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Raman Study of the Reactions in a Glass‐Forming Mixture with Molar Composition:30K 2 CO 3 ‐70SiO 2 ‐1As 2 O 3
Author(s) -
VERWEIJ HENK
Publication year - 1979
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1979.tb19103.x
Subject(s) - arsenate , raman spectroscopy , silicate , chemistry , alkali metal , potassium silicate , ion , carbonate , inorganic chemistry , analytical chemistry (journal) , phase (matter) , arsenic , arsenite , mineralogy , physics , organic chemistry , optics , chromatography
The results of a study of the reactions in a glass‐forming batch with molar composition 30K 2 CO 3 ‐70SiO 2 ‐lAs 2 O 3 are given. Laser Raman spectroscopy was used for nondestructive identification of silicate, carbonate, arsenite (As 3+ ), and arsenate (As 5+ ) ions in the vitreous or crystalline state, occurring in quenched reaction mixtures. It is shown that in the first stage of melting a potassium‐rich liquid phase is formed, containing metasilicate chains (SiO 2− 3 ) x and carbonate ions, in which all arsenic is present in the pentavalent state as AsO 1 3‐ ions. When this liquid phase reaches the final product glass composition the AsO 1 3‐ ions condense to As 2 O 4− 7 (As 5+ ) ions and AsO − 2 (As 3+ ) groups, during which process O 2 is formed. The preliminary results of studies on crystalline and vitreous potassium arsenates and arsenites and of arsenic‐containing potassium silicate glasses are given for identifying arsenate and arsenite groups. It is argued that the reaction mechanism found describes the effectiveness of As 2 O 3 as a fining agent. Contrary to the current view in the literature for the fining action of As 2 O 3 , which states that an O 2 evolution which is triggered by a temperature increase causes fining, an important effect is found in the O 2 evolution triggered by alkali oxide concentration variations during melting.