PT  - JOURNAL ARTICLE
AU  - Štaffenová, Nikoleta
AU  - Bajtošová, Lucia
AU  - Chochoľaková, Elena
AU  - Hanuš, Jan
AU  - Cieslar, Miroslav
TI  - Formation of TiO2 Hollow Nanoparticles Studied by in Situ TEM
DP  - 2025 Dec 23
TA  - Manufacturing Technology Journal
PG  - 788--793
VI  - 25
IP  - 6
AID - 10.21062/mft.2025.079
IS  - 12132489
AB  - Hollow TiO₂ architectures are attractive for catalysis and sensing but typically produced by wet-chemical templating and sub-micron sizes. Here we demonstrate a dry, template-free route to nanoscale hollow shells by combining DC magnetron sputtering with in situ TEM heating. Heating to 900 °C produces sub-50 nm TiO₂ hollow shells with ~20 nm compact walls via oxidation-driven Kirkendall hollowing. The oxide evolves from amorphous at low temperature to anatase locally (~500 °C) and then to a rutile/brookite mixture by ~600 °C. The hollow architecture withstands a temperature of 900 °C without measurable sintering. Beam-off regions and ex-situ air annealing show the same hollowing and phase evolution, confirming a thermally driven, not beam-induced, transformation reproducible in air.