Analysis of heat capacity and Mössbauer data for LuZnSn₂ compound

Abstract

Abstract. New analysis of heat capacity data is presented for LuZnSn 2 compound that takes into account anharmonic effects together with the existence of Einstein modes. Sn Mössbauer spectroscopy was used to monitor the hyperfi ne parameters at the two crystallographically inequivalent Sn sites in the studied compound. The problem of non-unique mathematical resonance spectrum description and the problem how to choose physically meaningful set of hyperfi ne parameters will be thoroughly discussed. Measured quadrupole interaction constants by 119m Sn Mössbauer spectroscopy give estimations for V zz component of electric fi eld gradient tensor at both Sn sites in LuZnSn 2 .

Mössbauer and heat capacity studies of ErZnSn2

“…However, it was shown that the experimental heat capacity data, C lat (T), for LuZnSn 2 [24] and ErZnSn 2 , as expounded in this work, can be successfully fi tted over the whole temperature range by taking into account anharmonic effects that occur at elevated temperatures, as well as by the inclusion of selected Einstein modes for LuZnSn 2 and ErZnSn 2 respectively using the extended Debye equation in the form:…”

“…2a and 2c sites, the spectrum recorded at room temperature can be reasonably fi tted with two quadrupole-split components including a single line of the metallic impurity tin (with isomer shift  IS kept constant and equal to 2.552(9) mm/s [25]), which is also evident from X-ray diffraction analysis and originates from the synthesis procedure as well as the known decomposition process of the probe over time. Similarly to the case of LuZnSn 2 [24], the resonance spectrum recorded for ErZnSn 2 at room temperature can be fi tted with different pairs of main quadrupole split subsets of hyperfi ne parameters (together with the respective pairs of isomer shifts) for two crystallographically inequivalent Sn sites. However, from a physical point of view, a fi t with only two different quadrupole interaction constants and comparable isomer shifts for both Sn sites (Fig.…”

“…One can underline here that such a situation is observed in the closely [21], where Sn atoms also occupy two different symmetry positions and where Mössbauer spectra can be fi tted in a suitable way with only two different quadrupole splittings, but with very similar isomer shifts for both Sn sites. On the other hand, an assumption that isomer shifts should be signifi cantly different at Sn sites seems to also be unreasonable, since for Sn atoms their transformation requires a rather big change in the valence electron sp confi guration of their own tin atoms [24], and this is not expected here, as in the 2a position Sn atoms interact directly with the other four Sn and Er atoms, respectively, while at the 2c site Sn atoms interact with four Zn (instead of Sn) and Er atoms, respectively, but valence electron s confi gurations of Sn and Zn atoms remain roughly identical. The observed systematics of the isomer shifts of Sn in most intermetallic systems (including ternary systems) [26] is in line with the previous statement, showing that the effective number of 5s tin electrons is merely the same and not much different than one (see Table 9a in [26]).…”