Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pressure-induced phase transition and bandgap collapse in the
  wide-bandgap semiconductor InTaO4   A pressure-induced phase transition, associated with an increase of the
coordination number of In and Ta, is detected beyond 13 GPa in InTaO4 by
combining synchrotron x-ray diffraction and Raman measurements in a diamond
anvil cell with ab-initio calculations. High-pressure optical-absorption
measurements were also carried out. The high-pressure phase has a monoclinic
structure which shares the same space group with the low-pressure phase (P2/c).
The structure of the high-pressure phase can be considered as a slight
distortion of an orthorhombic structure described by space group Pcna. The
phase transition occurs together with a unit-cell volume collapse and an
electronic bandgap collapse observed by experiments and calculations.
Additionally, a band crossing is found to occur in the low-pressure phase near
7 GPa. The pressure dependence of all the Raman-active modes is reported for
both phases as well as the pressure dependence of unit-cell parameters and the
equations of state. Calculations also provide information on IR-active phonons
and bond distances. These findings provide insights into the effects of
pressure on the physical properties of InTaO4.

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The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess