Zjawisko up-konwersji w nanomateriałach opartych o tlenofluorki, wanadany i fosforany domieszkowane jonami lantanowców
Loading...
Date
2020
Authors
Advisor
Editor
Journal Title
Journal ISSN
Volume Title
Publisher
Title alternative
Up-conversion phenomenon in nanomaterials based on oxyfluorides, vanadates and phosphates doped with lanthanide ions
Abstract
Celem pracy doktorskiej było zbadanie zjawiska konwersji energii w górę w nanokrystalicznych materiałach zawierających pierwiastki ziem rzadkich, takie jak tlenofluorek gadolinu (GdOF), wanadany (REVO4) oraz fosforany (REPO4) pierwiastków ziem rzadkich, gdzie RE = Y3+, La3+, Gd3+ i Lu3+. Układy te były domieszkowane jonami lantanowców w układzie Yb3+-Ln3+, Ln = Ho, Er, Tm, Er/Tm, Tb/Eu i Er/Tm/Eu-Tb. Materiały otrzymano zol-żelową metodą syntezy Pechini’ego oraz metodą współstrącania. Przy wzbudzeniu w bliskiej podczerwieni (NIR, 980 nm) układów jonów Yb3+ w parze z jonami Ho3+, Er3+, Tm3+, Tb3+, Eu3+, Er3+/Tm3+ i Tb3+/Eu3+ uzyskano intensywną emisję up-konwersyjną w szerokim zakresie spektralnym: od ultrafioletu, przez zakres widzialny, aż do bliskiej podczerwieni. Ponadto, dodatek jonów metali ziem alkalicznych, takich jak Mg2+, Sr2+ czy Ba2+ i jonów Sn4+ wpłynął na zwiększenie intensywności emisji matryc LaVO4. Dzięki zastosowaniu odpowiedniego źródła wzbudzenia (impulsowe, ciągłe) o długości fali: 800, 975, 1208 lub 1532 nm oraz techniki spektroskopii czasowo-rozdzielczej uzyskano efekt przestrojenia barwy luminescencji oraz lepiej poznano mechanizmów badanego procesu. Uzyskano również materiały luminescencyjne, u których zarejestrowano emisję wzbudzaną dwuzakresowo – w bliskiej podczerwieni i ultrafiolecie i jednocześnie będące nanosensorami temperatury, ze względu na termoczułą emisję jonów Tm3+.
The scientific aim of the doctoral thesis was to study the up-conversion phenomenon in nanocrystalline oxyfluorides (GdOF), vanadates (REVO4) and phosphates (REPO4) containing rare earth elements (RE = Y3+, La3+, Gd3+, Lu3+) and doped with the lanthanides (Ln3+) used as pairs or triple ions in sensitizer – emitter systems, i.e. Yb3+ – Ln3+, Ln = Ho, Er, Tm, Er/Tm, Tb/Eu or Er/Tm/Eu-Tb. The nanoparticles were synthesized with two methods: the sol – gel Pechini method and the co-precipitation method. The samples effectively absorbed the near infrared radiation (around 980 nm) and then showed intense and multicolor up-conversion emission from the ultraviolet to near-infrared spectral range. The additional doping with the alkaline earth metal ions M2+ (Mg2+, Sr2+, Ba2+) and M4+ (Sn4+) ions was used to increase the UC luminescence intensity of LaVO4 compounds. The UC emission color was tuned by using different excitation sources (pulsed and continuous-wave), different wavelengths (800, 975, 1208 or 1532 nm) and with use of the time-resolved spectroscopy. The UC mechanisms and number of UC photons were studied in detail. Moreover, the synthesized dual-mode luminescent nanoparticles can act as sensitive optical thermosensors, as they can be excited in NIR and UV range and show temperature-dependent Tm3+ emission.
The scientific aim of the doctoral thesis was to study the up-conversion phenomenon in nanocrystalline oxyfluorides (GdOF), vanadates (REVO4) and phosphates (REPO4) containing rare earth elements (RE = Y3+, La3+, Gd3+, Lu3+) and doped with the lanthanides (Ln3+) used as pairs or triple ions in sensitizer – emitter systems, i.e. Yb3+ – Ln3+, Ln = Ho, Er, Tm, Er/Tm, Tb/Eu or Er/Tm/Eu-Tb. The nanoparticles were synthesized with two methods: the sol – gel Pechini method and the co-precipitation method. The samples effectively absorbed the near infrared radiation (around 980 nm) and then showed intense and multicolor up-conversion emission from the ultraviolet to near-infrared spectral range. The additional doping with the alkaline earth metal ions M2+ (Mg2+, Sr2+, Ba2+) and M4+ (Sn4+) ions was used to increase the UC luminescence intensity of LaVO4 compounds. The UC emission color was tuned by using different excitation sources (pulsed and continuous-wave), different wavelengths (800, 975, 1208 or 1532 nm) and with use of the time-resolved spectroscopy. The UC mechanisms and number of UC photons were studied in detail. Moreover, the synthesized dual-mode luminescent nanoparticles can act as sensitive optical thermosensors, as they can be excited in NIR and UV range and show temperature-dependent Tm3+ emission.
Description
Wydział Chemii
Sponsor
Keywords
up-konwersja, up-conversion, down-konwersja, down-conversion, lanthanides, lantanowce, nanomaterials, nanomateriały, tunable emission, przestrajalna emisja