摘要:

A technique to determine the anisotropy distribution in a ferromagnetic powder consisting of uniaxial particles has been developed. This technique can be used for samples with randomly oriented particles as well as with oriented samples. In principle it eliminates incoherent magnetization reversals which led to errors in previous methods. It involves saturating the material in a magnetic field and then making torque measurements at an angle several degrees away from the saturating direction. In these measurements the torque on the specimen as a function of magnetic field is recorded as the field is cycled from zero to a specified field and then reduced to zero. This cycling procedure is continued, gradually increasing the maximum applied field upon subsequent cycles until the magnetic field exceeds the highest anisotropy field of the particles in the distribution. For elongated &ggr;‐Fe2O3particles this technique gives length‐to‐width distributions which approach those observed by the electron microscope technique. These results are compared to those obtained by remanence measurements which give smaller values of anisotropy constants, indicating the importance of incoherent magnetization reversals, when the remanence is acquired.

ISSN:0021-8979    

DOI:10.1063/1.1728489

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The anisotropic thermal expansion of the hexagonal elements, thallium, yttrium, beryllium, and zinc, has been measured. The temperature range for the thallium, yttrium, and zinc measurements was 4.2−273.2°K, while for beryllium the range was 77−273.2°K. Dimensional changes were detected by an interferometric technique, and the movement of the interference fringes was detected with a photomultiplier tube. From the measured values of &Dgr;L/L0the coefficients of thermal expansion and thec/aratios of the metals were calculated as a function of temperature. A review of previous measurements of the thermal expansion of these metals is also included.

ISSN:0021-8979    

DOI:10.1063/1.1728490

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728491

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728492

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728494

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728495

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728496

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728497

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728499

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1728500

出版商:AIP    

年代:1962

数据来源: AIP