Hydrothermal Synthesis and Luminescent Properties of Uniform CaSnO[sub 3]:Eu[sup 3+] Microcrystals with Controlled Morphology

Abstract

CaSnO 3 :Eu 3+ microcrystals with controlled morphology were prepared by a hydrothermal method followed by further calcining treatment without any template or capping reagents. Reactant concentration and reaction time showed strong effects on the phase formation and morphology of the products. The prepared samples were systematically characterized by powder X-ray diffraction, field-emission scanning electron microscopy, photoluminescence ͑PL͒, and photoluminescent excitation spectra. The possible formation mechanism was proposed. Furthermore, PL characterization of CaSnO 3 :Eu 3+ microcrystals was performed and discussed in detail.Nanometer-sized inorganic low dimensional systems exhibit a wide range of optical and electric properties 1 that greatly depend on the crystal shapes due to the association between surface atomic arrangement and material stabilities. 2 Nowadays, research interests have been expanded into controlling the shape of materials and understanding the correlations between the materials properties and their microstructure and morphology. 3-5 However, attempts to prepare inorganic materials with uniform shape and size in large quantities still remain a challenge. 6-11 Considerable strategies have been developed for the growth of inorganic materials with different morphologies, such as flowerlike, 12 star-shaped, 13 and doughnutlike morphology products from inorganic precursors. 14 A further investigation on the parameters that controlled crystal growth was necessary to extend the obtainable inorganic materials with uniform shapes and sizes.Recently, considerable interest in the optical and electrical properties of doped nanoparticles has emerged. Alternative classes of these materials that exhibit unique optical properties are those based on oxide-doped rare-earth ions. 15,16 The perovskite-type alkalineearth stannates ͑MSnO 3 , M = Ca, Sr, and Ba͒ have been extensively studied during the past century, especially on their very interesting application for display phosphor matrix, ceramic materials, thermally stable capacitors in electronic industries, and gas sensor host. 17-19 SnO 4 2− anions are reported to be optically inert and could be a candidate as a host material. 20 At present, many efforts have been devoted to the synthesis of CaSnO 3 microcrystals with various shapes by different methods. 21,22 CaSnO 3 microcubes can be prepared by a hydrothermal method with the assistance of polyvinylpyrrolidone surfactant. 21 Eight-horn or cubic CaSnO 3 microcrystals can be obtained by a precipitation method by the addition of a desired amount of NaOH or HCl solution to the Na 2 SnO 3 aqueous solution. 22 However, little attention has been paid to the luminescence properties of alkaline-earth stannate phosphors. 23-27 Most of the preparation processes employ high calcination temperatures ͑800-1600°C 28 ͒ or the products usually consist of particles with irregular shapes and wide size distributions. The methods mentioned in the literature required high temperature, special conditions, or tedious proced...

The Electronic Structure of Lanthanide Impurities in TiO2, ZnO, SnO2, and Related Compounds

“…The same values will be adopted for SrSnO 3 and BaSnO 3 . From the luminescence excitation and absorption maxima of undoped and rare earth doped CaSnO 3 63-66 we obtain E ex = 4.9 eV at 10 K. The Eu 3+ excitation band is clearest observed in the work by Fu et al 67,68 giving on average E CT is 4.26 eV. The resulting band diagram in Fig.…”

Thermal properties of the orthorhombic CaSnO3 perovskite under pressure from ab initio quasi-harmonic calculations

“…Calcium stannate, CaSnO 3 , is known as an effective phosphorous host [9][10][11][12][13][14][15][16][17][18][19][20], for its potential as constituent of multifunctional optoelectronic devices [21], and for its unconventional luminescent behavior [22][23][24]. At ambient conditions, CaSnO 3 exhibits a orthorhombic GdFeO 3 -type perovskite structure belonging to the P bnm space group, which is expected to be stable up to pressures of about 40 GPa and temperatures of about 2000 K [25].…”

In silico infrared and Raman spectroscopy under pressure: The case of CaSnO3 perovskite

“…[8][9][10][11][12][13][14][15][16] At ambient conditions, calcium stannate is a GdFeO 3type perovskite with an orthorhombic lattice characterized by the Pbnm space group and a structure which can be rationalized in terms of a framework of corner-sharing SnO 6 octahedra (see Figure 1). With respect to the ideal cubic structure, Pm3m, of many ABO 3 perovskites, SnO 6 octahedra are slightly tilted and distorted.…”