Studies of the phosphorescence of polycrystalline hafnia

Oxygen vacancy relationship to photoluminescence and heat treatment methods in hafnium oxide powders

“…This PL emission band in the aforementioned study was attributed to the presence of O vacancies [14][15][16][17]. Several reports have also indicated that these emissions are caused by interstitial defects in monoclinic HfO 2 [17,30]. Theoretical calculations suggest that when Hf atoms are seven coordinate within a monoclinic structure then the O atoms can occupy both the threefold and the fourfold positions.…”

“…[13][14][15][16][17][18]. This PL emission band in the aforementioned study was attributed to the presence of O vacancies [14][15][16][17].…”

“…Eliziário et al showed that for rice-like HfO 2 , which has an E gap value of 3.31 eV, the PL behavior was related to the oxygen vacancies and to the structural distortions of the stacking of the [HfO 6 ] clusters [16]. Indeed, there are many interesting studies that suggest that the influences of defects, self-trapped excitons, and impurities can affect the PL properties of the HfO 2 [17][18][19][20][21][22].…”

Blue Photoluminescence and Cyan-Colored Afterglow of Undoped SrSO4 Nanoplates

“…We have noticed that some undoped inorganic materials can give off afterglows. For instance, a blue afterglow peaking at 480–490 nm was reported for undoped HfO 2 , 9 , 10 and a blue afterglow peaking at 498 nm was reported for undoped inverse spinel Mg 2 SnO 4 . 11 Additionally, a blue afterglow peaking at about 440 nm has been recently reported for undoped CaAl 2 O 4 nanocrystals.…”

Afterglow and thermoluminescence of ZrO2 nanopowders

“…The origin of this emission is still disputable, but is probably due to either oxygen vacancies [3][4][5], Ti impurity centres [6][7][8] or their combined aggre-gates. This PL frequently reveals an afterglow in the time frame of hundreds to thousands of seconds [4,5,[7][8][9], suggesting a perspective for implementation of new persistent phosphors. Advantages of these materials over many existing phosphors are their relatively simple structure, easier preparation (using sol-gel method), superior mechanical, chemical and thermal endurance, and non-toxicity.…”