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Non-destructive compositional investigation of historical enamels by combining portable alpha-PIXE and XRF imaging techniques H.C. Santos, C. Caliri, L.

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Presentation on theme: "Non-destructive compositional investigation of historical enamels by combining portable alpha-PIXE and XRF imaging techniques H.C. Santos, C. Caliri, L."— Presentation transcript:

1 Non-destructive compositional investigation of historical enamels by combining portable alpha-PIXE and XRF imaging techniques H.C. Santos, C. Caliri, L. Pappalardo, R. Catalano, A. Orlando, F. Rizzo and F.P. Romano 101° Congresso SIF 21-25 seteembre 2015- Roma, Italia 1

2 Outline  Samples  Experimental Setup  portable Alpha-PIXE  portable XRF scanner  Results and Discussion 2 101° Congresso SIF 21-25 seteembre 2015- Roma, Italia

3 Samples Artwork enamels(smalto) on silvered support – dated back to XI-XII century A.Plaque – white, yellow, brown, blue and red; B.Pot – white C.Bottle – blue and green Are they forgeries? 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 3 8 A) B)C)

4 Approach – non-destructive techniques Alpha-PIXE (Particle Induced X-ray Emission) Characterize the glass matrix  high ionization cross section for low Z  identify the former, fluxes and stabilizers  low penetration XRF (X-ray Fluorescence) Identify the elemental composition of the colorants and opacifier  High ionization cross section for medium and high Z 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 4

5 Experimental setup 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 5

6 Alpha-PIXE 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 6 ParameterValue Primary beam  particle of 5 MeV energy (depth 10-20  m) Beam size8 mm diameter obtained by using a collimator SDD Detector20 mm 2 active area; 125 eV energy resolution at 5.9 keV Measurement time3600 sec. Measurement geometry 45° and 90° incidence and detecting angles; 4 mm and 6 mm incidence and detecting distances

7 XRF scanning 101° Congresso SIF - 21-25 seteembre 2015 - Roma, Italia 7 ParameterValue X-ray source30 W Rh-anode tube Focusing OpticPolycapillary with a focal distance of 1 cm Beam size at the focus 26  m diameter at the Rh K-lines SDD Detector 50 mm 2 active area; 133 eV energy resolution at 5.9 keV Measurement geometry 45° and 45° incidence and detecting angles Area of scansion20x20 cm 2 (max.) Step-size 50  m in the scanning micro-XRF 500  m in the scanning macro-XRF Dwell time150 ms (including overhead) Measurement time6.5 h for a 400x400 pixel image

8 Results and Discussion 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 8

9 Alpha-PIXE 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 9 PIXE quantitative data obtained by measuring some enamels decorating artworks Former ( matrix of the glass ): SiO 2 Flux ( decrease the melting temperature ): Na 2 O and K 2 O Stabilizer: CaO Typology: alkali silica glass Enamel (Sample)Na 2 OMgOAl 2 O 3 SiO 2 K2OK2OCaOFe 2 O 3 PbO White (Plaque)6.61.91.136.83.72.0- 38.4 Blue (Plaque) -- 2.434.53.34.80.724.2 Brown (Plaque) -- 2.432.24.51.42.327.4 Light blue (Bottle) - -4.349.07.91.0 -18.8 White (Pot)9.01.8 -34.12.01.4-29.8 Compounds presented higher values compared with ancient glass (XI-XII century)

10 XRF scanner - Plaque PyMca -Fast Fit (~2x10 4 spectra) Lead – less in the red Blue - Co Yellow - Cr(As,Pb) White - As Brown - Mn Red – Zn 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 10 Elemental distribution maps Zn in the red, As in the Yellow/white indicate recent manufacture

11 Red enamel – NNMA (PyMca) ZnS.CdSSe.BaSO4 (cadmium lithopone) 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 11

12 XRF scanner: Bottle and Pot Bottle Green –Cr Blue – Co Pot White – As, Pb 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 12

13 µ-XRF scanner: green enamel (Bottle)  Cr, Ca, K and Pb: homogeneous  Fe - inlay 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 13 Analysis of homogeneity of the green enamel Conclusion: Cr was used as colorant agent in the green enamel

14 Conclusions Alpha-PIXE Na, K and Ca characterize the enamels as alkali silica glass and the presence of Pb in high concentration(>20) suggests modern manufacture XRF scanner The elements Cr(green/yellow), Zn[Se, Ba, Cd](red) and the use of As characterize the enamels as modern – XVIII-XIX century Reference: Identification of forgeries in historical enamels by combining the non-destructive scanning XRF imaging and alpha-PIXE portable techniques DOI:10.1016/j.microc.2015.08.025 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 14

15 Grazie 101° Congresso SIF 21-25 seteembre 2015 - Roma, Italia 15


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