{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T03:00:26Z","timestamp":1787626826772,"version":"build-2736575974"},"reference-count":56,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T00:00:00Z","timestamp":1773619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["Project BG16RFPR002-1.014-0006"],"award-info":[{"award-number":["Project BG16RFPR002-1.014-0006"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Glasses with compositions (52.5 \u2212 x\/2)B2O3:(12.5 \u2212 x\/2)SiO2:25La2O3:5ZnO:5CaO:0.5Eu2O3:xWO3, x = 0, 2.5, 5, 7.5, 10, 20 (mol%) were prepared by conventional melt-quenching method and investigated by X-ray diffraction analysis, DSC analysis, DR-UV-Vis spectroscopy and photoluminescence spectroscopy. Physical parameters like density, molar volume, oxygen molar volume and oxygen packing density were also determined. Their values, as well as DR-UV-Vis spectroscopy results, indicate that the tungstate ions incorporate into the base borosilicate glass as tetrahedral WO4 and octahedral WO6 groups. With increasing WO3 content over 5 mol%, WO6 units are progressively linked to each other by W-O-W bonds, leading to the formation of a more connected and homogeneous glass network. Glasses are characterized by a high glass transition temperature (over 650 \u00b0C) and good thermal stability. The emission intensity of the Eu3+ ion increases with the introduction of WO3 due to the occurrence of non-radiative energy transfer from the tungstate groups to the active ion. The most intense luminescence peak observed at 612 nm suggests that the glasses are potential materials for red emission.<\/jats:p>","DOI":"10.3390\/molecules31061000","type":"journal-article","created":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T15:21:16Z","timestamp":1773674476000},"page":"1000","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Synthesis and Luminescent Properties of Eu3+-Doped Complex Borosilicate Glasses"],"prefix":"10.3390","volume":"31","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1856-5806","authenticated-orcid":false,"given":"Aneliya","family":"Yordanova","sequence":"first","affiliation":[{"name":"Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, G. Bonchev Str., Bld. 11, 1113 Sofia, Bulgaria"},{"name":"National Centre of Excellence Mechatronics and Clean Technologies, 8 bul., Kl. Ohridski, 1756 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Margarita","family":"Milanova","sequence":"additional","affiliation":[{"name":"Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, G. Bonchev Str., Bld. 11, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lyubomir","family":"Aleksandrov","sequence":"additional","affiliation":[{"name":"Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, G. Bonchev Str., Bld. 11, 1113 Sofia, Bulgaria"},{"name":"National Centre of Excellence Mechatronics and Clean Technologies, 8 bul., Kl. Ohridski, 1756 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3732-129X","authenticated-orcid":false,"given":"Reni","family":"Iordanova","sequence":"additional","affiliation":[{"name":"Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, G. Bonchev Str., Bld. 11, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6223-0923","authenticated-orcid":false,"given":"Petia","family":"Petrova","sequence":"additional","affiliation":[{"name":"Institute of Optical Materials and Technologies \u201cAcad. Jordan Malinowski\u201d, Bulgarian Academy of Sciences, Blvd. Akad. G. Bonchev Str., Bld. 109, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"8886","DOI":"10.1016\/j.ceramint.2017.04.024","article-title":"Optical characterization of Eu3+ ion doped alkali oxide modified borosilicate glasses for red laser and display device applications","volume":"43","author":"Reddy","year":"2017","journal-title":"Ceram. Int."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"6389","DOI":"10.1016\/j.matpr.2017.06.143","article-title":"Development of bismuth borosilicate glass doped with Eu3+ for reddish orange emission materials application","volume":"4","author":"Rakpanicha","year":"2017","journal-title":"Mater. Today Proc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"275","DOI":"10.1081\/SL-120003812","article-title":"Luminescence properties of Eu3+ doped ZnO\u2013B2O3\u2013SiO2 glasses","volume":"35","author":"Hussain","year":"2002","journal-title":"Spectrosc. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2260080","DOI":"10.1080\/16583655.2023.2260080","article-title":"Promising reddish-orange light as Eu3+ incorporated in zinc-borosilicate glass derived from the waste glass bottle","volume":"17","author":"Cheong","year":"2023","journal-title":"J. Taibah Univ. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"121184","DOI":"10.1016\/j.jnoncrysol.2021.121184","article-title":"Photoluminescence down-shifting studies of thermally stable Eu3+ ions doped borosilicate glasses for visible red photonic device applications","volume":"575","author":"Bajaj","year":"2022","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"110025","DOI":"10.1016\/j.optmat.2020.110025","article-title":"Regulation of luminescence properties of SBGNA:Eu3+ glass by the content of B2O3 and Al2O3","volume":"106","author":"Hu","year":"2020","journal-title":"Opt. Mater."},{"key":"ref_7","first-page":"35","article-title":"Eu3+ doped borosilicate glass for solid-state luminescence material","volume":"27","author":"Rakpanich","year":"2017","journal-title":"J. Met. Mater. Miner."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"482","DOI":"10.1016\/j.jre.2017.09.017","article-title":"Optical and luminescence characteristics of Eu3+-doped B2O3:SiO2:Y2O3:CaO glasses for visible red laser and scintillation material applications","volume":"36","author":"Aryal","year":"2018","journal-title":"J. Rare Earths"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"118689","DOI":"10.1016\/j.jlumin.2021.118689","article-title":"Effective sensitization of Eu3+ visible red emission by Sm3+ in thermally stable potassium zinc alumino borosilicate glasses for photonic device applications","volume":"244","author":"Ravita","year":"2022","journal-title":"J. Lumin."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"121392","DOI":"10.1016\/j.jnoncrysol.2021.121392","article-title":"Energy transfer dynamics in thermally stable Sm3+\/Eu3+ co-doped AEAlBS glasses for near UV triggered photonic device applications","volume":"580","author":"Sharma","year":"2022","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"123153","DOI":"10.1016\/j.jnoncrysol.2024.123153","article-title":"Luminescence and spectroscopic studies on Dy3+\u2013Eu3+ doped SiO2\u2013B2O3\u2013ZnO\u2013La2O3\u2013BaO glass for WLED","volume":"641","author":"Jin","year":"2024","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5890","DOI":"10.1111\/jace.16442","article-title":"Tunable colors and applications of Dy3+\/Eu3+ co-doped CaO\u2013B2O3\u2013SiO2 glasses","volume":"102","author":"Zhou","year":"2019","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"105151","DOI":"10.1016\/j.pnucene.2024.105151","article-title":"Exploring the radiation shielding properties of B2O3\u2013SiO2\u2013ZnO\u2013Na2O\u2013WO3 glasses: A comprehensive study on mechanical, gamma, and neutron attenuation characteristics","volume":"170","author":"Alsafi","year":"2024","journal-title":"Prog. Nucl. Energy"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"111089","DOI":"10.1016\/j.radphyschem.2023.111089","article-title":"Unveiling the structural, optical, and electromagnetic attenuation characteristics of B2O3\u2013SiO2\u2013CaO\u2013Bi2O3 glasses with varied WO3 content","volume":"212","author":"Ali","year":"2023","journal-title":"Radiat. Phys. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"423","DOI":"10.1016\/0022-3093(74)90148-3","article-title":"Composition-properties relationship in Inorganic Oxide Glasses","volume":"15","author":"Ray","year":"1974","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_16","unstructured":"Cottrell, T.L. (1958). The Strength of Chemical Bonds, Butterworth. [2nd ed.]."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1016\/j.physb.2007.05.004","article-title":"UV-vis absorption of the transition metal-doped SiO2-B2O3-Na2O3 glasses","volume":"398","author":"ElBatal","year":"2007","journal-title":"Phys. B"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"15089","DOI":"10.1021\/jp074219c","article-title":"Structural Determination of Bulk and Surface Tungsten Oxides with UV-vis Diffuse Reflectance Spectroscopy and Raman Spectroscopy","volume":"111","author":"Wachs","year":"2007","journal-title":"J. Phys. Chem. C"},{"key":"ref_19","first-page":"11","article-title":"Characterization of WO3-doped borophosphate glasses by optical, IR and ESR spectroscopic techniques before and after subjecting to gamma irradiation","volume":"51","author":"Ouis","year":"2013","journal-title":"Indian J. Pure Appl. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3267","DOI":"10.1016\/j.physb.2010.04.057","article-title":"A study of electronic and optical properties of NaBi(WO4)2: A disordered double tungstate crystal","volume":"405","author":"Tyagi","year":"2010","journal-title":"Physica B"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"15630\u221215640","DOI":"10.1021\/acs.jpcc.3c03512","article-title":"Band-Gap Energy and Electronic d\u2212d Transitions of NiWO4 Studied under High-Pressure Conditions","volume":"127","author":"Errandonea","year":"2023","journal-title":"J. Phys. Chem. C"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.jnoncrysol.2015.02.010","article-title":"Glass formation and structure of glasses in the WO3\u2013ZnO\u2013Nd2O3\u2013Al2O3 system","volume":"414","author":"Iordanova","year":"2015","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1111\/j.1551-2916.2009.03017.x","article-title":"Effects of Doping Trivalent Ions in Bismuth Borate Glasses","volume":"92","author":"Bajaj","year":"2009","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"669","DOI":"10.15251\/DJNB.2025.202.669","article-title":"Investigating the effects of Hg doping on WO3 nanoflakes: A hydrothermal route to tailored properties","volume":"20","author":"Saranya","year":"2025","journal-title":"Dig. J. Nanomater. Biostruct."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.apsusc.2015.03.140","article-title":"The existing states of doped B3+ions on the B doped TiO2","volume":"345","author":"Zhao","year":"2015","journal-title":"Appl. Surf. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1380","DOI":"10.1111\/j.1551-2916.2010.04260.x","article-title":"Effect of SiO2 on Densification and Microstructure Development in Nd:YAG Transparent Ceramics","volume":"94","author":"Stevenson","year":"2011","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2715","DOI":"10.1016\/j.jeurceramsoc.2006.12.003","article-title":"Physical and structural properties of glasses in the TeO2\u2013TiO2\u2013Nb2O5 system","volume":"27","author":"Villegas","year":"2007","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Blasse, G., and Grabmaier, B.C. (1994). Luminescent Materials, Springer. [1st ed.].","DOI":"10.1007\/978-3-642-79017-1"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/0022-4596(75)90242-X","article-title":"The charge-transfer absorption band of Eu3+ in oxides","volume":"15","author":"Hoefdraad","year":"1975","journal-title":"J. Solid State Chem."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"10859","DOI":"10.1039\/c2ra22144f","article-title":"Behaviour of electric and magnetic dipole transitions of Eu3+, 5D0\u22127F0 and Eu-O charge transfer band in Li+ co-doped YPO4:Eu3+","volume":"2","author":"Parchur","year":"2012","journal-title":"RSC Adv."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"117735","DOI":"10.1016\/j.jlumin.2020.117735","article-title":"Synthesis and luminescence properties of Eu3+ doped potassium titano telluroborate (KTTB) glasses for red laser applications","volume":"230","author":"Mariselvam","year":"2021","journal-title":"J. Lumin."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"012080","DOI":"10.1088\/1757-899X\/833\/1\/012080","article-title":"Zinc oxide with visible light photocatalytic activity originated from oxygen vacancy defects","volume":"833","author":"Nimpoeno","year":"2020","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"R3153","DOI":"10.1149\/2.022302jss","article-title":"Eu3+ activated molybdate and tungstate based red phosphors with charge transfer band in blue region","volume":"2","author":"Dutta","year":"2013","journal-title":"ECS J. Solid State Sci. Technol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"118244","DOI":"10.1016\/j.jlumin.2021.118244","article-title":"Microstructure investigation and fluorescence properties of Europium-doped scheelite crystals in glass-ceramics made under different synthesis conditions","volume":"238","author":"Thieme","year":"2021","journal-title":"J. Lumin."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1016\/bs.hpcre.2016.08.003","article-title":"Lanthanide luminescence: From a mystery to rationalization, understanding, and applications","volume":"Volume 50","author":"Bunzli","year":"2016","journal-title":"Handbook on the Physics and Chemistry of Rare Earths"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.ccr.2015.02.015","article-title":"Interpretation of europium (III) spectra","volume":"295","author":"Binnemans","year":"2015","journal-title":"Coord. Chem. Rev."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1016\/j.ceramint.2011.08.030","article-title":"Large-scale synthesis of WO3 nanoplates by a microwave-hydrothermal method","volume":"38","author":"Sungpanich","year":"2012","journal-title":"Ceram. Int."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"7824","DOI":"10.1007\/s10854-019-01101-w","article-title":"Selective sensing property of triclinic WO3 nanosheets towards ultra-low concentration of acetone","volume":"30","author":"Jia","year":"2019","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"260","DOI":"10.1016\/j.optmat.2017.08.010","article-title":"Compositional dependence of red luminescence from Eu3+ ions doped single and mixed alkali fluoro tungsten tellurite glasses","volume":"73","author":"Devi","year":"2017","journal-title":"Opt. Mater."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"6166","DOI":"10.1103\/PhysRevB.58.6166","article-title":"Effect of hydroxyl bonds on persistent spectral hole burning in Eu3+ doped BaO-P2O5 glasses","volume":"58","author":"Nogami","year":"1998","journal-title":"Phys. Rev. B"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/0022-2313(95)00073-9","article-title":"Blue, green and red fluorescence and energy transfer of Eu3+ in fluoride glasses","volume":"65","author":"Dejneka","year":"1995","journal-title":"J. Lumin."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Yordanova, A., Milanova, M., Iordanova, R., Fabian, M., Aleksandrov, L., and Petrova, P. (2023). Network Structure and Luminescent Properties of ZnO\u2013B2O3\u2013Bi2O3\u2013WO3: Eu3+ Glasses. Materials, 16.","DOI":"10.3390\/ma16206779"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"122006","DOI":"10.1016\/j.jnoncrysol.2022.122006","article-title":"Structural and luminescence behavior of Eu3+ ions in ZnO-B2O3-WO3 glasses","volume":"600","author":"Milanova","year":"2023","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Iordanova, R., Milanova, M., Yordanova, A., Aleksandrov, L., Nedyalkov, N., Kukeva, R., and Petrova, P. (2024). Structure and Luminescent Properties of Niobium-Modified ZnO-B2O3:Eu3+ Glass. Materials, 17.","DOI":"10.20944\/preprints202402.0939.v1"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/0022-3093(89)90282-2","article-title":"Europium (III) in oxide glasses: Dependence of the emission spectrum upon glass composition","volume":"111","author":"Oomen","year":"1989","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/0022-3093(96)00134-2","article-title":"Spectroscopic investigation of zinc borate glasses doped with trivalent europium ions","volume":"201","author":"Bettinelli","year":"1996","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.molstruc.2005.01.062","article-title":"Spectral properties of Eu3+: ZnO\u2013B2O3\u2013SiO2 glasses","volume":"741","author":"Annapurna","year":"2005","journal-title":"J. Mol. Struct."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1016\/j.jallcom.2008.06.134","article-title":"Spectral analysis of Eu3+: B2O3\u2013Al2O3\u2013MF2 (M = Zn, Ca, Pb) glasses","volume":"474","author":"Azeem","year":"2009","journal-title":"J. Alloys Compd."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"111340","DOI":"10.1016\/j.materresbull.2021.111340","article-title":"Time-resolved and excitation-emission matrix luminescence behaviour of boro-silicate glasses doped with Eu3+ ions for red luminescent application","volume":"140","author":"Nandyala","year":"2021","journal-title":"Mater. Res. Bull."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"368","DOI":"10.1016\/S0009-2614(03)00445-7","article-title":"Ultraviolet light-induced spectral change in cubic nanocrystalline Y2O3:Eu3+","volume":"372","author":"Song","year":"2003","journal-title":"Chem. Phys. Lett."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"10877","DOI":"10.1016\/j.ceramint.2014.03.081","article-title":"Co-precipitation synthesis of nano Y2O3:Eu3+ with different morphologies and its photoluminescence properties","volume":"40","author":"Kabir","year":"2014","journal-title":"Ceram. Int."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"500","DOI":"10.1016\/j.jallcom.2015.06.187","article-title":"Structure refinement and one-center luminescence of Eu3+ activated ZnBi2B2O7 under UV excitation","volume":"648","author":"Wu","year":"2015","journal-title":"J. Alloys Compd."},{"key":"ref_53","first-page":"173","article-title":"Application of the Eu3+ ion for site symmetry determination","volume":"14","author":"Binnemans","year":"1996","journal-title":"J. Rare Earths"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1088\/1475-4878\/33\/3\/301","article-title":"The CIE colorimetric standards and their use","volume":"33","author":"Smith","year":"1931","journal-title":"Trans. Opt. Soc."},{"key":"ref_55","unstructured":"Paolini, T.B. (2021, June 07). SpectraChroma (Version 1.0.1) [Computer Software]. Available online: https:\/\/zenodo.org\/records\/4906590."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"1047","DOI":"10.1149\/1.2412153","article-title":"Properties of Some Selected Europium\u2014Activated Red","volume":"116","author":"Trond","year":"1969","journal-title":"J. Electrochem. Soc."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/6\/1000\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T05:31:59Z","timestamp":1773811919000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/6\/1000"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,16]]},"references-count":56,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["molecules31061000"],"URL":"https:\/\/doi.org\/10.3390\/molecules31061000","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,16]]}}}