Hexagonal Th2Ni17-type Structure Research Articles

Microwave absorbing properties of Y2Fe16Si micropowders with broad bandwidth and strong absorption

The rare earth-Fe intermetallic compounds with planar magnetocrystalline anisotropy were deemed as hopeful candidates for microwave absorption owing to their higher Snoek’s limit as compared to the cubic spinel-type ferrites. In this work, The Y2Fe16Si alloy was massively produced through strip casting technique, and the microwave absorbing properties of Y2Fe16Si-paraffin composites were studied. The Y2Fe16Si alloy exhibits a single phase of hexagonal Th2Ni17-type structure with a planar magnetocrystalline anisotropy and has a saturation magnetization of 121 emu g−1. It was found that electromagnetic dissipation contributes to microwave absorption but is not the determinative factor in Y2Fe16Si-paraffin composites. Controlling the values of the complex permittivity and the complex permeability in a reasonable range can lead to proper impedance matching. Thus excellent microwave absorbing properties can be obtained. The sample with the mass ratio of 3:1 between Y2Fe16Si and paraffin displays high performance ascribed to its appropriate values of complex permittivity and permeability. A minimum reflection loss (RL) of −51.6 dB is obtained with a thickness of 1.8 mm. Full covers of the effective bandwidth (RL < −10 dB) on the X-band and the Ku-band are achieved when the thicknesses are 1.9 mm and 1.38 mm, respectively. Hence, Y2Fe16Si exhibits excellent potential as a high-performance microwave absorbing material.

Effect of Chromium Substitution for Iron on the Magnetic and Structural Properties of (TmxPr1– x)2Fe17

The (TmxPr1 – x)2Fe17 and (TmxPr1 – x)2Fe16.5Cr0.5 compounds crystallize with the formation of the rhombohedral Th2Zn17-type structure for the compositions with x = 0–0.4 and the hexagonal Th2Ni17-type structure for the compositions with x = 0.8–1 and x = 0.75–1, respectively. Both structures coexist in the (TmxPr1 – x)2Fe17 and (TmxPr1 – x)2Fe16.5Cr0.5 compounds with x = 0.5–0.75 and x = 0.5–0.6, respectively. The (TmxPr1 – x)2Fe17 compositions with 0 < x < 0.6 are ferrimagnets; at x = 0.6–1, additionally a high-temperature helical magnetic state is realized. The substitution of chromium for iron leads to the transformation of the helimagnet to ferrimagnet; in this case, the difference between the Curie temperatures of rhombohedral and hexagonal phases is unexpectedly high (25–28 К). For the composition with x = 0.8, the Curie and Neel temperatures and the ferrimagnet–helimagnet transformation temperature are minimum, and the microdeformations are maximum. The overlap of two peaks in –ΔSM(T), which correspond to the magnetic entropy change at two magnetic phase transformation temperatures, favors the realization of the higher cooling capacity of the two-phase compositions as compared to that of neighboring single-phase compositions.

Negative Thermal Expansion of the Dy2Fe16Cr Compound**Supported by the National Natural Science Foundation of China under Grant Nos 50871074 and 61474082.

Structural, thermal expansion, and magnetic properties of the Dy2Fe16Cr compound are investigated by means of x-ray diffraction and magnetization measurements. The Dy2Fe16Cr compound has a hexagonal Th2Ni17-type structure. There exists a negative thermal expansion resulting from a strong spontaneous magnetostriction in the magnetic state of the Dy2Fe16Cr compound. The average thermal expansion coefficient is −0.794 × 10−5/K in the temperature range 292–407 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.

Structural and magnetic properties of the R10Fe90-xSix alloys with R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er

In this study alloys with stoichiometry of R2Fe17 and R10Fe90-xSix (x = 0, 10, 15, 20) (R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) have been prepared. Structural transition from the ordered rhombohedral (OR) Th2Zn17-type structure and the ordered hexagonal (OH) Th2Ni17-type structure to their disordered structures (DR and DH) has been observed according to the XRD patterns. The lattice parameters were obtained by Rietveld analysis and based on the changing characteristic of the parameters, these samples are divided into two categories: alloys with R = Ce, Pr, Nd, Sm and alloys with R = Y, Gd, Td, Dy, Ho, Er. The lattice parameters of the two categories show different changing behavior. For example, from R2Fe17 to R10Fe90, the lattice parameters a decrease and c increase for the latter category, whereas for the former the lattice parameters a and c nearly have no change. In addition, increase of the ratio c/a has been found with increasing Fe or Si content, indicating the introduction of extra Fe dumbbells into the crystal cells, forming the DR or DH intermetallic compounds of R2-y(Fe,Si)17+2y. The obtained samples with disordered structure have shown better stability than the TbCu7-type metastable materials and the higher Fe concentration gives promise of higher magnetization. The mixed-rare-earth effect has also been studied in the (Ce,R)10Fe75Si15 alloys and transition between the DR and DH structures has been realized by changing the mixed R-type or adjusting the Ce/R ratio. As for the magnetic properties, the Curie temperatures are increased remarkably by the introduction of Si and the saturation magnetizations of R10Fe90-xSix are often higher than that of the R2Fe17 alloys.

Influence of Y substitution in Gd2-xYxFe17 compounds

Gd2−xYxFe17 (x = 0; 0.6; 1.0) compounds were prepared by standard arc melting method. Thereafter, samples were subjected to annealing for two days at T=1273 K, finishing with quenching to 273 K. The samples were cut into small portions to perform structural, electrical, and thermal characterization. Heat flow and Curie temperature (Tc) arise from measurements of thermal properties through Differential Scanning Calorimetry (DSC), structural properties were tested via X-ray diffraction (XRD) at T=273 K, electrical characterization was carried out through the Impedance Spectrometry (IS) method, upon zero applied magnetic field and temperature range between 300 K<T<500 K. Results show that Tc decreases when Y concentration increases. Tc is obtained as the maximum temperature variation of heat flux. The Gd2Fe17 compound shows two endothermic heat flux peaks; this fact can be attributed to not identifying an impurity phase from X-ray diffraction measurements. From Rietveld refined data, the crystal structure for all compounds is established, resulting in a hexagonal Th2Ni17-type structure. Measurements of impedance spectrometry as function of frequency were analyzed in terms of equivalent circuit method, finding that for temperatures below Tc they fit according to the model composed of one RL and two RC parallel circuits, in contrast to temperatures above Tc given by the model that consists of only two RC parallel circuits.

Magnetic Phase Diagrams of Tm&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;19-&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Mn&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and Tm&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;17+δ&lt;/sub&gt; Systems

The Tm2Fe19-xMnx (x = 0 - 1.5) and Tm2Fe16, Tm2Fe17, Tm2Fe18, Tm2Fe19 intermetallic compounds were synthesized and their magnetic and structural properties were studied. Magnetic measurements, X-ray and neutron diffraction investigations were used. The compounds crystallize in a disordered variant of the hexagonal Th2Ni17-type structure. The lattice parameters a, c increases in the Tm2Fe19-xMnx system, whereas c decreases and a increases in the Tm2Fe19 - Tm2Fe16 system as Fe content decreases. The temperatures of ferromagnetic ordering and spin-reorientation increase as Fe content decreases in these systems. Apparently, the decrease of occupation of defected dumbbell Fe (4e) site causes these regularities.

Magnetism and structure of near-stoichiometric Tm2Fe17+δ compounds

Magnetic and structural properties of the Tm2Fe16, Tm2Fe17, Tm2Fe18, and Tm2Fe19 intermetallic compounds were studied. Magnetic measurements, microprobe analysis, X-ray and neutron diffraction investigations were used. The compounds crystallize in a disordered variant of the hexagonal Th2Ni17-type structure. The lattice parameter c increases and lattice parameter a decreases as Fe content increases in the system. The temperatures of ferromagnetic ordering and spin-reorientation and the critical field of the FOMP decrease, whereas the Néel temperature, the spontaneous magnetization, and the magnetic anisotropy increase in the system. The increase of occupation of the defected “dumbbell” Fe(4e) site is likely to cause these regularities.

Theoretical study of structure, magnetism and lattice vibrations of intermetallics Lu2(Fe, T)17 and their hydrides

A systemic study of the structural properties of the rare-earth intermetallics Lu2(Fe, T)17 (T = Mn, Ru) and their hydrides has been performed by a series of interatomic pair potentials. The site preference of T atoms at Fe sites is evaluated and the order is given as 4f, 12k, 12j and 6g for Lu2(Fe, T)17. The interstitial H atoms only occupy 6h interstitial sites in Lu2(Fe, T)17. The calculated lattice constants agree with a report in the literature. We have calculated the magnetic moments of Lu2(Fe, T)17 compounds. Results showed that the calculated total magnetic moment of Lu2Fe17 compound is M = 37.34 μB/f.u. Furthermore, the total and partial phonon densities of states are evaluated first for Lu2(Fe, T)17 and their hydrides with the hexagonal Th2Ni17-type structure.

Structural and Magnetic Properties of ${\hbox {Tm}}_{2}{\hbox {CrFe}}_{16-x}{\hbox {Si}}_{x}$ Compounds

The structural and magnetic properties of Tm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16-x</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> =0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0) compounds are investigated by means of X-ray diffraction and magnetization measurements. The results show that the Tm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16-x</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> compounds are in a single phase with the hexagonal Th <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> -type structure. The lattice parameters <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</i> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> and the unit-cell volume <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</i> decrease monotonously with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> increasing. The Curie temperature <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> increases initially ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> <; 1.5) with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> increasing, followed by a decrease at higher concentrations ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> >; 1.5) . There is a maximum of the Curie temperature, which is about 450 K, at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> =1.5. Spin reorientations are observed in the temperature dependences of the magnetization of Tm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16-x</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> compounds. The spin reorientation temperature ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sr</sub> ) increases from 144 K at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> =0 to 259 K at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> =3.0 with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> increasing. This means that the Si atoms substituting for Fe atoms can increase obviously the easy-axis magnetocrystalline anisotropy. The analysis shows that the effect of Cr substitution and the effect of Si substitution on the Curie temperature and the magnetocrystalline anisotropy of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> compound can be superposed.

Negative Thermal Expansion of Tm&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;15&lt;/sub&gt;SiCr Compound

The thermal expansion and the Curie temperature of Tm2Fe15SiCr compound have been investigated by means of x-ray diffraction and magnetization measurements. The result shows that the Tm2Fe15SiCr compound has a hexagonal Th2Ni17-type structure. One Cr and one Si atoms substituting for two Fe atoms can increase the Curie temperature obviously. In magnetic state, an anisotropic anomalous thermal expansion was observed. Along the c-axis, the average linear thermal expansion coefficient αc=-2.04×10-5/K in the temperature range 303-460K. Along the a-axis, the average linear thermal expansion coefficient αa=-8.09×10-5/K in 370-410K. In the temperature range 370-450K, the average volume thermal expansion coefficient αv =-2.08×10-5/K. The mechanism of the thermal expansion anomaly of Tm2Fe15SiCr compound was discussed in this paper.

Negative Thermal Expansion of Gd&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;16.5&lt;/sub&gt;Cr&lt;sub&gt;0.5&lt;/sub&gt; Compound with Th&lt;sub&gt;2&lt;/sub&gt;Ni&lt;sub&gt;17&lt;/sub&gt;-Type Structure

The thermal expansion and the Curie temperature of Gd2Fe16.5Cr0.5 compound have been investigated by means of x-ray diffraction and magnetization measurements. The result shows that the Gd2Fe16.5Cr0.5 compound annealed at 1243°C has a hexagonal Th2Ni17-type structure. Cr atom substituting for Fe atom can increase the Curie temperature obviously. In magnetic state, an anisotropic anomolous thermal expansion was observed. Along the c-axis, the average linear thermal expansion coefficient αc=-2.79×10-6/K in the temperature range 294-472K, and αc =-3.09×10-5/K in 472-592K. Along the a-axis, the average linear thermal expansion coefficient αa =9.22×10-6/K in 294-552K, and αa =-1.41×10-5/K in 552-592K. In the temperature range 472-592K, the average volume thermal expansion coefficient αv =-2.14×10-5/K. The mechanism of the thermal expansion anomaly of Gd2Fe16.5Cr0.5 compound was discussed in this paper.

Phase-Transition and Magnetic Moment of the Gd3+ Ion in the Gd2Fe17 Compound

The structure and magnetic phase transitions of the Gd2Fe17 compound are investigated by using a differential thermal/thermogravimetric analyzer, x-ray diffraction, and magnetization measurements. The result shows that there are two phase structures for the Gd2Fe17 compound: the hexagonal Th2Ni17-type structure at high temperatures (above 1243°C), and the rhombohedral Th2Zn17-type structure, respectively. A method to measure the magnetic moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound is presented. The moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound from 77 to 500 K are measured in this way with a vibrating sample magnetometer. A detailed discussion is presented.

Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3 Compound

The structure and magnetic properties of Y2Fe14Al3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe14Al3 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion is found in Y2Fe14Al3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is ᾱ = –2.54 × 10−5 K−1. The spontaneous magnetostrictive deformations from 283 to 470K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωS decreases from 5.74 × 10−3 to nearly zero with temperature increasing from 283 to 470 K, the spontaneous linear magnetostrictive deformation λc along the c-axis is larger than the spontaneous linear magnetostrictive deformation λa in basal-plane in the same temperature below 350 K.

The structure, magnetic properties, and positron annihilation spectra of Tb2AlFe16-xMnx compounds

The structural and magnetic properties have been investigated by means of X-ray diffraction, magnetization measurements, and positron annihilation technique. The X-ray diffraction shows that the Tb2AlFe16-xMnx （x=1—8） compounds have a hexagonal Th2Ni17-type structure. The positron annihilation spectra show that Mn substitution for Fe has the ferromagnetic interaction decreased, and that there exists a strong magnetoelastic effect in Tb2AlFe16-xMnx compound. The magnetization measurement shows that the Curie temperature and the spontaneous magnetization of Tb2AlFe16-xMnx compounds decrease rapidly with increasing x.

Thermal Expansion Anomaly of Tb2Fe14Cr3 Compound

We investigate the thermal expansion property of the Tb2Fe14Cr3 compound by means of x-ray diffraction. The result shows that the Tb2Fe14Cr3 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion is found in the Tb2Fe14Cr3 compound from 296 to 493K by x-ray dilatometry The coefficient of the average thermal expansion is ᾱ = -2.82 × 10−5K−1. In the temperature range 493–692K, the coefficient of the average thermal expansion is ᾱ = 1.59 × 10−5K−1. The physical mechanism of thermal expansion anomaly of the Tb2Fe14Cr3 compound is discussed according to the temperature dependence of magnetization measured by a superconducting quantum interference device.

Anomalous magnetic and magnetocaloric properties of Er2Ni17

Intermetallic compound Er2Ni17 crystallizes in the hexagonal Th2Ni17-type structure with the space group P63/mmc and lattice parameters a = b = 8.282 Å and c = 8.033 Å. The magnetization measurements show that it is ferrimagnetic below its magnetic ordering temperature of 150 K. The temperature variation of zero-field-cooled magnetization in a field of 200 Oe shows the compensation point at about 63 K. On the other hand, the field-cooled magnetization in low fields is found to be negative at low temperatures. The compensation temperature is found to shift to low temperatures with an increase in the field. These variations are explained on the basis of the two sublattice model. The intersublattice molecular field coefficient (nRT) and the intersublattice exchange coupling constant (JRT) have been calculated using the high-field free-powder method. The nRT and JRT values are found to be 1.4 Tf.u./μB and 5.2 K, respectively. The magnetocaloric effect has been measured in terms of the isothermal magnetic entropy change, using the magnetization isotherms. The maximum entropy change is about 2 J kg−1 K−1 for a field of 50 kOe.

Effect of Mn substitution on the structure and magnetic properties of Dy2AlFe16－xMnx compounds

The structural and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe16-xMnx compounds have a hexagonal Th2Ni17-type st ructure. The thermal expansion of Dy2AlFe16-xMnx (x=1 and 2) compounds have been investigated by X-ray dilatometry in the tempe rature range 104—647K. The results show that there is a thermal expansion anoma ly at low temperature and a negative thermal expansion near the Curie temperatur e. There exists a strong and anisotropic spontaneous magnetostriction in the mag netic state of Dy2AlFe16-xMnx compounds. The sp ontaneous volume magnetostrictive deformation at low temperature decreases with increasing x. The result of magnetization measurement shows that the Curie tempe rature and the spontaneous magnetization of Dy2AlFe16-xMnx compounds at 5K decrease rapidly with increasing x.

Magnetic properties and thermal expansion anomaly of Er2AlFe16－xMnx compounds

The structure and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Er2AlFe16-xMnx (x=1, 2, 3, 4, 6 and 8) compounds have a hexagonal Th2Ni17-type structure. The thermal expansion of Er2AlFe16-xMnx (x=1, 2, 3, and 4) compounds have been investigated by X-ray dilatometry in the temperature range 103—654K. The results show that there is a thermal expansion anomaly at low temperature and a negative thermal expansion near the Curie temperature. There exists a strong and anisotropic spontaneous magnetostriction in the magnetic state of Er2AlFe16-xMnx compounds. The spin reorientation at low temperature results in an enhancement of the spontaneous volume magnetostrictive deformation of Er2AlFe16-xMnx compounds. Magnetization measurement shows that the Curie temperature and the spontaneous magnetization at 5K of Er2AlFe16-xMnx compounds decrease rapidly with increasing x, and that the Mn substitution for Fe results in obvious change of the magnetic anisotropy.

Spontaneous magnetostriction of Dy 2 AlFe 13 Mn 3 compound

The structural and magnetic properties of Dy2AlFe13Mn3 compound have been investigated by means of x-ray diffraction and magnetization measurements. The Dy2AlFe13Mn3 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion is found in the Dy2AlFe13Mn3 compound at the temperatures ranging from 245 to 344K by x-ray dilatometry. The coefficient of the average thermal expansion is = −1.1×10−4K−1. The spontaneous magnetostrictive deformations in the 105–360K temperature range have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs increases from 7.0×10−3 at 105K to 9.1×10−3 at 245K and then decreases with the temperature increasing. The spontaneous linear magnetostrictive deformation λc along thec axis decreases as temperature increases. The spontaneous linear magnetostrictive deformationλa in basal-plane increases from 0.8×10−3 at 105K to 3.4×10−3 at 270K and then decreases with the temperature increasing further.

Negative thermal expansion and spontaneous magnetostriction of Tb2Fe16.5Cr0.5 compound

The structure and magnetic properties of Tb2Fe16.5Cr0.5 compound have been investigated by means of x-ray diffraction and magnetization measurements. The Tb2Fe16.5Cr0.5 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Tb2Fe16.5Cr0.5 compound from 293 to 522 K by x-ray dilatometry. The coefficient of the average thermal expansion is α¯=−1.53×10−6K−1 from 293 to 500 K, and α¯=−1.53×10−4K−1 from 500 to 522 K, respectively. The magnetostrictive deformations from 293 to 522 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The magnetization measurement shows that small amount of Cr atoms substitute for Fe atoms can increase obviously the Curie temperature of the Tb2Fe17 compound.