9 Appendix

The purpose of this Appendix is to determine the per-unit-length parameters for tertiary circuits in Fig. 2 with the returnpath on the shield of the disturbing line. Writing Kirchhoffslaw in the loop between the / and /th coaxials:

AV—Ax i=0

Ij(x*Ax)

V,(x*Ax)

x* Ax

Fig. 2 The per-unit-length equivalent circuit of tertiary circuits forFig. 1

Noting that

Itto = ~th

After some manipulation, and comparing with eqn. 8, theper-unit-length parameters are given by:

[R.]g = Rsi + Rsi Lsi - 2Mtj

-Mfi -Mki

Utilising Kirchhoffs current law for the /th conductor andignoring the conductive losses,

L(x + Ax)-L{x) , A \-& ^ }— = -ja>CJr Vj(x + Ax)

- t JuCn{Vj(x + Ax) - V,(x + Ax)}i=i

This equation may be arranged to yield

[C]JJ = CM+tcjk [C\jk = -Cjkfe=l

Book reviewCrystalline electric field and structural effects in /-electronsystemsJ.E. Crow, R.P. Guertin and T.W. Mihalisin (Eds.)Plenum Press, 1980, 638pp., $69.50ISBN: 0-306-40443

The lanthanide (rare earth) series of elements with incomplete4 / electron shells has provided physicists with an excitingvariety of phenomena for investigation since the metals beganto be available in reasonably pure form as a result of the workof Spedding and his group at Ames in the 1960s. In the follow-ing decade purity was further improved, and, as a result, ele-ments, alloys and compounds are now available in highly puresingle-crystal form. Many of their striking properties arise fromthe fact that magnetic ordering due to indirect exchangecoupling is found at sufficiently low temperatures in most lan-thanide systems. Additionally the crystalline electric field cancause splitting of the ionic ground state and give rise to a rangeof other effects, some of which manifest themselves by thestrong directional dependence of physical properties. In parallelwith, although a little behind, the work on lanthanides hasbeen a corresponding investigation of the actinide series inwhich the 5/shell is being progressively filled. The propertiesof both lanthanides and actinides were dealt with at a con-ference in Philadelphia, the proceedings of which are pre-sented in the work under review.

The report contains 63 papers, 25 of which were invited,

and is a valuable survey of the state of the subject at the endof 1979. There is a good balance between review and originalmaterial and between experimental results and theory. Post-presentation discussions, apparently verbatim, are also included.

Four major invited papers set the background in the firstsection, and these discuss the influence of crystal fields indetermining magnetic properties and causing structural effectsincluding phase transitions and magnetostrictive strains. Theeffect of pressure in changing lattice spacing and inducing mag-netic order is examined and the role of crystal fields in amorph-ous materials is briefly discussed.

The remaining eight sections cover these and other topics inmore detail. They include much of fundamental importance.Those interested in magnetoelastic and structural phenomena,neutron diffraction and magnetic excitations, intermediate ormixed valence systems, transport properties, including Kondoeffect, and the coexistence of magnetic ordering and supercon-ductivity will all find papers of relevance. There is less of directinterest for readers seeking information about useful materialsand applications. Those who persist will find some work onintermetallic compounds between rare earths (R) and transitionmetals (T) particularly those on the Laves phase RT2 compo-sition of interest for the production of transducers. In additionwork is reported on the RTS intermetallics, some of which arepotential permanent magnet materials, on hydrogen adsorptionand on rare earth garnets. Nevertheless the solid-state phycisistwill experience more excitement than the engineer.

W.D. CORNER

166 IEE PROC, Vol. 129, Pt. A, No. 3, MA Y 1982