1. P. A. Arsen’ev, V. B. Glushkova, et al., Rare-Earth Compoyunds: Zirconates, Hafnates, Niobates, Tantalates, and Antimonates (Nauka, Moscow, 1985) [in Russian].
2. K. I. Portnoi, N. I. Timofeeva, S. E. Alibekov, et al., Izv. Akad. Nauk SSSR, Ser. Neorg. Mater. 6, 289 (1970).
3. F. A. Rozhdestvenskii, M. G. Zuev, and A. A. Fotiev, Tervalent Metal Tantalates (Nauka, Moscow, 1986) [in Russian].
4. K. P. Siqueira, AP. Carmo, M. J. V. Bell, et al., J. Lumin. 179, 146 (2016).
https://doi.org/10.1016/j.jlumin.2016.06.054
5. A. Dias, K. P. Siqueira, and R. L. Moreira, J. Alloys Compd. 693, 1243 (2017).
https://doi.org/10.1016/j.jallcom.2016.10.077