Energy-dispersive x-ray diffraction and Raman scattering of Zn1−xMnxSe bulk crystals at high pressure

Abstract

Energy-dispersive x-ray diffraction experiments were carried out to investigate the structure of phase transitions under high pressure. It was found that the zinc blende (B3) to rock salt (B1) phase transition pressures of Zn0.93Mn0.07Se and Zn0.76Mn0.24Se bulk crystals are found 11.8±1.5 and 9.9±0.5 GPa, respectively. The respective bulk moduli are 61.8±0.8 and 60.5±0.8 GPa. The pressure-induced zinc blende (ZB) to rock salt (RS) structure phase transition is interpreted as a signature of the semiconductor to metal transition for Zn1−xMnxSe. The above interpretation is further corroborated by the observation of the disappearance of the longitudinal optical phonon at the pressure where the ZB to RS structure transition occurs.

Structural stability and Raman scattering of ZnSe nanoribbons under high pressure

“…3. At the lower pressure like 0.1 GPa, the LO and TO phonon modes are observed at about 251 and 205 cm −1 , respectively, which are in agreement with related reports [19,25]. With increasing pressure up to about 5.5 GPa, the TO phonon mode splits into two peaks.…”

High-pressure structural and optical properties of wurtzite-type Zn1−Mg Se

“…Generally, it may be concluded that wurtzite-type Zn 0.53 Mg 0.47 Se is stable at pressures studied in this work. This observation is in agreement with expectations based on the known behaviour of Zn 1−x Mg x Se [18] as well as ZnSe alloyed with iron and manganese [19,20]. The transition point is ∼8.5 GPa according to the extrapolated data (phase transition points determined from a change of optical properties) from Ref.…”

“…Our sample was of wurtzite-type, but a similar bonding type justifies performing such extrapolation. For related Zn 0.84 Fe 0.16 Se and Zn 0.76 Mn 0.24 Se compounds the transition points are comparable: the tetrahedral structure remains stable up to about 10 GPa [19,20], i.e. in about twice as wide pressure range than that applied in the present study.…”

“…2. The bulk-modulus value, 48 GPa, is found to be considerably lower than that for ZnSe (about 60 GPa [20][21][22]), but it is equal to the theoretical one for zincblende-type MgSe, 48 GPa [23]. The result obtained shows that the influence of magnesium substitution on B is different than the earlier reported effect of manganese: a slight increase of B value with increasing Mn content has been reported for ZnSe with partial Mn substitution at cationic sites [17,20].…”

“…The bulk-modulus value, 48 GPa, is found to be considerably lower than that for ZnSe (about 60 GPa [20][21][22]), but it is equal to the theoretical one for zincblende-type MgSe, 48 GPa [23]. The result obtained shows that the influence of magnesium substitution on B is different than the earlier reported effect of manganese: a slight increase of B value with increasing Mn content has been reported for ZnSe with partial Mn substitution at cationic sites [17,20]. The low value of bulk modulus for Zn 1−x Mg x Se as compared to ∼60 GPa for ZnSe and still higher values for Zn 1−x Mn x Se (61-67 GPa [17,24]) is attributed to higher ionicity of tetrahedral MgSe (resulting in weaker bonding for the mixed Zn 1−x Mg x Se crystal).…”