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Our and others’ results on the thermal expansion of compounds and the crystal-chemical information about their structure have been used to properly select compositions of new NASICON materials with small thermal expansion and low thermal expansion anisotropy: M
x
M
1−
x
′Ti
2
(PO
4
)
3
(M and M′ are alkali metals, 0 ≤
x
≤ 1), M″FeTi(PO
4
)
3
(M″ is an alkaline-earth metal), and Ca
0.5(1 +
x
)
Fe
x
Ti
2 −
x
(PO
4
)
3
(0 ≤
x
≤ 1). Such materials have been synthesized through salt coprecipitation from aqueous solutions and their thermal expansion has been assessed by high-temperature X-ray diffraction. We have determined their unit-cell parameters as functions of temperature and correlated their thermal expansion parameters and composition. The K
0.5
Rb
0.5
Ti
2
(PO
4
)
3
and Rb
0.8
Cs
0.2
Ti
2
(PO
4
)
3
materials obtained combine small volumetric thermal expansion and near-zero thermal expansion anisotropy.