Showing papers in "Materials Letters in 1990"

TL;DR: A new combustion synthesis method, the glycine-nitrate process, has been used to prepare oxide ceramic powders, including substituted chromite and manganite powders of high quality.

TL;DR: The immobilized purified ALP from bovine intestinal mucosa had a 30% activity yield and an improved stability to thermal deactivation compared to a solution, and the composite bioactive glass was preserved in water at room temperature for two months without loosing activity.

TL;DR: In this paper, the effective heat of formation (ΔH') of any compound can be calculated as a function of the concentration of its components, and the first phase formation and phase sequence has been successfully predicted for Al/Ni, Al/NgAl, Ni/NiAl3, NiAl3/Ni3Al and Al/ NiAlAl/Ni structures.

TL;DR: In this article, it was shown that AISI 304 and 310 stainless steels have extremely strong and wear-resistant surfaces due to high-dose nitrogen ion implantation at elevated temperatures.

TL;DR: In this paper, it is shown that it is possible to prepare lowvoltage varistors from TiO 2 by doping with acceptors and by freezing in high-temperature defect equilibria.

TL;DR: A diphasic nanocomposite sol-gel processing has become an excellent way of producing stoichiometric homogeneous powders with many advantages over the solid state reaction method as well as the solution solgel method as mentioned in this paper.

TL;DR: In this article, the formation of a wide variety of metal sulfide films such as SnS and CdS by an electrochemical ion exchange process where the metal cation of the desired product film exchanges with the Zn(II) in a ZnS film deposited on nonconductive substrates by chemical-precipitation solution techniques was investigated.

TL;DR: In this paper, a series of silica-alumina catalysts were prepared and calcined at 773 and 973 K. The surface acidity (acid amount and acid strength) was determined for each catalyst by thermal programmed desorption (TPD) of pyridine.

TL;DR: In this paper, a nano-size barium titanate was synthesized using barium acetate and potassium titanyl oxalate as precursors, and the calcined powder was characterized using different techniques such as XRD, DTA/ TG/DTG, SEM/TEM and IR.

TL;DR: The structural analysis of Nd 4 Fe 77 B 19 magnets, which are magnetically isotropic, indicates magnetic particles smaller than or equal to the critical single domain particle diameters as mentioned in this paper.

TL;DR: In this paper, the inhomogeneous distributions of internal shear stress and electrical field induced by external shear or applied electric field around a Griffith's type III crack tip in ferroelectric ceramics have been analyzed.

TL;DR: A neutron Rietveld refinement study of the brown phase BaNd 2 CuO 5 showed that this material is isostructural with the La analog, but adopts a totally different structure from that of the green phase BaR 2CuO 5 formed for R = Y and most lanthanide elements.

TL;DR: In this article, an aqueous heterogeneous redox mixture containing aluminium nitrate, silica fume (soot), and urea in appropriate mole ratio, when rapidly heated to 500°C, boils, foams and ignites with a flame to yield weakly crystalline mullite powder in less than 5 min.

TL;DR: In this article, the effect of an external dc electric field of 1 kV/cm on the hardenability of two steels (02 and 4340) was investigated, where the experiment consisted of making the specimen one electrode of an electrostatic circuit and applying a potential during austenitizing or quenching in several media representing a range in cooling rates.

TL;DR: In this article, the diffusivity and solubility of oxygen in solid silver were determined in the temperature range 740-915 ° C by means of a gas-tight yttria-stabilized zirconia electrochemical cell.

TL;DR: In this article, the stability of phase-pure YBCO powders with CO2 partial pressure was studied and the zero-field critical current density (Jc) in the sintered samples decreased with increasing CO 2 partial pressure in the mixtures.

TL;DR: In this article, the threshold concentrations for the destruction of strong and weak antiferromagnetic (AF) longrange order and for the insulator-conductor transition are calculated in La(Sr,Ba)CuO and YBaCuO.

TL;DR: This article evaluated 17 IMS alumina-calcia fibers (50-80% Al 2 O 3 ) which were melt spun into propane gas and found that they were X-ray amorphous, had tensile strengths of 21-151 kpsi, diameters of 141-450 μm, and melt and crystallization temperatures ranging from 1341 to 1842°C and from 969 to 1021°C, respectively.

TL;DR: In this paper, the structure of thermally evaporated lead phthalocyanine films prepared from commercial grade material was found to differ markedly from films fabricated from PbPc prepared in-house even after purification of the former by entrainer sublimation.

TL;DR: The authors used excimer laser processing in air to grow oxide layers on AISI 304 stainless steel and have characterized the resulting oxide layer using a variety of techniques including Mossbauer, Auger, and Rutherford backscattering spectroscopy, X-ray and electron diffraction, transmission electron microscopy, and nuclear reaction analysis.

TL;DR: In this article, the SHG signal between 25 and 250°C was measured for a flux-grown single crystal, high-purity single-crystal fibers, and powder (0.5 μm average particle size).

TL;DR: In this paper, the P-T diagram of c-BN formation with Mg2NF as flux-precursor is investigated and the synthesis mechanism is discussed, and the conversion yields are much higher than those observed when pure magnesium nitride, Mg3N2, is used.

TL;DR: In this article, solid phase crystallization in amorphous Si films of different thicknesses is investigated and it is found that the rate (per unit area) at which crystalline grains nucleate increases with layer thickness.

TL;DR: In this paper, the electrical properties of grain and grain boundary of the sample were studied by a combination of complex-plane impedance analysis and impedance spectra methods, and the PTC originated only in the grain boundary material.

TL;DR: A ferroelastic transition has been observed in yttria-stabilised tetragonal zirconia polycrystalline ceramics (TZP) via X-ray diffraction and ultrasound non-destructive testing (NDT), measured as a function of applied uniaxial stress.

TL;DR: In this article, superconducting films of YBa 2 Cu 3 O 7−δ have been prepared on yttrium stabilized cubic zirconia in situ by laser ablation.

TL;DR: In this paper, the role played in the microstructure evolution by the recovery of defective structures (dislocations and stacking faults), the precipitation of carbides and the α ′ → γ reversion is discussed with reference to the two stages of transformation evidenced by experimental results.

TL;DR: In this article, the effect of cooling rate on the surface structure of habit faces of $KTiOPO_4$ crystals grown from potassium phosphate flux is reported, and different dendritic structures have been observed on the habit faces, the complexity of which depended on cooling rates.

TL;DR: In this article, the ternary chalcogenides TlInTe2, TlSe2 and TlGaTe2 were determined at room temperature by Rietveld refinement of high-precision X-ray powder diffraction data.

TL;DR: In this paper, an electrical breakdown strength of 3-4 MV/cm was found for buried layers of silicon nitride in silicon-on-insulator (SOI) structures, synthesized by post-implant annealing of high-dose nitrogen-implanted silicon.