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Effects of ND2o3 on the crystallization and properties of glass ceramic in Li2o–K2o–Al2o3–Sio2– P2o5 system

Glass ceramics (GCs), which often contain a small amount of rare earth oxides to improve their performance, are ideal for dental restorative applications. The aim of this study was to investigate the various effects of Nd2O3 content (0–1 wt%) on crystallization and properties of GC derived from Li2O–K2O–Al2O3–SiO2–P2O5 system. | Journal of Science and Technology 55 (1B) (2017) 238–248 EFFECTS OF Nd2O3 ON THE CRYSTALLIZATION AND PROPERTIES OF GLASS CERAMIC IN Li2O–K2O–Al2O3–SiO2– P2O5 SYSTEM Minh N. H. *, Hung H. T. D., Khoi T. N., Minh Q. D. Faculty of Materials Technology, HCMUT–VNUHCM 268 Ly Thuong Kiet Street, Ward 14, District 10, Ho Chi Minh City, Vietnam * Email: hnminh@hcmut.edu.vn Received: 30 December 2016; Accepted for publication: 9 March 2017 ABSTRACT Glass ceramics (GCs), which often contain a small amount of rare earth oxides to improve their performance, are ideal for dental restorative applications. The aim of this study was to investigate the various effects of Nd2O3 content (0–1 wt%) on crystallization and properties of GC derived from Li2O–K2O–Al2O3–SiO2–P2O5 system. The glass blocks were formed from the molten at 1450 °C. Based on the DTA results, the glass samples were experienced by two–stage heat–treatment (600 °C/ 90 min + 720 °C/ 30 min) to change to ingots. After that, the ingot samples were fired in a hot pressing furnace EP3000 at 930 °C for 30 min. The results of powder X–ray diffraction (XRD) indicated that the final GCs contained crystals such as lithium disilicate (Li2Si2O5 or LS2), lithium metasilicate (Li2SiO3 or LS) and the traces of lithium phosphate (Li3PO4). With increasing Nd2O3 content, the relative amount of LS phase increased slightly while LS2 phase decreased. However, the final GC containing 0.75 wt% Nd2O3 had the highest bending strength at 293 MPa, the lowest chemical solubility and relative high Vicker hardness. These samples had a high degree of crystallization and the highest relative content of desired LS2 phase. Keywords: glass ceramic, dental ceramic, lithium disilicate, rare earth oxide, neodymium oxide Nd2O3. 1. INTRODUCTION Glass ceramics (GCs) containing lithium disilicate (Li2Si2O5 or LS2) as main crystal phase are ideally suitable for multi options of dental restorative applications: esthetic, layer technique, hot pressing or .