Showing papers in "Materials Research Bulletin in 1993"

TL;DR: In this paper, a microemulsion-mediated synthesis of zinc oxide nanoparticles for varistor studies and possible applications is described, and the microstructure, high density and electrical conductivity of sintered disks of pure and doped ZnO nanoparticles resulting from clean interfaces of particles and scaled down size of grains are found to result in higher critical electric field and a higher coefficient of nonlinearity in the logE versus logJ curve.

TL;DR: In this paper, Rietveld refinements of X-ray data of LiCoO2 prepared at 400°C and a chemically-delithiated product Li0.5CoO 2 using space group symmetries R3m and Fd3m are reported.

TL;DR: In this article, orthorhombic LiMnO[sub 2] products, synthesized by the reaction of [gamma]-MnOs and LiOH in argon at 600--620 C using carbon as a reducing agent, have been evaluated as electrode materials in lithium cells.

TL;DR: In this article, two defect-spinel compounds synthesized by the reaction of MnCO3 and Li2CO3 at 400°C were determined by neutron-diffraction to be {Li.85□.15}8a[Mn1.26]16dO4 and Li.87 □.71Li.

TL;DR: In this paper, a single crystal of the new phase Bi8Te9 has been obtained by thermal annealing and preliminary diffraction study shows an hexagonal lattice with a = 4.41 A and c ≈ 103 A.

TL;DR: The structures of LT-LiCoO2 (synthesised by reaction of Li2CO3 and CoCO3 at 400°C) and its delithiated product LT-LCoO 2 have been reinvestigated by neutron powder diffraction as mentioned in this paper.

TL;DR: In this article, a graphite-lithium intercalation was carried out using a cathode of pyrographite in a LiClO 4 -ethylene carbonate (EC) electrolyte.

TL;DR: In this article, the structure of BaY 2 F 8 and BaYb 2F 8 was determined by X-ray diffraction at room temperature and both crystals were studied by Raman spectroscopy from room temperature down to 20 K. At room temperature, all the results are consistent with the monoclinic structure C2/m as already proposed for BaY2 F 8, but the structure refinements suggest a slight disorder around one of the fluorine sites.

TL;DR: In this paper, single crystals of low temperature form of BiNbO4 (α-form) were grown from BiOF flux below 900°C and solved by means of single crystal x-ray diffraction and refined to R = 0.031.

TL;DR: In this article, a comparison of the compositions of magnetites prepared by different aqueous routes was made, namely: a) by employing a mixture of Fe 2+ Fe 3+, b) by oxidising at 363K a suspension of Fe(OH)2 and c) by giving a hydrothermal treatment at 523k to a Fe( OH)2 slurry.

TL;DR: In this article, the capacity of sodium phyllomanganate at the third cycle is 188 mAh/kg, i.e. ca. 3V and below 2 V. The first one corresponds to reduction to a disordered Mn3+ phase (Δx ≈ 0.6) and was found reversible for A = Na and K.

TL;DR: In this paper, a solid state reaction model for the formation of β″-Al 2 O 3 is proposed, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina.

TL;DR: In this paper, it has been demonstrated that the (Bi[sub 2]O[Sub 2])[sup 2+] layers of the Aurivillius oxide can be doped with the Pb[sup2+] cation, which also possesses a stereochemically active lone pair.

TL;DR: In this paper, spray pyrolysis was used to produce dense, spherical palladium metal particles at and above 900 °C in air and 800 °C of nitrogen, well below the melting point of palladium (1554 °C).

TL;DR: In this paper, the photocatalytic properties of MoO[sub 3]/TiO [sub 2] mixed oxide powders were evaluated by the degradation of 1,4-dichlorobenzene (DCB).

TL;DR: In this article, the growth of an organometallic nonlinear optical material tri-allylthiourea mercury bromide from aqueous solution by temperature-lowering method is described.

TL;DR: In this paper, the authors describe a process which, also operating below one atmosphere pressure, transforms virtually any form of finely divided solid carbon into crystalline diamond in the reaction chamber, which is the key to the process is the creation of a two or more phase micro (or nano) composite of the carbon solid form (graphite, carbon black, charcoal, etc.) with a few percent of very fine diamond (or SiC or Si or BN, etc.).

TL;DR: In this paper, a pyrochlore type compound in PbO flux (Pb1.86Mg 0.24Nb 1.76O6.5) was grown.

TL;DR: In this paper, single crystals up to 2.0 mm in size have been grown from solution into capillaries which are previously punctuated into a gel layer through which the precipitant agent diffuse.

TL;DR: In this article, spin coating and spray pyrolysis were used to produce TiO2 thin films for photodecomposing organic impurities in water, and the observed photocatalytic activity is the same for films prepared by both techniques.

TL;DR: Anomalous retardation of the sintering kinetics of ZnO with addition of Bi[sub 4]Ti[sub 3]O[sub 12] (BIT) and a low voltage varistor composition was investigated in this article.

TL;DR: In this article, a route of low temperature preparation of manganese cobaltite spinels Mn x CO 3−x O 4 (0 ≤ x ≤ 1) is described, and gels obtained by addition of n-butylamine to mixed Co 2+ and Mn 2+ solutions, after aged at 80° and heated at 200°C correspond to the spinel-type material.

TL;DR: A new copper diammine divanadate Cu(NH 3, H 2 O and VO 3 ) 2 has been synthesized and structurally characterized in this article, where the unit cell is monoclinic, space group Pc, a = 5616(2) A, b = 5591(1) A, c = 11331(2), A, β = 9091(2 )°, V = 3557(3) A 3, Z = 2, Z = 0.

TL;DR: In this article, starting material perovskite powder and grinded dielectric resonator ceramic of this compound have been studied by X-ray diffraction and using Rietveld's method.

TL;DR: In this paper, the influence of different plasma spray parameters on the amount of the B phase formed was discussed and the main properties of Y2O3 B and C phases in these deposits such as structural characteristics, thermal stability and mechanical behavior.

TL;DR: The structure of polycrystalline Ca2MnO4.00 has been investigated by high-temperature X-ray diffractometry and Rietveld analysis as discussed by the authors.

TL;DR: Using a sol-gel process for rare-earth ions doping, a minimum optical loss of less than 2 dB/km in the region of 1.15μm has been reproducibly achieved in Er 3+ doped Al 2 O 3 SiO 2 glass single-mode fibers as mentioned in this paper.

TL;DR: In this paper, a step-scanned XRD profiles by the Rietveld structure refinement code (DBW) was used to show that the displacive P2 1 n·1·1(M ) ⇆ Pnma (O1) polymorphic phase transition occurs between 77 and 90°C (≈83°C).

TL;DR: In this article, single crystals of yttrium fluoride YF3 have been grown by the Czokralski method and studied by Raman scattering in the temperature range 20 K - 730 K.

TL;DR: In this paper, the crystal structure of indium titanate (In[sub 2]TiO[sub 5]) has been refined from X-ray powder diffraction data by Rietveld refinement.