Kazimierz Latka

Structure, magnetic properties and {sup 119}Sn Mossbauer spectroscopy of PrRhSn

AbstractPrRhSnwassynthesizedinpolycrystallineformbyareactionofpraseodymium,rhodium,andtininanarc-meltingfurnace.Thesample was investigated by powder and single crystal X-ray diffraction: ZrNiAl type, space group P¯62 m; a ¼ 742:49ð7Þ,c ¼ 415:05ð5Þpm, wR 2 ¼ 0.0737, 353F 2 values and 14 variables. The PrRhSn structure has two crystallographically independentrhodiumsiteswithatricappedtrigonalprismaticcoordination,i.e.[Rh1Sn 3 Pr 6 ]and[Rh2Sn 6 Pr 3 ].Therhodiumandtinatomsbuildup a three-dimensional [RhSn] network with short Rh–Sn contacts (278 and 285pm), in which the praseodymium atoms filldistorted hexagonal channels. The magnetic and electronic properties of PrRhSn have been studied by means of AC and DCmagnetic susceptibility measurements as well as 119 Sn Mo¨ssbauer spectroscopy. A transition from a paramagnetic to aferromagneticstatewasfoundatT C ¼ 3:0K.r 2005ElsevierInc.Allrightsreserved. Keywords: Intermetalliccompound;Magnetism;Mo¨ssbauerspectroscopy 1. IntroductionThe rare-earth metal based stannides RERhSn(RE ¼ rare-earthelement)havethoroughlybeeninves-tigated in recent years [1–5, and references therein].A detailed literature overview is given in [1] and [5].Especially, the valence fluctuations of CeRhSn andthe heavy fermion behavior of YbRhSn are of greatinterest.The crystal chemistry and the physical propertiesof the RERhSn stannides with the early rare-earthelementshavecontroversiallybeendiscussed.ThelatticeparametersforCeRhSn,PrRhSn,andNdRhSnreportedbyRoutsietal.[6]aredifferentfromthosereportedbyMishra et al. [1]. A recent single crystal study of theNdRhSnstructure[7]clearlyconfirmedtheX-raypowderdatagivenin[1].Thetwodifferentstudiesalsorevealedadiscrepancyconcerningthemagneticordering.Whilenohint for magnetic ordering was evident in the originalwork [6], ferromagnetic ordering at T

Structural and magnetic properties of RET2Sn2 compounds (RE=La, Ce, Sm; T=Ni, Cu)

The following compounds have been synthesized: LaCu2Sn2, CeCu2Sn2, SmCu2Sn2 and SmNi2Sn2. By means of X-ray diffraction their structure was determined to be primitive tetragonal of CaBe2Ge2-type (space group P4/nmm) and the lattice parameters were obtained.119Sn Mössbauer measurements were performed in a temperature range between 4.2 K and 300 K. The temperature dependence of the Lamb-Mössbauer factor reveals considerable softening of lattice vibration modes below 160 K. Only SmCu2Sn2 orders magnetically above 4.2 K.

Europium valence transition in EuCu2Si2 and EuPd2Si2 investigated with 119Sn mössbauer spectroscopy

Abstract The influence of the europium ion valence instability on the electronic structure of the compounds EuCu 2 Si 2 and EuPd 2 Si 2 is observed by the Mossbauer effect with diluted 119 Sn probes. The effects are unambiguously visible for the compound EuPd 2 Si 2 where the valence transition spans a much narrower temperature range than in the case of EuCu 2 Si 2 . The temperature variation of the electric field gradient at the 119 Sn nucleus sitting in the silicon sublattice of the former compound was successfully described in the framework of the interconfigurational fluctuation model yielding a form of the temperature dependence of the excitation energy and the level width of the divalent europium configuration. The step-like turn of the Mossbauer line position observed in addition to the Doppler temperature shift is a consequence of the variation in electronic density at 119 Sn in the Si site which in turn is due to the change in the spatial distribution of the Eu electrons.