Structural-chemical mechanism of formation of solid solutions in the La2SrAl2O2-Ho2SrAl2O7 system

Abstract

The processes of phase formation in the La 2 O 3 -Ho 2 O 3 -SrO-Al 2 O 3 system are investigated in the temperature range 1200-1500°C. The structural characteristics of the compounds described in the studied system are presented. It is established that the formation of (La 1 -x Ho x ) 2 SrAl 2 O 7 solid solutions proceeds through the formation of LaAlO 3 , LaSrAlO 4 , SrAl 2 O 4 , and SrHo 2 O 4 compounds. An increase in the holmium content and the temperature leads to a crossover from the mechanism in which the interaction of LaAlO 3 and LaSrAlO 4 is a limiting stage to the mechanism in which the decisive role is played by the interactions of SrAl 2 O 4 with

A new ~1 μm laser crystal Nd:Gd2SrAl2O7: growth, thermal, spectral and lasing properties

“…The aluminate crystals are well-known since a long time as a type of excellent laser gain hosts due to their good thermomechanical properties. In recent years, a number of layered perovskite-like aluminate compounds with the general formula Ln 2 SrAl 2 O 7 (Ln = rare-earth elements) have aroused great research interest owing to their unique structural properties, and many of them have been synthesized and investigated [12][13][14][15][16]. These compounds crystallize in the Sr 3 Ti 2 O 7 structural type (space group I4/mmm, No.139) and have a block structure that is formed by perovskite (P) and rock salt (RS) interpenetrating in the sequence P2/RS [17,18].…”

“…These compounds crystallize in the Sr 3 Ti 2 O 7 structural type (space group I4/mmm, No.139) and have a block structure that is formed by perovskite (P) and rock salt (RS) interpenetrating in the sequence P2/RS [17,18]. In the structure of Ln 2 SrAl 2 O 7 (Ln = La-Ho), Ln 3+ and Sr 2+ cations occupy two structural positions: the twelve-coordinated site in the P layer and the nine-coordinated site in the RS layer [13]. Among these compounds, Gd 2 SrAl 2 O 7 (GSAO) is par ticularly interesting.…”

Formation of the complex oxide NaNdTiO4

“…For the perovskite-like oxides, which relate to the Ruddlesden-Popper phases, the most comprehensively studied are the processes of formation of layered aluminates of rare-earth and alkaline-earth elements in which all elements reside in a stable oxidation state [15][16][17][18]. The mechanism of formation of a layered structure of manganites and ferrites [19][20][21][22], for which it is necessary not only to ensure the specified crystal-chemical characteristics (such as the structural type and the distribution of cations over different structural positions) but also to provide the stability of the valence state of the manganese and iron atoms, has proved to be more complex.…”

Thermodynamics of formation of lanthanide hydroxo complexes in aqueous solutions

“…Among the studies of the synthesis, thermodynamics, and kinetics of formation in lanthanide based systems (see, e.g., [2]), those dealing with lanthanide complexes, specifically hydroxo complexes, hold a noticeable place [1]. The thermodynamics of formation of hydroxo cations in aqueous solutions is important for understanding the mechanisms of hydrometallurgical processes and for predicting their optimal parameters.…”