G″ undergo a thermal hysteresis and in the Q phase, the G′ and G″ values were smaller during cooling from the H phase than during heating from the R phase and G′ was smaller than G″ in the cooling process. From these results, the formation and structure of the Q phase are discussed.

Formation and Thermal Decomposition of Indium Oxynitride Compounds

During the reactions of lithium oxide with indium nitride, lithium nitride with indium oxide, and lithium nitride with lithium indate LiInO2, the formation of a previously unknown crystalline phase, of composition Li4InNO2, was observed. The course of thermal decomposition of the new compound was determined.

A novel open framework zincophosphate: Synthesis and characterization

The crystallization of a reactive zincophosphate gel (which may contain Co(II) component) in the presence of sodium cations at ambient temperature and pressure yielded products (abbreviated ZnPO-HEX or CoZnPO-HEX) with a novel anionic open framework topology. The Co(II) ions isomorphously replace zinc(II) in this zincophosphate lattice up to 30%. The hopeite phase appears as a precursor in the crystallization of these new products. The single crystal structure determination of CoZnPO-HEX reveals that the structure belongs to the hexagonal P6 1 space group with unit cell parameters a = 10.447(3) and c = 15.049(5)Å. The structure consists of a three-dimensional tetrahedral framework containing one-dimensional six-ring channels. An infinite helix built up of sodium cations and water molecules has been found inside the channel. The helix plays an important structural role because a complete dehydration of the materials is the cause for the transformation of the hexagonal structure to an unknown crystalline phase.

Structural relaxation in amorphous biphenyl and a new crystalline phase

Raman spectra of amorphous biphenyl films were measured as the films were annealed at constant temperatures. It was revealed that an unknown crystalline phase consisting of twisted molecules is obtained by the annealing at 120 or 130 K. This new crystalline phase turns into the known room-temperature crystalline phase when the temperature is raised above 200 K. Structural features of the new phase are discussed in comparison with those of the amorphous and known crystalline phases.

A Search/Match Procedure for Electron Diffraction Data Based on Pattern Matching in Binary Bit Maps

AbstractA unique file structure and search algorithm have been developed for the purpose of obtaining matches between experimental electron diffraction and qualitative energy dispersive X-ray compositional data from an unknown crystalline phase and the reference data in the JCPDS Powder Diffraction File. The reference data for over 32,000 inorganic compounds from sets 1–33 were compressed and stored in binary format as bit pattern maps. The entire data set and searching programs require less than 4 Mbyte and retain the precision appropriate for electron diffraction analysis. The search algorithm, written in both RT-11 FORTRAN and Flextran, is based on pattern matching between bit maps obtained for the unknown and reference compounds for both composition and diffraction data. Special attention is given to double diffraction effects commonly encountered in electron diffraction analysis. The programs run on an interactive basis on a microcomputer dedicated to the X-ray energy dispersive spectrometer on an analytical electron microscope. A typical search takes about 15 seconds to run and extracts about 10–15 different compounds.

Perturbed angular correlation studies of chemically generated electric field gradients in Hf compounds

The time-differential-perturbed-angular-correlation (TDPAC) technique has been applied to the study of electric quadrupole interactions in HfO2, HfO(H2PO4) ⋅H2O, and HfP2O7. Strong perturbations were seen in each case, with time evolution characteristic of the static electric field gradients generated by the electron distributions in chemical bonds. Analysis of the experimental data within a theoretical framework has permitted derivation of the electric field gradient parameters associated with the Hf–O bonds in the oxide and the two phosphate compounds. A simple model calculation involving orbital populations appears capable of reproducing the experimental results and provides insight into the bonding features of these relatively complex, but structurally known, systems. The TDPAC signature of each compound appears sufficiently unique so as to offer the possibility of its adaptation as a microscopic probe of more complicated or unknown crystalline and liquid systems.

The structure of Willstätter's compound: 3‐benzoyloxy‐2‐methoxycarbonyl‐2‐tropene

AbstractWillstätter et al. obtained an unknown crystalline product by the benzoylation of 2‐methoxycarbonyl‐3‐tropanone. Proton magnetic resonance and infrared spectrometry have shown this product to be 3‐benzoyloxy‐2‐methoxycarbonyl‐2‐tropene, III. Attempted hydrogenation of III to a cocaine failed.

ON THE SOME NITROGENOUS CONSTITUENTS OF THE LEAVES OF KUZU (The Japanese arrow-root plant, Pueraria hirsuta, Matsum.)

The nitrogenous constituents of the japanese arrow-root plant “Kuzu” have been studied with the following results. 1) A protein was obtained from the alkaline alcohol extract of the sample by neutralizing with dilute hydrochloric acid. It contains 14.2% of nitrogen. Its distribution of nitrogen is as follows: Arginine N 8.80%, Cystine N 0.14/, Histidine N 4.63%, Lysine N 2.00% and N of Mono-amino acid 48.149% in total nitrogen. 2) The filtrate obtained from the precipitate produced by adding dilute hydrochloric acid to the alkaline alcohol extract of the sample was further examined, and two bases, two amino acids and one fatty acid were obtained. Those are adenin, a base yielding a chlo: aerate melting at 117-118°C, asparagin, glutamic acid and butyric acid. 3) An unknown crystalline nitrogenous substance, melting at 185-187°C, was obtained. But the amount was too small to permit of identification.