Synthetic hackmanites and their optical properties – from theory to applications

Synthetic hackmanite is a material that resembles the natural mineral, hackmanite. The structure of hackmanite, Na8Al6Si6O24(Cl,S)2, together with its simple preparation with solid state synthesis enables the doping of different ions into the hackmanite matrix, resulting in materials with a wide variety of optical properties. The synthetic hackmanites show photoluminescence, persistent luminescence and photochromism, when excited with different wavelengths. During this thesis work, a synthetic hackmanite material showing up-conversion luminescence was also prepared. This thesis focuses on the optical properties of synthetic hackmanites and their mechanisms. A detailed mechanism for persistent luminescence as well as photochromism in synthetic hackmanite materials is presented. Also, a new method called thermotenebrescence is introduced. This method can be used to study the energetics of photochromism. With wide and tunable optical properties, cheap production and the fact that synthetic hackmanites do not include any heavy metals or toxic elements, many possible applications can be presented for the materials and they are listed in the end of the thesi

UV-Sensing Cellulose Fibers Manufactured by Direct Incorporation of Photochromic Minerals

Textile-based wearable sensors integrated into daily wear offer opportunities for on-demand, real-time self-diagnosis to monitor health conditions with changing environmental surroundings and hazards. One still underrated environmental hazard is accumulated UV irradiation, causing skin burns, accelerated aging, and skin cancers. Here, we have demonstrated a sustainable fiber manufacture process to integrate photochromic hackmanite micro-particles directly into a cellulose body to achieve UV-sensing functionality in daily-life textiles. The hackmanite particles were dispersed into an ionic liquid cellulose dope using ultrasonication and nanofibrillated cellulose as a dispersant, resulting in good spinnability. The obtained fibers possess high mechanical strength with up to 10% photochromic hackmanite loading. To demonstrate its application in wearable UV sensors, the fibers were spun into yarn and then knitted into a piece of jersey fabric. The coloration of hackmanite-incorporated textiles under UV irradiation is readily quantified by image analysis using red–green–blue ratios, which was further utilized for UV dosimetry with a smartphone application showcasing the practical use of the UV sensor. The UV-sensing functionality remained the same after intensive washing and abrasion tests, further demonstrating the feasibility of its application in everyday garments.</p

Novel borosilicate bioactive scaffolds with persistent luminescence

Persistent luminescent amorphous borosilicate scaffolds were successfully prepared, for the first time, with a porosity of >70% using the burn-off technique. The persistent luminescence was obtained by adding the SrAl2O4:Eu2+,Dy3+ microparticles: i) in the glass melt or ii) in the glass crushed into powder prior to the sintering. The scaffolds prepared by adding the microparticles in the glass melt exhibits lower persistent luminescence and a slower reaction rate in simulated body fluid than the scaffolds prepared by adding the microparticles in the glass powder due to the release of strontium from the microparticles into the glass during the glass melting.</p

Detection of X-Ray Doses with Color-Changing Hackmanites: Mechanism and Application

Hackmanites, a variety of sodalite with the general formula Na$_{8}$Al$_{6}$Si$_{6}$O$_{24}$(Cl,S)$_{2}$, are a family of nature-based smart materials having the ability for reversible photochromism upon UV or X-ray exposure. Being nontoxic, cheap, and durable, hackmanite would be an optimal material for the visual detection of the presence of X-rays in simple portable systems. However, its X-ray-induced coloring abilities are so far known only qualitatively. In this work, a combination of experimental and computational methods is used to reveal the mechanism of X-ray-induced color changing in these materials. Finally, their use is demonstrated both in color intensity-based X-ray dosimetry and photochromic X-ray imaging

Detection of X-Ray Doses with Color-Changing Hackmanites: Mechanism and Application

Hackmanites, a variety of sodalite with the general formula Na8Al6Si6O24(Cl,S)(2), are a family of nature-based smart materials having the ability for reversible photochromism upon UV or X-ray exposure. Being nontoxic, cheap, and durable, hackmanite would be an optimal material for the visual detection of the presence of X-rays in simple portable systems. However, its X-ray-induced coloring abilities are so far known only qualitatively. In this work, a combination of experimental and computational methods is used to reveal the mechanism of X-ray-induced color changing in these materials. Finally, their use is demonstrated both in color intensity-based X-ray dosimetry and photochromic X-ray imaging

Sodaliittien Na8(AlSiO4)6(Cl,S)2 tenebresenssin ja luminesenssin tutkiminen NMR ja EPR spektroskopioita apuna käyttäen

Sodaliitit ovat mineraaleja, joiden ominaisuuksia ovat tenebresenssi, luminesenssi ja kestoluminesenssi. Sodaliitteja voidaan löytää luonnosta, mutta niitä pystytään valmistamaan myös laboratoriossa kiinteän olomuodon menetelmällä. Yksi sodaliittien erityistapauksista on hackmaniitti. Hackamiittiin tutustumalla voidaan helposti tutustua yleisesti sodaliitteihin. Hackamniitin rakenne perustuu rakennekaavaan Na8[AlSiO4]6[Cl,S]2. Rakenteeseen voidaan kuitenkin tehdä hienovaraisia muutoksia, joilla saadaan aikaan ominaisuuksien muutoksia syntyvissä tuotteissa. Työssä valmistettiin synteettisiä sodaliitteja, joiden kloori- ja rikkiatomien suhdetta ja vakanssien määrää muutettiin. Syntyneiden tuotteiden kiderakenne vastasi luonnollisen sodaliitin kiderakennetta. Kiderakenteen sisällä olevat muutokset vaikuttivat kuitenkin sodaliittien luminesenssin intensiteettiin ja tenebresenssissä syntyvän värin tummuuteen ja värin kestoon. Koska rakenne selkeästi vaikuttaa sodaliitin ominaisuuksiin, pyrittiin työssä löytämään parhaat menetelmät, joilla rakennetta voidaan tutkia. Perinteisten rakennetutkimusmenetelmien, (kuten XPD:n) lisäksi tutkittiin magneettiseen värähtelyyn perustuvien tekniikoiden (NMR ja EPR) käyttöä sodaliittien tutkimisessa. Sodaliitteja on tutkittu toistaiseksi kovin vähän. Tulevaisuudessa sodaliitit ovat kuitenkin mielenkiintoinen tutkimuskohde, sillä niissä saadaan aikaan useita optisia ominaisuuksia eri viritysaallonpituuksilla. Työssä esitettyjen tutkimusmenetelmien avulla sodaliitteja voidaan jatkossa tutkia entistä paremmin ja niiden rakenteestaSiirretty Doriast

Revealing the Photochromism Mechanism of Sulphur-Doped Sodalites using DFT, TD-DFT and SAC-CI methods.

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