ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14978.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The microstructure of SGBF graphite was observed under tensile and compressive stresses. Increasing stress generated extensive cracking parallel to the layering direction in the particles. Such cracking, however, was not necessarily directly attributable to the low strength of the graphite crystallites in the c direction but rather to flaws or weak regions which tended to occur between the layer planes. For tensile stress, the cracks were perpendicular to the direction of the applied stress, whereas in compression, the cracking was parallel to the applied stress. Analysis of the stress‐strain relations for SGBF graphite in tension indicates a discrepancy with the previously proposed plastic deformation model. The discrepancy is attributed to the effect of the observed cracking on the internal stress distribution. An alternative explanation is proposed on the basis of internal stresses, localized cracking, and interlayer sli

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14979.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Splat and other rapid quenching techniques were applied to a systematic study of simple oxides, and four new pure oxide glasses were obtained (V2O5, TeO2, MoO3, and WO2). The high‐temperature tetragonal form of WO3coexists with a metastable short‐range‐order‐only phase. The structure of a new metastable high‐temperature phase, δ‐Ta2O6, resembles δ‐Nb2O6. Predominant phases found in quenched Al2O3belong to the γ‐(s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14980.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Gamma irradiation of potassium borate glasses containing about 1.8 mole % Tl+, Pb2+, or Bi3+resulted in two induced absorption bands which the authors callTandLbands. TheTband was observed at about 1.1, 1.55, or 1.8 ev, and theLband was observed at about 1.8, 2.6, or 2.7 ev in alkali borate glasses containing Tl+, Pb2+, or Bi3+, respectively. The shifting of the band positions to higher energies was attributed to the increasing polarizing power of these ions as in the case of theFband induced in alkali halides. The effect of the addition of cerium on the intensity of theTandLbands induced in glasses containing lead or thallium and prepared under different melting conditions suggested strongly that these two bands are associated with electron trap centers near these ions.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14981.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Assuming that a temperature‐dependent endpoint density occurs in the sintering process, a scheme for describing the progress of sintering is developed using reduced variables. A sine function is given to describe the path. Experimental results from the literature are compared to this function for calcium fluoride, glass, thorium oxide, aluminum oxide, and copper, and for magnesium oxide with a eutectic addition. New results are presented and compared for yttrium oxide, erbium oxide, dysprosium oxide, and aluminum oxide. The correlation between the data and the sine function is very high. Apparent activation energies are give

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14982.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Density, NMR absorption, and ionic conductivity were measured for cesium and thallium silicate glasses. Results indicate that the cesium ions change their environment between 20 and 35 mole % Cs2O, possibly by means of a phase separation. These observations are consistent with the composition independence of the activation energy for conduction above 25 mole % Cs2O but do not reflect the rapid change in activation energy below 25 mole %. The extreme breadth of the205Tl NMR Une varied with Tl2O content in the same manner as the activation energy for conduction. This result indicates that the distribution of ionic environments may provide a similar distribution of energy barriers to ionic motion. The relation between ionic conduction and structure appears to be different in cesium and thallium silicate glasses.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14983.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Glasses in the systems MoO3‐P2O5‐Ag2O and MoO3‐P2O5‐K2O were investigated and general areas of composition for good glass formation were determined by X‐ray diffraction methods. Temperature coefficients of electrical resistivity and linear expansion were determined for the glasses along with density, durability, and other thermal characteristics. Resistivity of the glasses was effectively reduced by the additio

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14984.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The phases present in the 2 to 50 at.% lithium region for the system lithium‐carbon below 700° C are carbon and stoichiometric Li2C2. The unit cell of Li2C2was identified as primitive monoclinic. A lithium boride phase of composition LiBio10.85 ± 0.35was synthesized in the lithium‐boron system for samples containing up to 50 at.% lithium. The Debye‐Scherrer X‐ray powder pattern for this phase can be indexed on the basis of a tetragonal unit cell. Lithium reacts with boron carbide to form lithium carbide and lithi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14985.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Glass formation was observed in the system ZnO‐TeO2in mixtures containing 20 to 40 mole % ZnO. Softening occurred at 350°C and the glasses crystallized at 400°C. High dielectric constants (ca. 20) and high electrical resistivities (ca. 1011ohm‐cm−1) were measured. The zinc tellurite glasses have a higher density and refractive index and are considerably softer than silicate glasses. The optical transmission range was between 0.38 and 6.6μ with two absorption bands in the infrared. Spectra of Cu2+and Nd3+doped samples are al

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14986.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Dielectric loss was measured on CaF2single crystals heated in air at 750° C for 30 hr to introduce O2‐ions. The loss measurements were made in parallel and in perpendicular directions to the CaF2surface region which contained most of the O2‐. The layer containing O2‐was more conducting and therefore produced a space charge relaxation near 10 kcps at 210°C. A similar loss peak was previously reported as due to oxygen ion‐fluorine vacancy dipole r

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1967.tb14987.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY