摘要:

An oxide phase which is isostructural with PdO has been obtained as a thin film by reactive dc diode sputtering of Pt in argon‐oxygen mixtures. Films in which this is the only crystalline phase observed have been prepared; they have a density of 13.5±1.0 g/cm3. The oxide phase is unstable at temperatures above 500 °C, and the film is converted to platinum. Thermogravimetric analysis of the films indicates that the original composition is close to PtO. Mixtures of PtO and Pt can also be obtained and the temperature coefficient of resistance of the films becomes more negative with increasing PtO content; values between +1800 and −25 000 ppm/°C have been measured.

ISSN:0021-8979    

DOI:10.1063/1.1663583

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Eddy‐current‐compensated toroidal deflection yokes are more convenient to precisely design and fabricate than their saddle‐type equivalents. A simple and practical design criterion to obtain nominal compensation, which equalizes the (coil area)(ampere‐turn) products for the inner and outer toroidal yokes, has been experimentally supported.

ISSN:0021-8979    

DOI:10.1063/1.1663584

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A new technique is proposed for measuring thermal diffusivities of materials at high temperature. A thin‐slab specimen is heated with a steady flux of energy on one or both faces. The flux to one face is then interrupted momentarily during which time radiative heat losses cause a negative temperature pulse to develop in the specimen and to propagate through it. The thermal diffusivity is determined from an analysis of the temperature excursion of the opposite face. A theoretical analysis of this heat‐transfer problem for which one‐dimensional heat flow and a general linearized form of surface heat loss are assumed is presented. Data analysis techniques are discussed, and the results are given for some measurements on AXM‐9Q graphite to 3250 K. A 250‐W CO2continuous‐wave laser was used as the heat source.

ISSN:0021-8979    

DOI:10.1063/1.1663585

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In order to obtain information about the nuclear transitions that produce fission‐fragment x rays, the yield ofKx rays emitted in the thermal‐neutron fission of U235was measured as a function of the time after fission for times between 1 and 60 nsec, as a function of the mass of the fragment emitting the x ray, and as a function of the total kinetic energy of the fragment pair emitting the x ray. Three‐parameter data were recorded event by event. Two of the parameters contained information about the energies of the fission fragments from which it was possible to calculate the mass of each fragment. The third parameter contained information from which the elapsed time between the detection of one of the fission fragments and the detection of the x ray could be calculated. The results are compared with previously reported results for Cf252and U235. There appears to be little difference between the Cf252and U235x‐ray yields per fragment. A sufficient understanding of the mechanisms responsible for x‐ray emission would permit the independent yield distributions of nuclides produced in fission to be obtained from measured x‐ray yields.

ISSN:0021-8979    

DOI:10.1063/1.1663586

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The characteristics of an accelerating lens system composed of three anodes in the scanning electron microscope are described. The main advantages of this accelerating lens system are that the working distance can be changed freely or the accelerating voltage can be changed over a wide range (about 0.3–100 kV) without changing the working distance, by adjusting only the control voltage of the second anode. Some problems in the manufacturing and operating conditions are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.1663587

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Recent work on electrode polarization effects in ionic conductors is discussed and extended. Contrary to a recent suggestion, analysis of the ac conduction and electrode processes occurring in such materials should involve effectively mobile charged species of both signs, not just a single mobile species. Special consideration of likely charge‐transfer reactions in solid materials such as &bgr;‐alumina with platinum electrodes leads to a new specific result for the Warburg impedance appropriate for such situations. The over‐all impedance of the system involves a very high parallel capacitance showing &ohgr;−mfrequency response, with 0.5≤m≤1.5, of the type very frequently found experimentally.

ISSN:0021-8979    

DOI:10.1063/1.1663588

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In the framework of a simple compression wave and a weak shock wave, an isentrope of the Tait type and a Hugoniot adiabat based on the linear velocity relation are shown to verify each other consistently. Thus, the two empirical equations of state are given a semianalytical treatment on favorable terms.

ISSN:0021-8979    

DOI:10.1063/1.1663589

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

It is shown that the observations of Gyorgy, Sturge, and Van Uitert, on the anisotropy of Y3−xLuxFe5O12, are in excellent agreement with the mechanism suggested by Akselrad and Callen. The data are consistent with a tetrahedral iron mechanism, although they do not exclude an octahedral iron mechanism. The relative contributions of the two sublattices and the relevant physical considerations are discussed. The mechanism of preferential site ordering is also discussed further, with particular reference to relative site sizes.

ISSN:0021-8979    

DOI:10.1063/1.1663590

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Structure in appearance potential spectra which does not correspond to a characteristic absorption edge has been reported by Ramachandran and Cox. It is suggested that at least part of this structure is due to an energy‐dependent electron reflection coefficient which modulates the current entering the sample, and ways in which this hypothesis could be tested are suggested. Experimentally observed changes in the reflection of electrons incident on an evaporated aluminum film are reported.

ISSN:0021-8979    

DOI:10.1063/1.1663591

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The output fluctuations of a Nd:YAG laser have been determined for high‐frequency pulse pumping using GaAlAs injection laser diodes. The results for a 100‐mW‐output laser show that a very high pump‐pulse frequency (≥1 MHz) must be used to achieve quasi‐cw output with low ripple amplitude.

ISSN:0021-8979    

DOI:10.1063/1.1663592

出版商:AIP    

年代:1974

数据来源: AIP