JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 11, No. 10, October 2009, p. 1549 - 1552 Structure and magnetic properties of multiferroic YCr 1-x Fe x O 3 (0≤x≤1) ♣ S. KOVACHEV * , D. KOVACHEVA a , S. ALEKSOVSKA b , E. SVAB c , K. KREZHOV Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria. a Institute of General and Inorganic Chemistry, Bulgarian Academy of Science, "Acad. Georgi Bonchev" str. bld. 11, 1113 Sofia, Bulgaria. b Institute of Chemistry, Faculty of Natural Sciences and Mathematics, University "Sts. Cyril and Methodius", 1000 Skopje, Republic of Macedonia. c Research Institute for Solid State Physics and Optics, H-1525 Budapest, POB 49, Hungary. Samples from the mixed oxide system YCr1-xFexO3 (0≤x≤1) were prepared by self-propagation combustion techniques and studied by neutron and X-ray diffraction at 290 K and by magnetic measurements in the range 2–800 K. The average observed metal-oxygen distances based on refinements in the space group Pnma are in agreement with the expected distances from the valence bond approach. The non-collinear spin arrangement (mode Γ4) of YFeO3 and YCrO3 is preserved for the rest (x ≥0.33) of the compounds magnetic at 290 K. The findings indicate that YCrO3 and YFeO3 form a solid solution with strongly frustrated magnetic interactions. (Received November 5, 2008; accepted December 15, 2008) Keywords: Multiferroics, ferroelectricity, diffraction, perovskite, solid solution ♣ Paper presented at the International School on Condensed Matter Physics, Varna, Bulgaria, September 2008 1. Introduction In multiferroic materials the magnetic and ferroelectric orderings coexist and are coupled [1]. Beside important implications for novel electronic devices [2], the physics behind the expected complex magnetoelectric phenomena is of great current interest [3]. Few multiferroic compounds with effective magnetoelectric properties are known (e.g. BiFeO 3 , BiMnO 3 , YMnO 3 ), since proper ferroelectricity and magnetism are usually antithetic [1,3]. Much of the current interest is in the so- called improper multiferroics (with magnetically induced ferroelectricity) such as RMnO 3 , RMn 2 O 5 (R= rare earth) and other perovskite-like materials with frustrated magnetic interactions and non-collinear spin ordering [3,4]. In this paper, the subjects of investigation are mixed oxides Y-Fe-Cr-O (0≤x≤1) whose end members YFeO 3 and YCrO 3 display intriguing magnetic and electric properties (ferroelectric data for YCrO 3 are given in [3]). Previous research work drew attention to the great complexity of the magnetic properties in the system [5-7]. We found the structural information for the system very limited and undertook a systematic structural and magnetic characterization of phases in the system. 2. Sample preparation Materials with the general formula YCr 1-x Fe x O 3 (x = 1.0, 0.875, 0.75, 0.67, 0.5, 0.33, 0.25, 0.125, 0.0) were obtained as polycrystalline powders by implementing a modified self-propagation combustion method [8]. The reaction products were characterized by X-Ray diffraction (XRD) for phase identification and to assess phase purity. YCrO 3 was synthesized by slow evaporation and self- ignition of a stoichiometric reaction mixture of Y(NO 3 ) 3 .5H 2 O, Cr(NO 3 ) 3 .9H 2 O and an organic component (sucrose – C 12 H 22 O 11 ). The other members of the series were prepared by the same method, where a stoichiometric amount of Fe(NO 3 ) 3 .9H 2 O was added. In contrast to YCrO 3 , the synthesis of YCr 1-x Fe x O 3 (0<x<1) material proceeded without intermediate forming of YCrO 4 . 3. Experimental