Cryst. Res. Technol. 39, No. 10, 859 – 863 (2004) / DOI 10.1002/crat.200410266 © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Growth and evaluation of lanthanoids orthoniobates single crystals processed by a miniature pedestal growth technique E. S. Octaviano 1 , D. Reyes Ardila* 2 , L. H. C. Andrade 3 , M. Siu Li 3 , and J. P. Andreeta 3 1 Universidade Camilo Castelo Branco, Campus 8, Av. Hilário de Silva Passos 950, Descalvado, SP, 13690- 000, Brazil 2 Departmento de Física, Universidad de Santiago de Chile, Santiago, 7254758, Chile 3 Instituto de Física de São Carlos, Departamento de Física e Ciência dos Materiais, Universidade de São Paulo, Av. Trabalhador SãoCarlense 400, São Carlos, SP, 13560-970, Brazil Received 5 January 2004, revised 13 February 2004, accepted 2 May 2004 Published online 1 September 2004 Key words laser processing, absorption, doping. PACS 81.10.Fq, 82.20.Ej, 77.84.Dy Optimized conditions for the growth of lanthanoids orthoniobates (LnNbO 4 , Ln = lanthanide elements) single crystal minirods by a floating zone technique were investigated. Adequate atmospheres and pulling to feeding speed ratios to grow these materials were determined. Emphasis is given to the study of LaNbO 4 because of their more favorable growth conditions and crystalline quality. This material can be efficiently doped with rare earth elements such as erbium. It grows with high crystallinity and its preferential growth direction is [1 1 0]. A preliminary evaluation of optical properties of Er 3+ -doped LaNbO 4 single crystal under the Judd- Ofelt formalism indicates spectral parameters Ω t close and even larger than for Er 3+ ions in YVO 4 . © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction LnNbO 4 compounds (Ln = La, Ce, Pr, Nd, Sm, Eu, Dy, Ho and Er) are peculiar minerals that crystallize in the fergusonite structure [1, 2, 3, 4]. They exhibit remarkable paramagnetic properties (NdNbO 4 , GdNbO 4 and HoNbO 4 , mainly) and a characteristic ferroelasticity (pseudoelasticity or rubber-like behavior) attributed to domain walls formed during phase transitions [1, 5, 6, 7, 8]. Compounds containing La, Gd and Lu, show efficient intrinsic deep-blue emission. LuNbO 4 exhibits blue luminescence (maximum emission at 405 nm) under ultraviolet excitation (at 260 nm) [9] comparable to that of YNbO 4 at the same experimental conditions. Recently, attention to LaNbO 4 was renewed because of its large negative compressibility in at least one direction. This property makes LaNbO 4 attractive for potential applications in high pressure environments as those found in optical line systems installed in oceans [10]. Although all these applications are known, the research and study of LnNbO 4 compounds have been scarce due to the large difficulty found to grow them as single crystals through traditional techniques that demand a crucible due to their aggressive melts reactivity and high melting points. For instance, NdNbO 4 , GdNbO 4 and HoNbO 4 bulk crystal growth by Czochralski method [5] at temperature above 2300 °C was reported at the beginning of the last decade, while the first growths of LaNbO 4 and NdNbO 4 crystals by the same method and similar conditions were reported about three decades ago [6]. Other LnNbO 4 crystals investigated in past years were prepared by flux growth methods [11, 12, 13, 14]. The scarce research on the growth of these materials by a containerless method motivated us to investigate the feasibility and convenience of a floating zone technique against already used growth methods. ____________________ * Corresponding author: e-mail: dreyes@usach.cl