Pressure‐induced phase transition in Co‐doped ZnO

Mori, Yojiro; Niiya, N.; Mizuno, Takafumi; Nishii, Takaya; Fujii, Atsuhiro; Fujii, Yoshiko; Takarabe, Kenichi; Wang, Y.; Jiang, J.Z.

doi:10.1002/pssb.200672549

Cited by 14 publications

(11 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to previous works on Zn 1– x Co x O thin films and microcrystalline powders, the W- to RS-phase transition in bulk materials and thin films occurs at lower pressures for larger Co content. It decreases from 9 GPa in pure ZnO to 6 GPa in Zn 0.7 Co 0.3 O.…”

Section: Structural and Compositional Characterization: Electron Micr...supporting

confidence: 87%

“…18,33−36 High-pressure techniques are well suited to investigate the electronic structure of semiconductor materials 37 already been used to study the electronic structure of Zn 1−x Co x O NPs, 38 thin films, 35,39−41 and single crystals. 4,42 High pressure was also crucial to elucidate electronic structure effects related to quantum confinement in quantum dots. 43 The present work investigates the effect of pressure on the structure and electronic properties of Zn 1−x Co x O NPs.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Structural Metastability and Quantum Confinement in Zn_1–xCo_xO Nanoparticles

et al. 2016

View full text Add to dashboard Cite

This paper investigates the electronic structure of wurtzite (W) and rock-salt (RS) Zn1-xCoxO nanoparticles (NPs) by means of optical measurements under pressure (up to 25 GPa), X-ray absorption, and transmission electron microscopy. W-NPs were chemically synthesized at ambient conditions and RS-NPs were obtained by pressure-induced transformation of W-NPs. In contrast to the abrupt phase transition in W-Zn1-xCoxO as thin film or single crystal, occurring sharply at about 9 GPa, spectroscopic signatures of tetrahedral Co(2+) are observed in NPs from ambient pressure to about 17 GPa. Above this pressure, several changes in the absorption spectrum reveal a gradual and irreversible W-to-RS phase transition: (i) the fundamental band-to-band edge shifts to higher photon energies; (ii) the charge-transfer absorption band virtually disappears (or overlaps the fundamental edge); and (iii) the intensity of the crystal-field absorption peaks of Co(2+) around 2 eV decreases by an order of magnitude and shifts to 2.5 eV. After incomplete phase transition pressure cycles, the absorption edge of nontransformed W-NPs at ambient pressure exhibits a blue shift of 0.22 eV. This extra shift is interpreted in terms of quantum confinement effects. The observed gradual phase transition and metastability are related to the NP size distribution: the larger the NP, the lower the W-to-RS transition pressure.

show abstract

Section: Structural and Compositional Characterization: Electron Micr...supporting

confidence: 87%

mentioning

confidence: 99%

Structural Metastability and Quantum Confinement in Zn_1–xCo_xO Nanoparticles

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Recently, it has been shown that the pressure of the wurtzite-to-rock-salt transformation decreases for Co-and Mn-doped ZnO as compared to pure ZnO [7][8][9]. The high pressure -high temperature (HPHT) synthesis of ZnO-rich rs solid solutions Mn 0.25 Zn 0.75 O and Co 0.27 Zn 0.73 O in the form of thin films has been reported [8,9], however, in the case of bulk samples the situation may be different.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of rock-salt MeO–ZnO solid solutions (Me=Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺) at high pressure and high temperature

Баранов

Соколов

Kurakevych

et al. 2008

High Pressure Research

View full text Add to dashboard Cite

Series of metastableMe 1-x Zn x O solid solutions (Me = Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ ) with the rocksalt (rs) crystal structure have been synthesized from the binary oxides by quenching from 7.7 GPa and 1450-1650 K. Phase composition of the samples, as well as structural properties and stoichiometry of synthesized solid solutions have been studied by X-ray powder diffraction, both conventional and with synchrotron radiation. The widest (0.3 ≤ x ≤ 0.8) composition range of the existence of individual rock-salt solid solution has been established for the NiO-ZnO system. The bulk rs-Co 1-x Zn x O, rs-Fe 1-x Zn x O and rs-Mn 1-x Zn x O solid solutions may be quenched down to ambient conditions only with twice lower ZnO content, i.e. x ≤ 0.5, 0.5 and 0.4, respectively; while formation of rock-salt solid solutions in the CdO-ZnO system has not been observed in the whole concentration range.

show abstract

“…This effect should be especially pronounced in diamond-like direct-bandgap semiconductors of n-А 3 В 5 and n-А 2 В 4 С 5 2 families, which is caused by, alongside with a χ(Р) dependence, a noticeable m n (P) dependence. As has been mentioned above, a sharp decrease of the resistivity by some orders of magnitude is observed, which testifies to the presence of the phase transition from diamond to NaCltype structure at P > 9 GPa [5,6]. According to formulas derived in the framework of the 'heterophase structureeffective medium' model [12], the relative volume fractions of the phases in the vicinity of the critical region of the polymorphous transformation (Fig.…”

mentioning

confidence: 68%