Contentslistsavailableat ScienceDirect JournalofNon-CrystallineSolids journal homepage: www.elsevier.com/locate/jnoncrysol Thermally-inducedprecipitationofgoldnanoparticlesinphosphateglass: efectontheopticalpropertiesofEr 3+ ions G.Yu.Shakhgildyan a, ⁎ ,M.Z.Ziyatdinova a,b ,M.P.Vetchinnikov a ,S.V.Lotarev a ,V.I.Savinkov a , N.N.Presnyakova c ,E.V.Lopatina a ,G.A.Vilkovisky b ,V.N.Sigaev a a Mendeleev University of Chemical Technology of Russia, 125047, Miusskaya sq., 9, Moscow, Russia b P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 119333, Leninskiy av., 53, Moscow, Russia c National Research Center “Kurchatov Institute”,123098, Akademika Kurchatova sq., 1, Moscow, Russia ARTICLEINFO Keywords: Phosphateglass Goldclusters Goldnanoparticles Pre-plasmonicparticles Luminescence ABSTRACT Goldnanoparticlesincorporatedinglassmediumaretheobjectofkeeninterestduetotheiruniqueproperties inducedbyplasmonicefects:coloration,noticeableopticalnonlinearityandrareearthionsphotoluminescence enhancement. In this work, we examine the structure and optical properties of potassium aluminophosphate glassesdopedwithEr 3+ ionsandAuundertheheattreatmentbelowandaboveglasstransitiontemperature. TheheattreatmentoftheglassattemperaturesaboveT g isshowntofacilitatetheformationofplasmonicgold nanoparticles and decrease near-infrared luminescence intensity of Er 3+ ions. On the contrary, a similar treatmentofthestudiedglassesattemperaturesbelowT g doesn'tinduceplasmonicabsorptionandleadstothe intensity enhancement of Er 3+ luminescence. Formation of gold clusters in the glass treated at lower tem- peraturesissupposedtoenabletheenergytransferprocessbetweenclustersandrare-earthionswhichisex- pressedinluminescenceintensityenhancement. 1. Introduction Inrecentdecades,metalnanoparticles(NPs)exhibitinglocalsurface plasmon resonance (LSPR) have been the subject of an exponentially growing amount of studies devoted to applications in medicine [1], optical sensing and spectroscopy [2], catalysis [3], nonlinear optical processes [4] andmore. GlassescontainingplasmonicgoldandsilverNPsareknownsince ancienttimesduetothecharacteristiccolorofsphericalNPsthatcould beformedinaglassduringthethermaltreatment [5].Besidestheefect of coloration, noble metal NPs dispersed in glasses are of interest for applications in photonics as nonlinear optical materials [6–8],insur- face-enhanced Raman spectroscopy [9,10], optical memory [11–13] andopticalwaveguides [14]. OneofthemostprominentphotonicapplicationsofNPsdispersed in glasses is connected with attempts to increase the rare-earth ions (REI)luminescenceintensitybythelocalfeldenhancementorenergy transferbetweenNPsandREI.TheLSPRofNPscanraisetheelectric feld strength around the nanoparticle providing enhanced emission from rare-earth ions located within the region of the enhanced feld [15]. REI luminescence intensity enhancement has been found in glasses of diferent glass-forming systems containing silver and gold NPs [16–23].However,ithasalsobeenshownthatsuchplasmonicNPs can lead to quenching of the luminescence by a non-radiative energy transfer [24–26]. On the other hand, the so-called pre-plasmonic particles or mole- cularclustersofnoblemetalsexhibitvarioustypesofopticalproperties, whichcouldinturn,beutilizedintheREIluminescenceenhancement applications.Electronicstructureofpre-plasmonicparticlesrepresents discreteenergylevelswithasignifcantenergygapbetweenthehighest occupiedandlowestunoccupiedmolecularorbitals [27].Thisresultsin ahighprobabilityofradiativetransitionsand,asaconsequence,ahigh luminescenceefciencyofsuchparticlesandlowdensityofstatesinthe absenceoftheLSPRefect [28]. ItwasreportedinaseriesofstudiesoftheAu/Erimplantedfused silica that gold pre-plasmonic particles can act as a sensitizer for the luminescentenhancementoftheEr 3+ ions [29–32].However,auseof the ion implantation technique for the Au/Er incorporation with the subsequent thermal treatment of samples in the inert gas atmosphere seems technologically challenging as compared to the cost-efective glassmelt-quenchingtechnique. Moreover,boththeluminescenceenhancementandthequenching efects strongly depend on the REI-NPs distance and NPs size. Therefore,studiesofopticalpropertiesofsuchsystemswithvaryingthe https://doi.org/10.1016/j.jnoncrysol.2020.120408 Received19May2020;Receivedinrevisedform27August2020;Accepted2September2020 ⁎ Correspondingauthor. E-mail address: georgiy.shahgildyan@gmail.com (G.Y.Shakhgildyan). Journal of Non-Crystalline Solids 550 (2020) 120408 0022-3093/ © 2020 Elsevier B.V. All rights reserved. T