  The ternary intermetallic RTX compounds (R = rare earth, T = transitional
metal, X = p-block metal) have been investigated extensively in the past few
decades due to their interesting physical properties. Recently, much attention
has been paid to the magnetocaloric effect (MCE) of these RTX compounds,
especially the ones with heavy rare-earth, for their potential application in
low temperature magnetic refrigeration. In this paper, we review the MCE of
RTSi and RTAl systems with R = Gd~Tm, T = Fe~Cu and Pd, which are widely
investigated in recent years. It is found that these RTX compounds exhibit
various crystal structures and magnetic properties, which then result in
different MCE. Large MCE has been observed not only in the typical
ferromagnetic materials but also in the antiferromagnetic materials. The
magnetic properties have been studied in detail to discuss the physical
mechanism of large MCE in RTX compounds. Particularly, some RTX compounds, such
as ErFeSi, HoCuSi, HoCuAl, etc, exhibit large reversible MCE under low magnetic
field change, which suggests that these compounds could be promising materials
for magnetic refrigeration in low temperature range.
