We report on the single crystal growth of Eu(Pd1−xAux)2Si2, 0 < x ≤ 0.2, from a levitating
Eu-rich melt using the Czochralski method. Our structural analysis of the samples confirms the
ThCr2Si2-type structure as well as an increase of the room temperature a and c lattice parameters
with increasing x. Chemical analysis reveals that, depending on the Au concentration, only about
25-35% of the amount of Au available in the initial melt is incorporated into the crystal structure,
resulting in a decreasing substitution level for increasing x. Through Au substitution, chemical
pressure is applied and large changes in valence crossover temperatures are already observed for
low substitution levels x. In contrast to previous studies, we do not find any signs of a first-order
transition in samples with xnom = 0.1 or AFM order for higher x. Furthermore, we observe the
formation of quarternary side phases for a higher amount of Au in the melt.
In addition, cubic-mm-sized single crystals of EuPd2(Si1−xGex)2 with xnom = 0.2 were grown. The
analysis of the X-ray fluorescence revealed that the crystals exhibit a slight variation in the Ge
content. Such tiny compositional changes can cause changes in the sample properties concerning
variations of the crossover temperature or changes of the type of the transition from crossover to
magnetic order. Furthermore, we report on a new orthorhombic phase EuPd1.42Si1.27Ge0.31 that
orders antiferromagnetically below 17 K.