Synthesis and in situ high pressure Raman spectroscopy study of AlN dendritic crystal

•The sample is the typical dendritic crystal structure.•The phase transition of AlN dendritic crystal is researched.•The Raman signal of rock salt AlN is observed under high pressure.•Grüneisen parameters and phase transition criterion are discussed. AlN dendritic crystal was synthesized by the dire...

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Published inMaterials research bulletin Vol. 48; no. 9; pp. 3310 - 3314
Main Authors Li, Xuefei, Kong, Lingnan, Shen, Longhai, Yang, Jinghai, Gao, Ming, Hu, Tingjing, Wu, Xingtong, Li, Ming
Format Journal Article
LanguageEnglish
Published United States Elsevier Ltd 01.09.2013
Subjects
A. Nitrides
ALUMINIUM NITRIDES
C. High pressure
C. Raman spectroscopy
CRYSTAL STRUCTURE
D. Phase transition
DENDRITES
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
PHASE TRANSFORMATIONS
PRESSURE COEFFICIENT
RAMAN EFFECT
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SALT DEPOSITS
SCANNING ELECTRON MICROSCOPY
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
A. Nitrides
C. Raman spectroscopy
C. High pressure
D. Phase transition
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Summary:•The sample is the typical dendritic crystal structure.•The phase transition of AlN dendritic crystal is researched.•The Raman signal of rock salt AlN is observed under high pressure.•Grüneisen parameters and phase transition criterion are discussed. AlN dendritic crystal was synthesized by the direct current arc discharge apparatus. X-ray diffraction (XRD) patterns indicated that the sample is hexagonal AlN and preferentially grown along the a-axis direction. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images reveal that the product mainly consists of micron AlN dendritic crystal. In situ high pressure Raman spectra of AlN dendritic crystal has been measured in the pressure ranged from ambient pressure to 32.97GPa at room temperature by using diamond anvil cell. According to the Raman scattering results, the phase transition from the wurtzite to rock salt was found at about 20.73GPa by the appearance of a new Raman signal. Above 20.73GPa, a new Raman signal due to disorder-activated Raman scattering in the rock salt phase was observed. In addition, the pressure coefficients, phase transition criterion, and mode Grüneisen parameters of AlN dendritic crystal, which could be different from that of other AlN, are carefully discussed.
ISSN:0025-5408
1873-4227
DOI:10.1016/j.materresbull.2013.05.002