Compressibility of the nitridosilicate SrYb[Si₄N₇] and the oxonitridoaluminosilicates MYb[Si_4−x Al _x O _x N_7−x] (x = 2; M = Sr, Ba)

Single-crystal structure ofHoBaCo4O7at ambient conditions, at low temperature, and at high pressure

“…Moreover, it is known that the tetrahedral network dominates the compressibility in siliconitrides, aluminiumsiliconoxonitrides, and siliconcarbidenitrides. 14,15,44 Therefore, we will focus our discussion on the corner-sharing tetrahedral network ͓starshaped building blocks, X ͓4͔ ͑RW 3 ͓2͔ ͒ 4 ; ͑X , W͒ =N,C,O and R =Si,Al,Co͔. A comparison of R − X ͓4͔ and R − W ͓2͔ bond lengths is shown in Fig.…”

“…We have already performed high-pressure x-ray diffraction experiments on siliconitrides, aluminiumsiliconoxonitrides, and siliconcarbidenitrides, where no fourfoldcoordinated oxygen ions ͑O ͓4͔ ͒ have been observed. 14,15 These compounds are very stable with respect to pressure, and no structural phase transition has been observed up to 42 GPa. Nothing is known about the influence of pressure on MBaCo 4 O 7 structures, but the apparent thermal instability suggests that these compounds may undergo structural phase transitions at elevated pressures.…”

Virtual crystal approximation study of nitridosilicates and oxonitridoaluminosilicates

“…However, this calculation resulted in the same structure as our P6 3 mc calculation. Therefore, the VCA calculations give no evidence for a pressure-induced structural phase transformation due to elastic instabilities in BaYb SiAlON, and the unusual stability at high pressures reported experimentally by Juarez-Arellano et al [8] is confirmed. The dependence of the theoretical cell parameters as a function of pressure is plotted in figure 6.…”

“…A c c e p t e d m a n u s c r i p t 8 In order to make complex trends visible which are not directly apparent from a p-V plot, the data were transformed into normalized pressure, F, and Eulerian strain, f [24]. Figure 5.…”

“…Recently, we have investigated the BaYb Si 2 Al 2 O 2 N 5 system by in situ high-pressure powder X-ray diffraction at pressures of up to 37 GPa using the diamond-anvil cell technique [8]. However, due to inherent restrictions related to in situ high-pressure powder X-ray diffraction, it was not possible to determine the compression mechanism.…”