Abstract
Full Text
Physics
V. A. Kazantsev
STUDY OF THE Ni \(K_{\beta_5}\)-BANDS OF THE X-RAY SPECTRUM OF NICKEL IN ALLOYS OF THE Mn—Ni SYSTEM
(Presented by Academician N. V. Belov on 23 VI 1961)
The article gives results that are a continuation of studies of alloys of the Mn—Ni system by means of X-ray spectra \((^1)\). The form, width, intensity, and position of the Ni \(K_{\beta_5}\)-bands on the energy scale under the influence of changes in the composition, temperature, and magnetic transformations of the alloys were investigated. Some information concerning the Ni \(K_{\beta_1}\) line was also obtained. Alloys Nos. 2, 3, 5 \((\theta = 250.5^\circ)\) and No. 6 \((\theta = 297.5^\circ)\), containing respectively 51.3; 59.2; 86.21 and 92.43 wt.% Ni, were studied—the same alloy specimens as in work \((^1)\).
Fig. 1. Shape and position on the energy scale of the Ni \(K_{\beta_5}\)-band in alloys of the Mn—Ni system
The \(K\)-spectra of nickel were excited by the primary method and recorded with a short-wavelength tube spectrograph with a bent crystal* (the Cauchois method). The dispersion in the region of the \(K_\beta\)-group of the nickel spectrum was \(3.92\ \text{X}\cdot\text{mm}^{-1}\). The temperature of the alloys on the anode of the X-ray tube was monitored with the aid of indicator alloys \((^1)\). An experimental check of this method as applied to the short-wavelength spectrograph showed that the temperature of the specimen changes nonlinearly with increasing specific load on the X-ray tube. This method does not make it possible to control the specimen temperature more accurately than \(\pm 20^\circ\); therefore, the spectra were recorded not in the immediate vicinity of the Curie “point,” but in regions 50–60° away from it. By varying the dimensions of the focal spot and the specific load supplied to the tube, it was possible to reach readily the regions of the ferro- and paramagnetic states of the alloys.
Results. In Fig. 2, for illustration, a microphotogram of the \(K_\beta\)-group of the nickel spectrum in alloy No. 3 is shown. Consideration of the micro-
* Spectrograph of M. A. Blokhin \((^2)\) with a safe X-ray tube designed by V. A. Kazantsev.
photograms shows that the satellite Ni \(K_{\beta'}\) is superposed on the long-wavelength branch of the line \(K_{\beta_1}\) and merges with it. For this reason, judgments about Ni \(K_{\beta'}\) become impossible. No effect of temperature, nor of alloy composition, on the Ni \(K_{\beta_1}\) line was detected; its wavelength in all alloys retains the value \(1497.2 \pm 0.1\) X. The satellite Ni \(K_{\beta''}\) is not detected either in first-order spectra or in second-order reflection spectra.
Some results showing the dependence of various characteristics of Ni \(K_{\beta_5}\) on composition, temperature, and magnetic transformations of the alloys are given in the corresponding Tables 1–3. In all tables the following notation is adopted: \(\lambda K_{\beta_5}\) is the wavelength of the intensity maximum of Ni \(K_{\beta_5}\) (error \(\pm 0.04\) X.U.); \(\Delta E_{\beta_5}\) is the change in energy of the Ni \(K_{\beta_5}\)-photon (error 0.2 eV); \(\Delta E_{1/2}^{*}\) is the width of Ni \(K_{\beta_5}\) at half the intensity maximum (error \(\pm 0.5\) eV); \(I_{\max}\) is the relative intensity of the maximum of Ni \(K_{\beta_5}\) (accuracy 4%); \(I_i\) is the integral intensity in relative units (accuracy 8–10%); \(a_{\beta_5}\) is the asymmetry index of the Ni \(K_{\beta_5}\)-band; f.m. and p.m. are, respectively, the ferromagnetic and paramagnetic states of the alloys.
Table 1
Dependence of the characteristics of Ni \(K_{\beta_5}\) on the composition of alloys; all alloys are paramagnetic
| Alloy No. | Alloy temp., °C | \(\lambda K_{\beta_5}\), X | \(\Delta E_{1/2}\), eV | \(I_{\max}\) | \(I_i\) | \(a_{\beta_5}\) |
|---|---|---|---|---|---|---|
| 2 | \(\sim 450\) | 1485.70 | 13.4 | 0.85 | 1.2 | 1.06 |
| 3 | 120 | 1485.79 | 14.0 | 1.14 | 1.5 | 1.17 |
| 3 | 450 | 1485.41 | 13.5 | 1.00 | 1.2 | 1.13 |
| 5 | 450 | 1485.36 | 15.2 | 1.57 | 1.4 | 1.33 |
Analysis of the experiment leads to the following conclusions:
- An increase in the nickel content in the alloys at low temperatures has no effect on the characteristics of Ni \(K_{\beta_5}\) \((\lambda, \Delta E_{1/2})\). Only an increase in the intensity of this band is observed, which is natural.
At high temperatures, the influence of the nickel content, in particular on \(\lambda K_{\beta_5}\), apparently does exist: the wavelength of Ni \(K_{\beta_5}\) decreases noticeably with increasing nickel content, while its width increases.
-
The transition of the alloys to the paramagnetic state, caused by an increase in the manganese content in the alloys, is accompanied by an increase in the energy of the Ni \(K_{\beta_5}\)-photon by an average of 2.2 eV. In this case Ni \(K_{\beta_5}\) becomes more asymmetric. A noticeable increase in intensity and some increase in the width of this band are observed.**
-
The magnetic transformation that occurred under the influence of an increase in the temperature of the alloys is accompanied by an increase in the energy of the Ni \(K_{\beta_5}\)-photon by an average of 2.1–2.8 eV for different alloys. The emission band Ni \(K_{\beta_5}\) thereby becomes more intense and strongly asymmetric (see Fig. 1).
Taking into account the results of work (1), the following can be said concerning Mn \(K_{\beta_5}\) and Ni \(K_{\beta_5}\). The transition of Mn—Ni alloys to the paramagnetic state, whether achieved under the influence of a change in alloy composition or under the influence of temperature (without a change in composition), leads to identical changes in the characteristics of the \(K_{\beta_5}\)-bands for manganese and nickel, respectively. The changes in the intensities and widths of the \(K_{\beta_5}\)-bands, as well as their shifts for manganese and nickel, proceed in opposite directions and are of the same order of magnitude. This makes it possible to suppose that the paramag-
Fig. 2. Microphotogram of the \(K_{\beta}\)-group of the nickel spectrum in alloy No. 3
* Without corrections for broadening during focusing from a bent crystal.
** Similar effects were found in Heusler-type alloys by E. E. Vainshtein and B. I. Kotlyar (3).
Table 2
Dependence of the characteristics of Ni \(K_{\beta_5}\) on the magnetic transformation occurring under the influence of changes in alloy composition
| Alloy No. | Magnetic state | \(-\lambda K_{\beta_5}\), X | \(\Delta \lambda K_{\beta_5}\), X | \(\Delta E_{\beta_5}\), eV | \(I_{\max}\) | \(I_i\) | \(\Delta E_{1/2}\) | \(a_{\beta_5}\) |
|---|---|---|---|---|---|---|---|---|
| 6 | f. m. | 1485.78 | 1.00 | 1.0 | 13.7 | 1.08 | ||
| 5 | p. m. | 1485.39 | −0.39 | \(2.2 \pm 0.2\) | 1.37 | 1.4 | 15.0 | 1.32 |
Table 3
Dependence of the characteristics of Ni \(K_{\beta_5}\) on magnetic transformations of alloys occurring under the influence of temperature (transition through the Curie point)
| Alloy No. | Magnetic state | \(\lambda K_{\gamma_5}\), X | \(\Delta \lambda K_{\beta_5}\), X | \(\Delta E_{\beta_5}\), eV | \(I_{\max}\) | \(I_i\) | \(\Delta E_{1/2}\) | \(a_{\beta_5}\) |
|---|---|---|---|---|---|---|---|---|
| 5 | f. m. | 1485.76 | 1.00 | 1.0 | 14.0 | 1.12 | ||
| 5 | p. m. | 1485.39 | −0.37 | \(+2.1 \pm 0.2\) | 1.37 | 1.4 | 15.0 | 1.32 |
| 6 | f. m. | 1485.78 | 1.00 | 1.0 | 13.7 | 1.08 | ||
| 6 | p. m. | 1485.28 | −0.50 | \(+2.0 \pm 0.2\) | 1.33 | 1.3 | 14.6 | 1.24 |
—magnetic state of Mn—Ni alloys, regardless of the path by which it is reached, is characterized by a quite definite distribution of \(3d\), \(4sp\)-energy states occupied by electrons in the lattice of the paramagnetic alloy.
Tula State Pedagogical Institute
named after L. N. Tolstoy
Received
4 XI 1960
CITED LITERATURE
- V. A. Kazantsev, DAN, 123, No. 3, 449 (1958).
- M. A. Blokhin, Methods of X-ray Spectral Investigations, Moscow, 1959, pp. 17 and 180.
- E. E. Weinstein, B. I. Kotlyar, DAN, 110, No. 1 (1956).