Optik 125 (2014) 5515–5518 Contents lists available at ScienceDirect Optik jo ur nal homepage: www.elsevier.de/ijleo Studies on the growth aspects and characterization of sodium para-nitro phenolate single crystals for nonlinear optical applications M. Mahadevan a,b , P. Anandan c,d , K. Ramachandran a,∗ , M. Arivanandhan d , Y. Hayakawa d a Department of Physics, SRM University, Vadapalani Campus, Chennai 600026, India b Department of Physics, Adhiparasakthi Engineering College, Melmaruvathur 603319, India c Department of Physics, Thiruvalluvar College of Engineering and Technology, Vandavasi 604505, India d Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu 432-8011, Japan a r t i c l e i n f o Article history: Received 3 October 2013 Accepted 1 May 2014 Keywords: Optical materials Crystal growth X-ray diffraction Thermogravimetric analysis a b s t r a c t Using slow evaporation solution growth technique, single crystals of sodium para nitro phenolate have been grown from the solutions prepared from three different molecular ratios of para-nitro phenol and sodium hydroxide. Structural analyses were carried out by powder X-ray diffraction and Fourier trans- form infrared spectrum to conform the grown crystals. Thermal stability of the grown crystals was studied by thermogravimetric (TG) and differential thermal analyses (DTA). UV–vis spectral analysis has been carried out to find the cut off wavelength of the grown crystals. Variations in the cut off wavelengths have been observed. Nonlinear optical property has been confirmed by Kurtz powder technique. The observed optical properties have confirmed that the molar concentration of para nitro phenol influenced significantly on the linear and nonlinear optical properties. © 2014 Elsevier GmbH. All rights reserved. 1. Introduction Various industrial applications of single crystals made the phenomena of crystal growth as one of the thrust areas of research for the past few decades. The crystals are classified in to three categories as organic, inorganic and semi organic single crystals depending upon the raw chemicals used for the growth of sin- gle crystals. Since the semi organic single crystals possess the good properties of both organic and inorganic crystals, scientists and researchers focused their interest in growing variety of semi organic single crystals [1–3]. Para nitro phenol was identified as potential organic material which gives variety of derivatives with alkali metal hydroxides [4–10]. Single crystals of potassium para nitrophenolate dihydrate have been grown and some new bonding properties have been reported by Boaz et al. [4]. Lithium para nitro- phenolate trihydrate crystal has been reported by same authors and studied the properties to some extent [5]. The same crystal has also been grown by recently developed SR method and some properties have been reported [6]. Sodium para nitrophenolate (NPNa) has different hydrated form when it is grown from water solvent. The dihydrate form of NPNa has NLO activity, but tetrahydrate does not have [11]. Though extensive investigations were carried out ∗ Corresponding author. Tel.: +91 9790834728. E-mail address: ramach76@yahoo.com (K. Ramachandran). on this material [11–15], we are still interested in studying the growth aspects and effect of molar concentration of para nitro phe- nol of NPNa single crystals in different type of solutions prepared with different molar concentrations of para nitro phenol in sodium hydroxide base. In the present study, single crystals have been grown from three different solutions prepared by changing the molar concentration of para nitro phenol with fixed amount of sodium hydroxide using slow evaporation method. The structural, thermal and optical prop- erties have been studied by suitable methods and detailed report has been presented in this paper. 2. Experimental 2.1. Growth of single crystals As purchased para nitro phenol (98% pure) and sodium hydrox- ide (Merk Product) were used as starting materials to prepare the solutions to grow the single crystals of NPNa. Para nitro phenol and sodium hydroxide have been added in 0.25:1, 0.5:1 and 1:1 in excess of double distilled deionized water to prepare different solutions and stirred well. After the solutions became homoge- neous (i.e., after continuous stirring for at least 2 h), the solutions were filtered to avoid the inclusion of impurities during the stirring and maintained at room temperature by using a constant tempera- ture bath controlled to an accuracy of ±0.01 ◦ C. The excess solvent http://dx.doi.org/10.1016/j.ijleo.2014.06.083 0030-4026/© 2014 Elsevier GmbH. All rights reserved.