Stability and microwave dielectric characteristics of (Ca1−x Sr x )LaAlO4 ceramics

Abstract

The stability of K 2 NiF 4 structure in MRAlO 4 (M= Sr and Ca; R==La, Nd, Sm, and Y) ceramics was discussed via calculating the relative difference between the tolerance factors for ABCO 4 and ABO 3 structure, and the K 2 NiF 4 structure became unstable when the above difference was greater than 4.3%. Among the above ceramics, CaLaAlO 4 and SrYAlO 4 were not stable. To improve the stability of K 2 NiF 4 structure in CaLaAlO 4 , the effects of Sr substitution for Ca were investigated. The stability of K 2 NiF 4 structure in (Ca 1−x Sr x )LaAlO 4 ceramics increased with increasing x, and it became stable when x >0.9. Good microwave dielectric properties were achieved in (Ca 0.05 Sr 0.95 )LaAlO 4 ceramics: e=16.7, Q.f =28,171 GHz, t f =−52.4 ppm/°C.

Structural, magnetic and dielectric properties of La2−xCaxNiO4+δ (x=0, 0.1, 0.2, 0.3)

“…In addition, in the process of searching for new types of giant dielectric constant materials [4][5][6][7][8][9][10][11], modified K 2 NiF 4 structured materials also play an important role and exhibit excellent dielectric properties, for instance substituted CaLaAlO 4 , CaNdAlO 4 , SrNdCoO 4 [12][13][14]. La 2 NiO 4+ı is another member of K 2 NiF 4 family and therefore it is meaningful to study the dielectric properties of modified La 2 NiO 4+ı system.…”

Ruddlesden-Popper phase A2BO4 oxides: Recent studies on structure, electrical, dielectric, and optical properties

“…This is because, for these two oxides the difference between tolerance factor " " of layered perovskite and its perovskite unit (i.e., LaAlO in CaLaAlO , and YAlO in SrYAlO ) is greater than 4.3%. Stability of CaLaAlO has been improved by substituting Sr at Ca, in Ca Sr LaAlO stability is reported for composition with > 0.9 [135]. In the crystal structure of MLnBO , large distortion in (M, Ln)O polyhedra and BO octahedra are observed in the crystal structure.…”

Mg/Ti co‐substituted CaSmAlO4‐based microwave dielectric ceramics with temperature stability in a wide temperature range

“…ABCO 4 ‐type MRAlO 4 (M = Sr, Ca; R = La, Nd, Sm, and Y) based on the tetragonal K 2 NiF 4 structure possesses excellent microwave dielectric properties 9,10 . Therefore, it is of positive significance to explore the MRAlO 4 (M = Ca, Sr; R = La, Nd, Sm, and Y) system to obtain microwave dielectric ceramic materials with excellent dielectric properties and temperature stability over a wide temperature range 11–13 . Fan et al.…”