Available online at www.sciencedirect.com Journal of the European Ceramic Society 33 (2013) 629–635 Short communication A simple approach to observe non-conductive hydrated materials with FE-SEM: Case study on porous hydroxyapatite green bodies Chisato Takahashi a , Deepak K. Pattanayak a,b , Takashi Shirai a , Masayoshi Fuji a,∗ a Advanced Ceramics Research Center, Nagoya Institute of Technology, 3-101-1, Honmachi, Tajimi, Gifu 507-0033, Japan b CSIR-Central Electrochemical Research Institute, Karaikudi, Tamilnadu 630006, India Received 10 July 2012; received in revised form 23 September 2012; accepted 5 October 2012 Available online 28 November 2012 Abstract The purpose of this study is to develop a simple method to observe the surface morphology of non-conductive material in its hydrated condition. Here porous hydroxyapatite (HAp) green body prepared by gelcasting process was considered as a case study, and, the resultant body was subsequently treated with hydrophilic ionic liquid (IL). The surface morphology and the pore structure of the IL-treated porous HAp green body were successfully observed even in hydrated condition without any charging using field emission scanning electron microscope (FE-SEM). Results showed that the pore diameter from 300 to 600 m in as-prepared green body was reduced to 100–300 m in the sample sintered at 1000 ◦ C. Raman results showed that the IL forms weak hydrogen bond with water molecules within the sample and, that prevents from drying in vacuum condition. In addition, the IL acts as a conducting media for HAp ceramics to be observed under FE-SEM. © 2012 Elsevier Ltd. All rights reserved. Keywords: Ionic liquid; Gelcasting; Hydroxyapatite; Hydrated materials; FE-SEM 1. Introduction Room temperature ionic liquid (RTIL) ([emim][BF 4 ]) was reported in 1992. Since then, ionic liquids (ILs) have gained popularity among the researchers due to their unique properties such as non-volatile, non-flammable, chemical/thermal stability and high conductivity. 1–4 These ILs are composed of asymmet- rically substituted organic cations with anions, and, remained as fused salts at room temperature. Most significantly, the ILs with different combinations of cations and anions affect the properties such as polarity, melting point, hydrophilicity and hydropho- bicity. Therefore, the IL properties can be adjusted to suit the requirements of a particular process. The ILs are widely used in bio-materials and agro-materials to improve the properties such as compatibility and thermal sta- bility, etc. 5,6 In addition, formation of conductive polymer using the IL showed useful applications especially in the field of life sciences. 7–10 The ILs are also used as solvents in various chem- ical reactions, or in dispersion of carbohydrate polymers such ∗ Corresponding author. Tel.: +81 572 24 8110; fax: +81 572 24 8109. E-mail address: fuji@nitech.ac.jp (M. Fuji). as cellulose and starch, etc. Besides, composite gel mixed with the IL is used in drug delivery as well as fabrication of contact lenses. 11–14 Recently, alkylimidazolium ILs such as alkylimida- zolium tetrafluoroborates and hexafluorophosphates have shown promising lubricating properties as base oils for a variety of contacts. 15–18 The ILs are also used for fabricating good solid electrolytes for safer lithium batteries. 19–21 Besides above mentioned applications, due to negligible vapor pressure coupled with high conductivity, specimens treated with the IL is used in various electron microscopic obser- vations (SEM/TEM) under vacuum conditions. 22–31 Kuwabata et al. initially proposed the application of IL for observation of biological sample using SEM. Later on, several research groups reported that biological materials such as human cul- ture cells, fungal, chicken tissues and other biological samples can be observed in SEM under vacuum. Most recently, present authors also proposed that agar gel which is a hydrated material can be observed in FE-SEM when it is previously treated with the IL solution. 29–31 Although some reports suggest the suitabil- ity of IL for microscopic observation, still this method is limited to few kinds of materials. In the present study, a simple method of microstructure obser- vation of hydrated ceramic materials is attempted. In order to 0955-2219/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jeurceramsoc.2012.10.037