Ba4Na2Ge25
= Ba4Na2Ge25
{c}
{title2=$\mathrm{Ba_4Na_2Ge_{25}}$}
A germanium cage compound with barium and sodium guests. Its low-temperature heat capacity supplies an example of a <rattling mode> in addition to the leading electronic and acoustic contributions.<Superconductivity in the Filled Cage Compounds Ba6Ge25 and Ba4Na2Ge25 by Friedrich Malte Grosche and others>[Figure 3: calorimetric example]{ref}