Defect Structure Versus Superconductivity in MeB2 Compounds (Me = Refractory Metals) and One-Dimensional Superconductors

Phonon Dispersions as Indicators of Dynamic Symmetry Reduction in Superconductors

“…element doping or substitution) and do not display anomalies in their phonon dispersions. Such modification to the structure type, for example, adding boron to form NbB 2.5 [49], or substituting other elements, such as in Zr 1-x V x B 2 [50][51][52] or Zr 1-x Nb x B 2 [53] leads to superconductivity; as also suggested by Pickett et al [54] based on DFT calculations of AlB 2 -type structures. These minor modifications to the stoichiometry of an MB 2 structure are excellent examples of "fine-tuning" that achieves a dramatic change in material property.…”

Discovery of superconductivity in AlB2-type hexagonal YGa2

“…For examples, ZrB 2 was reported by Gasprov et al [12] to have a superconducting transition of 5.5 K, whereas Leyrovska and Leyrovski [13] reported no such transition. Similarly in the case of TaB 2 , where Gasprov et al and others [12][13][14][15] have not observed superconductivity, whereas Kaczorowski et al [16] reported a transition temperature of 9.5 K. Alike, the data on NbB 2 are even more contrastive [17], since many researchers [13,[18][19][20][21][22] found different values of critical temperature between 0.62 and 9.2 K. These literature data stimulate us to search for new superconductors crystallizing in the hexagonal AlB 2 -type structure.…”

Estrutura cristalina e propriedades físicas do condutor anômalo KxMoO2-δ

“…Para maiores detalhes veja a referência (NEUMEIER;. ; et al, 1999), que é definido como: 2) onde N é o número de observações e P o número de parâmetros utilizados no refinamento.…”