First‐Principles Studies on the Structural Transition of ZnO Nanowires at High Pressure

Abstract

The structural transition of ZnO nanowires at high pressures from wurtzite to rocksalt structure has been studied by first-principles density functional calculations using the SIESTA code. The size effect was studied by calculating a series of nanowires with different diameters, and the doping effect was studied by ion substitution. It is found that the critical pressure of structural transition for nanowires is lower than that of the bulk, and it decreases as the diameter of the nanowire decreases. It is also found that Mn doping can reduce the transition pressure. The size effect and doping effect are discussed in terms of the chemical bonding and energies of the nanowires.

Heat Capacities of Nanostructured Wurtzite and Rock Salt ZnO: Challenges of ZnO Nano-Phase Diagram

“…The variation of the calculated values by a factor of two does not allow making any reliable evaluation of thermodynamic stabilities of bulk phases at low temperatures. At the same time, the ab initio simulations of structural transition in ZnO nanowires at high pressures (calculations using the SIESTA code) indicated that passage from bulk crystal to nanograins reduces ΔHf (0 K) from 23 kJ mol -1 down to 10 kJ mol -1 [18]. This result is consistent with the data in Ref.…”

Structural, diffused reflectance and photoluminescence study of cerium doped ZnO nanoparticles synthesized through simple sol–gel method

“…Due to its large binding energy (60meV), wide band gap (3.37eV) [7][8][9][10] and easy synthesis and assembly methods, the utilization of ZnO has covered various fields such as electric transistors [11], photovoltaic devices [12][13][14] and chemical and biological sensors [15][16][17][18]. Nowadays, the nanostructured ZnO materials such as ZnO nanowires [19][20][21][22][23], nanoparticles [24], and nanotetrapods [25] have attracted wide attention since their large surface area and enhanced quantum confinement lead to novel electrical and optical properties for device application. There are various methods available to synthesize ZnO nanostructures from either physical or chemical method.…”

Microstructural Study of ZnO Nanostructures by Rietveld Analysis

“…Nowadays, the interest in nanostructured ZnO materials has taken more relevance due to its wide range of applications and the scientific interest in polymorphism depending on synthesis conditions. Zinc oxide is a II-VI semiconductor with a band gap of 3.37 eV; it is thermally and chemically stable [1] and presents interesting properties [2][3][4]. These properties make the ZnO feasible for applications in many field, such as energy conversion [5][6][7], optoelectronics [8][9][10] and sensing devices [11][12][13][14], in particular when it is synthesized in one-dimensional (1D) geometry [15][16][17].…”

“…These properties make the ZnO feasible for applications in many field, such as energy conversion [5][6][7], optoelectronics [8][9][10] and sensing devices [11][12][13][14], in particular when it is synthesized in one-dimensional (1D) geometry [15][16][17]. Among all the geometries, the most feasible for these types of applications are nanowires [1,[18][19][20], nanobelts [21,22], nanotubes and nanorods, and singles or arrays of them [23,24]. Several methods for the synthesis of nanostructured ZnO have been explored, but some of them are highly power demanding (in temperature or pressure) [25], or they use sophisticated processes to obtain the materials by means of a vapor-liquid-solid mechanisms [26][27][28], that makes the scaling-up a complicated challenge [29].…”