Materials Science and Engineering B 138 (2007) 135–138 Analysis of the internal glass surfaces of vacuum glazing L. So ∗ , N. Ng, M. Bilek School of Physics, University of Sydney, NSW 2006, Australia Received 15 April 2005; received in revised form 10 July 2005; accepted 20 September 2005 Abstract XPS has been used to study the internal glass surfaces of vacuum glazing. In order to retain the vacuum state of the sample and to avoid carbon contamination of the test area, specially evacuated samples were designed in this study. A customized sample holder was made and a lever device was incorporated into the preparation chamber of an XPS system to break these samples in situ. The relative atomic concentration of different elements on commercial low-emittance tin-oxide-coated and uncoated glass was compared. The effect of high temperature outgassing on the carbon concentration on the internal glass surfaces of vacuum glazing has been investigated. The study shows that when the sample is baked at high temperatures, the carbon concentration on the glass surface can be reduced to a low level. © 2006 Elsevier B.V. All rights reserved. Keywords: X-ray photoelectron spectroscopy; Vacuum glazing; Outgassing; Carbon compound 1. Introduction The surface properties of a material are often the reasons for it to be chosen for an industrial application. In modern indus- tries, it is important to monitor the surface properties of products to ensure proper functionality. As a result, surface analysis is a powerful tool for today’s process development. X-ray photoelec- tron spectroscopy (XPS) is one of the most widely used surface analysis techniques for materials. It is used for analyzing the relative concentrations of the surface constituents of a mate- rial. It is able to detect the elemental composition of a surface through wide scan survey spectra and the chemical structure of elements on the surface with detailed regional scans. However, great care has to be taken in performing XPS measurements. Hydrocarbon contamination of surfaces which were studied by XPS is widely documented [1,2]. It was found that contamina- tion occurs rapidly on evacuated glass surfaces prior to XPS [3]. In this study, special vacuum glass panel samples together with a customized sample holder were designed and a lever device was incorporated into the preparation chamber of the XPS system to enable the in situ breakage of glazing samples within the XPS system. Vacuum glazing is a transparent thermal insulator that has the potential for widespread applications in the windows of energy ∗ Corresponding author. E-mail address: catwin@physics.usyd.edu.au (L. So). efficient buildings [4]. Fig. 1 is a schematic diagram of a vacuum glazing. It consists of two plane sheets of soda-lime glass, with a very narrow evacuated space in between, hermetically sealed together around the edges with solder glass. The two glass sheets are kept apart by an array of small support pillars in the evac- uated space. Transparent low-emittance tin-oxide coatings are usually used on one or both of the glass sheets to reduce radia- tive heat transport to a low level. In order to achieve a high level of thermal insulation, the internal pressure of vacuum glazing has to be kept below 10 −3 Torr. Previous studies on outgassing during baking and evacuation of vacuum glazing have shown that when the sample is heated from room temperature to above 300 ◦ C, the major gases released are H 2 O, CO 2 and CO [5,6]. The outgassing data (Fig. 2) show that the rate of gas evolu- tion increases continuously as the temperature increases up to 150 ◦ C, and then decreases slightly. However, as the tempera- ture reaches 180 ◦ C, the rate of evolution of CO 2 and CO again increases and continues up to the temperature of 320 ◦ C. In con- trast, the rate of evolution of H 2 O steadily decreases over this temperature range. It is well known that the evolution of H 2 O from glass evacuated device is a diffusion process [5,7,8], but the mechanisms associated with the release of carbon compound molecules have not been found [6]. One of the aims of this work is to investigate the effect of temperature treatments on glass surfaces under vacuum in order to understand the mechanisms associated with the evolution of CO 2 and CO. The XPS spectra of uncoated soda-lime glass and soda-lime glass coated with a commercial low-emittance coating were compared. The internal 0921-5107/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2005.09.065