Appl Phys A (2009) 97: 205–210 DOI 10.1007/s00339-009-5165-7 Ferroelectric and phase transition studies in cesium nitrate: poly(vinyl alcohol) composite films Arvind Nautiyal · K.C. Sekhar · N.P. Pathak · R. Nath Received: 2 December 2008 / Accepted: 25 February 2009 / Published online: 14 March 2009 © Springer-Verlag 2009 Abstract The composite films of cesium nitrate (CsNO 3 ) and poly(vinyl alcohol) (PVA) with varying composition were prepared using the solvent cast method. The hys- teresis loop characteristics show optimum remnant polar- ization (P r ) of 2.75 μC/cm 2 at 50 wt.% composition. The field emission scanning electron microscope images show a nearly homogeneous distribution of CsNO 3 grains in the 50 wt.% composite film. The temperature dependence of the remnant polarization shows a diffused transition temper- ature range from the ferroelectric to the paraelectric phase and this has been attributed to the reduced enthalpy. The butterfly features of the dielectric constant–voltage (ε–V ) characteristics have been attributed to polarization switch- ing. PACS 77.80.Fm · 77.22.Ej A. Nautiyal ( ) · K.C. Sekhar · R. Nath Ferroelectric Materials and Devices Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India e-mail: nautyphysics@gmail.com K.C. Sekhar e-mail: sekardph@iitr.ernet.in R. Nath e-mail: rnathfph@iitr.ernet.in N.P. Pathak Radio Frequency Integrated Circuits Research Laboratory, Department of Electronics & Computer Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India e-mail: nagppfec@iitr.ernet.in 1 Introduction Ferroelectric materials are being widely studied due to their potential use in device applications such as FeRAM and mi- crowave tunable components [1, 2]. The basic requirement for ferroelectric memory devices is that the remnant polar- ization should be high and the dielectric constant should be low, since the high dielectric constant makes it hard for the sense amplifier to discriminate between +P r and −P r . In this respect, conventional ferroelectric materials such as PZT have high P r and high dielectric constant. Therefore, the ceramics belonging to the XNO 3 (X = Na, K, Cs etc.) family may be suitable for these applications due to their high P r and low dielectric constant values. KNO 3 is the most studied material of the XNO 3 family in thin film form for memory applications [3–7]. We have chosen the less studied CsNO 3 out of the XNO 3 family of materials to in- vestigate its ferroelectric properties. Cesium nitrate (CsNO 3 ) is a ferroelectric material of the class of perovskite type. Neutron diffraction studies have shown that CsNO 3 possesses a trigonal symmetry with space group P 3 1 or P 3 2 at room temperature [8]. CsNO 3 has been found to exhibit a structural phase transition from the high temperature cubic phase to the low temperature trigonal phase near 154 ◦ C in the Brillouin scattering ex- periment [9]. The thermal expansion coefficient, the dielec- tric constant and the conductivity of CsNO 3 show an anom- alous behavior around the transition temperature [10, 11]. Recently, the ferroelectricity has been reported in CsNO 3 single crystal by direct observation of the P –E hysteresis loop characteristics [12]. However there are no detailed fer- roelectric studies in the film form of CsNO 3 . This mater- ial may provide many useful applications in the nonvolatile memory devices, when prepared in the film form by dispers- ing in a polymer matrix.