We review preparations and crystal structures of various kinds of new niobium oxides. Ilmenite-type ANbO
3 (A=Li, Na), which were prepared by low temperature hydrothermal reaction and ion-exchange reaction, are the first examples of ilmenite-type niobium oxides. These niobium oxides are metastable phases and transform into the stable phases at elavated temperatures. A new reduced niobium oxide, Rb
1.51Nb
10O
17 has a Nb
6O
12 cluster characteristic of strongly reduced niobium oxides. Weakly reduced niobium oxides, K
2YNb
5O
15-δ and K
6Nb
10.9O
30 have NaNb
6O
15F-type and tetragonal tungsten bronze type strcutures, respective-ly. In the A
2O-MO- Nb
2O
5 (A=K, Rb, Cs; M=Mg, Fe) system, two types of compounds K
2M
2Nb
4O
13 and A (M, Nb)
2O
5, which are isostructural with K
2Ti
6O
13 and KTiNbO
5 respectively, were obtained.
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