Effect of Heat Treatment on the DC Conductivity and Activity Energy of Li2O-Fe2O3-P2O5 Glasses

2007 ◽  
Vol 336-338 ◽  
pp. 1827-1828 ◽  
Author(s):  
Ji Yong Pan ◽  
Jiang Hong Gong
Keyword(s):  
Heat Treatment ◽  
Electrical Properties ◽  
Heat Treating ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Sample Heat ◽  
Heat Treated ◽  
Maximum Conductivity ◽  
Iron Phosphate Glasses ◽  
Activity Energy

Iron phosphate glasses with composition of 20Li2O-32Fe2O3-48P2O5 (in mol%) was prepared by melting, crushing and heat-treating process and the electrical properties were examined. It was found that the sample heat-treated at a temperature close to the glass transition temperature exhibit the maximum conductivity and the lowest activation energy, implying that heat-treatment may play an important role in the electrical properties of the glasses.

Speciation of sulphate ions in sodium alumino(iron)phosphate glasses

2019 ◽  
Vol 512 ◽  
pp. 81-89 ◽  
Author(s):  
S.V. Stefanovsky ◽  
O.I. Stefanovsky ◽  
I.L. Prusakov ◽  
M.I. Kadyko ◽  
A.A. Averin ◽  
...  
Keyword(s):  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Iron Phosphate Glasses

The Effect of Electron Irradiation on the Structure of Sodium Aluminum-Iron Phosphate Glasses

MRS Advances ◽  
2016 ◽  
Vol 1 (63-64) ◽  
pp. 4227-4232 ◽  
Author(s):  
S.V. Stefanovsky ◽  
O.I. Stefanovsky ◽  
M.I Kadyko ◽  
V.A. Zhachkin ◽  
L.D. Bogomolova
Keyword(s):  
Room Temperature ◽  
Structural Evolution ◽  
Iron Phosphate ◽  
Esr Spectra ◽  
Phosphate Glasses ◽  
Water Molecules ◽  
Oxygen Hole ◽  
Bending Modes ◽  
Iron Phosphate Glasses ◽  
Hole Centers

ABSTRACTGlasses of the series (mol.%) 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 were irradiated with 8 MeV electrons to doses equivalent of 0.1, 0.5, and 1.0 MGy and characterized by FTIR spectroscopy and ESR at room temperature. FTIR spectra of all the glasses consist of strong bands due to O-P-O stretching modes in (PO4)3- and (P2O7)4- units at 1000-1200 cm-1, P-O-P stretching modes at 900-950 cm-1 (νas) and 700-750 cm-1 (νs), and bending modes in the PO4 units. The wavenumber range lower 800 cm-1 has some contribution due to stretching modes in MO4 and MO6 (M = Al, Fe) units. Moreover the bands at 3300-3700 cm-1 and 1550-1650 cm-1 due to stretching and bending modes in both absorbed and structurally bound H2O molecules were present. As irradiation dose increases the bands due to stretching and bending modes in water molecules and M-O-H bonds become stronger and are split. No essential changes with increasing dose were observed within the spectral range of stretching modes of the O-P-O and P-O-P bonds. Irradiation yields phosphorus-oxygen hole centers - PO42- (D5) and PO42- (D6), and PO32- ion-radicals (D2) observable in ESR spectra of low-Fe glasses. At x>5 their responses are overlapped with strong broad line due to Fe(III). On the whole, with the increase in iron content the glass structural evolution decrease.

scholarly journals Portable, non-destructive colorimetry and visible reflectance spectroscopy can accurately identify heat-treated South African silcrete

2021 ◽  
Author(s):  
John K. Murray ◽  
Simen Oestmo ◽  
Andrew M. Zipkin
Keyword(s):  
Heat Treatment ◽  
Visible Spectrum ◽  
Heat Treating ◽  
Reflectance Spectroscopy ◽  
Modern Human ◽  
Middle Stone Age ◽  
Majority Voting ◽  
K Nearest Neighbors ◽  
Heat Treated ◽  
Visible Reflectance

The objective of this study was to determine if visible reflectance spectroscopy and quantitative colorimetry represent viable approaches to classifying the heat treatment state of silcrete. Silcrete is a soil duricrust that has been used as toolstone since at least the Middle Stone Age. The ancient practice of heat treating silcrete prior to knapping is of considerable interest to paleolithic archaeologists because of its implications for early modern human complex cognition generally and the ability to manipulate the material properties of stone specifically. Here, we demonstrate that our quantitative, non-invasive, and portable approach to measuring color, used in conjunction with k-Nearest Neighbors “lazy” machine learning, is a highly promising method for heat treatment detection. Traditional, expert human analyst approaches typically rely upon subjective assessments of color and lustre and comparison to experimental reference collections. This strongly visual method can prove quite accurate, if difficult to reproduce between different analysts. It is thus surprising that until now, no published study has sought to exploit an instrumental approach to measuring color for classifying heat treatment state in silcrete. In this work, we measured percent reflectance for the visible spectrum (1018 variables) and tristimulus color values (CIEL*a*b*) in unheated and experimentally heat treated silcrete specimens from three sources in South Africa. k-NN classification proved highly effective with both the spectroscopy and colorimetry data sets. An important innovation was using the heat treatment state predicted by the k-NN model for the majority of replicate observations of a single specimen to predict the heat treatment state for the specimen overall. When this majority voting approach was applied to the 746 individual observations in this study, associated with 94 discrete silcrete flakes, both spectroscopy and colorimetry k-NN models yielded 0% test set misclassification rates at the specimen level.

scholarly journals Iron Phosphate Glasses: An Alternative for Vitrifying Certain Nuclear Wastes

2002 ◽  
Author(s):  
Day, Delbert, E. ◽  
Chandra S Ray ◽  
Cheol-Woon Kim ◽  
Wenhai Huang ◽  
Robert D Leerssen ◽  
...  
Keyword(s):  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Nuclear Wastes ◽  
Iron Phosphate Glasses
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