Magnetic-dilution in the solid solutions Eu _{1− <i>x</i>} Ca _<i>x</i> PtSn and Eu _{1− <i>x</i>} Sr _<i>x</i> PtSn – crystal structure, magnetism, and ¹⁵¹ Eu and ¹¹⁹ Sn Mössbauer spe

The TiNiSi-type stannide EuPtSn (space group <i>Pnma</i>) forms complete solid solutions with the isotypic compounds CaPtSn and SrPtSn. Samples in 10 mol% steps with composition Eu_1-<i>x</i>Ca_<i>x</i>PtSn and Eu_1-<i>x</i>Sr_<i>x</i>PtSn (0 ≤ <i>x</i> ≤ 1) were synthesized and studied by X-ray powder diffraction, magnetization, and ¹⁵¹Eu and ¹¹⁹Sn Mössbauer spectroscopy measurements. The cell volumes decrease with increasing calcium content and increase with strontium substitution. The crystal structures of CaPtSn, Eu_0.606(2)Ca_0.394Pt_0.987(4)Sn_1.013 and Eu_0.426(4)Sr_0.574PtSn were refined from single crystal X-ray diffraction data, confirming their TiNiSi-type structure and the mixed occupancies Eu/Ca, respectively Eu/Sr. Temperature dependent magnetic susceptibility measurements show diamagnetism for the border phases CaPtSn and SrPtSn. The Eu_1-<i>x</i>Ca_<i>x</i>PtSn and Eu_1-<i>x</i>Sr_<i>x</i>PtSn samples show all stable divalent ground states with experimental magnetic moments close to the free ion value of 7.94<i>μ</i>_B for Eu²⁺. This finding is also corroborated by ¹⁵¹Eu Mössbauer spectroscopy. The compounds order antiferromagnetically at low temperatures. The stable antiferromagnetic ground state is underpinned by their metamagnetic (AFM → FM) transitions. A remarkable feature is the linear decrease of the Néel temperature, <i>T</i>_N, in both solid solutions Eu_1-<i>x</i>Ca_<i>x</i>PtSn and Eu_1-<i>x</i>Sr_<i>x</i>PtSn, from 28.5 K (EuPtSn) to 3.2(1) K for Eu_0.2Ca_0.8PtSn and 3.4(1) K for Eu_0.2Sr_0.8PtSn. The decrease of the Néel temperature is continuous, however with slightly different slopes for Ca and Sr substitution.