Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions

Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−Co Sb2/3O6

“…In double perovskites La 2 Ni 4/3 À x Co 1/3 Sb 2/3 O 6 there could be two magnetic phases: one corresponding to Ni 2 þ ions and other to Co 2 þ . However the step like behavior is observed even for x ¼4/3, as it was previously reported [19] and not observed for x ¼0. So, in this scenario both, softer and harder magnetic phases, must be intrinsically related to the Co 2 þ ion.…”

“…The replacement of Ni 2 þ for a larger ion, Co 2 þ , implies a higher difference between the mean radius of M 2 þ and Sb 5 þ radius, and thus a higher degree of order. According to this tendency, the double perovskite La 2 Co 4/3 Sb 2/3 O 6 (x¼4/3) is totally ordered [19]. Regarding the distribution of Ni 2 þ and Co 2 þ , due to the same charge and similar radii, no special distribution of them among 2d and 2c sites is found.…”

“…6(a), where a clear decrease is observed as the cobalt doping is increased. T C (x¼ 0) ¼98(2) K and T C ðx ¼ 4=3Þ % 55 K were extracted from [17,18] and [19] respectively.…”

“…Also the synthesis, structure and magnetic properties of the double perovskite La 2 Co 4/3 Sb 2/3 O 6 were reported [19]. Here we present the crystal structure of La 2 Ni 4/3 Sb 2/3 O 6 , which was not detailed before, and also the synthesis and crystal structure of three solid solutions between the perovskite with only Ni 2 þ or Co 2 þ : La 2 Ni 4/3 À x Co x Sb 2/3 O 6 , where x¼1/3, 2/3 and 1.…”

CARACTERIZAÇÃO VIBRACIONAL E ELÉTRICA DE PEROVSKITAS Ca3Mn2B’’O6 (COM B’’ = Nb, Ta E W)

“…Outra estequiometria de bastante interesse é a do tipo A3B'2B"O9 que pode assumir a forma anterior através da fórmula geral A2B'1,33B"0,66O6. Podemos citar, como exemplo a La3Co2SbO9, que possui propriedades ferromagnéticas para temperaturas abaixo de 55 K (FRANCO et al, 2012) e Sr3Fe2TeO9, que apresenta magnetoeletricidade (INANOV et al, 2007). Dada a importância das perovskitas, contudo do manganês, propomos neste trabalho caracterizar vibracionalmente e eletricamente as perovskitas duplas B" , (com B" = Nb E W).…”