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The boundaries of the homogeneity regions of the phases SmCo 5 , GdCo 5 and Gd 2 Co 17 have been determined by microscopic investigation. At elevated temperatures the homogeneity region of the phases SmCo 5 and GdCo 5 extends to the Co-rich as well as to the Co-deficient side whereas the phases Gd 2 Co 17 and Sm 2 Co 17 show almost no Co solubility. A tentative diagram is presented for the phase relationships involved in the transition between the two allotropic forms of Gd 2 Co 17 . The occurrence of various types of microstructures in as-cast and annealed RCo 5 samples is explained in terms of the peculiar shape of the solvus of the RCo 5 homogeneity regions at high temperatures.

The magnetic properties of rare earth-magnesium compounds with the CsCl structure have been determined in the temperature range 4.2–300 K with applied magnetic fields up to 18 kOe. There is a change in sign of the asymptotic Curie temperatures in going from compounds with light rare-earth elements to those with heavy rare-earth elements. The temperature dependence of the magnetization in the magnetically ordered region points to antiferromagnetism for the former compounds and to ferromagnetism for the latter compounds. For all compounds investigated the lattice constants have been determined.

The pressure derivative of the Curie temperature, the compressibility, and the thermal expansion of several representative members of the group of R -Co and R -Fe intermetallics ( R stands for rare-earth elements Y, Th, and in one case Zr) has been studied. The results derived for the volume dependence of T c agree rather well with the relation ( d \ln T_{c})/(d \ln V) = a+b/T_{c}^{2} in which, for both series of compounds (Co and Fe), the constant a equals about -5/3. This result favors an interpretation of the magnetic properties of these compounds in terms of the collective electron model rather than one in terms of localized moments. For some compounds the thermal expansion above room temperature has been studied. A considerable reduction of the thermal expansion has been observed near T c for those compounds for which dT_{c}/dp is large and negative (invar effect).

The decomposition of CaCu5-type rare earth-cobalt compounds has been studied at various stages. It is shown that the occurrence of one of the phases, after decomposition in the form of closely-spaced parallel lamellae, corresponds to an intermediate stage of the decomposition process in which the initial precipitates have not yet coalesced into larger regions. The influence of various impurities on the metastable character of the RCo5 compounds has been investigated. It is shown that impurities can shift the decomposition temperature over a range of several hundred degrees Celsius.

The influence of cubic crystalline fields on the magnetic moment of the ${\mathrm{Sm}}^{3+}$ ion is calculated, with inclusion of the mixing of higher multiplet levels into the ground multiplet. It is shown that the magnetic moment residing on the samarium, which in a number of intermetallics is observed to be substantially reduced with respect to the free-ion value, can easily be explained on this basis. From a comparison with the corresponding gadolinium compounds it is found that the moment reduction by conduction-electron polarization is less important.

Mossbauer spectra were taken of the compounds YFe2, YFe3, Y6Fe23 and Y2Fe17 at temperatures ranging from 15K to well above the Curie temperatures (Tc=540, 538, 496 and 358K, respectively). The various spectra were analysed by means of subspectra due to the different nonequivalent Fe sites occurring in these compounds. For each of these sites the temperature dependence of the hyperfine field was determined and shown to be similar for different sites within the same compound.

The series Th(CoxFe1−x)5 was investigated by means of neutron diffraction. All compounds investigated (x = 0, 0.2, 0.4, 0.6, and 1.0) were found to crystallize in the hexagonal CaCu5 type of structure. Their lattice constants were determined at 4.2 K as well as at room temperature. It is shown that only part of these compounds are true ferromagnets. For the compounds with x = 0 and x = 0.2 antiferromagnetic cimponents are also present, leading to a doubling of the magnetic unit cell. For all compounds investigated the magnetic structure is given in detail. Die Th(CoxFe1−x)5-Serie wurde mit Neutronenbeugung untersucht. Alle untersuchten Verbindungen (x = 0; 0,2; 0,4; 0,6 und 1,0) kristallisieren in der hexagonalen CaCu5-Sturktur. Ihre Gitterkonstanten wurden sowohl bei 4,2 K als auch bei Raumtemperatur bestimmt. Es wird gezeig, das nur ein Teil dieser Verbindungen echte Ferromagnete sind. Fur die Verbindungen mit x = 0 und x = 0,2 sind antiferromagnetische Komponenten anwesend, die zu einer Verdopplung der magnetischen Elementarzelle fuhren. Fur alle untersuchten Verbindungen wird die magnetische Struktur ausfuhrlich angegeben.

Determinations have been made of the thermal expansion of the compounds SmCo5, Sm2Co7, SmCo3, Gd2Co17, GdCo5, Gd2Co7, GdCo3 and GdCo2 in the range from room temperature to 700 °C. With the exception of Gd2Co17 all compounds show an abnormal thermal expansion below the Curie temperature. These results are in keeping with the pressure dependence of the Curie temperature observed for the rare earth-cobalt compounds.

Results are given of a study of the change in hydrogen sorption properties caused by partly replacing La or Ni in LaNi5 by other metals. Desorption isotherms at 40 deg C were measured for or Cu, and for La0.8R0.2Ni5, where represents Nd, Gd, Y, and Er, also Th and Zr. Equilibrium hydrogen pressures in the two-phase region can be explained qualitatively by assuming that the more stable the original RNi5 compound, the weaker is the tendency to form a RNi5--hydride, i.e., the higher the equilibrium pressure obtained for the hydride. This assumption which connects the stability of ternary hydrides with the heat of formation of the original compounds can also be formulated in a more quantitative way. This leads to a fair description of the experimental observations for the compounds having the CaCu5 type of structure.

The magnetization was measured at 4.2 to 300 deg K. Zero-field resonanccs of /sup 155/Gd, /sup 157/Gd, /sup 27/Al, and /sup 67/Zn were determin ed using spin-echo techniques, and hyperfine field coupling constants were also determined. Hyperfine fields at the magnetic and nonmagnetic ion sites were determined. The coupling constant for the core polarization varies 1.5% per 8O deg K for GdAl/sub 2/ and 1.0% per 170 deg K for GdZn. (DLC)

The dependence of the composition on iron concentration has been studied for pseudobinary CaCu 5 -type compounds of Y with Fe and Co. Increasing Fe concentration leads to an increasing deviation from the stoichiometric composition. The temperature range in which these pseudobinary compounds are stable increases with Fe concentration. At low temperatures the compound YCo 5 is shown to undergo a eutectoid decomposition. Iron impurities increase the decomposition temperature. The application of the pseudobinary CaCu 5 -type compounds as starting materials for permanent magnets is briefly discussed.

The variation of Curie temperature with number of conduction electrons in compounds GdAg1 − x, Inx, GdAg1 − x Znx, and GdZn1 − x, Inx is interpreted in terms of the RKKY model. Especially, the influence of a nonconstant exchange integral with a cutoff wavenumber is discussed. The Curie temperatures of compounds with a constant number of conduction electrons were determined for GdCd1 − x Znx and GdAg0.5(1 − x)In0.5(1 − x)Znx. It is shown, that the mean free path of the conduction electrons modifies the strength of the indirect exchange interaction, which can explain, that different Curie temperatures are obtained in compounds with equal number of conduction electrons. The variation of the Pauli susceptibility was estimated from determinations of the magnetic susceptibility of the compounds YAg1 − x Inx YAg1 − xZnx, and LaAg0.5(1 − x)In0.5(1 − xZnx.

The Knight shift of the ${\mathrm{Al}}^{27}$ NMR in Sm${\mathrm{Al}}_{3}$ has been measured in the temperature region from 78 to 400\ifmmode^\circ\else\textdegree\fi{}K, and the susceptibility of Sm${\mathrm{Al}}_{3}$ has been measured up to 850\ifmmode^\circ\else\textdegree\fi{}K. The part of the Knight shift arising from polarization of the conduction electrons through exchange with the $4f$ electrons reverses sign at (310\ifmmode\pm\else\textpm\fi{}20) \ifmmode^\circ\else\textdegree\fi{}K, and the relation between the Knight shift and the susceptibility is not linear. This behavior results mainly from Van Vleck-type paramagnetism, and could adequately be calculated on the basis of free ${\mathrm{Sm}}^{3+}$ ions. The parameters used are the multiplet splitting constant $\frac{A}{k}=(410\ifmmode\pm\else\textpm\fi{}20)\ifmmode^\circ\else\textdegree\fi{}$K, and the interionic exchange constant $\frac{{\mathcal{I}}_{\mathrm{ff}}}{k}=\ensuremath{-}(15\ifmmode\pm\else\textpm\fi{}5)\ifmmode^\circ\else\textdegree\fi{}$K, indicating antiferromagnetic ordering at low temperatures. The effective exchange constant between the conduction-electron spins and the $4f$-electron spins has been found to be ${\mathcal{I}}_{\mathrm{sf}}=\ensuremath{-}0.21$ eV, equalling those derived for other R${\mathrm{Al}}_{3}$ compounds (R=rare earth). The nuclear quadrupole coupling has been measured to be $\frac{|{e}^{2}qQ|}{h}=(0.8\ifmmode\pm\else\textpm\fi{}0.1)$ Mc/sec, and is discussed in terms of the point-charge model.

The homogeneity region of the compound ThCo5 has been studied by X-ray diffraction and magnetic measurements. The increase in Co concentration corresponds to a substitution of a pair of Co atoms for each Th atom. An increase of the Co concentration of less than 2 at% brings about approximately a doubling of the Curie temperature. Der Homogenitatsbereich der Verbindung ThCo5 wurde mit Rontgenstrahlenbeugung und magnetischen Messungen untersucht. Das Ansteigen der Co-Konzentration entspricht einer Substitution eines Co-Paares fur jedes Th-Atom. Ein Ansteigen der Co-Konzentration von weniger als 2 At% verdoppelt naherungsweise die Curietemperatur.

The g-shift and the linewidths in the EPR of gadolinium in GdxY1−xAg have been studied as a function of temperature and concentration. For x > 0.002 a bottleneck in the relaxation of the conduction electrons to the lattice has been observed. The results can be described by Hasegawa's equations; the dynamic effect, predicted in these formulas could not be observed, however.

$^{27}\mathrm{Al}$ NMR in ferromagnetic $R{\mathrm{Al}}_{2}$ ($R=\mathrm{P}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{S}\mathrm{m},\phantom{\rule{0ex}{0ex}}\mathrm{G}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{T}\mathrm{b},\phantom{\rule{0ex}{0ex}}\mathrm{D}\mathrm{y},\phantom{\rule{0ex}{0ex}}\mathrm{H}\mathrm{o}$) has been studied. The easy direction of magnetization has been observed experimentally for the first time and a theoretical calculation, in accord with the observation, has been developed. The $s\ensuremath{-}f$ exchange parameters have been examined and in addition to the isotropic exchange parameter ${\ensuremath{\Gamma}}_{\mathrm{sf}}$, the existence of a small but significant anisotropic $s\ensuremath{-}f$ exchange term is verified experimentally for the first time. The accurately determined (\ifmmode\pm\else\textpm\fi{}1%) isotropic exchange parameters are compared with presently available theoretical predictions.

The temperature dependence of the electrical resistivity (1.3-300 \ifmmode^\circ\else\textdegree\fi{}K) has been studied for the isomorphous compounds ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{Al}}_{3}$, ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Y}}_{x}{\mathrm{Al}}_{3}$, and ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Th}}_{x}{\mathrm{Al}}_{3}$. In these compounds, one or two maxima have been observed in the $\ensuremath{\rho}\ensuremath{-}\mathrm{v}\mathrm{s}\ensuremath{-}T$ curve. An analysis of the experimental results is presented in terms of the Kondo sideband theory, which describes Kondo exchange scattering of the conduction electrons in the presence of localized moments whose ground-state manifold is split owing to the presence of crystalline fields. It is shown that the changes observed in $\ensuremath{\rho}$ behavior for Ce${\mathrm{Al}}_{3}$ upon replacement of Ce by La, Y, or Th can be correlated with changes in the crystal field parameters, and in the case of Th also with changes in the density of states of the conduction electrons.

The pressure dependence of the Curie temperature (Tc) of several intermetallic compounds of iron has been determined by means of the temperature dependence of the electrical resistivity at various pressures. Pressures up to 40 kbar were applied. The value of dTc/dp was observed to be negative in the compounds R2Fe17 (R=Pr,Nd,Er, and Th), Y6Fe23, Er6Fe23, ErFe3, Th2Fe7, ThFe3, CeFe2, and ZrFe2. The Curie temperature of the compound ThFe5 is pressure independent within experimental error. In the compounds RFe2 (R=Gd,Ho,Er, and Y), the value of dTc/dp was found to be positive. The experimental data are discussed in terms of Friedel's semilocalized model and the collective electron model.

The electrical resistivity has been measured between 4.2 and 300°K for RA1 2 compounds, where R denotes the rare-earth elements La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb and Y. From an analysis of the resistivity behaviour of the ferromagnetic compounds values are deduced for the effective s-f exchange coupling constants. These values agree reasonably well with data given in literature for the Knight shift of the A1 nuclear magnetic resonance. For CeA1 2 a resistivity minimum has been observed at 13°K.

At low temperatures the compounds GdCo5 and SmCo5 decompose into the corresponding phases R2Co7 and R2Co17. This transformation is connected with the dependence of the coercive force of powder compacts on sintering temperature.

The thermal expansion coefficient of the compounds ZrFe 2 , TiFe 2 , YFe 2 , ErFe 2 , ErFe 3 , Er 6 Fe 23 and Er 2 Fe 17 has been determined from room temperature up to 700°C. The anomalous thermal expansion of some of these compounds observed at temperatures below their Curie temperature ( T c ) is shown to be related to a strong pressure dependence of T c . (d T c /d P is large and negative).

Curie temperatures and magnetizations are measured in the cubic Laves phases RxM1−xAl2 (R = Gd, Tb, Er and M = Y, La, Th). Upon dilution with Y or La a linear decrease of the Curie temperature, passing through zero for x = 0, is found. Dilution with Th results in an additional decrease of the Curie temperature. This effect is attributed to small changes of the Fermi wave-vector. The results, as compared with Knight shifts, are discussed in terms of the Ruderman-Kittel-Kasuya-Yosida theory. The exchange integral Γ is found to be of the order of −0.9 eV, and definitely negative. Fur die kubischen Laves-Phasen RxM1−xAl2 (R = Gd, Tb, Er and M = Y, La, Th) werden die Curietemperaturen und Magnetisierungen bestimmt. Bei Verdunnung mit Y oder La wird eine lineare Abnahme der Curietemperatur gefunden, die fur x = 0 den Wert Null erreicht. Verdunnen mit Th fuhrt zu einer zusatzlichen Abnahme der Curietemperatur. Dieser Effekt wird auf eine leichte anderung des Fermivektors zuruckgefhrt. Die Ergebnisse werden mit Ergebnissen von Knight-Shift-Messungen verglichen und mit der Ruderman-Kittel-Kasuya-Yosida-Theorie diskutiert. Fur das Austauschintegral Γ wird ein Wert von etwa −0,9 eV ermittelt. Dieses Integral ist definitiv negativ.

A number of rare-earth-copper alloys and thorium-copper alloys near 86 at.% Cu have been investigated by X-ray diffraction. It is shown that the compounds ThCu 6 and RCu 6 , with R = Pr , Nd, Sm, Gd are isotypic and have the orthorhombic CeCu 6 type of structure. For R = Tb and Dy no stable compound of this structure type exists.

The Knight shifts of the 27Al NMR in LaAl3, CeAl3, PrAl3, NdAl3, GdAl3, and TbAl3 have been measured at temperatures from 78° up to 450°K. The effective exchange constants J between the 4f electrons localized at the rare‐earth ions and the conduction electrons at the Al nuclei have been derived to be −0.2 eV. Ruderman—Kittle—Yosida periodic oscillations of the conduction electron polarization have been used to relate the results with those obtained for RAl2. Nuclear quadrupole coupling constants have been measured to be |e2qQ|=0.8 Mc/sec. On the basis of the ionic point model e2qQ has been calculated for RAl3 and RAl2.

The crystal structure of YbCu6.5 has been determined from powder data with the use of difference Fourier syntheses. It is related to the CaCu5 structure, but 18% of the Ca sites are occupied by pairs of Cu atoms. The magnetic susceptibility and the lattice constants show that Yb is divalent in this compound.

Various rare-earth nickel alloys with 70–80 at.% Ni have been studied by X-ray diffraction and metallography. The lattice parameters of compounds of the type RNi3 and R2Ni7 have been determined for R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y. A structure determination is given for La2Ni7 and Sm2Ni7. Some of the compounds R2Ni7 have been observed to have two modifications. Indications have been obtained that the transformation between these two modifications is of the martensitic type. It is shown that the crystal structure of the R2Ni7 compounds is size-dependent.

The compounds ThCo5−5xFe5x and ThNi5−5xFe5x form two series of complete solid solutions. All compounds investigated show the hexagonal CaCu5 structure. The lattice constants, the Curie temperatures, and the saturation moments at 4.2 K have been determined as a function of x. The ThM5 compounds possess two nonequivalent crystallographic sites for the M atoms (M = Fe, Co, Ni). By means of the Mossbauer effect it is shown that the physical nature of atoms occupying these sites differs appreciably. It is also shown that replacement of Co or Ni by Fe in ThCo5 or ThNi5 proceeds with a strong preference for one of these two sites. The crystalline anisotropy of the compounds ThCo5−5xFe5x was studied as a function of x. It could be shown that the anisotropy in ThCo5 is not particularly due to one of the two Co sites. With decreasing values for x, starting from ThFe5, the Fe moment increases down to x = 0.6. This is explained in terms of a rigid‐band model.

The holmium-cobalt system has been investigated over the whole concentration range by means of X-ray diffraction, thermoanalysis, and metallography. The following intermetallic compounds have been identified: Ho 3 Co, Ho x Co (x≈ 7 4 ) , Ho 4 Co 3 , HoCo 2 , HoCo 3 , Ho 2 Co 7 , HoCo 5.5 , and Ho 2 Co 17 . For all compounds except Ho x Co the crystal structure and the lattice constants are given. For the compounds HoCo 5.5 and Ho 2 Co 17 large homogeneity regions exist at elevated temperatures. The compound HoCo 5.5 is not stable below 1150 °C.

Zusammenfassung Es wird eine zirkulare papicrchromatographische Methode beschrieben zur schnellen Trennung und Identifizierung der Erdalkalicn. Die mobile Phase besteht aus einem Genisch von Methylalkohol, Salzsaure und Tetrahydrofuran, woran das Reagens Oxin zugefugt wird. Mit dieser Methode kann I μg jedwedes Kations in Gegenwart von insgesamt hundertfacher Menge der anderen drei Kationen nachgewiesen werden. Bei Mg ist die Empfindlichkeit 0.25 μg.

The magnetic properties of the intermetallic compounds GdxTh1−xCuAl (0.2≤x≤1.0) are reported for temperatures between 2.1 and 300 K. These compounds become ferromagnetic at low temperatures. Curie temperatures and magnetic moments are derived. The paramagnetic Curie temperature varies quite anomalously with x. The variation is compared with that calculated in terms of the Ruderman‐Kittel‐Kasuya‐Yosida theory. In GdCuAl, the 27Al Knight shift was measured between 190 and 300 K. For the effective exchange constant Γ and the Fermi wave vector kF, values of +0.5 eV and 1.13 A−1, respectively, were estimated.

The LaNi system has been reinvestigated in the range 50–100 at. % Ni. The following compounds were observed: LaNi, LaNi 1.4 , LaNi 2 , LaNi 3 , La 2 Ni 7 and LaNi 5 . For these compounds the lattice constants have been determined. The phase LaNi 5 has a relatively large homogeneity region at elevated temperatures. For the compounds LaNi x within this region the equilibrium hydrogen pressure, p , of the 40 °C isotherms was found to change from 2.75 atm for LaNi 4.9 to about 9.2 atm for LaNi 5.4 according to In p = Cx + q with C = 2.4, q = − 10.75.

Neither of the intermetallics Sm${\mathrm{Al}}_{2}$ (a ferromagnet below ${T}_{C}=120$ K) and Sm${\mathrm{Sn}}_{3}$ (an antiferromagnet below ${T}_{N}=11$ K) show the sign reversal predicted by White and Van Vleck for the $4f$-induced Knight shift in the paramagnetic region. On the other hand, no particular anomaly has been observed in the temperature dependence of the susceptibility. An explanation for this is given in terms of mixing of excited $J$ levels of ${\mathrm{Sm}}^{3+}$ into the $J=\frac{5}{2}$ ground multiplet by cubic crystal fields. The calculation is described of the crystal field matrix elements of ${\mathrm{Sm}}^{3+}$ between any $J$ and ${J}^{\ensuremath{'}}$, and expressions are derived for the Knight shift and the susceptibility in the presence of crystalline and molecular fields. It is shown that the sixth-order component of the crystal field is important, and that the anomalous behavior is enhanced by ferromagnetic exchange between the Sm ions. A study of the lattice constants and the $^{27}\mathrm{Al}$ quadrupolar coupling in comparison with other $R{\mathrm{Al}}_{2}$ ($R=\mathrm{rare}\mathrm{earth}$) compounds excludes the possibility of Sm in Sm${\mathrm{Al}}_{2}$ not being trivalent.

Low-temperature measurements of the specific heat are reported for Ce 1−x La x Al 3 and Y 1−x Th x Al 3 . The observed maxima for Ce 1−x La x Al 3 are attributed to crystalline field effects. The marked variations in the electronic density of states for Y 1−x Th x Al 3 are ascribed to influences of Brillouin zones. Results are related to the Kondo sideband model.

The extension of the temperature region in which the rare earth-cobalt phases with a CaCu5-type of structure are stable has been studied for all rare-earth elements except Pm and Eu. This region is limited by the melting point at high temperatures and by a eutectoid transformation at lower temperatures. It extends over about 600 °C for the light rare-earth elements but decreases appreciably for the heavier rare-earth elements and vanishes altogether for the elements beyond Tm.

By means of spin echo techniques the zero field resonance of Gd155, Gd157, Ag107, Ag109, and Zn67 nuclei could be detected in the ferromagnetically ordered CsCl type compounds GdAg1−xInx, GdAg1 - xZnx, and GdZn1−xInx. In some cases well resolved lines could not be obtained due to broadening. Both, the hyperfine field of the magnetic and of the nonmagnetic ions are negative. No significant hyperfine field variation with conduction electron concentration is observed for the nonmagnetic ions while for the Gd ions it is appreciable. This cannot be explained by the simple RKKY approach, in which the interaction between the localized Gd-moments and the conduction electrons is considered to be a δ-function interaction and in which the Fermi surface is assumed to be spherical. The variation of the hyperfine fields was also studied in the systems GdCdZnx and Gd1no.5 (1−x)-Ag0,5 (1−x)Znx, in which the number of conduction electrons remains constant. Essentially no change is found in GdCdZnx, where divalent Cd is replaced by divalent Zn. In Gd1n0,5 (1−x)Ag0,5 (1−x)Znx, where divalent Zn is replaced by monovalent Ag and trivalent In, the hyperfine fields become smaller with decreasing x. Apparently the reduction of the conduction electrons' mean free path due to potential scattering modifies their polarization. Mittels Spin-Echo-Technik wurde die Nullfeld-Resonanz von Gd155, Gd157, Ag107, Ag109 und Zn67-Kernen in den ferromagnetisch geordneten Verbindungen mit CsCl-Struktur, GdAg1−xInx, GdAgZnx und GdZn1−xInx, nachgewiesen. In einigen Fallen konnten wegen Verbreiterung keine gut aufgelosten Linien erhalten werden. Das Hyperfeinfeld ist sowohl fur die magnetischen wie fur die nichtmagnetischen Ionen negativ. Eine bedeutende Hyperfeinfeldvariation mit der Leitungselektronenkonzentration fur die nichtmagnetischen Ionen wurde nicht beobachtet, wahrend sie fur die Gd-Ionen betrachtlich ist. Dies kann nicht mit der einfachen RKKY-Naherung erklart werden, in der die Wechselwirkung zwischen den lokalisierten Gd-Momenten und den Leitungselektronen als δ-Funktion-Wechselwirkung berucksichtigt wird und in der angenommen wird, das die Permiflache kugelformig ist. Die Aderung des Hyperfeinfeldes wurde in den Systemen GdCdZnx und GdIn0,5(1−x)Ag0,5 (1−x)Znx, in der die Zahl der Leitungselektronen konstant ist, ebenfalls untersucht. Im wesentlichen werden in GdCdZnx, bei dem zweiwertiges Cd durch zweiwertiges Zn ersetzt wird, keine Aderungen gefunden. In GdIn0,5 (1−x)Ag0,5 (1−x)Znx, bei dem zweiwertiges Zn durch einwertiges Ag und dreiwertiges In ersetzt wird, werden die Hyperfeinfelder mit abnehmendem x kleiner. Offensichtlich modifiziert die Verkleinerung der mittleren freien Weglange der Leitungselektronen durch Potentialstreuung ihre Polarisation.

The binary system erbium-nickel has been investigated by X-ray diffraction, thermoanalysis and metallography. A constitutional diagram has been constructed. Eleven intermetallic compounds have been identified: Er 3 Ni, Er 5 Ni 3 , ErNi, ErNi 2 , ErNi 3 , Er 2 Ni 7 , ErNi 4 , Er 4 Ni 17 , Er 5 Ni 22 , ErNi 5 and Er 2 Ni 17 . For all compounds the lattice constants have been determined. Crystal structures are given for all the compounds except Er 5 Ni 3 , ErNi 4 , Er 4 Ni 17 and Er 5 Ni 22 . A possible hexagonal structure for the last three compounds is indicated, in which the peculiar stacking along the c -direction leads to extremely large unit cells. The magnetic properties of most of the compounds have been investigated: Er 5 Ni 3 , ErNi, ErNi 2 , ErNi 3 , Er 2 Ni 7 , ErNi 5 and Er 2 Ni 17 are either ferro- or ferrimagnetic; Er 3 Ni is antiferromagnetic.

The technology of making SmCo5 magnets with energy products of 20 × 106 GOe is described. This technology consists of the preparation of a powder by grinding, aligning the powder particles in a magnetic field, and cold pressing by applying a uniaxial deformation at 20 kbar. The permanent magnetic properties of the SmCo5 powders are shown to vary appreciably with various applied chemical treatments and with the composition of the alloy. The intrinsic coercive force appears to decrease with time but remains so large that the demagnetization of the induction is hardly affected. Some properties of the magnets are discussed.

A number of intermetallic compounds of the form R 2 Ni 17 , R 2 Co 17 and R 2 Fe 17 has been investigated by X-ray diffraction. The structure of these compounds is shown to depend on the size of the rare-earth component and on the temperature. For some of the compounds a low- and a high-temperature modification is observed. For most compounds the type of structure and the lattice constants of each modification are given.

The magnetization for the ferrimagnetic compounds Er2Co17, ErCo6, and Er2Co7 has been studied in the temperature range 4.2 to 1250 °K and at field strengths up to 30 kOe. The Curie temperatures and the saturation magnetizations at 4.2 °K have been determined. For all compounds a maximum has been observed in the magnetization versus temperature curves. Er2Co7 shows a compensation point at 140 °K. For this compound changes in the crystalline anisotropy were observed near the compensation point. The values of the coercive force obtained by mortar grinding samples of Er2Co17, ErCo6, Er2Co7, and ErCo3 are compared with the variation of the lattice parameters for these compounds. Die Magnetisierung fur die ferrimagnetischen Verbindungen Er2Co17, ErCo6 und Er2Co7 wurde im Temperaturbereich 4,2 bis 1250 °K bei Feldstarken bis zu 30 kOe untersucht. Die Curietemperaturen und Sattigungsmagnetisierung bei 4,2 °K wurden bestimmt. Bei allen Verbindungen wurde ein Maximum in der Magnetisierungs-Temperaturabhangigkeit beobachtet. Er2Co7 zeigt einen Kompensationspunkt bei 140 °K. Bei dieser Verbindung wurden Anderungen in der Kristallanisotropie in der Nahe des Kompensationspunktes beobachtet. Die Werte fur die Koerzitivkraft von zermorserten Proben von Er2Co17, ErCo6, Er2Co7 und ErCo3 werden mit Anderungen der Gitterparameter dieser Verbindungen verglichen.

Lattice constants are given for the following intermediate phases: LaAl and CeAl (CeAl type, orthorhombic); PrAl, NdAl, SmAl, GdAl, TbAl, DyAl, HoAl, and ErAl (ErAl type, orthorhombic); Gd 3 Al 2 , Tb 3 Al 2 , Dy 3 Al 2 , Ho 3 Al 2 , Er 3 Al 2 and Y 3 A1 2 (Zr 3 Al 2 type, tetragonal). It is shown that the stability of these compounds is sensitive to the atomic radii of the rare earth metals.

The phase relations, crystal structures, and magnetic properties of intermetallic compounds occurring in the Er–Fe system have been investigated. A phase diagram is given. The lattice constants of the compounds ErFe2, ErFe3, Er6Fe23, and Er2Fe17 have been determined. These compounds are ferrimagnetic with the Fe moments coupled antiparallel to the Er moments. Their Curie temperatures decrease with increasing Fe concentration. The compounds ErFe2, ErFe3, and Er6Fe23 have been observed to show a compensation point. Die Phasenbeziehungen, Kristallstrukturen und magnetischen Eigenschaften intermetallischer Verbindungen, die im Er–Fe-System auftreten, wurden untersucht. Ein Phasendiagramm wird angegeben. Fur die Verbindungen ErFe2, ErFe3, Er6Fe23, und Er2Fe17 wurden die Gitterkonstanten bestimmt. Diese Verbindungen sind ferrimagnetisch mit antiparallel zu den Er-Momenten gekoppelten Fe-Momenten. Ihre Curie-Punkte nehmen mit steigender Fe-Konzetration ab. Fur die Verbindungen ErFe2, ErFe3, und Er6Fe23 wurde ein Kompensationspunkt beobachtet.